The History of My Car & Engine

from Rally Bashing Hack to Weekend Racer

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 did a fair bit 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 with 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 30-40hours porting the new cylinder head too, following the theory I used on my last high compression head.  I bought a set of Crow Cams 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).  

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.

Check out STAGE 5 - G200 Draw Through Turbo.