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I don't give a rat's *** what the loss factor is.. (archive)

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Posted by Stan on December 18, 2001 at 10:52:44:

In Reply to: lets clear up the drive train loss theory! posted by eric_m3 on December 17, 2001 at 16:22:13:

I just want any test to be REPEATABLE and CONSISTENT. I don't care if a chassis dyno shows 10 more HP than another chassis dyno. If back and forth mod tests show *more* you are ahead. So you make changes and then find out if things are better/worse and at what RPMs. Area-under-the-curve rules!! Max area under the curve in a given RPM range makes the car the fastest. For max race capability you want max area under the curve using optimized CR gears and in the RPM range that will be used in those gears. For the street or for autocross you need more action below the RPM ranges used in the race example. This does not always lead to the highest claimed peak HP figures.

An easy way to max out area-under-the curve is to select an RPM range you'd like to max out. In a given gear you'd go from a particular speed/RPM to another speed/RPM. Combos that do this in the least elapsed time for comparable hp/torque curve shapes have the most a-u-t-curve.

If you can you measure the actual distance required to make that speed/RPM change. Least distance covered while doing that = most a-u-t-c and is what we really want - to be ahead of the other guy. That evens things out for cars with grossly different curve shapes. It's easy to do stuff like that with an AP22 fpr example. On my M3 a particular ignition wire seems to save 2-3 feet on a 15-60 MPH run in 2nd gear. So if you had two identical cars running side by side one would gain a fender on the other in that instance. Yet it may not have the highest HP.

Check these out if you'd like to read about this interesting topic.

http://www.pumaracing.co.uk/power3.htm

http://www.pumaracing.co.uk/coastdwn.htm

Stan




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