downpipe?
02-20-2006, 05:31 PM
#1
0.5 BAR
Thread Starter
Join Date: Jan 2006
Posts: 98
downpipe?
Why would you run a bigger downpipe than the outlet to the exhaust housing on a turbo?
IE: t3 .48\.60 exhaust turbine is ~2" so why would someone run a 2.5" downpipe?
wouldn't it be benifitual to run the same size tubing throughout the whole exhaust as the exhaust turbine outlet?
IE: t3 .48\.60 exhaust turbine is ~2" so why would someone run a 2.5" downpipe?
wouldn't it be benifitual to run the same size tubing throughout the whole exhaust as the exhaust turbine outlet?
02-20-2006, 07:54 PM
#3
3.0 BAR
Join Date: Mar 2003
Posts: 21,479
Re: downpipe?
A 2" pipe all the way back is going to be restrictive and kill spool time. You might not notice any huge difference if just the downpipe was 2" and the rest was 2.5" though. Turbos love open downpipes. 
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02-20-2006, 08:15 PM
#4
3.0 BAR
Join Date: Mar 2005
Posts: 3,161
Re: downpipe?
Originally Posted by Dr.Boost
A 2" pipe all the way back is going to be restrictive and kill spool time. You might not notice any huge difference if just the downpipe was 2" and the rest was 2.5" though. Turbos love open downpipes.
JP
02-20-2006, 08:22 PM
#5
0.5 BAR
Join Date: Apr 2005
Posts: 179
Re: downpipe?
The 2" extended pipe would end up being restrictive on a turbo vehicle I believe. A vacuum is desired for exhaust, which ends up pulling on the piston as the exhaust valve is open, and with a long stretch of piping that is not large enough, that vacuum would be unachievable. Short pipe yet same width, fine, long pipe larger width would be fine as well though.
02-21-2006, 04:07 PM
#7
1.5 BAR
Join Date: Feb 2005
Posts: 691
Re: downpipe?
Originally Posted by Premium Dude
Ok, so what is better. Having a large downpipe leading to a smaller exhaust, like lets say 2.75" dp --> 2.25" exhaust OR a 2.25" dp --> 2.75" exhaust?
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02-22-2006, 03:46 PM
#9
0.5 BAR
Thread Starter
Join Date: Jan 2006
Posts: 98
Re: downpipe?
so should i just start out with a large downpipe to begin with on my t3? Maybe 2.5, then up to 3? I eventually want to get a 3" exhaust but the outlet on the hot side is 2.25 and i want to use the stock wastegate until i can upgrade.
02-22-2006, 04:12 PM
#10
0.0 BAR
Join Date: Jun 2003
Posts: 0
Re: downpipe?
Originally Posted by UltimX
Why would you run a bigger downpipe than the outlet to the exhaust housing on a turbo?
IE: t3 .48\.60 exhaust turbine is ~2" so why would someone run a 2.5" downpipe?
wouldn't it be benifitual to run the same size tubing throughout the whole exhaust as the exhaust turbine outlet?
IE: t3 .48\.60 exhaust turbine is ~2" so why would someone run a 2.5" downpipe?
wouldn't it be benifitual to run the same size tubing throughout the whole exhaust as the exhaust turbine outlet?
The decrease the pressure differential on the turbine wheel. Less pressure at the exducer, the faster the spool time will be. If you can hook up a vaccum to the downpipe it would be beneficial
