quote:Originally posted by 4NHOTROD:
[QUOTE]Originally posted by Daniel_Jones:
> Peak HP is at 4600.
I was unable to read the legend on the graph but do you mean peak HP at
6400 RPM or peak torque at 4600 RPM.? 500 HP at 4600 RPM would be over
570 ft-lbs at that RPM and imply even more torque at a lower RPM.
> Great for the street. Both my motors built the most power at that range.
> Motors go boom at high rpm's.
Yes. Also, remember you generally shift around 500 RPM above power peak
for best average acceleration (it is the area under the curve that matters,
not peak values) so design your engine to peak 500 RPM below where you want
to shift. The best way is to calculate the RPM band between shifts and
concentrate the power there (e.g. when shifting at 6500 RPM, the engine
falls back to 4000 RPM on the shift into the next higher gear).
> ZF loss is roughly 22%
I see people claiming that but 22% of 500 HP is 110 HP. That's the power
of a small 4 cylinder engine, one that will move an entire car at over
100 MPH. If your ZF takes a small 4 cylinder engine just to spin it,
something is very wrong and I want to see the transaxle cooler you are
using to dissipate that 110 HP. There may be a 22% difference between
the same engine on a chassis dyno and an engine dyno but the transaxle
loss is only a fraction of that.
Yes, I should have stated that the total loss between an engine dyno and a chassis dyno is 22%. Not all from the ZF
Will
I agree that there are other power losses on an engine such as the water pump, alternator and pulleys. What I question is why the 22% power loss through the ZF is the general number that seems to be used. As horsepower goes up so does the power loss and I just can't see this as being a linear number. I don't have any engine dyno numbers for my new stroker engine yet, but when this project is done, I should have both engine and chassis dyno numbers. That should give me a pretty good idea of what is happening. I have heard from that the ZF power loss is about 80 horsepower. If there are any mechanical engineers on here I would love to have this explained to me.