RE: FW: [COUPERS-TECH] HALT testing

[Charles Waldo]

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Folks

 

   I sent the this email off to one of my engineering friends.....below is what he had to add to the problem......

 

Chuck

 

 

Very interesting article. He defiantly covered some valid points. He also acknowledged he has simplified his analysis. I agree with him but the other major contributor to the loading on the crank is the dynamic loading due to the pistons.

 

Pure torque can be related as a force applied to an arm so his approach is correct. What adds to this force on the crank is the force generated by the accelerating and decelerating of the pistons and connecting rods. This is a function of the rpm but is exponential (http://www.engineersedge.com/engine_formula_automotive.htm for pistonfiltered=Mass * Accel). So dropping from 6500 to 6000 should be a 15% reduction in the dynamic loading.

 

At this point one must know more on the details of the masses involved to really decide if the 7% increase in torque is offset by the 15% reduction in dynamic forces. I’m sure my input also misses other contributing effects as well.

 

Enough for one lunch break.

 

Have fun.

Jeff

John Cooper <[EMAIL PROTECTED]> wrote:

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At 12:18 PM 8/4/2006, Wood, Percy wrote:

Torque in what

lbs-ft

  times
Engine speed in RPM?

Yes

BMEP stands for what kind of pressure (in PSI)?

Brake Mean Effective Pressure in psi.  It's the force driving the piston down the bore.

John Cooper, A&P
Skyport Services
PO Box 249
4996 Delaware Tnpk
Rensselaerville, NY 12147
518 797-3064
Fax 518 797-3865
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