With the water turned on we were able to up our boost pressure to 27.8 psi and gradually taper it to 22.7 psi. At this point we had absolutely no knock count but we figured we were at the maximum point for our stock turbo and any more boost would simply thrash the air and not make much power. More power would have to come from further tuning.
|Naji hard at work at the keyboard.|
We then added more timing advance in the high load cells until we registered a slight amount of knock count and backed off on the timing a couple of degrees at that point. We played around with the air fuel ratio a bit and richened it up in a few places to make the tune more conservative and less likely to detonate. Finally we retarded the intake cam to the max at high rpm. Previously we had it advanced slightly to lower cylinder pressure and reduce knock count but the water allowed us to keep it retarded.
The results were impressive: 371 whp and 353 lb/ft of torque, a gain of 32 hp and 24 lb ft of torque over pump gas. Our tune is very conservative with zero knock count anywhere. In Naji’s opinion a knock count of 3 is usually pretty safe but we had nothing. This was much less that the stock ECU tune!
|Our slight loss in bottom end power is due to us reducing the boost in the 3400-4400 range to avoid compressor surge. We could have gotten more power but we didn’t want to harm the turbo.|
Stay tuned, in our next segments of Project EVO, we are going to try to break past 400 whp on pump gas and water while still retaining the stock turbo.