[Diy_efi] Throttle body sizing

[Perry Harrington]

Here's some empirical data (I have a 5.0l, I've run 55, 65, and 75MM TBs).

These are NA numbers, in forced induction the numbers will be higher (50%
or so I would estimate).

The 55MM TB is good for 240HP or so.

The 65MM TB is good for 300HP or so.

The 75MM TB is good for 400HP+.

The last number top end is unkown, because I switched from the 65 to 75 and
my motor peaked at 320HP at last dyno; the TB isn't the restriction.

Another thing to note is that all things being equal, a bigger TB doesn't give
you more power.  The reason why those TBs were good for that power is because
they exactly matched the intake manifold.  The bigger the manifold, the more
power.

--Perry

On Fri, Oct 11, 2002 at 09:32:54PM +0100, William Shurvinton wrote:
> 63mm is a tad big. 55mm is more the norm. readily available. Got a couple in
> the garage. A 55mm TB will be good to 180BHP in the right engine.
> 
> Bill

-- 
Perry Harrington			Data Acquisition & Instrumentation, Inc	
perry at dainst dot com					 http://www.dainst.com/

Those who would give up essential liberty to purchase a little temporary safety
deserve neither liberty or safety. Nor, are they likely to end up with either.
                             -- Benjamin Franklin

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