downpipe
downpipe
01 January 2005, 10:17 PM
#2
Just so happens I have an example of each on my garage floor!
The Open neck is a short funnel fabricated into the D/P from the flange where it bolts onto the turbo to the actual D/P tube, about 75mm long. It makes an open chamberallowing the waste gate (when it opens) to flow it's gases into the exhaust main stream relatively un interrupted. This is now a very popular design.
The Twin Dump Pipe design is where the same turbo flange area has the D/P tube welded to it to take the min stream exhaust gases, but the wastegate gases are taken into the D/P via a much smaller tube, about 30mm diameter that is welded (and venting into) to the D/P about 100mm from the flange.
Will send you a pic on this thread if you like tomorrow. A picture speaks a 1000 words!
Generally, most feel the Open Neck to be the better of the two.
911
The Open neck is a short funnel fabricated into the D/P from the flange where it bolts onto the turbo to the actual D/P tube, about 75mm long. It makes an open chamberallowing the waste gate (when it opens) to flow it's gases into the exhaust main stream relatively un interrupted. This is now a very popular design.
The Twin Dump Pipe design is where the same turbo flange area has the D/P tube welded to it to take the min stream exhaust gases, but the wastegate gases are taken into the D/P via a much smaller tube, about 30mm diameter that is welded (and venting into) to the D/P about 100mm from the flange.
Will send you a pic on this thread if you like tomorrow. A picture speaks a 1000 words!
Generally, most feel the Open Neck to be the better of the two.
911
Last edited by 911; 01 January 2005 at 10:18 PM. Reason: missed a bit
01 January 2005, 11:23 PM
#3
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The trouble with the twin dump is that when the wastegate opens it partially blocks the dump pipe and most of the gasses end up going down the main dump leg.
Andy
Andy
02 January 2005, 08:32 AM
#5
Looks like i may be about to make a mistake then:
The choice I have of D/P:
open neck (of sorts) Magnex but 3''
twin tube (with sports cat), 3''
general view:
The tech argument is to dump both and get a new true open neck and sport cat in the centre pipe. Too much $$$ at this point, so which one of these two? I really want to run a cat this year. The 'open neck' has run great for 3 years now.
911
The choice I have of D/P:
open neck (of sorts) Magnex but 3''
twin tube (with sports cat), 3''
general view:
The tech argument is to dump both and get a new true open neck and sport cat in the centre pipe. Too much $$$ at this point, so which one of these two? I really want to run a cat this year. The 'open neck' has run great for 3 years now.
911
03 January 2005, 07:34 AM
#7
Maybe not.
It is all about the interruption of the main gas flow when the waste gate opens as boost limit is reached.
I'm not so sure it is worth worrying about to be honest Bob. I'm fitting the Cat anyway for now.
Graham.
It is all about the interruption of the main gas flow when the waste gate opens as boost limit is reached.
I'm not so sure it is worth worrying about to be honest Bob. I'm fitting the Cat anyway for now.
Graham.
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