2.5" vs. 3" downpipe

[buickpower2]

Hi all, just wondering if anyone has made a direct comparison between these two like on a dyno or at the track (not likely)? Is there a documented hp/et gain? Trying to help a friend determine what the cost/benefit would be vs. his 2.5.

 

[BRAD_PADGETT]

The answer is with a stock or TA 33 C turbo a two 1/2 downpipe is plenty. The key is to eliminate the two inch turbo elbow and use a flange. You have to go bigger all the way. For example 2 inch turbo elbow, three inch downpipe and exhaust gets you zero performance increase. The system will only flow at the most restricted point. In this case-2 inches due to the turbo elbow. Until you custom weld on 86/87 larger turbos a 2 1/2 inch system is fine. My opinion. Brad

 

[BRAD_PADGETT]

I forgot to mention that the outlet from the stock an TA33C turbo is two inches. Brad

 

[buickpower2]

There might be potential there then, since the car has a ta33c with the stock elbow and an ATR 2.5 down from there. Guess I was under the impression that the ta33 elbow was milled out a bit from stock.

thanks

 

[BRAD_PADGETT]

There might be potential there then, since the car has a ta33c with the stock elbow and an ATR 2.5 down from there. Guess I was under the impression that the ta33 elbow was milled out a bit from stock.

thanks

Forget the stock turbow elbow. A looser from the get go. This part thrashes the entire exhaust syetem. Loose it or face the consequences. Good luck- Brad

 

[buickpower2]

p.s. I meant there would be potential for more gain by getting rid of it. I'm glad about this.

thanks

 

[GreatDaneShane]

theoretically it would be better than stock. less restriction (sort of). cut a hole in the hood and run stacks son!