Ancient History

Darrell Norquay dnorquay at awinc.com
Tue Sep 10 02:56:58 GMT 1996


At 06:17 PM 9/9/96 -0500, John Faubion wrote:

>> I wasn't aware of the magic number of 5252 RPM, how did you arrive at it?

>Well actually I didn't. :)  

At least you're honest...

Obviously, I should have consulted my elementary Physics text.  This brings
us to the formula:

> RPMxTorque
>------------ = Horsepower
>   5252

And, from a previous post:

>Of course the ONLY rpm where torque, horsepower and VE could all peak at
>the same time is at 5252 rpm.

I don't see how you arrive at this conclusion.  If you substitute 5252 for
RPM in the above equation, all you get is the fact that HP must = Torque at
this particular RPM.  This does not mean that they are all maximums at this
RPM, only that they must be equal.  This should mean that regardless of the
engine, the horsepower and torque curves should cross each other at 5250
RPM.  I dug out some old HP Books editions like "How to Hotrod Smallblock
Chevys" and perused some of the comparative "before + after" Dyno curves.  A
few of them had torque and HP curves equal at 5250 RPM, but most didn't.
Obviously, there are other factors at work here.

>If they considered the entire
>car as a system and matched the components to run in a compatible range and
>then changed the gear ratios to use that particular range, they would be
>much happier and the car would be much faster. 

I agree wholeheartedly.  Unfortuneately, most speed shops are only
interested in getting your money, not your money's worth.


regards
dn
dnorquay at awinc.com




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