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07-02-2009, 07:35 AM

#11

Norm Peterson

6th Gear Member

Join Date: Feb 2007

Location: state of confusion

Posts: 7,635

Quote:

Originally Posted by lundefinedl

I am only saying to use an average as opposed to a peak value to determine performance.

There's the small matter of defining that average torque. I imagine that the average of peak torque and torque at peak HP rpm would work acceptably well most of the time, though that's just the first thought that came to mind (might not work so well with peaky engines, VTEC-style arrangements at rpms below the cam switch-over rpm, or turbocharged engines when off boost).

Quote:

With a torque curve you can fairly easily do a kind of computer simulation that will approximate what would happen, but I'm sure there must be some way to do this more accurately with calculus and physics. The best way to do it I think would be with work and energy as opposed to messing with F=ma.

I'd hate to attempt a real mathematical integration of the full equation, and a step-wise numerical solution is probably at least as good as the data that's available anyway.

No matter what units you decide to work with in your equations, the basic usable engine output is still torque. It just seems easier to start with what the engine puts out and stick with that all the way to the drive wheel contact patches (where you end up with +FX), especially in the more complete equation that also considers drag forces (-FX), torque lost to powertrain inefficiencies, and torque siphoned off to rotationally accelerate wheels, flywheels, and such.

Norm

Last edited by Norm Peterson; 07-02-2009 at 07:38 AM.