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The History of My Car & Engine from Rally Bashing Hack to Weekend Racer
STAGE 6 - G200 Blow Through Turbo So after rebuild #2 of the G200 (a couple of pistons had cracked at the ring lands), I fabricated an air box for the top of my 32/36 Weber I was using on my 1600 engine, 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. 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 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. 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. |
