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3" elbow down pipe

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aporschefan

PCGB Member
Member
Can someone recommend where to source a 3" replacement for the standard turbo downpipe? Think the original was 2.5"? Is it called an elbow pipe? (The rest of the system is 3" including cat bypass.)

I think Fabspeed do one but IIRC, wasn't there a company in Newcastle who made these too?
 
aporschefan said:
Can someone recommend where to source a 3" replacement for the standard turbo downpipe? Think the original was 2.5"? Is it called an elbow pipe? (The rest of the system is 3" including cat bypass.)

I think Fabspeed do one but IIRC, wasn't there a company in Newcastle who made these too?
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Eldavo on here is your man as he had his custom made . give him a pm it he may see this and answer.

i wanted one but am going to probably make my own as i’m doing a full ststem one day.

atb
Daniel
 
Turbo discharge pipe. Not much point unless your turbine exit is the same size...
 
I’m inclined to disagree there. The bigger the pressure differential, the more effective/efficient the Turbo is. Having a less restrictive downpipe at the exit of the Turbo contributes positively to the pressure differential due to the suction effect caused by the gas expansion. Hence why the most efficient Turbo would be dumping straight to atmosphere - although that’s massively impractical/dangerous/hilarious.


Contact Stuart at AAS in Newcastle and he’ll make you a Fabspeed style 2.75” pipe up with a lifetime warranty For around £150-ish. You’ll need to cut your own gaskets but the MLS material is £8.50 a sheet delivered off eBay.
 
Eldavo said:
I’m inclined to disagree there. The bigger the pressure differential, the more effective/efficient the Turbo is. Having a less restrictive downpipe at the exit of the Turbo contributes positively to the pressure differential due to the suction effect caused by the gas expansion. Hence why the most efficient Turbo would be dumping straight to atmosphere - although that’s massively impractical/dangerous/hilarious.
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You, Lindsey Racing, plus most of Rennlist. What works at constant full throttle doesn't necessarily translate to an efficient 944 turbo road car. I fitted a downpipe to tailpipe 3" system on my 87 Cosworth, and dumped all but one silencer. It made more top end, but at the expense of bottom end response. More recently I ran a straight through exhaust on my 944, same thing. The turbo whistle down the exhaust sounded nice though. Also you can get fairly close to 2.75" just by gutting the standard discharge pipe.
 
Good point.
I'll double down on stating the obvious but my goal right from the off was linear and smooth power delivery. Not max HP.

For those that have made the change, it would be interesting to hear your thoughts and if there is a real world gain or just what they've hear or read and with which turbo?
 
It‘s pretty much a given universal truth that backpressure on a Turbo is bad news for power. The best exhaust for a Turbo is no exhaust, hence all the funky bonnet or side mounted units on high HP crazy builds.


N/A engines might need back pressure and pulses to work for scavenging, etc. but us Twbo folk are a simple breed - get as much pressurised hot air out as quickly as possible.


What I will agree upon is that the Downpipe isn’t some wonder pipe where swapping it out will give you +25bhpeez like you get on some modern cars where it has a secondary Cat or suchlike in it. Rather, it’s a piece of the puzzle that should be changed as a suite of upgrades.


I will be back running my hybrid 26/8 somewhere between 18-22psi for 350-370bhp. Might change the boost pressure sensor in the VEMS ECU from a 3 to a 4 bar one as my Turbo is good for 25psi and the engine will be built for all that and more.
 
Real world experience. I took all the silencing out of my 944 exhaust, it sounded like a tractor and ran like one under 4k revs too. I put baffles in the tailpipes, and all the pull from 3k came back. Take all of the exhaust off your 944, go up the road, then come back and tell us how it ran? I reckon you may be creating some heat at 22psi using a 26/8 turbo as a base too.
 
hmmm.. interesting debate going on here...for my two pence worth.... too much back pressure is bad and no exhaust at all isn't going to help much either... A tuned/matched setup gives the best of both worlds. In regards to the downpipe, bigger is better but only if you are fitting a larger turbo and pushing for more power top end. The whole exhaust system needs to be taken into consideration, for a 2.5ltr 951 engine 3" is the biggest you want to go, it is pointless and counterproductive fitting anything larger, especially if using a small turbo, I consider the 26/8 as a small turbo.
I think you need to rethink your turbo David or your expected BHP? You aren't going to get 350-370bhp out of a 26/8, what you will get is massive heat soak and possibly a damaged engine. IIRC 18psi is about as far as you want to safely push a 26/8 turbo.
 
Torque makes road cars feel fast. And it wouldn't surprise me if 25psi ended in tears.
 
It’s not a standard 26/8. The internals got binned and the housing has been machined a fair bit.


Turbo is good for 25psi from bench testing and the dyno plots I got with it after I had it rebuilt - I’m intending to run at 21psi. Someone with the same Turbo, mods and map made a safe 368bhp at 23psi I’m not pushing it that far but there’s a lot of posts on here of "you can’t do this and you can’t do that” but there’s a lot more people that can and have done that don’t post on here.
 
Eldavo said:
there’s a lot of posts on here of "you can’t do this and you can’t do that” but there’s a lot more people that can and have done that don’t post on here.
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Who posted that? You can run 30psi if you like [:D].
 
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