CLLLSLS@aol.com says:
>
> Hey everyone,
>
> Finally got Corky Bells "Maximum Boost" in the mail yesterday. Very good
> book! Really covers the everything, but I'm having a not so easy time
> understanding exactly how to select the turbo I need.
Great book. I've read it cover to cover twice now.
> The basic formula for flow rate (cfm): cid X rpm X .5 X VE
> 1728
>
> 279 X 3500 X .5 X .75 / 1728= 212 CFM
>
> I want to run a pretty serious 7-10 pounds boost through my 270, so figuring
> for 10 PSI, the pressure ratio ((14.7+boost)/14.7) is 1.68. Yes, I will be
> doing some serious intercooling.
>
> 1.68 X 212 = 356 CFM
>
> So I need a turbo with a compressor that will operate most efficiently @ 10
> PSI @ 356 CFM. It seems as if using the redline RPM in the formula would mean
> my turbo's gonna be working most efficiently, creating the least heat, when
> the engine's at it's redline. Is this the way it should be?
>
> If these specs are right, selecting the right compressor shouldn't be hard,
> but what about the turbine? Corky focusses entirely on street and racing
You need something like a Garrett T3, with a 60 Compressor, running a HSG
A/R Turbine of around 1 - 1.1 you should see about 320 bhp.
This is assuming you are going to spin as high a 5000 rpm, if you go for
lower top rpm, the compressor will have to be smaller and the turbine as
well.
> Do I want to lean one way or the other towards more top end torque and later
> boost with a larger turbine or more low end torque and less top end with a
> smaller turbine or is right in the middle the perfect solution for my truck?
> What's gonna make this truck the funnest to drive?
That's up to you. Do you want to spin the engine up or have low end grunt?
And now here's the reason I responded to the list instead of privately:
this link http://www.turbofast.com.au/TFmatch.html
has a java applet to help you size turbos for just about any application.
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Miq Millman miq@teleport.com
Tualatin, OR
oletrucks is devoted to Chevy and GM trucks built between 1941 and 1959
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