My Desktop Dyno Figures

[CCX33911]

I was out of town and missed the discussions. I agree mostly with Andy in that the bottom line is that TQ at the rear wheels at any speed is what accelerates the car. You can turn high HP into TQ with the appropriate gear ratios. Look at the S2000. Not much torque but good HP and thus good acceleration.

The most important thing for acceleration (not drive ability necessarily) is to have the best average HP over a spread of RPM that at least covers the spread for the largest gear change that you make in your transmission. For example if your first gear is 3.3:1 and your second gear is 2.0:1 the ratio is 2.0/3.3 = 0.606. Now multiply that times your projected shift RPM (say 7k) and that will tell you what RPM will fall to after a shift. In this example, 4242 RPM. Thus if your engine makes best average HP over the 4242 - 7000 RPM range you will accelerate the fastest.

I sent in an e-mail to Motion software to suggest an enhancement to Dyno 2000 such that you could use there iterator to design an engine with best average torque or average HP over a range of RPM (not just peak numbers like current version). I think this would significantly improve the use of the iterator. I encourage owners of this program to also send in e-mails asking for this request and maybe they will add it.

Thanks
Gary