The History of My Car & Engine

STAGE 2 – Racing The Boys At Uni

I then got serious.  I thought if I am going to mod this engine, and make any decent gains, I want to be able to measure it, so I bought a G-Tech accelerometer to measure 1/4 mile times and trap speeds.  A 19 second quarter mile was a great time to improve upon.  It didn’t really matter about the launch, it wouldn’t wheel spin much but I couldn’t improve the time by launching harder.  It would just chirp then bog down.  Severe lack of power.

Off came the head, cant really remember why exactly, I was playing with dirt bikes at the time and had been shaving their heads, so it was probably just to give it a shave to increase the compression ratio.  I had not long before bought a die grinder, so I thought I’d do a bit of porting at the same time.  I cleaned up the ports, removing casting marks, just trying  to make everything bigger.  It was a TD head, so had the same size ports and valves as the “big valve” TX heads.  I don’t think they changed at all until the TE models that introduced the EGR valve and extra pollution control gear.  These TE model heads also had the smaller inlet valves, and bigger combustion chambers for a lower compression ratio.

The manifolds were off so I gave them a port match, taking the ports out to the size of the gaskets on both manifolds and the head.  That was with both the stock inlet manifold and the factory cast iron exhaust manifold.  Probably wasting my time there.  I suppose every little bit helps.

Not long after, I bought a second hand muffler off a mate, and got a new exhaust fitted.  It was 2.25″ press bent, and I fitted some Genie 4-2-1 extractors at the same time.  6500-7000 rpm was a common occurrence, and it sounded loud enough to be fast.  It was putting out a little bit more power,  but I think that the muffler was a pretty bad unit, it was noisy and restrictive.  It was 2.25″ pipe though, so for a 1600cc engine, it probably wasn’t too bad overall.

The car was great for burnouts, the single spinner diff meant I kept having to replace the right rear tyre.  I found fresh retreads make great tyre smoke, and burnout competitions were a weekly event at uni, especially in the uni car park on Friday nights.  And while the other boys were breaking diffs, I don’t think mine had enough power to break anything, so it just kept going and going.

So the mods so far, slightly more compression, mild port job, port matched stock inlet manifold, 4-2-1 extractors and 2.25″ exhaust.  This engine combo was doing mid 17’s on the drag strip with my G-Tech.  A good improvement over the 19sec quarters the stock car was doing.

STAGE 3 – High Compression, Lumpy Cam, Weber Fed Screamer

The power wasn’t really there though, not anywhere near what I wanted.  So I bought a new crow camshaft, 284deg advertised duration.  This didn’t make much difference at the time, it was lumpy at idle, and seemed to have a bit more in the mid range, but it didn’t make much power at higher rpm.  There was an airflow bottleneck somewhere, likely the stock carby being a restriction.

The car was getting a little bit quicker, but very minor improvements.  It’s always hard to tell with the “seatofthepantsometer”.  I thought more compression is probably the answer, so off came the head again.  I noticed there were some small marks on the top of the standard 1600 flat top pistons from where the valves had been just hitting.  Would have been a combination of the higher lift cam, shaving the head, and valve bounce at over 6000rpm.

I got the head shaved down to the valve seats which was about another 2mm off, and ended up with 40cc combustion chambers, giving  9.6:1 static compression with the stock 1600 pistons.  It now had a decent compression ratio as a base, and a big increase over the 8.7:1 stock ratio.  I also did a lot more porting of the head, and un-shrouded the valve seats in the combustion chambers.  I simply imagined how the air was flowing through the port, and tried to smooth or remove any restrictions the air might face.  This took about 20-30 hours.  I didn’t have access to a flow bench at that time, but later testing has shown the head flows really well, it’s head #1 on the ‘stage 12‘ page.

At the same time, out came the engine for new rings and bearings.  With the head shaved as far as it was, and fitted with the big cam, the valves were definitely going to hit the pistons, so I had to machine some valve reliefs in them.  I did this myself by positioning each piston at TDC, and with a spare head fitted to the block, I would spin a special valve in an electric drill, the valve was modified to cut into the piston, which grinded a valve relief into the top of the piston in the exact location needed.  You can just make out the valve reliefs in the photo below.

I then got a 32/36 DGAV Weber and adaptor plate, hoping for a bit more flow and hp.  The DGAV has the hot water “aqua” choke, but I had to remove that as it was hitting the brake master cylinder.  I ported the plenum area of the inlet manifold as per this manifold page.   The engine was lumpy, sounded tough, and loved to rev.  It had more power right throughout the rev range, and was better at higher rpm too, where the stock Nikki carby had been choking it previously.  Again, no dyno data on this exact engine, but it definitely made a good improvement.

My little tacho often saw 7500rpm.  I never got it tuned properly though, which is why it would have been a bit down on power compared to what it could have made.  It was way too rich, and I couldn’t seem to find a sweet spot with the ignition timing.  I could wind in around 50deg of static ignition timing, but couldn’t hear the engine detonate because everything was so loud, so I couldn’t tell the point at which detonation started to occur so just set it to where I thought is should be.  If I had of put it on a dyno, I probably could have got an extra 20% power with the right air/fuel ratios and optimal timing.

At this stage, I was running low 16’s 1/4 mile time at 140km/h.  This was with old hard rear tyres, and a bit of wheel spin.  Slicks and softer rear suspension probably would have got the car into the 15’s easily.  I am guessing going by other engines we’ve tuned that it had about 90-95 hp at the flywheel.

I fitted a 38mm DGMS Weber which is a bigger carby (twin 38mm butterflies) and actually felt quicker, but I couldn’t get any better than low 16’s 1/4 mile times.  Again, the jetting was too rich for the engine and I never measured a/f ratios or had it dynoed.  It probably made an extra 5hp with this carby, but thinking back now there was potential for so much more.  The 38DGMS would have made an even bigger difference on an engine flowing more air than mine, like a G200 for eg.

STAGE 4 – Low compression G200

I had wanted to turbo the engine for a long long time, but thought the cost of buying a turbocharger alone was too expensive, let along all the other bits like fuel pump, exhaust manifold, all the fabrication and welding, etc.  However by the time I finished buying all the bits separately, and cost and time spent, I can see why so many people are keen on the idea of bolt on turbo kits, as it saves a lot of time and hassle.  I spent much more (especially in time/labour) trying to do it on the cheap than I would have if I’d been able to buy an off the shelf turbo kit.

I did a lot of research and read lots of books and magazines on the subject, and basically taught myself everything I needed to know.

I bought a G200 from a Rodeo and rebuilt it with dished pistons.  These were off the shelf flat tops and I had a dish machined into them.  These pistons coupled with a TG pollution head (used because of lower compression than original head) gave me a static compression ratio of about 8:1.  I had the whole assembly (clutch to balancer) balanced, and had the block o-ringed.  I spent another 30 odd hours porting the new cylinder head too, following the theory I used on my last high compression head.  I bought a set of Crow Cams heavy duty valve springs to make sure I didn’t get any valve float at higher rpm.  The old ones would have been pretty worn out by now from all the high revving.

The pollution heads from TE onwards have smaller inlet valves, so I had my TG valve seats machined to accept the larger valves from my TD head.  I got the flywheel lightened, I cant remember exact weights, but I had a few kg’s removed.  I also bought a RPM heavy duty clutch kit, this used a standard full face clutch plate, with a heavy duty pressure plate.

Before I had the turbo set-up organised, I put the engine together using the extractors, 32/36 Weber and lumpy Crow cam from my previous 1600 engine.  I had to retard the cam timing a fair bit so that the valves wouldn’t hit the pistons as these ones didn’t have valve reliefs (the dished tops alone weren’t enough, not because of the depth, but because of the location of the dish).

At the local drag strip with my G-Tech, I could get 17 seconds flat over the quarter mile consistently.  So the reduction in compression and retarded camshaft timing pretty much cancelled out the increase in capacity to 2 litres.  I was also using the TG pollution head which flows a bit less that the TD high compression head, as the ports are smaller and more restrictive.

STAGE 5 – G200 Draw Through Turbo

I finally got the turbo set-up fitted.  Before bolting it to the engine, I set it all up on a spare head that I had in the workshop, to make sure everything would fit.  I got hold of a piazza exhaust manifold and a stock VL Commodore T3 Turbo .  I got a flange laser cut to suit the turbo exhaust housing and had it welded to the piazza manifold.  I then ported the manifold and head to get a smooth transition from the square Gemini head exhaust ports to the round manifold ports.  I made a 3″ dump pipe that had a conical section which blended back into my 2.25″ exhaust.  I also put a stock cam back in as a lumpy cam designed for an NA engine is not ideal for a turbo engine.

The turbo needed an oil supply, so used one of the spare oil gallery ports for this, and had to fit a large barbed fitting to the sump for the oil return.  I also teed into both heater hoses for the turbo water cooling bearing housing.

I had bought a 45mm side draught Weber, and planned a draw through set-up.  I got a few aluminium plates laser cut so I could use an aluminium cross over pipe and bolt it to the stock inlet manifold using the Nikki mounting studs.  I also got a plate laser cut to suit the Weber mounting flange and fabricated a ‘y’ piece to mount the Weber on the front of the turbo.  I put the battery in the boot, because the Weber and air cleaner now used that space.  I bought a HZ accelerator cable which was plenty long enough.

The cross over pipe was longer to go from the turbo to the inlet manifold, but I cut it short one day to use the pipe for my blow through set-up.  I thought I could always rejoin it later if I had to, but you get the idea of what it all looked like.

I remember the very first time I drove it out of the yard and felt the Gem engine boost up for the first time, only a few psi then I backed off, the sound was awesome, and compared to what I was used to, so was the push in the back.  I couldn’t go back now, and you couldn’t wipe the smile off my face.  I’d built my first turbo engine.

I also couldn’t go past about half throttle, as the engine would die, just like it had no fuel.  I was sure the fuel bowl in the Weber was getting fuel, had to be a jetting issue I think.  It was jetted to be half of a twin Weber set-up of a Datsun L20 engine from memory, so it was jetted to only deliver fuel for 1 litre of engine displacement (twin Webers fed a 2 litre engine).

I also had another problem, every time I let the engine idle, or whilst cruising along and then boosting it, it would blow plumes of white smoke out the exhaust pipe.  The VL turbo is designed for blowing into an EFI throttle body, so it is never supposed to see any vacuum before the compressor.  With my draw through setup, the Weber was obviously before the turbo compressor, and the vacuum at idle and part load was sucking oil past the compressor oil seals and it was being fed into the engine under heavy load.

Because of the carby issue, I couldn’t really get it to boost at full throttle, so couldn’t have that much fun with it.  Was great at half throttle though.  One thing I didn’t really know at that stage was how much timing I was actually running total, let alone how much I should be running.  I was also only guessing at my air/fuel ratios.  That motor didn’t last long.

And because of the smoke issue, I knew I had to move the throttle body to after the turbo.  This meant either a Gas Research throttle body and straight LPG, an EFI set-up, or a blow through carby set-up.  I didn’t like gas that much (it’s good for BBQ’s) and figured the carby was the cheapest option, and I already had the 32/36 Weber, and I thought I could do it myself, so I read some more books….

STAGE 6 – G200 Blow Through Turbo

So after rebuild #2 of the G200 (a couple of pistons had cracked at the ring lands from detonation), I fabricated an air box for the top of my 32/36 Weber I was using before the turbo setup, and used the aluminium cross over pipe from my draw through setup to feed it air from the turbo.

With the Weber draw through combo, the whole engine bay looked very alien, it didn’t really look like the Gemmy set-up that I was used to, which was a Weber and extractors.  After I put the 32/36 Weber back on, this thing now looked like my old engine combo, except the extractors were replaced with the turbo, and I had an aluminium air box on the carby with a pipe connecting the two.  I bought a finer filter pod to put on the front of the turbo, and fitted an Accel super coil to make sure I get a good spark under boost.

The fuel system was the first problem, I knew that I had to upgrade the fuel system so that fuel pressure was above boost pressure, or else the boost forces the fuel out of the fuel bowl, back down the lines and into the tank.

I hadn’t bought a fuel pump or regulator yet, but I couldn’t wait for any of that, I had to go for a spin.  I took it around the block, it drove 100% like a naturally aspirated gem off boost, but as soon as I loaded it up, boost started to rise, and at about 5 psi, it would cut out, like it was out of fuel.  I knew it would happen, just wanted to see for myself.  I had modified the stock in-tank electric pump to deliver about 6psi of fuel pressure, but as soon as I hit about 5psi of boost or higher, the engine would cut out.

I bought an EFI fuel pump and regulator off a Nissan N13 pulsar, and modified the regulator to deliver 7psi of fuel pressure, instead of 35ish psi.  Any more than about 7psi of fuel pressure and the Weber would flood.  I put the EFI pump in series with the stock in-tank electric pump, and used both the stock return line and the steel pollution line to return fuel to the tank.   It took a while to get the fuel pressure right, I also used a ball valve in one of the return lines to fine tune it, because if you restrict the return line, your fuel pressure will rise, and vice versa.  I had to use both steel lines as return lines to the tank because the base fuel pressure was too high with just the single stock return line as it didn’t flow enough by itself.

Everything was sweet now, I could go flat out at full boost (7psi), now that was great fun.  Trying to launch hard with the 1600 and my old hard tyres used to be a problem, now it was a lot harder.  And burnout comps were still a plenty.

I played around with the carby jetting with the theory of needing a richer fuel mix for a turbo engine, but I couldn’t really measure what I was doing, I didn’t have an a/f gauge at the time.  So I was guessing at air/fuel ratios, and I still didn’t know what my timing should be set at, from memory, I was running about 10deg static, giving about 34 degrees total timing.  So instead of getting these checked during a dyno run, I put my time and efforts into building a wastegate bleed system to increase the boost from the stock 7psi figure to about 11psi.  That motor didn’t last too long after that.

STAGE 7 – G200 Blow Through Turbo – Locked Dizzy

So after rebuild #3 of the G200, (more cracked pistons), and having built 2 G160’s before that, I was getting pretty quick at engine rebuilds.

I got some good advice about the ignition timing, and decided the easiest way to control it was to lock the distributor.  I pulled the dizzy apart, removed the springs and weights, and MIG welded the mechanical advance solid.

I set it at 18degrees static timing, any more timing advance and the starter motor had trouble cranking over the engine, especially when hot.  I knew the engine would make more power with more ignition advance like around 25deg, which would have been safe at my boost levels, but modifying the mechanical advance mechanism was not part of my vocabulary yet.

I thought I would try out the 38DGMS Weber that I has used previously on the 1600, I know it would flow more and should make more power.  I did a G-Tech run at the drag strip and recorded a best of 14.6 sec at 160km/h on 11psi of boost.  The problem was traction with my tyres.  I know that if I could get traction by using a set of slicks, I might have cracked a 13 second quarter.  Keep in mind, a stock Gem will do a 19sec quarter, so I was making some good progress.

I found fuel economy with the 38DGMS to be pretty bad, as the carby is synchronous (both butterflies open at the same time, just like a 2 barrel Holley) and I had it jetted pretty rich.  I decided a progressive carb like my 32/36 would be better suited, as I could keep the primary jetting fairly stock for good off-boost economy and richen up the secondary circuit to provide a rich air/fuel mixture under boost.

I fitted an narrow band oxy sensor to the turbo dump pipe, and built a Dick Smith mixture meter to check the mixtures throughout the rev range.  A narrow band oxy sensor is not the best thing for checking an air/fuel ratio in the 12:1 region, but it can give an very basic indication.  Especially if you lean out, it will show you are getting close to the stoic value of 14.7, which is bad under boost!

So I increased the boost a bit more because it’s so much fun, and boost is like an addictive drug, and for whatever reason, probably low octane fuel or compressor outlet temps being too high, I got detonation and blew the motor again.  To be more specific, I broke the pistons at the ring lands.

Remember I hadn’t been to a dyno yet, hadn’t had mixtures checked, and wasn’t intercooling.  So I might have been a bit lean under full boost, and the compressor outlet temps would have been getting pretty hot.  A combination that will cause detonation.

I was becoming a regular at the local machine shop where I bought my pistons.  As I did all the work myself except fit the pistons to the rods, each time I blew a motor, I was only up for pistons, rings, and gaskets.  I didn’t always need to fit new bearings, and sometimes I didn’t have to buy a set of pistons, as I could make a set of 4 good pistons from the remains of the last few engines.  So each build would only cost me a few hundred $$ for gaskets, rings, oil, etc.

STAGE 8 – G200 Blow Through Turbo – Dyno Tuning & Water/Methanol Injection

So after rebuild # 4, I was a bit wiser, I stopped pinching pennies, and went to a dyno workshop.  I was also getting sick of replacing broken pistons.  If I had spent the money in the first place, I would have saved all those broken engines, and would have had more cash in my bank account.

We played around a bit on the dyno, wound up the boost a bit and measured inlet temps at the carby air box.  I can recommend that anyone tuning their own engine should at least get a power run done on the dyno to get air/fuel mixtures checked, and maybe a quick play with the ignition timing, as you could be way out with your guestimations, and plus you also get to know how much power you are really making.

So dyno run # 1:

• I had a freshly built G200, balanced, o-ringed, etc. 
• 32/36 Weber fitted on my ported inlet manifold, same jetting as earlier. 
• Stock cam in the ported TG pollution head.
•  Standard VL T3 turbo on piazza exhaust manifold, 3″ dump pipe into 2.25″ exhaust with restrictive muffler.
•  My notes say the dizzy was locked at 15deg now, I must have been scared that 18deg might be causing me detonation problems.  
•  Boost was set at 7psi.

It made 90hp @ wheels.  This is less than I was hoping for at the time, but it all makes sense now.  The air/fuel ratios were too rich at 11.5:1, the inlet temps at only 7psi were pretty hot at 90deg C, and it didn’t want to rev out properly, we thought at the time that it was due to the spark plug gap being at 40thou, probably a bit much.  I cant remember if we adjusted this before continuing, we did a few more runs though.

Dyno run # 2:

Boost increase from 7psi to 12psi.

It made 105hp @ wheels.  Inlet temps rose to 120deg C, this was considered too high so we thought we would try spraying some water/methanol mix into the turbo inlet.

We rigged up a jet from the carby spare parts box, and used the windscreen washer bottle.  Mixed up a 50/50 mix of water and methanol, and manually varied flow by kinking the hose.  Agricultural, but it was only for testing purposes.

Dyno run # 3:

Boost increase from 12psi to 13psi. 

50/50 water/methanol injection.

It made 120 hp @ wheels and the inlet temps had dropped to about 90deg C again, which is the temp I had at 7psi of boost.  This was a great power improvement, however the engine seemed a bit “boggy” due to too much water/methanol flow.  We didn’t have a proper jet to inject it, it wasn’t a mist at all, and limiting flow by kinking the water line didn’t work very well, as the pump supply pressure wasn’t very high.  So to get a decent spray into the compressor inlet meant the amount of water/methanol was too much for this boost level.

Dyno run # 4:

Boost increase from 13psi to 16psi.

It made 130 hp @ wheels and the inlet temps were around 100deg C.  The water/methanol injection was working well, Still had the hose kinked.  Air/fuel mix was still too rich, and the air box on the carby was starting to leak at the rubber gaskets.  I hadn’t cut the gasket out very well between the carby and airbox, and you could see the water/methanol coming out from the gasket under boost.

Dyno run # 5:

Boost increase from 16psi to 18psi.

It made 140 hp @ wheels and the inlet temps were starting to climb too high again, around 120deg C.  We couldn’t hold the engine under load for long for fear of detonation at these temps.  This was showing the turbo was starting to become pretty inefficient at these boost and air flow levels.  The water/methanol injection was working well, I think we didn’t kink the hose anymore at this boost level.  Air/fuel mix was still too rich, and the air box on the carby was leaking all over the place.

I came away from there pretty happy, knowing that I had built a decent motor, assembled everything myself, put together the turbo set-up myself, and now it was making some decent numbers.  These were about the same power levels as a stock Holden 253ci V8.  The car felt pretty quick too.

This also shows how we increased power from 90hp@wheels to 140hp@wheels and didn’t touch the carby jetting, and it gave nearly the same a/f ratios.  So once you get a carbys jetting right, varying amounts of air flow (power levels) don’t always demand re-jetting.

I went home and made a few more changes.  I made new gaskets for the air box to try and eliminate any leakage.  I made a decent jet for the water/ methanol injection and installed a VDO boost pressure switch to turn it on at about 12psi, not too early, or else it tended to bog down the engine.  If I switched it on at lower boost, you could tell when it switched on as power would drop off.

It was flowing the right amount for 18psi of boost, but too much for lower boost levels.  I normally drove around on about 15psi though.  I actually bought a higher pressure pump to replace the stock washer bottle pump hoping to get more of a mist than a stream from the jet, but it didn’t make a noticeable difference.

Back to the drag strip, 17psi of boost, dizzy locked at 17deg, absolutely no traction, kept spinning the wheels through 1st and 2nd gear.  I had the same old crappy hard tyres on the back.  They were 225’s, and fat looking things, but they were simply too hard and I couldn’t take off very quick.  I had to slip the clutch a lot so as not to break into too much wheel spin.

The best time I could get was a 14.7 second pass @ 170km/h.  The trap speed was up, and I knew other cars doing that trap speed (~106mph) were doing 12 second passes.  But they had the right suspension and slicks, I didn’t have either.  Some decent rear tyres would have made a big difference though.

So wheel spin city.  I did go through a diff and 5 speed at this stage, the high horsepower must have got to them.  Probably too many attempted drag starts, as that puts an immense strain on the drive train.

STAGE 9 – G200 Blow Through Turbo – Intercooled & Modified Points Distributor

I had always known about the benefits of an intercooler, and I finally got around to fitting one.  I had put it off till now purely because of the plumbing issue, and having to cut out holes in the radiator support panel.

I bought an RX7 series 5 cooler from Dalton Automotive and modified it to become a front mount unit.  Check this intercooler installation link.  I modified the carby air box so that the inlet was at the front, and I made a cone section to try and give the air a better transition from the round plumbing into the square box.  The old side inlet was simply blocked off.

I remember the first chance I got to drive it after fitting the intercooler, I set the boost back to 7psi and went around the block.  It made as much power on 7psi intercooled, as it used to at about 12psi non-intercooled.  This had to be due to the reduction in inlet temps.  It made a really good difference.  Also as my fuel mixture was a little rich, and the colder denser air carries more oxygen for a given volume, this effectively leaned out my a/f ratios a little bit and I found more of a sweet spot which made even more power.

Its often the case with some mods that you cant actually tell what difference they made.  However this was a really noticeable improvement, just like turning up the boost.

I also modified the distributor so that I had some mechanical advance again.  I know I wanted to run about 24deg total timing at 18psi of boost with my combo, but with the locked dizzy, the most I could run was 18deg, so this would give me a bit more power both on and off boost.  Check this link for modifying the ignition timing.

I had been trying to do a bit more fine tuning of the air/fuel ratios, mainly to get some fuel economy on the highway.  This was the benefit of using the 32/36, I had separate primary and secondary circuits in the carby to tune.  I could tune the primary for cruising economy, and the secondary for max power.

I managed to lean it out a bit whilst cruising, but was still a bit rich under full boost.  Carbys are hard to get perfect, and its always a bit of a compromise.  This is where EFI comes in handy.  So back to the dyno to check air/fuel ratios and the new power output with the intercooler.

Dyno run #1:

• I had a rebuilt G200, balanced, o-ringed, etc.
•  32/36 Weber fitted on my ported inlet manifold.
•  Stock cam in the ported TG pollution head.
•  Standard VL T3 turbo on piazza exhaust manifold, 3″ dump pipe into 2.25″ exhaust with restrictive muffler.
•  My dizzy was set to give 24deg total advance, with 15deg static timing. 
•   Boost was set at 18psi.

It made 150hp @ wheels.  This is less of an improvement as I was hoping for over the last dyno run, but there are a few possibilities for this.  It was a different day.  You have heard the expression “same shit, different day”?  Well with a dyno, its often “different day, different shit”!

Fitting the intercooler, although of huge benefit, also introduces flow restrictions into the system, with the air having to flow through around 1.5metres of extra pipe work and the intercooler core itself.

I never measured compressor outlet temps, but if they were low enough, I could have increased the boost even further.  Something I couldn’t have done without the intercooler.

I also feel that the 32/36 Weber was starting to approach its flow limit, and would probably struggle to support much more power than this.  I also had a poor flowing muffler which would have been a bottleneck.

This would be around 200hp at the flywheel though, not bad power results from this carby.  We didn’t check air inlet temps, but the air/fuel ratio was still too rich for optimum power.  It might have made another 5 or 10hp with mixture and timing tweaks.

I never made it back to the drag strip, but it was about then that I started getting into circuit racing.  I took the car to Winton Raceway for a day of tearing down the straights, and braking hard before the corners.

A few weeks before going to Winton, I had a bit of a drag (didn’t measure time), and wound it out to a bit over 200km/h, then I tried to stop!  I had 100% stock brakes at that stage, and when I went to brake, I got some pretty bad brake fade about half way through the stop, and my brakes would have been fairly cool before this.  A tee intersection was fast approaching, and I thought I was going to go straight through it.  I stopped with the nose of the car about half way into the lane of the intersecting road.  I heard circuit racing was pretty hard on brakes, so I went and got a set of Bendix Ultimate pads before driving to Winton.  I also fitted a new set of shocks, as car was getting a bit “bouncy” at speed.

I was actually surprised how well the Ultimate pads worked.  I could do about 3 hot laps before the brake pedal would go to the floor, but I was using the gears a lot to help slow down.  I knew that if my car only had half the power, I probably could have raced continually because there would have been a lot more time between corners, and my speed wouldn’t have been as high.

It was a good day, and a bad day all at the same time.  I got a speeding ticket on the way to the track.  Had an awesome time racing, I was overtaking a lot of the other cars, going as fast as I could, I had just got some new 16″ wheels and the handling improvement was great, better tyres too.  It was a hot day, over 30deg C on the track.  My engine was running a bit hot, I had just put a new 3 core radiator in and was running a 10″ thermo fan, but the temp gauge was still a bit high.  To counter the higher track temps and engine temp, I was only on about 15psi of boost.  Then I blew the motor before the day was finished.  It had been about a year since I blew my last motor, at that stage, a year was a long time for an engine and me to stick together.

It happened because carbys in general don’t like to experience high lateral g forces, such as when cornering hard.  The fuel sloshes around in the fuel bowl, and you can uncover a main fuel jet if cornering really hard.  Also, unless you have a surge tank, you need to make sure you have plenty of fuel in the tank so that the pump is always submerged.  A combination of these two things meant that often halfway through a long sweeping corner, the engine would hesitate and splutter, like it was short on fuel.

I felt this happen, but often just kept the accelerator applied as it was only for short periods that the engine would play up.  However this lack of fuel is a classic lean condition that promoted piston breaking detonation.  That’s exactly what happened.  I’d blown another motor and had broken pistons.

STAGE 10 – G200 EFI Turbo – Installation & Dyno Tuning

So after rebuild #5, I was getting sick of throwing money at fixing the engine and replacing pistons, I would rather be buying a bigger turbo, or fitting a bigger exhaust, stuff like that.  I had been sticking with cast pistons because I knew they were structurally strong enough to handle the cylinder pressures and loading of a properly tuned engine.  They are also much cheaper, at about $200 a set, compared to about $1200 for a set of forged pistons.

Detonation is what breaks pistons.  Detonation will break both cast and forged pistons, forgies will just be more resilient as they are stronger, but if the detonation is bad enough, they will break too.  Therefore, if you tune your engine right, with the right air/fuel ratios, and right ignition timing, if you keep inlet temps under control, and make sure you have high quality fuel in the tank, you should be okay with cast or stock pistons.

I really enjoyed circuit racing and decided the only way I could continue was to fit EFI, and that would give me a safe and reliable tune so that cast pistons could still be used.  I did a lot of research on this, and couldn’t find any instances of cast pistons failing simply due to high cylinder pressures, not at my relatively low power levels anyway.

I bought an EFI manifold from a late 90’s model Holden Rodeo and a Microtech MTX-8 computer which could run sequential fuel injection as well as direct fire ignition (one coil per cylinder).  I bought a distributor from a Mitsubishi TP Magna that has two hall effect sensors built in.  One senses each cylinder reaching TDC, and the other measures TDC of piston # 1 only.  You need both of these sensors to run direct fire ignition.  Its so the computer knows not only when to fire a coil, but which one to fire.  I got the magna dizzy housing machined a little bit, then had the dizzy shaft grafted to the Gemini dizzy shaft so it mounted up as per standard in the stock gemmy timing cover.

The manifold had to be modified a fair bit to fit, grinding clearances and cutting bits off here and there, but the stud pattern is the same as the Gemini head, so it slides over the gemmy inlet manifold studs.  The injectors were also pretty big, at 330cc each.  These turned out to be big enough to run 15psi of boost on my engine.  The inlet runners are pretty big, bigger than the carby manifold runners, and the throttle body is also a decent size, 60mm in diameter.

My Nissan Pulsar fuel pump was showing signs of giving up under the stress of running at the 47psi fuel rail pressure now with the Rodeo EFI manifold.  So I bought a new Bosch VL Turbo fuel pump.  Dont be fooled by what everyone tells you, the VL turbo and NA pumps are not the same pump.  The turbo one flows more fuel at the same fuel pressure.  The part number is 0 580 464 070, the turbo pump has threaded electrical connections with little nuts on them, whilst the NA pump has electrical spade terminals, just like the Pulsar pump I was originally running.  The NA pump is probably an 0 580 464 008 or similar, there are heaps of different Bosch external EFI pumps from factory cars that look similar.  A true VL turbo spec pump looks like this.

My clutch had been slipping a little bit with the last engine combo, particularly when trying to launch hard (burnouts maybe??), so I bought a 5 puck ceramic button clutch plate and used the existing RPM heavy duty pressure plate (the yellow bit).  This is a pretty good clutch combo for the money, the RPM kit was about $150, and the 5 puck clutch plate was about $140, Daikin brand I think.

I was also thinking of ways to keep engine temps a bit lower, so I fitted an RX7 oil cooler just under the radiator, with a sandwich plate between the oil pump outlet and the oil filter.  I needed to use a short oil filter now, and the EFI V8 Commodore filters are a perfect fit.  This has helped with temps, now they never get over 96deg C, unless there is a problem.  Typical temps for my engine whilst racing are 90-94 degrees.  You see see both the oil cooler and intercooler here.

It took a while to get the computer to fire up the engine, the fuel maps were way out, and the exhaust kept filling with fuel, then igniting, giving an almighty back fire.  At the time, I had no idea what sort of injector pulse widths I needed to start the car.  The maps in the computer were for a GSR Lancer and had really long injector pulse widths in the fuel maps, they must have smaller injectors than 330cc as my engine just kept flooding with the same pulse widths. I flattened a few batteries too.  Nearly cooked the starter motor.

Anyway, finally got it running, and did all the tuning myself on the road with my narrow band oxy sensor measuring a/f ratios.  I knew by trail and error that I could run 15psi of boost with the stock injectors, as if I would up the boost any higher, the air/fuel ratios would start to lean out.  I think they were reaching 100% duty cycle.  So I got a set of 500cc RX7 series 5 injectors, which almost were a straight swap for the 330cc Rodeo items.  No more fuel shortage!

The wheel spin problem became much worse.  I could crank in a lot more timing advance at low rpm, this coupled with the low rpm torque of the G200 meant that it was really responsive down low, and would wheel spin very easily with the single spinner open centered diff.  Whether it be in straight lines or through corners, the RHS rear wheel would loose grip very easily.  So I decided to chase down an LSD option.  It was really hard to find one, but I eventually did, and booked it in the following week to get it fitted at G & E Differentials in Keysborough on the outskirts of Melbourne.

I had a week to kill, and a mate had got the diff locked in his girlfriend’s Toyota Corolla, so I knew basically what to expect, but was keen to see how a locked diff would feel in the Gem, so I got a spare centre welded up the weekend before (CIG locker) and took it for a spin.  After leaving rubber all over the streets, and getting dizzy from going in circles, I decided that locked diffs are for crazy people, or for straight line racing only.  If you are partly turning a corner, and give it too much curry and break into wheel spin, the whole car will spin around pretty easily, and quite quickly.  Instant oversteer.

I got an early model Commodore 6 cylinder LSD centre fitted to my diff, this literally bolted in, same axles, etc, just fitted my crown gear from my original diff centre to this new one.  I got it reconditioned before install, and fitted with heavier springs so that it engages sooner and harder as wheel slip is detected.  They are a cone style LSD, and its a bit weak for my engine, often it still slips so that only one wheel spins, but for the money, there aren’t any better options.

I really need something larger for optimum traction.  From a strength point of view, I have only ever broken two diffs, and the spider gears went in both of them.  I have not had a trouble with this LSD diff, so its probably stronger overall.  It was from a 6 cylinder car.  The handling/traction improvement was great, I could take a corner at high speed and accelerate out of it, without massive oversteer like the locked diff.  The car was a lot slower through corners with the single spinner diff, and I couldn’t accelerate out of corners very fast, it was really hard not to wheel spin.  Now I can if I try, but not accidentally.

I Did a few races around the tracks at Calder Park and Phillip Island.  Hadn’t been on a dyno yet, so ran it pretty conservatively with rich mixtures and only 15psi of boost.  Once again, it was awesome.  Overtook pretty much every car in sight on the straights, then some of them would catch me through the corners.  I needed better tyres and suspension.

Now that the back was over steering a lot, I had to get used to it with the extra power of the EFI set-up.  I had one small mishap where I spun half way through a corner and ended up boot first into a concrete wall at Calder.  I put the power on too early coming off the second corner after the main straight, it boosted up and I ended up spinning and kissing the wall.  After it hit, the car flicked around and my front right wheel crunched the wall, bending the stub axle and breaking the disk rotor off the hub section.  It was a cold morning when I took the photos below, ice on everything.  I painted the damaged area to stop it rusting.  It didn’t matter that much, because the panels were replaced anyway.

This required a brand new rear quarter panel and rear beaver from Holden, and a new paint job, which was nice.  Needing to replace the damaged brakes on the front, it prompted me to look at brake upgrades and after this I put my option 2 brake kit on, which worked better than I could have hoped.

I had also fitted a bigger Selby swaybar on the front end, and splashed out and bought some Yokohama Advan A032R race rubber for each corner.  These are awesome tyres.  They are often referred to as a “grooved slick”, which I know is a contradiction, but they are a soft sticky grippy compound.  You can see the tread pattern in the pic below, the brakes fitted in the photo are my option 1 kit.

Tried to do a few G-Tech runs on the drag strip, but did it before I bought my race tyres or started mucking around with the diff, it was like trying to launch hard in the wet.  Wheel spin!  I couldn’t recorded any decent times, I actually had better times in the early turbo days, even though now I had much more hp.

EFI itself doesn’t make power.  EFI simply sends a signal to fuel injectors to provide enough fuel to get the desired air/fuel ratio.  A carby can do this too.  However, EFI has some other benefits.  Usually, to fit EFI, you use an EFI manifold like I did, which flows more air than the old carby inlet manifold and 32/36 Weber I was using.  This increase in air flow does make more power.  Therefore, if you had equal air flows, you could make the same power at a particular engine RPM with either EFI or a carby.

However EFI can also give you the correct air/fuel ratios over the entire operating range of the engine, which means better fuel economy, better throttle response and part throttle power, as well as reliable full power air/fuel ratios, under all conditions, such as taking corners hard, and probably even upside down.  The carby will struggle to give the desired air/fuel ratios over the same range of engine operating conditions (load and rpm).

I had some pretty rough intercooler piping, I wanted to do it right, but I also wanted to drive the car, so I took some shortcuts.  Nothing dangerous, it just didn’t look all that nice with heaps of rubber bends and hose clamps everywhere.

I took the car to the dyno to get the computer fine tuned and see how many ponies could be found at the wheels.  I knew it was more than before, it just felt better overall, more response, more power through the whole rev range.  The computer also controlled the new direct fire ignition system which included timing adjustments with respect to RPM, boost, air and water temp.  This in itself gives much better part throttle response and lets you accurately map your ignition timing.

So dyno run # 1:

• G200, rebuilt, balanced,  o-ringed, etc
• I had the Rodeo EFI manifold with 500cc RX7 injectors and 60mm TB.
•  Mazda RX7 series 5 intercooler with below average intercooler piping. 
• Stock cam in the ported TG pollution head. 
• Standard VL T3 turbo on piazza exhaust manifold, 3″ dump pipe into 2.25″ exhaust with restrictive muffler. 
• Microtech computer controlling fuel and ignition, direct fire (one coil per cylinder) ignition.  
•  Boost was set at 10.5 psi.

It made 125hp @ wheels.  (90kW @ wheels).  This boost was chosen to start fine tuning the computer with.  This was a bit more power than the carby set-up, but with similar air fuel ratios and ignition timing, I didn’t expect the EFI to make much more power.  I was hoping that the EFI manifold would be able to flow more air than the old carby and inlet manifold at higher power levels.  It made a bit more power now, but to properly check this, I needed to turn up the boost to where the carby set-up was causing a flow restriction.

Dyno run # 2:

Boost increase from 7psi to 19psi.

It made 197hp @ wheels.  (147kW @ wheels).  Not wanting to push it too far, I was pretty happy with this result, so we left it there.  We just did a bit more tuning with the fuel side of things to get some cruise economy and adjusted the accelerator pump settings to get crisp throttle response.

Once again, I cant recommend highly enough the importance of getting your car tuned properly, with the help of a dyno, or at least a wide band oxy sensor.  I was running too rich, and I knew I was rich, but I was loosing a lot of power because of it.  We leaned it out to about 11.8:1 to make this hp, so it would have made a bit more at around 12.5:1 probably, but temps would have increased and more chance of detonation.  It never felt as quick as it did after I left the dyno workshop, and part throttle and mid range power was up, it was much ‘crisper’ overall because it wasn’t getting bogged down with extra fuel from my overly rich tune.

The engine always pulled hard to about 5500rpm, then the power seemed to taper off sharply.  It would rev higher, but wouldn’t keep pulling.  I knew that the existing 2.25″ exhaust and super turbo muffler were probably the bottleneck now.  I also knew from previous inlet air temperature testing that the turbo is pretty much at the end of its efficiency at this boost level of 19psi.  Diminishing returns mean more boost will make a lot more heat, which is not good for a circuit racer.  So I had a few plans to take it a step further.

I fitted a Wade turbo cam, which was a surprising improvement.  I have fitted cams to engines before, and often its hard to really define where the extra power is.  A new cam billet was not available, and I was in a hurry, so I ordered the biggest cam I could get as a regrind.  This cam increased mid-range power a lot and the top end a little bit.  The Mid-range improvement was like night and day, a lot like running more boost, just like the power increase I got when I fitted the intercooler.  The top-end power gains were also noticeable, but not as dramatic.  Probably everything else is holding it back now, like exhaust, turbo and cylinder head.

I then fitted some new intercooler to throttle body plumbing and a blow off valve.  My old plumbing was a mis-match in internal diameters, with heaps of rubber hose joined sections.  This would have caused a fair bit of turbulence and restriction.  The new plumbing is all 2.5″ pipe with bends cut from a donut, which is like a continuous mandrel bend, but you just cut sections from the donut to make the angle of bend you need.

In an attempt to increase the efficiency of my intercooler, I painted the cooler black and added some air guides.  Black is the best colour for heat transfer, however I’m not sure if the coating of paint acts as insulation and this cancels out any benefits of the colour itself.

The air guides are to increase the pressure immediately in front of the core, forcing more air through and increasing the cooling effect.  You may notice that the guides are pointing inwards, opposite to a normal funnel.  This is intentional, as a higher pressure level is achievable this way.  I have not done any temp measurements to see what difference this has made, might be worth a couple of hp.

I then went down to Phillip Island for a day of circuit racing.  Phillip Island is one of the best race tracks you will ever see, its very fast, and you take some sweeping corners flat out in 5th gear at about 5-6000rpm.  Around 200km/h anyway.  Once again, I hadn’t been to the dyno for a while, and was only running about 15psi boost, with a conservative (rich) tune just to be safe.

One of my coolant lines for the turbo was rubbing on an engine mount, and sprung a leak.  I thought I could hear some detonation as some stages of the racing.  With the engine roaring, and your helmet on, its pretty hard to hear anything.  I started to lock up my front left wheel when braking, I since found that coolant was getting on the tyre, causing it to slip.

By the time I saw my water temperature was over 100degC, it was too late.  I had lost a heap of water, the excessive heat had caused some detonation, and I had broken some pistons.  I now have the Microtech running a temperature warning light, and I recommend every racer use one.  It would have saved my engine, but I was running a shift light at the time.  The Microtech version I have only has 1 programmable output.  Its either temp, boost, or revs, or a combination.

So I drove home all upset, (yes it still drives pretty good with a blown motor, just lots of blow-by).  This motor just doesn’t like my engine bay!  After a few months of sulking, I decided I needed a new exhaust system.

The old restrictive pipes had to go.  So I used the existing 3″ dump pipe and continued it back to up and over the diff.  I then branch off into a pair of 2.5″ tailpipes, and have a stainless muffler under each side of the boot floor.  When it was at the panel beaters getting the new rear quarter and beaver panel, I got the boot floor modified on the passenger side so it has a recess for a muffler, just like the drivers side.

The exhaust took a long time to build to make sure it cleared the diff under all conditions, and that the mufflers were equally spaced and looked right from the rear.  A lot of people warned me about the pipe clunking on the diff, particularly when a gem is lowered, but if you do it right and hug the floor as best as you can, you shouldn’t have any problems.  Its all mandrel bent, and it has several flanges so I can unbolt sections.  Should be good for a few more hp.  Just have to rebuild the engine.

With the new 3″ exhaust, bigger turbo grind cam, and new intercooler plumbing, I am hoping for 220-230 hp @ wheels at the same boost level of 19psi.  As soon as I build the new engine, I will report the dyno figures.  I am only guessing, but I would think this combo would do an 11 second quarter, especially with the LSD and my race tyres for grip.

I plan on one more stage of development, as discussed in the next section, but before I get there, I will assemble the engine how it was before it blew, with the bigger exhaust to see how it has improved on the dyno.  The only difference will be I have done a lot of development on my cylinder head, which I will have to fit.  This is all described in the next section, but I will come back and update this one.

Well……….. 2 years later………….2005

After building the G180 as described in Stage 12, but with the same induction and turbo combination as before, the only difference to this new engine compared with before is that I have fitted the heavily ported head and bigger inlet and exhaust valves.

Compared to the last dyno run when the car made 197hp @ wheels, this combo has the big turbo cam, the 3″ mandrel bent exhaust, better intercooler plumbing, and the much better flowing cylinder head.  I went to a different dyno this time, I used Dalton Automotive in Geelong.

Dyno run # 1: (2005)

• I had a freshly built G180 (see Stage 12)
• I had the Rodeo EFI manifold with 500cc RX7 injectors and 60mm TB. 
• Mazda RX7 series 5 intercooler with 2.5″ mandrel bent intercooler piping. Wade turbo grind cam in the heavily ported TG pollution head with bigger valves (see Stage 12). 
• Standard VL T3 turbo on piazza exhaust manifold, 3″ dump pipe into 3″ mandrel bent exhaust with twin 2.5″ tailpipes and mufflers. 
• Microtech computer controlling fuel and ignition, direct fire (one coil per cylinder) ignition.   

Boost was set at 18-19 psi.

It made 192hp @ wheels.  (143kW @ wheels).  

That’s right, after all those power making improvements, I actually went backwards in hp.  The first thing I should point out is that its a different dyno, and they said that the dyno I used previously had consistently given readings slightly higher than theirs, but not that much!

The theory put forward is that my piazza exhaust manifold is simply an airflow bottleneck, as they have seen very similar set-ups to mine make more power, but with a custom exhaust manifold.

I drove the car home, and decided that a manifold swap was needed to make sure it was the problem.  I had a few custom manifolds lying around, none of them were exactly what I wanted, but one was pretty good.  It was a sort of high mount made from steam pipe bends, and it had much better flow characteristics than the piazza manifold, and that was the main thing.  The photo below shows the new manifold and the turbo mounted up higher.

Unfortunately, almost as soon as I had it fitted up, I had a coolant leak in one of my cylinders, I suspect its the thin walls of the inlet ports in the heavily ported head, one has cracked allowing coolant to be drawn straight into the cylinder.  I did have a short drive before it happened and was amazed at the different turbo sounds I could hear with the new manifold.  I am still to remove the head to investigate further.

Well……….. another 2 years later………….Feb 2008

I had finally gotten round to pulling of the head to find 1 inlet port had a small crack which was letting coolant in.  Had the crack welded up and smoothed out the repair, and the head was re-fitted.

Back to the Dalton Automotive dyno in Geelong and started to spin the rollers.

I had a feeling it was about as quick as it used to be, but I had the boost back on 15psi just to be safe until I could get the mixtures checked again.  So with exactly the same engine combo as the previous dyno run, except for the different exhaust manifold.

Dyno run # 1: (16-02-2008)

• I had a freshly built G180 (see Stage 12)
• I had the Rodeo EFI manifold with 500cc RX7 injectors and 60mm TB. 
• Mazda RX7 series 5 intercooler with beautiful 2.5″ mandrel bent intercooler piping. 
• Wade turbo grind cam in the heavily ported TG pollution head with bigger valves (see Stage 12). 
• Standard VL T3 turbo on custom tubular exhaust manifold, 3″ dump pipe into 3″ mandrel bent exhaust with twin 2.5″ tailpipes and mufflers. 
• Microtech computer controlling fuel and ignition, direct fire (one coil per cylinder) ignition. 
•   Boost was set at 15 psi.

It made 187hp @ wheels.  (140kW @ wheels).  

Not bad, pretty much what it made last time, but it was only 15psi, so had to wind it up some more.  Also the mixtures were a bit lean.  So the Microtech handset was getting its buttons clicked and some more fuel added in.  The engine also wasn’t revved right out because was a bit lean.

Dyno run # 2: (16-02-2008)

• Same specs as dyno run #1 
• A/F ratios tweaked to richen the mixtures a bit

It made 198hp @ wheels.  (148kW @ wheels).

Picked up quite a few horses with a mixture tweak.  The extra air flow from the new exhaust manifold has effectively leaned out the mixtures, so had to add some more fuel under boost to get the a/f ratio back to around 12.5:1.

Dyno run # 3: (16-02-2008)

• Boost was set at 16 psi.

It made 205hp @ wheels.  (154kW @ wheels).

Now that’s more like it, and only a 1psi boost increase.  We wound it up a bit more because I wanted to run around 18-19psi, as that’s what I ran with the previous engine combo in stage 10.

We also checked if the air filter was being a restriction and pulled it off, only to find a piece of electrical tape across the pipe opening that leads to the compressor housing.  This was blocking airflow, and removing it along with the boost increase showed a good power gain.

Dyno run # 4: (16-02-2008)

• Boost was set at 18 psi. 
• No air filter

It made 217hp @ wheels.  (162kW @ wheels).

Boost was spiking at these air flow levels, it would hit 20 psi and then drop back to 18psi which is where peak power was made.  The turbine housing being the suspected culprit in limiting boost, with the turbine wheel simply not flowing enough air to spin the compressor any harder.  This was maximum boost, it didn’t matter how the bleed valve was adjusted.

The suggested fix… an external wastegate.  But I have my new bigger turbo to fit up, which has a bigger turbine wheel, so will see how that performs.

This power level also shows that having a piece of electrical tape covering up part of the inlet pipe going to the turbo compressor will restrict air flow.  What a surprise!

So we stuck the air filter back on just to see if the filter element itself is a restriction.

Dyno run # 5: (16-02-2008)

• Same as dyno run #4 
• Put air filter back on

It made 216hp @ wheels.  (161kW @ wheels).

Only a 1hp loss with the Finer Filter pod, not too bad at all.

So with roughly a 30hp@wheels gain since the last dyno session, and the only modification being the different exhaust manifold, its clear that this new one is a better design.  If you’re chasing about 200hp@wheels (150kw@wheels), then the piazza exhaust manifold will do the job, but if you’re after more power, you’ll have to lean towards a custom job.

You can see the difference in the two exhaust manifolds, the photo below shows my modified cast iron piazza manifold, which is pretty much a “log” design where the runners for ports 1 and 4 head-but each other at the collector, and there is no real directional flow into the turbo exhaust housing.

STAGE 12 – G180 EFI Turbo – Big Everything!

This will be the final stage of development for this engine (I think??).  If I wanted more power after this, then I may as well fit a bigger engine, such as a quad cam V6 or an alloy V8 and work that over.  This combo should produce enough power for 10 second quarter mile times, and will probably be too much power for the circuit racing I want to do, but I am sure it will be a fun ride!

I decided to bite the bullet and buy some forged pistons.  After shopping around for a while, I came across an engine package that seemed like a pretty good deal.  The new engine, a G180, came as a bare block with a bunch of parts in boxes.

Block

The block’s been bored to fit 87mm pistons (2 litre pistons).   So this engine is the same displacement as a stock G200 (G180 and G200 have the same stroke).  The block has been o-ringed to help seal against the head gasket under extreme cylinder pressures, internally de-burred and painted to improve oil flow back to the sump, the rods have been linished and shot peened to reduce high stress areas, and the crank has been cross drilled for extra oil flow to the bearings.  These last three mods will allow more reliable high rpm operation.  Here are the block, crank, pistons, etc, being assembled.

I have since assembled the engine with the modified head (see cylinder head section below) so I can verify the performance improvement from the mods detailed in Stage 11.  Once completed, all the components listed in this section will be bolted on.

Pistons:

As I said above, the block’s been bored to fit 2 litre size pistons.  The difference though is the pistons are forged SPS items.  Even though I know that a cast piston will handle the power, and both cast and forged pistons will die with detonation, but my time is more valuable to me today, and I don’t want to waste it rebuilding engines when a water line breaks, or something similar.  A forged piston is stronger and should survive most incidents except for extreme or continuous detonation.  I am also running Total Seal gapless rings to retain the high cylinder pressures.

These pistons have oil return holes instead of slots.  The slots in most factory pistons cause weak spots where the high stresses from detonation will cause cracking.  By simply having holes, the piston is a stronger unit.  Obviously, being a forged piston means the base material is stronger as well.  The pistons have a small dish with valve reliefs to suit my high lift cam.  You can see the linished and shot peened rod in the photo above also.  There is normally a seam from the casting process of the rods, which is removed to avoid any areas where stress concentration can occur.  This allows the rods to be used reliably at higher power levels.  I have never had a problem with the stock rods, but I have seen many engines where a rod has broken and punched a hole through the side of the block.  Not a pretty sight.  Also note the o-rings in the block in the photo below.

Cylinder Head:

I have done a lot of development with the cylinder head and manifolds on a flow bench (thanks to Andrew at Specialised Power Porting).  I had 3 different cylinder heads flowed;

1.  My old TD 1600 big port, big valve, high compression head.  This is the sought after head that most people refer to as the TX head, I have found them fitted on TX’s to TD’s from factory.  Fitted with 42mm inlet & 34mm exhaust valves.  I had spent a lot of time porting this head, blending the valve seats into the ports, un-shrouding the valve area in the combustion chambers, and basically trying to direct the air flow at the valve over the last bit of length of the port.  It has also been shaved down to the valve seats, giving 40cc chambers.

2.  My current turbo head (TG pollution head with low compression big chambers).  I got this head flowed to see where it was at, whether it was worth keeping and doing further work on, and where the improvements can be made.  Being a pollution head, its the one with the air pump ports at the top of the exhaust port outlets.  These heads have smaller ports with a sharper turn in the port bowl area than in head #1.  The smaller diameter port means air velocity will be a bit higher, so flows at lower valve lifts might be higher, but as flow increases, velocity increases, and so does the friction of the air on the port walls, which will limit the peak flow figures.

I wanted to stick with this head because I wanted to keep the compression low, however I was concerned that I simply wouldn’t get it to flow as much as head #1 due to the poorer inlet port design.  These heads are originally fitted with 40.4mm inlet valves, but I had the seats machined out to suit the 42mm inlet valves from my TD head.  The exhaust valves are the same.  I did the exact same porting as I did with head #1, probably spent more time overall on it trying to do a better job, as I was aware the ports are smaller than those in head #1.  I also removed a bit of material from the chamber to get the compression even lower.  The chambers are now 52cc.

3.  Stock G200 head.  This head has the same size valves and ports as a TE or later G161 head (from what I can tell).  I also got it flowed so I could get a baseline of where a stock head is, and what sort of improvements I have made when porting my other two heads.  I didn’t’ have a stock 1600 head to flow, but I think this one would be very similar.  Valve sizes are 40.4mm inlet, and 34mm exhaust.  Combustion chamber size is about 58cc.  So this head is basically the same design as head #2 above, but in stock standard condition, no porting, no bigger valves, and it doesn’t have the air pump inlets in the exhaust ports.  As its from a G200, they also have larger chambers to keep stock compression ratios under 9:1 with factory flat top pistons.

All testing was performed at 28″ of water.  Measurements were taken in 50thou valve lift increments.  Out of interest for some people, what I have recently read is that if the flow measurement is done correctly, it doesn’t matter what the level of vacuum or suction (i.e. 28″ of water) is used to do the test, as the calculated flow should be the same.  Typically, the greater the suction, the more accurate the results.  Below are the results for the inlet ports:

As I predicted, head #1 is out-flowing head #2.  Luckily for me, both heads #1 and #2 outflow head #3, as if they didn’t, it would mean I can’t port to save myself.  There are heaps of interesting things to note from these results though:

I thought due to the better port design of head #1, it would outflow the other heads across the board.  It is almost identical to head #3 until valve lift reaches 250thou.  Head #1 maxes out at 178cfm. Head #2 manages to flow more than head #1 until valve lift reaches 300thou.  Due probably to port geometry, it performs better that the bigger port of head #1, possibly due to slightly higher air velocity creating less turbulence in the port. The stock head #3 is woeful, with a peak of 127cfm @ 500thou valve lift.  Any time you have your head off the engine is a good time to chase more hp by attacking it with a die grinder. When looking at this flow data, you don’t just want to get the highest peak flow figure you can.  Its a bit like a dyno graph where you want to get high power, but would want to be able to create that high power over a wide rpm range.  With head flows, you want to be able to flow a lot of air during the entire valve opening phase, not just at peak lift.  The total amount of air that will flow through the valve can be derived by calculating the area under the line on the graph.  Using this theory, heads #1 and #2  would flow a similar amount of air overall, with head #1 flowing more at higher lifts, and head #2 flowing more at the lower lifts.  Another thing to note from these types of graphs is how a particular flow is reached, and no matter how much further the valve is opened, the flow doesn’t increase.  This means that the port itself is the restriction, not the valve.  An increase in valve size alone will have little effect on peak flow figures.  This is where better porting is required.  Head #3 is a typical example of this.  Perhaps if it had the better ports like heads #1 and #2, it might follow the flow data of head #1 more closely, even with the smaller valves. Concentrating on the data for head #2, the flow seems to hit a brick wall at about 250thou lift.  138cfm is achieved at 250thou lift, and doubling the valve lift to 500thou total only increases flow to 153cfm, an increase of only 15cfm.  This tells me that the port itself must be the restriction, so some more porting is required to get the flow up.  Even if I fit a bigger valve, flows may rise slightly, but the port itself can only flow so much. 

This has given me some good news to work with, as now I know I am not hurting performance by using the pollution head #2 on my engine.  In fact, if my cam only provided valve lift of up to 300thou, head #2 would make the most power.  However, my cam has a lift of 420thou, and I would like to increase the flow in the 300-400thou valve lift range to at least try and get it closer to the flow of head #1, which would make head #2 definitely flow the most overall.  Because of the lift of my cam, and figures measured over 420thou of lift are irrelevant to my engine, but are still of interest.

These are the results for the exhaust ports:

These exhaust port flows are also surprising.  All three heads have the same exhaust valve size (34mm), but I spent a considerable amount of time on heads #1 and #2 to try and increase their flow.  Obviously it hasn’t had a huge impact, but the porting does show an improvement from 300 thou lift onwards.  This would lead you to think that if you are trying to save time or money, don’t bother playing with the exhaust ports, as there is very little gain to be had, unless you have a super high lift cam.  If you read on, you will see that this is not the case.

Since I needed a low compression head and I had already invested so much time in my current turbo head #2, I decided to see how much more flow I could get out of it.  Increasing the flow is to be achieved by more extensive porting and bigger valves.  Head #2 has received some bigger inlet valves and seats from a Commodore V6 Ecotec engine, the valves stems are cut down to the same length as the Gemini valves, the valve size is now 46mm up from 44mm.

I have also fitted some bigger exhaust valves keeping the standard exhaust valve seats but machining them out to suit the larger valves.  These valves are off the shelf Isuzu 2.3l 4ZD1 exhaust valves and are 36mm diameter, up from 34mm.   The photo below shows the larger valves and how the valve seat to combustion chamber is a smooth transition.  This is what is mean by unshrouding the valves.  Usually there is a sharp step/ridge next to the valve seat caused by machining the chamber to accept the valve seat.  Removing this sharp ridge improves airflow into the combustion chamber when the valve opens, and out into the exhaust port.

Then some more porting has been done to make this head flow enough to utilise the larger valves.  The graph below of the flow figures tells the story.

I am very happy with this result.  It looks like a different head now with massive flow gains right across the range of valve lifts.   Once again though, it hits a bit of a wall at 300thou lift.  The again means the port is the restriction, but the port walls are very thin now from so much porting, and we have already made a hole in one port through to the water jacket that needed to be welded up.  As my Wade turbo cam only lifts to 420 though, I probably wouldn’t benefit much from more flow right at the peak valve lift areas, as the valve is only open for a very short time at peak lift, so the peak lift figure is not that critical. I believe the lower lift areas are more important as the valve spends more time on those areas during the intake stroke of the engine.  So unless I fit an even bigger camshaft, I think the current flows at the respective valves lifts will be great.

Its interesting how changing angles within the port and a common sense approach to where the air will flow can dramatically improve the flow of a port.  I would recommend anyone who is serious about making power should get in touch with an experienced head porter with access to a flow bench.  If not, its all a bit of a guess, and although you may make good gains, you wont get all the gains available.

The bigger exhaust valve has given a great flow improvement simply because the valve on exhaust ports are usually the biggest restriction.  This is shown by the constant rise of air flow as the valve is opened further.  When you think about it, the exhaust ports are similar in size to the inlet ports, but the exhaust valves are around 20% smaller.  Therefore simply increasing valve size makes a big difference, and often the ports themselves don’t need to be touched, as the port has the potential to flow a lot more than what the valve will let through.

So my turbo head (#2) has not only equalled the flow of head #1, but its gone way past it.  Head #2 has gained a lot in low lift flow figures, which is the most critical area, and also achieved peak flow figures of 45% greater than a stock head.

Turbo:

Next on the list of upgrades is the turbo.  I have bought a new turbo which is a fair bit bigger than the stock VL Commodore T3, which is nearing its flow limit.  The new turbo is a T3/T04E hybrid running a 56 trim T04E compressor wheel and stage III Turbonetics turbine wheel, with a 0.63 A/R T3 exhaust housing.  This will have the capability to flow in between 400 and 500hp, and should easily get me to 300-350hp @ wheels.  I kept it internal waste-gated for manifold simplicity, these power levels can be achieved without the need to go to an external gate.

You can see the high flowing Turbonetics turbine wheel below, its less aggressive than your typical OEM turbine wheel, which means the air doesn’t hit it as hard.  The downside is more airflow is required to make the turbo spool up, the upside is there is less flow restriction, so overall air flow and power will increase.  For a circuit racer, you find that engine rpm is usually pretty high all the time, so turbo lag is not a huge issue.  Its often the case that the engine rpm is high enough that as soon as you open the throttle, the turbo will boost almost instantly.

This photo shows the compressor size compared with an RB20DET turbo, which is of a physically similar size to my VL turbo.

Exhaust Manifold:

Since the piazza turbo manifold is suspected of being the bottleneck of the combination, I have decided to try a new manifold.  Although the piazza exhaust manifold has been shown to flow enough air, I’m aiming for a manifold with smaller than average pipe diameters so the turbo is hit hard and boosted up quicker.  Obviously not too small or else overall power will be affected.  This is important for street driving as the new turbo is bigger that my last one, and I don’t want turbo lag to make the car unpleasant to drive.

The new manifold is a high mount custom manifold made from steam pipe bends, with much better flow characteristics than the piazza manifold.  The piazza manifold is the almost a “log” style, there is almost no directional flow, it simply provides a mounting for the turbo and passage for exhaust to reach the turbine.  Cylinders #2 & #3 are directed towards the turbo, but the manifold incorporates very tight bends and the exhaust gasses from cylinder #1 run directly into the exhaust gasses from cylinder #4, head butting each other.  The piazza manifold does a good job for power levels around 200hp@wheels, but if chasing more than that, a better design is a better choice.

This photo shows the underside of a standard piazza manifold fitted with the original Piazza IHI turbo.  The factory piazza dump pipe can also be seen.

The manifold I have fitted has the exhaust gas from each port aimed at the turbine inlet, the exhaust pulses don’t combat each other as they do with the piazza manifold.  This should improve overall flow and hp.

I am using this manifold to verify the performance improvement from the mods detailed in Stage 11.  If it turns out to be a good performer, I may use it to mount my big turbo, otherwise I’ll get a manifold made.

Well……….. a few years after writing this Stage 12 section………….Feb 2008

Well it turns out that this manifold above has given a 30hp improvement at the wheels while still using the VL T3 turbo.  For details check out stage 11.

Exhaust:

Due purely to the noise level of the exhaust, I’ve fitted a 3″ straight through muffler in the normal muffler location under the RHS just before the diff.  This dropped the noise level a couple of dB’s, and hopefully without affecting flow at all.

PIC OF extra muffler

Intercooler:

The other major mod is a larger front mount intercooler.  I had been trying to decide between a water/air unit, or just a bigger air/air unit, and air/air is more simple, with less maintenance, so I will go that way.  The RX7 unit is probably getting maxed out with the current levels of flow and inlet temps.

I purchased a cheap ebay front mount that will fit in front of the radiator without too much hassle, core size is a fair bit bigger than the RX7 cooler, so it should keep temps under control.  I will put it on the flow bench and compare it to the RX7 cooler before making piping to suit in case its a step backwards.  If so, I will have to look at a good brand name front mount such as PWR, etc.

Interior:

I am also improving the interior a bit, it started with some new black carpet, now I have a pristine black dash to go in, and have fitted a pair 300ZX electric seats, trimmed in yellow leather.  These seats are pretty easy to install, just need the standard 300ZX rails modified a little bit.  The width of the gem rails is the same as the Nissan.  These suit my harnesses well too.

These new bits of hardware, combined with my new exhaust and cam should make for a really fun ride, with an aim of 300-350hp @ wheels (250kW @ wheels).  That should be plenty for a 900kg car.

I will update this as I finish the build and get flow and dyno data.

Well……….. another year later………..2009

The big turbo is finally fitted to the same manifold I was using for the T3, and the bigger intercooler is installed.

With these mods along with the extra 3″ muffler in the exhaust system, I have had it on the dyno again.

Dyno run # 1: (2009)

• G180 – 2 litre capacity, fresh rebuild, balanced,  o-ringed, etc, as per above.
• Rodeo EFI manifold with 550cc RX7 injectors and 60mm TB. 
• Larger front mount intercooler with beautiful 2.5″ mandrel bent intercooler piping. 
• Wade turbo grind cam in the heavily ported TG pollution head with bigger valves as above. 
• T3/T04E turbo on custom tubular exhaust manifold, 3″ dump pipe into 3″ mandrel bent exhaust with twin 2.5″ tailpipes and mufflers and extra 3″ straight through muffler before diff. 
• Microtech computer controlling fuel and ignition, direct fire (one coil per cylinder) ignition.   
• Boost was set at 18psi.

It made 245hp @ wheels.  (183kW @ wheels).  

Not bad, but not as much as I was aiming for.  I thought I would be pushing 300hp@wheels with this combo.  Again, I used a different dyno, a local Ballarat dyno to save heading back to Geelong.  It made 216hp@wheels on the last dyno run (Stage 11, dyno run#5), the only different being the bigger turbo and bigger intercooler.  So again, roughly another 30hp (12%) improvement. But, it was a different dyno, so its hard to do a direct comparison.

So still not at my target hp level of at least 300hp@wheels, I thought this turbo would make all the difference, and although giving a good power increase, there is a bottleneck in the system somewhere, just have to find it.

Time for a Stage 13!

STAGE 13 – G180 EFI Turbo – Chasing More Power

After doing all the typical mods to an engine, I’m chasing 300hp@wheels, but have come up short at only 245hp@wheels.  So the next step is to find which components need upgrading to achieve my power target.

The main parts of an engine that make power are those that limit how much air the engine can flow.  These components are the intake system, turbo, manifolds, valve train, cylinder head and ports, and exhaust system.

INTAKE – I’m using a finer filter pod which I’ve shown to only drop 1hp@wheels when fitted at the 217hp level.  See Stage 11 for those results.  So this proves the filter is not a restriction.  The plumbing from filter to turbo is 2.5″ mandrel bent pipe and is also plenty big enough.

TURBO – Although an older technology plain bearing turbo, the compressor and turbines on the T3/T04E turbo are large enough to support 400-500hp, so the turbo is not a restriction either.

HEAD – the head has had bigger valves fitted and been ported as much as practical due to the port walls becoming very thin, and I’ve already had a few leaks develop which required pulling the head off and welding the ports up and then re-porting.  So although getting more head flow would help, I’ve found that other people making more power than me are using heads with similar flow figures, so I don’t think the head is a restriction.

INLET MANIFOLD – the rodeo EFI manifolds are used on plenty of high hp engines, with noticable differences to my setup being custom plenum chambers and bigger throttle bodies.  I have already had a manifold on the flow bench with a custom plenum we have designed, with the stock 60mm throttle body, and this showed a 10% flow increase, so this needs to be bolted on and checked on the dyno.

EXHAUST MANIFOLD – the manifold i’m using is not a bad design, but it does have some flaws and could be improved.  I will be trying one of our new TurboGemini SS tuned length manifolds to compare outright power output, and I’m predicting a benefit from the Turbogemini manifold of both quicker spool up and more overall power, probably in the 10-20% range, but until I get on the dyno, that’s just a guess, it might make a huge difference.

CAMSHAFT – I could go a bigger cam, but like the other components, its already a fairly big turbo profile.  However I can use a profile that sacrifices some low end and mid range power to increase top end performance.  Not ideal for street driving, but great for making big dyno numbers.

INTERCOOLER – although the core size is about the max I can fit without over the top cutting of the radiator support panel, it is only a cheap cooler and maybe it’s worth investing in some better technology here, as it’s not that expensive.

EXHAUST SYSTEM – the exhaust is a 3″ mandrel bent system from the turbo all the way to over the diff where it splits into twin 2.5″ tailpipes, with a 3″ straight through muffler before the diff, and 2.5″ straight through mufflers forming the end of each tailpipe, the numbers say it won’t be a restriction either, but something funny could be going on where the split into 2.5″ pipes is, so this needs to be looked at.  A simple check is to drop the pipe before the split which also removes the rear mufflers.  Being all straight through perforated tube, I don’t think they will be increasing back pressure much, but its an easy check on a dyno, can do a before and after within 20mins of each other.

So the changes are:

Plenum Chamber:

I have made a custom plenum chamber so I can mount the TB at the front, instead of locating it over the rocker cover.  This will allow more direct air flow into the plenum, instead of the induction piping having to snake up over the engine and rocker cover, reducing friction losses.  The plenum is also big, at around 4 litres, it should be a good thing.  It has bell mouthed entries to each inlet runner, unlike the stock Rodeo plenum with has more square edged entries.  The stock rodeo plenum isn’t too bad, but this new plenum flows more air, showing a 10% flow improvement to each cylinder on the flow bench.  That’s with the stock 60mm Rodeo throttle body.  I can also mount a larger throttle body if I need to like an XF unit, but the whole manifold assembly didn’t flow any more air when fitted with the XF TB than the stock Rodeo TB, which means the plenum and inlet runners are the restriction, not the TB.

This photo shows the XF TB.  The plenum here is a round cross section, we are actually developing these to manufacture and sell, however they will be a rectangular cross section for ease of fabrication, but everything else is the same.

Exhaust System:

As a simple check, I’ll drop the rear section before it splits into twin 2.5″ pipes to confirm this transition pipe section is not disrupting flow too much.

Intercooler:

I’ve decided to ditch the no-name cooler and have invested in a PWR unit with pretty much the same core size, and the same 2.5″ plumbing, but I’m changing from a bar and plate to a tube and fin style.  The bar and plate is supposed to flow more, whereas the tube and fin is supposed to be more efficient at cooling the compressed air, and on top of that, PWR claim there new range of cores are even more efficient again, so it’s likely that the flow potential will drop, but the colder and therefore denser air will more than make up for it.  Will bolt it on, and give it a run on the rollers!

Exhaust Manifold:

fitment of one of the new TurboGemini manifolds to compare outright power output.  These have an excellent collector where the 4 pipes join at the turbo flange, with potential to flow more air as all 4 cylinders airflow are directed straight at the turbo.  It will be interesting to see how much better the boost response is too.