CFM Continued...

[Gary Derian]

If a stock TPI runs out of breath at 4800 rpm on a 350, it will run out much
sooner on a 434, something like 3800 rpm.  My personal view is that it
starts running out at 4000 on a 350 and 3200 rpm on a 434.  Just as your
turbos are coming on, your intake will go out to lunch.  Using boost to
cover up a poorly flowing intake or exhaust system works to limit the
efficiency of the engine.

I recommend a proper large flow passage intake system.  The tube ID should
be approximately the same as your intake valve.  If you intend to run in the
3000 to 5000 rpm range, the TPI tubes are OK for length, but too small a
diameter.  If you intend to run above 5000 rpm, you need shorter and larger
diameter tubes.

Don't forget, the only time you will be below 3000 rpm is in first gear
where you will be traction limited anyway.

Gary Derian <gderian at oh.verio.com>


> Thanks to Ken, Todd & Gary for your answers regarding CFM.  Perhaps I
didn't
> ask the question correctly.   A stock TPI runs out of flow about 4800 rpm
on
> a stock 350 ci engine.  I'm looking for an EFI intake system for my twin
> turbo 434 ci engine.
>