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Old 05-13-2008, 05:47 PM   #46 (permalink)
Duffman
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Quote:
Originally Posted by monroe74 View Post
duff: "The RPM that peak torque occurs at is a published value."

Yes, 4500 rpm.

"That will be the sweet spot for fuel economy for your engine."

I don't think so. Peak torque is not the same thing as optimal BSFC. And the graphs we've been looking at seem to indicate that optimal BSFC occurs at low rpm. That's not usually where peak torque is.

"More data around this region would be more valuable."

I'm not very interested in what happens at 4500 rpm, because the amount of time I spend doing 4500 rpm is essentially zero.

"Record TPS voltage, RPM and A/F ratio and build a map like a BSFC map."

I would be looking at injector activity, not AFR, because the former is a direct measure of fuel consumption, and the latter is not. But I still wouldn't be getting useful data, because I would only be observing that injector activity is directly proportional to throttle angle. We already know that. What we want to know is how much power the engine is actually producing, at a given rpm and fuel input. That's why a dyno is needed.
Yes 4500 is too high, I forgot we were dealing with hondas. But that said the lowest BSFC can still be at 4500, and not be your best cruise RPM.

Measuring injector activity doesnt tell you much because you do not know the power generated for the fuel injected. The fuel injected is not entirely proportional to throttle angle as you are saying that the ECU is changing the A/F ratio with throttle angle. I dont know what else to say, if you dont want to try it I understand because it is your time after all.

Last edited by Duffman; 05-13-2008 at 05:53 PM..
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