I'm just asking a question as my searching abilities are not the greatest. What benifit would there be going to a throttle body with a larger diameter than the mouth opening of the intake? And do you have the numbers to back up what you say? It would seem to me that a better flowing throttle body would be better that a larger diameter TB as some times larger doesnt mean it will flow better. Thanks John

 

What you are saying is correct, bigger is only better when all of the parts are set up to work with each other. If the throttle body is bigger then the port opening on the manifold when the air hits it it will cause turbulence, which will reduce port velocity. The object is to get as much air in the engine as smoothly and quickly as possible. If you get more air in the engine then you can add more fuel and then you will make more power.

 

Idk what you're setup is, but it's tough to get power out of more flowing TBs. The 90mm LS2/3/7 works very well...all you really need is a nice port/polish and you're good to go.

Unless you have a crazy big cube setup, you won't really need more than what a nicely ported 90mm can provide.

 

Exactly what RARON said, its pointless to throw on, say a FAST 90 intake manifold and be using a factory TB. All the air is going to get choked as it enters the TB so it defeats the purpose of having a good flowing manifold.

 

My goal is to use the stock ls6/ls1 intake. It has a mouth opening of 78mm. And the stock throttle body is at 75mm. Going to a 90mm makes no since to me. So I'm thinking if I can get the stock TB ported and smoothed, it should flow much better than going to an say 85 or 90 mm TB. Would you agree? Thanks John

 

BBK, FAST, lots of people made 78mm TB's and you can usually pick them up relatively cheap used. I think I read on here a guy ported his LS6 intake to 80mm and got a 80mm TB, that's all he felt safe going with fear of getting into the O-ring channel.