Originally posted by Bradness:
On this point I shall disagree with Demon that an optimized SVT t-body will flow "XX" amount. It all depends on how much of the shaft has been removed/streamlined, whether countersunk or button head screws are used, whether the threaded portion of the screws are cut perfectly flush with the shaft, is the shaft the same thickness from side to side, how thick the plate is, etc.


The difference between one optimization to another are extremely minor in the grand scale of maximum airflow.

Also in an optimization I would take several things for a given. (or really it "wouldn't be optimized")

Countersunk screws, half the throttle rod, and knife edged frontal areas.
So that sets the overall flow area at a fairly exact amount for any optimized TB of the same size.

You make it sound like the difference between one TB and another would be significant when that's just not the case. The difference between the most detailed job and the least would be about 2% Most would be within 1% of each other. You know me, I'd take that extra 2% but by itself it's not a tremendous amount. That's 2% flow area and not 2% power by the way.

Originally posted by Bradness:
So we have addressed the quantity of airflow, but how about quality? What affect does it have?


More efficient - a MAF with a small air horn.
Less efficient - a MAF with a center bar post.
More efficient - a smooth tapering intake pipe.
Less efficient - a intake tube with pleats or ribs.
More efficient - an Extrude Honed manifold
Less efficient - a stock manifold
More efficient - a LIM without restrictive rods and plates
Less efficient - a LIM without restrictive rods and plates below 2500rpm (had to throw that in before someone whined about it )


I'm sure you get my point by now.

I could have listed the head ports, exhaust valves, pre-cats, et cetera.
Everything must work together because any time you remove the most restrictive piece another one then just becomes the most restrictive.

Restriction can cause both airflow "quantity" and "quality" to drop. For the most part the more turbulent the air the less efficiently it will move. Also the lower the cylinder filling ability will be.

Turbulence before the TB is not as bad as it inside the manifold. Restriction is more of a factor before the TB. Well at least to the point where the TB is more restrictive then the pieces before it.

Now turbulence before the MAF is very bad but that's for other reasons; consistent airflow readings.

2000 SVT #674 13.47 @ 102 - All Motor! It was not broke; Yet I fixed it anyway.