X pipe on a remote mount Twin Turbo?
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TECH Apprentice
Joined: Apr 2012
Posts: 333
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From: New Zealand
X pipe on a remote mount Twin Turbo? I am looking to redo my twin turbo LS3 to pick up velocity so I can run a bigger AR and pick up a little response at the same time. Currently I run long tube headers with 3" collectors then down to twin 2.5" pipes all the way back to the turbos which are where the rear seats used to be. I used 2 x 3" stainless braided flexi joints before the step down.
My thoughts are to recoat the headers then add sleeves to retain heat, then step down via a long cone from 3" to 2.25", ceramic coat and sleeve those as well... and move the flexi joins right up onto the collectors with a anti-reversion cone that helps velocity and reduces pressure on the flexi joints... an experiment lol.
If budget allows I may spring for short tube headers that step DOWN and make anti-reversion cones on the exhaust flanges (think port extensions with a primary pipe flared right over it creating space above the cones). This should aid velocity and reduce reversion back into the port during overlap.... but for now I'm keeping headers I have as they work and cost nothing but a recoat and sleeves.
Should I add an x pipe before the turbos along the new 2.25" length - or are they not going to add anything on a TT? I currently run no balance tube between sides. Only the intake gets blended as the intercooler runs single inlet/outlet.
Thoughts from anyone that has tried with and without an X pipe pre turbo (only relevant on a remote mount)
My thoughts are to recoat the headers then add sleeves to retain heat, then step down via a long cone from 3" to 2.25", ceramic coat and sleeve those as well... and move the flexi joins right up onto the collectors with a anti-reversion cone that helps velocity and reduces pressure on the flexi joints... an experiment lol.
If budget allows I may spring for short tube headers that step DOWN and make anti-reversion cones on the exhaust flanges (think port extensions with a primary pipe flared right over it creating space above the cones). This should aid velocity and reduce reversion back into the port during overlap.... but for now I'm keeping headers I have as they work and cost nothing but a recoat and sleeves.
Should I add an x pipe before the turbos along the new 2.25" length - or are they not going to add anything on a TT? I currently run no balance tube between sides. Only the intake gets blended as the intercooler runs single inlet/outlet.
Thoughts from anyone that has tried with and without an X pipe pre turbo (only relevant on a remote mount)
Last edited by Bazman; Oct 30, 2018 at 05:27 PM.
You don't want to hear this, but those longtubes are absolutely killing your turbo response. You need factory cast iron manifolds that won't bleed off so much preturbo heat.
Thread Starter
TECH Apprentice
Joined: Apr 2012
Posts: 333
Likes: 4
From: New Zealand
Yeah, I have come to the conclusion I should have ditched them at the start. The upside is the power delivery is very controllable - which is why I can use WOT from 1st gear on in the dry (once the Nitto NT01's are warm) and even in the wet from top of 3rd gear. Despite taking off like a mildly built NA Ls3, once under way, it's pretty rapid, 663rw is still 663rw.
I'm going to design a set of shorty's and get them custom made.... more cost but I think it will be worth it. Cast iron manifolds may be better for response but will increase back pressure I fear and I'd rather have a softer power delivery with a stronger top end than vice versa because I often have to race in the wet
re X pipe - I did some research and consensus was it's a bad idea pre-turbo. While it may help velocity on a NA motor, the back pressure from the turbos will likely eliminate that advantage and will simply add volume, therefore reduce response was what I got out of reading on this. Could not find any science or real world hard evidence though.
I'm going to design a set of shorty's and get them custom made.... more cost but I think it will be worth it. Cast iron manifolds may be better for response but will increase back pressure I fear and I'd rather have a softer power delivery with a stronger top end than vice versa because I often have to race in the wet
re X pipe - I did some research and consensus was it's a bad idea pre-turbo. While it may help velocity on a NA motor, the back pressure from the turbos will likely eliminate that advantage and will simply add volume, therefore reduce response was what I got out of reading on this. Could not find any science or real world hard evidence though.
9 Second Club
Joined: Nov 2003
Posts: 13,616
Likes: 185
From: Norn Iron
Turbos will increase back pressure more than the OEM exhaust manifolds.
But they will not be a power limitation at all in a turbo application.
As for X-Pipe....hard one to say one way or another but would be an interesting experiment. Shouldnt be too hard to fab a system to make a swappable H or X section to test ?
But they will not be a power limitation at all in a turbo application.
As for X-Pipe....hard one to say one way or another but would be an interesting experiment. Shouldnt be too hard to fab a system to make a swappable H or X section to test ?
