Wicked69

I have a UMI throttle body and am using 3" for the cold side. I purchased a 4"-3" reducer but can't get the 4" side over the throttle body. I couldn't find anywhere I could get a 4.25 reducer. Is there anything I can do to get this reducer to fit or do I need to try something else?

1BADAZZSS

iTrader: (23)

Straight, 90? Check ebay. Look for 4.25 silicone transition

Wicked69

Straight. Thanks. I was just checking on this site. I'll check ebay.

So.jerZ-28

iTrader: (20)

use a heat gun or blow dryer to enable the silicone coupler to stretch over it if needed

ZTwentyAteU

iTrader: (12)

If you cant get it, put a SMALL slit in it, heat it up, lube it up and pop it on

LS1NOVA

iTrader: (12)

http://www.racepartsolutions.com/products.asp?cat=38

Wicked69

I got my reducer from racepartsolutions. I totally missed the 4.25. It is listed kind of by itself. I will try heating it up and a small slit as mentioned first. Thanks.

stevieturbo

Why such a large TB ?

Wicked69

You got me? It is a UMI 90mm and that is how big the opening is. I am using a vic jr intake, edelbrock tall 90 elbow and the 90mm UMI throttle body. This is on a twin turbo 5.3 running E85. I was told this was a pretty good match up. I got too good of a deal to pass it up. I got all the stuff listed above for less than $500.

stevieturbo

Fair enough on the pricing etc.

But dont forget. You did state your IC piping is only 3". ie 76mm OD.

Your plumbing will be far more restrictive than the TB. SO chances are anything from 60-100% throttle wont actually make any difference to airflow into the engine.

Excessively large TB's just reduce throttle control. Although for drag cars etc that isnt really an issue I guess.

Wicked69

Okay. You bring up a point. My turbo's are only 2.5" to the compressor so that was why I was going to use 3" intake piping. I could use 4" all the way down and reduce it to 2.5" with the silicone adapters. I could also use aluminum here. Would that work better?

05HD

If it was mine, I'd do the whole cold side I/C piping in 4.25" and leave the hot side smaller.

LS1NOVA

iTrader: (12)

Absolutely no reason to use 4.25 cold side. Keep it a little smaller to keep the velocity up. Similiar to hot side charge pipes (2.5 or smaller). Id use 3.5 on the pipe to the tb just to make the transition a little less abrupt. I doubt the intercooler outlet is bigger than 3 or 3.5 anyways.

stevieturbo

I certainly wasnt suggesting to use 4" or larger plumbing, that would just be ridiculous unless you're looking to go well into 4 figure power.