Engine load vs RPM and torque

Greg Hermann bearbvd at sni.net
Thu Apr 8 01:47:16 GMT 1999


>Hi all,
>
>This is a little off charter but is still related somewhat (especially to
>those with artificial aspiration.)
>
>I'm looking for some software or code (Matlab, Working Model etc...) that
>will allow me to calculate the loads seen by the piston, rod, etc for
>various torque/speed combinations. For instance, is it better to make 100 HP
>using 15 psi of boost at 5500 rpm or 100 HP at 6500 RPM using 7 psi of
>boost...
>
>I'd like to be able to input the weights of the piston and rod, and the
>torque value to obtain their loadings. Most people will tell you the largest
>loads are seen on the exhuast stroke at TDC,

This is in tension---

 but that doesn't explain why
>those turbo Honda's start bending rods at 10 psi...

This is instability under compressive loading (column failure.
>
>I have a small single cyl that I'm going to be putting a blower on. In it's
>current configuration, the factory tells me additional revs will seriously
>comprimise reliability. OK, but with the blower, what is the ideal speed for
>my desired HP?
>
>Repond off list if you feel compelled. Thanks.

Right off the top--I section rods are more stable under compression loading
(boost), as are aluminium rods (heftier section for same weight) (which is
why fuelers like them). H section rods will be lighter for same strength,
to get higher revs, but not as stable under high compressive loads.
Aluminium is not good for SUSTAINED high revs because of no fixed endurance
limit in tension.

Regards, Greg
>
>
>Matt Beaubien
>mbeaubie at ualberta.ca
>3 x 510
>1 x 300ZXT





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