98lingvet

I currently have a 78mm FAST on my LS1 ported with a port matched Throttle body. I am wanting to go with a bigger size FAST like a 90mm or 92mm.
Can I use my existing connections and throttle body or do I have to get a bigger throttle body too?
What all must be done to make it work? Thanks.

silver408z

You will have to upgrade your throttle body also. The 78mm TB has 3 bolts in a triangle. The 90mm + tb have 4 bolts in a square pattern. Also FAST stopped making the 90 and 92 mm intakes. They only sell the 102mm intake new now. So you would have to find a used 90/92 intake and at times they can be hard locate it seems. I personally went with a 102mm intake and tb

98lingvet

Thanks for the input. What exact throttle body would I need to get for that intake? Also, could I use my fuel rails and injectors?

Last C5

If you go with the 102 Fast and an LS3 92mm throttle body make sure you use a transition ring behind the throttle body. You'll need the wiring adapter to convert to the 92 and new fuel rails, but your injectors should be fine.

kenpvette

i have a 2003...am thinking on porting my intake and TB....what kind of power will this make...not much on numbers i understand but what about throttle response

RonSSNova

What is this transition ring? I have never heard it mentioned. Although mine has one.

Ron

printmanjackson

http://forums.corvetteforum.com/c5-t...le-inside.html

baxsom

according to Tony Mamo here, a properly ported and tuned FAST 78 will perform with a few HP of a FAST 90. They have the same runner size just a different size opening. Something to think about.

QCVette

That was my question too. I was wondering how much improvement over the FAST 78 to see if it would even be worth the expensive swap. I thought the FAST 78 was a pretty good manifold.

98lingvet

Would there be a big difference between the ported 78mm and the 102?