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Re: Corky Bell's Book
This opinion is also shared with Joe Moragn and it does seem to work.He
told me in one conversation that the biggest gains on our cars comes from a
better turbocharger and intercooler set-up.
At 02:50 PM 9/10/97 -0600, Carl Morris wrote:
> I just thought I'd mention a few things that I
>find interesting about the book.
>Corky's opinion on what NOT to spend time/money on:
>1. Big cams, heavy port work, expensive high RPM parts.
> He points out that the forces due to combustion
>are only about 20% of the load on the pistons, crank, and
>rods on a naturally aspirated motor. Everything else is
>stress due to RPM and simply compressing the charge.
>Since the RPM related stresses get squared every time you
>double the RPM, you only have to drop your peak RPM about
>10% to put yourself at 80% loading, which gives you the 20%
>margin you need to double your horspower without any additional
>stress on the motor(assuming you're not causing any pre-ignition
>or detonation). The point is just that for a given strength of
>motor, you can gain more power by running more boost and less
>RPM than vice-versa (doing both is not an option once the motor
>is maxed out).
> To me, this sounds like an argument for putting better
>rods in our motors (the weak link) which would make them good
>for about 7000 RPM, but leaving the stock redline
>alone and buying efficient turbos and intercoolers and
>running lots of boost (and good enough gas for that boost).
>Corky's opinion regarding porting: It works, but taken to the
>extreme, it reduces low RPM driveability and there's no need for
>it if you have (once again) the right turbo and IC. The
>problem is that most turbos are only efficient to about
>3:1 pressure ratios. For you guys at sea level that'll
>get you to about 30 pounds of boost, probably as much
>as you can use even with race gas. Up here at this
>elevation, that only gets me to about 24 pounds of boost.
>I'd probably need to do some porting if I were trying to
>max the motor out on race gas and keep the boost within
>the turbo's efficiency range.
>Corky's opinion of what TO spend time/money on:
>1. You guessed it, turbos and intercoolers.
> A turbo that will run in the 70% efficiency
>range at 400-500cfm, and a good, large frontal area
>fairly thin low restriction front-mount intercooler.
>This, combined with a fuel system that will deliver
>a consistent 13:1 A/F ratio will make monster power
>on our motors, without huge internal motor mods.
>I guess this should all be taken with a grain of
>salt, but I do find it all interesting, I consider
>the source to be as reliable as any other I know of...