Welcome to the SR20 Community Forum - The Dash.
Register
SR20 forum logo

Thread: Turbo downpipe

+ Reply To Thread
Posts: 1-10 of 22
2011-04-04 02:52:38
#1
Turbo downpipe
I have top mount turbo(GT3076r) with a 2.5 dp, which goes to the bottom of the motor and a 3 inch full exhaust. Question is have that 2.5 chocking the turbo or it really dont make a difference. I have asked many people atp turbo, Mikes turbo, garrett and a few performance shops and everyone is giving me different stories. Atp gave me the best answer which was "the first bind of the turbo is very important you want that to be big for more flow. A gt3076r gives 550hp after 300 hp the 2.5 dp will choke the turbo. So u made 350 on 14 psi upgrade to a 3inch dp and u can make that on 10 or less psi and your top end power would be much better". Just wanted to know from you guys is this is this true or 2.5 downpipe does not matter. Thanks
2011-04-04 07:36:38
#2
imo point blank its like a bottle neck, if you had a 3'' exhaust you would see 3'' exhaust flows, but since you have the 2.5in to 3'' exhaust you are as of right now only seeing the benifits of a 2.5'' exhaust flow.

if you get a larger downpipe mated with the larger exhaust you will then open up the turbos ability to flow greater volumes of exhaust gases in return letting you see the benifits of a larger exhaust.

there are benifits to a smaller exhaust system if you are running say stock or near stock boost levels. however if i had ur turbo i definitly would be near stock numbers, and i would definitly want ot take advantage of the 3'' exhaust i had by upgrading to a 3'' downpipe too.

some would say smaller wiill yeild you better torque numbers, and better spool times, some people go from 3'' dp to 2.5'' exhuast, others do like you did, really its all up to the person at hand as to what they think works best for them, like you have seen you have getten different responses as to what is better and thats tipical as to when you ask for opinions.

if you are pushing greater volumes of air, the air is becoming restricted by the space it has to release the volume in. if you open up that space, then you will equal the ammount of volume and space and let the exhaust volume flow become greater. you may see downfalls to a 3'' dp when you go if you go to a 3'' dp however in the grand scheme of things its all about power and a larger diameter will allow for larger power numbers.
2011-04-04 12:40:03
#3
I really don't care for quick spoiling I'm more for the top end. When I launch my car I rip 1st 2nd but 3rd gear the car seems dead. In 3rd gear the car doesn't perform great and this is at 19 psi. A buddy of mine rips 1st thru 3rd with a gtir on 15 psi. So can my small dp cause this
2011-04-04 12:47:01
#4
Yeah I will say go to 3" downpipe, with that turbo you should see an improvement right away
2011-04-04 12:49:11
#5
how much HP and torque you making?

I ripped the hell out of 3rd with a Master Power T60 at 12 psi with street tires
2011-04-04 12:56:46
#6
yeah you would definitly benifit from a larger downpipe. any reason you never went with a 3'' off the bat?
2011-04-04 12:57:57
#7
Before I did injector swap I made 370 on 21 psi with 50lb inj. upgraded to 850 injectors now didn't dyno yet
2011-04-04 13:02:18
#8
Originally Posted by GT2871RBLUBIRD
yeah you would definitly benifit from a larger downpipe. any reason you never went with a 3'' off the bat?


I had a t3 50 trim 48 exhaust housing 4 bolt . When I upgraded the turbo the guy at the shop I bought it from told me 2.5 u can make 400hp easy. So I never did
2011-04-04 16:34:48
#9
you should have gone with a 3"

Damn and with 370 and you dont rip 3rd like mad?
2011-04-04 16:54:12
#10
Originally Posted by beto
you should have gone with a 3"

Damn and with 370 and you dont rip 3rd like mad?


I'm on 17s so I don't know if that would effect it
+ Reply To Thread
  • [Type to search users.]
  • Quick Reply
    Thread Information
    There are currently ? users browsing this thread. (? members & ? guests)
    StubUserName

    Back to top