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Originally Posted by pimpmaro
BTW, horsepower is a made up number. Torque (ft-lbs) = (hp x 5252)/RPM. If you ever look at a dyno graph, torque and hp always
cross at 5252 rpm....
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Hmm, what if my axes are not in units of ft-lbf, rpm, and hp? Say, for example, they were in SI units, like N*m and kW, the way you're most likely to find them at an engine OEM? Then my dyno graph wouldn't follow your rule, would it? Heck, unless you're looking at a US hotrod magazine, chances are your dyno graph won't conform to the above...
Quote:
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Originally Posted by pimpmaro
If you'd really like to get into a complex engine discussion, I can start next with BMEP, which is the Brake Mean Effective Pressure that an engine operates at, and which is the limiting factor of the power that an engine can reliably produce.
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BMEP? That's another made-up number! It's just the work per cycle divided by the fluid displaced per cycle! You can calculate it from displacement and torque, in much the same way that you can calculate power from torque & rpm... I wouldn't say that BMEP limits the power output of an engine, but it is a good indicator of how hard an engine is working.