Here is the latest up to date research going on in the quest for more power. Note that on the bottom two power charts, peak power had not been reached. Another 5-6 hp was easily possible. However at these power levels, we always sacrifice the last 5 - 10- hp by retarding the ignition and running a bit richer. It is hardly
noticeable and increases the life of the engine.
The bottom chart in green shows the JRSC Race kit with 5psi and Toda headers. The catback is stock, which cost about 10-12 hp.
For the next run in red a smaller 3.4" blower pulley and DC catback was installed. Boost pressure was up about 2 pounds from 6000rpm to the redline. Power increased by 30 HP from 250 wheel hp to 280 wheel hp. 550cc injectors were installed to cope with the additional fuel required. Very roughly each pound of boost gives 10 hp. We obviously did not have enough power, so it was on with the nitrous bottle. This power run was compared to a supercharged K20A. The K20A had a better intake, 0.5 more compression and longer duration camshafts. Even so the supercharged K20A2 was within 2-3 hp. Without changing camshafts on the RSX our guess is that installing ITR camshafts after the supercharger is installed is not good value for money.
We used an Edelbrock RSX Kit. It was purchased as a wet kit, but was installed as a dry kit. Control and additional fuel was provided by the Hondata K series programmable ECU . The jet size was 32 thou - rated as a 70 shot. As we did not have a bottle heater, the pressure was down and the nitrous delivered was more like a 40-45 shot. For this dyno run nitrous was activated at 3800 rpm, but in practice 5000 rpm is better. As the ECU activated the nitrous, it also added fuel and retarded the timing 4 degrees. Total power was 318 to the wheels. The supercharger is a great device to thoroughly mix the nitrous for even distribution to the cylinders.
Many things were learned from this exercise.
- Firstly to make any more power than this, bigger injectors will be needed. The 550s were running at 95%.
- We are close the limits of the stock RSX fuel pump. For more power a bigger fuel pump will be needed.
- Seven pounds of boost is not enough for 300 wheel hp. 10 pounds will be needed. We will fit a smaller pulley and belt and re-dyno. Even so it might be difficult to hit 300 without the nitrous or some form of charge cooling. As the boost goes up, so do the intake temps.
- A limited slip differential is now a must.
The Hondata K series Programmable ECU was used for the tuning of this car.
Testing was done on a Dynapack. Dynojet figures will be lower.