throttle body

Hey guys, will the stock throttle body be a direct fit to a 3 inch intercooler pipe or would I have to do something else to make it fit?

Im pretty sure the factory 2g throttle body is 2" but I may be wrong.

ok just did some measurements and I got that the actually pipe comming off is about 2 1/4" big and my pipe that I have on there is about 2.8" I dono if 3" would fit though, I would just guess and check. Just remember that for the upper piping the larger you use the more lag you could potentially have. but larger lower piping is good.

I have been wondering about this too. My intercooler has 3 inch inlet and outlet. Anybody ever use 3 inch? Gains? Draw backs?

I have been wondering about this too. My intercooler has 3 inch inlet and outlet. Anybody ever use 3 inch? Gains? Draw backs?


On a smaller turbo, 3" intercooler piping is only going to hurt performance (mainly spool-up). Larger turbos can fill that 3" intercooler piping much better and will actually see airflow gains with it if the entire intake tract is 3" up to the intake manifold (so a 3" TB would be needed). 2.5" intercooler piping is more than enough for the majority of turbos smaller than a "60 trim", IMO.

On a smaller turbo, 3" intercooler piping is only going to hurt performance (mainly spool-up). Larger turbos can fill that 3" intercooler piping much better and will actually see airflow gains with it if the entire intake tract is 3" up to the intake manifold (so a 3" TB would be needed). 2.5" intercooler piping is more than enough for the majority of turbos smaller than a "60 trim", IMO.


Sweet, thanks man, Now All I need is a big ass turbo..LOL

On a smaller turbo, 3" intercooler piping is only going to hurt performance (mainly spool-up). Larger turbos can fill that 3" intercooler piping much better and will actually see airflow gains with it if the entire intake tract is 3" up to the intake manifold (so a 3" TB would be needed). 2.5" intercooler piping is more than enough for the majority of turbos smaller than a "60 trim", IMO.

Ya, I will be upgrading to an evo3 16g when I get some money. I only ask this now cause on ebay, there is a really nice core for $185, but the inlet and outlet are 3'

It doesn't matter if the inlet/outlet is 3''. That's what reducers are for. 2.5 is more like it, nobody is running 600whp.

I made a 3 inch to 3.5 inch UICP, but I had specific reasons (needed to fit 3.5 inch GM MAF with no abrupt transitions). You should be able to see it at www.posracing.net/bigmaf.html if I didnt pork the URL. Most FMICs come with 2.5" piping and TB elbow. The TB inlet is barely 2.5 inches, the bore of 60mm is 2.36 inches. Sp going bigger doesnt help in the flow department. I Went to a NT TB that accepts a 3" silicone coupler (with 2.75" spacer) just to make fitment easier, not for flow.

I made a 3 inch to 3.5 inch UICP, but I had specific reasons (needed to fit 3.5 inch GM MAF with no abrupt transitions). You should be able to see it at www.posracing.net/bigmaf.html if I didnt pork the URL. Most FMICs come with 2.5" piping and TB elbow. The TB inlet is barely 2.5 inches, the bore of 60mm is 2.36 inches. Sp going bigger doesnt help in the flow department. I Went to a NT TB that accepts a 3" silicone coupler (with 2.75" spacer) just to make fitment easier, not for flow.


So having full 3 inch intercooler piping would not be good even if you had a 3 inch throttle body? Is it really going to cause alot of lag? Alot of pressure drop? Or any noticable diffrence at all?

You have to relate things to the proper causes. Just increasing the TB to 3'' isn't going to make 3'' IC piping 10 times more effective. Yes, it will cause more lag because the inner volume of the piping is larger. Yes it will cause pressure drop. On a side note, a lot of higher power cars have stock TB's, which are really restrictive. Hal Landry is currently doing the Q45 80mm bore TB to 3.5 GM MAF... I'm excited to see how it works out.

Ok, thanks guys!

So what I'm getting out of this is to run 3' pipes on the lower end, but use a reducer to 2.5' for the uicp to the tb?

Yes it will work, coz I have that on my set up on my 98 GST.