Engine speed vs. efficiency ?

I am looking for a graph between engine speed and engine efficiency of pontiac sunfire 2003. Any idea where on the internet can I find that? (GM said they do not have such a graph. I think this is not possible.)

thanks

m_tariq snipped-for-privacy@yahoo.com

Reply to
M Tariq Iqbal
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get a vibe, ive gotten as much as 39mpg, and the acceleration numbers are the same as the sunfire (and is governeds at 117 mph) so it will move!!! also lighter than a sunfire.,,,, i do have the 5 speed by the way...

more room, better mileage... what more could a man want??

Reply to
mike

An engine's torque curve is close to a match to its efficiency, not in absolute numbers, but relatively to the peak efficiency over the RPM range.

HTH

Reply to
Neo

I was thinking that if you knew the airflow or the fuel being fed to the engine at different RPM's you could calulate this. You'd have to know the work output but you could use a published horsepower curve for that. The engine control knows BOTH numbers already. Using a scanner to capture the mass air flow at WOT and different RPM's might actually be practical.

In any case, the original poster is correct. GM clearly has this information. They just aren't going to bother sending it to you.

Reply to
Joe

Definitely. When looking for a scanner, I came across one that came with a nice application that was able to log a lot of data from the ECU, including instantaneus fuel consumption, throttle angle, RPM, etc. If one uses such an application at WOT (because that's how an engine's public curves are plotted), it should be easy to calculate the the engine efficiency at several RPM.

I've actually seen this information in an Italian car magazine and for gas engines it's usually 25%, plus or minus 5, after the transmission, at 100Km/h.

Of course not.

Reply to
Neo

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