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Shawn did an initial pull and we were disappointed but not really surprised to find that the car detonated badly and we had to abort the pull to avoid damaging the engine. Afterall we had increased the compression ratio 1.5 points and were running California piss poor 91 octane pump gas.
Our untuned power levels actually dropped but we didn’t finish the run and shut the engine off before redline due to detonation.
Shawn retuned our car using Up Rev’s Osiris tuning software to reflash the stock ECU. Osiris allow user tunability for all the functions of the stock ECU, enough to tune our high compression engine. Osiris features the ability to manipulate these items: Up to 5 Maps on cruise control equipped vehicles, Idle RPM, Speed Limiter, Electronic Throttle Control to achieve Wide Open Throttle at all speeds, Rev Limiter, DTC disable, AFR Targets, Fuel Compensation, Ignition Timing Advance, Cam Phasing for equipped vehicles, MAF transfer function, Cranking Enrichment and Ignition Advance, Injector Latency, K Fuel Multiplier and Intake Temp, Calculated Load vs. RPM, Minimum Effective Injector Pulse Width. After establishing a baseline, Shawn noted that Project Z had a decent air fuel ratio just about unchanged from the last tuning session.He also noted that our cam’s mapping was still good even though we were running a slightly bigger JWT intake cam. Shawn then went about tuning the timing tables to get rid of detonation.
After tuning, Shawn was able to extract 303 whp from 91 octane or about 3 more hp than before. This was somewhat disappointing. Shawn told us that the engine was knocking quite a bit and he had to take a lot of timing out and richen up the fuel mixture. We feel that 11.5:1 is too high of a compression ratio to use with California gas. Had we known this we would have milled some off the top of the pistons. This would have solved the spark plug clearance issue as well.
We had a full tank of fuel but Shawn threw in a splash of VP 110 race fuel, really a little less than a gallon to see what would happen. The tank was too full to add more race fuel.
With just this change, and just a little more timing, Shawn was able to extract 316 whp. This means that if you can get 92 or 93 octane in your area, you should be able to tune your car just fine. We would still advise milling the pistons for 11:1 compression. We entered this as a higher octane map. Shawn felt that he could easily get another 10 hp with better fuel as his timing was very conservative. Shawn also told us this was one of the highest hp naturally aspirated VQ35DE engines that he has tuned to date. We opted to run this program and if the car is run at the track, it will need a bit of octane booster for safety.With our engine running and tuned, we have accomplished our goal and have an engine with more power and torque across the board. We learned that in the future that the engine is very knock limited and that JE’s shelf pistons probably have too high of a compression ratio for track use and pump gas.
We have accomplished our goals creating a fun low buck all around track and drift day beater. This car really does do well and is super fun to drive. We are trying to talk the cars owner to go all the way and make Project Z a full time race car with a cage. What do you think?
