Exhaust, singel or dual, what´s best?
#16
Three Wheelin'
My -86 with 32v engine has the same exhaust as the S4, ie dual 2,1/4" tubing. I found out that the stock exhaust was dead heavy and not an ideal thing for a sportscar.
I´m about to build a new exhaust for the car but cannot decide what way to go.
1# Dual 2,5" with X-pipe.
Pro: Good flow
Con: Not very lightweight
2# Dual 2,5" forming an Y-pipe and mate into a single 3" tubing.
Pro: Lightweight
Con: What about exhaustflow, is it enought?
3# Dual 2,5" forming an Y-pipe and mate into a singel 3,5" tubing.
Pro: Flow must be good
Con: ...
What would you choose? Pros and cons?
/Tobias, Sweden
I´m about to build a new exhaust for the car but cannot decide what way to go.
1# Dual 2,5" with X-pipe.
Pro: Good flow
Con: Not very lightweight
2# Dual 2,5" forming an Y-pipe and mate into a single 3" tubing.
Pro: Lightweight
Con: What about exhaustflow, is it enought?
3# Dual 2,5" forming an Y-pipe and mate into a singel 3,5" tubing.
Pro: Flow must be good
Con: ...
What would you choose? Pros and cons?
/Tobias, Sweden
Check the dyno charts in the link provided by Rick Carter. That tells the story.
#17
Thanks Louie. Thats what I was looking for - the comment you have made here. "Difficult to muffle inadequately, means too loud to me. Is that what you mean?
#18
Three Wheelin'
That's what I meant. Check the offerings of the 3.5" mufflers and then see where they will fit. One muffler won't be adequate. You can put one behind the Y and in front of the transmission. It's really hard to put a 3.5" muffler beside the tranny unless it's quite short. The inlet angle there makes things really tight with the big tubing. You can put another muffler in the rear.
#19
Three Wheelin'
When I did these exhaust tests I had an X pipe with nothing behind it. I had a good "Y" merge pipe (one Tom Cloutier made) with nothing behind that. There was no noticeable difference between them. The dual 2.5" X pipe, and the "Y" merge (two 2.5" inlets and merging into a 3.5" outlet was the same. Next step was to connect an exhaust system to go out the rear. Adding the dual 2.5" pipes with 2.5" straight through Bullet brand mufflers showed a torque increase from below 3000 to about 4500 rpm as compared to no rear exhaust. Top end was the same. Next was to put on a 3.5" rear exhaust connected to the "Y" merge and try that. The 3.5" rear exhaust showed no change from having no rear exhaust at all. That is less torque from 3000 to 4500 than the X pipe with 2.5" duals. True, it isn't much of a difference, but a series of small improvemente adds up.
#20
Race Director
#21
Race Director
My thoughts on exhausts kinda work like this.....for a race shark.....where noise isn't as much of a concern....i would go with a 3.5" single system for a stockish motor...bumped to 4" for a stroker
On a street 928.....dual 2.5" is plenty for stockish motors....dual 3" for S/C-strokers....
On a street 928.....dual 2.5" is plenty for stockish motors....dual 3" for S/C-strokers....
#22
Rennlist Member
Am expecting delivery of rest of parts this week to try 2.25 dual on a 16V.
No science. So I can say I have duals.
Seems like there are real advantages for single, though.
No science. So I can say I have duals.
Seems like there are real advantages for single, though.
#23
Three Wheelin'
On a euro S with MSDS headers having a 3 inch collector could you run 3" into 3" cats into a y pipe and then 3.5 after the Y? My thinking was to run as large a cat as possible to minimize its affect and to also add a small amount of muffling.
#24
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Okey guys, I´m convinced. I will go with the dual 2,5" with an X to be on the safe side so to speak. I´ll try to use one dual muffler at the rear to get the tones down but still retain a good roar
Thanks for your inputs and opinions.
/Tobias, Sweden
Thanks for your inputs and opinions.
/Tobias, Sweden
#25
Rennlist Member
I've been thinking about a dual 2.5 system as well and was wondering how the 2.5 inch tubes mate up to the exhaust manifold, i.e. what is the internal diameter of the manifold?
#26
Three Wheelin'
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I prefer my set-up, but would have gone to this if not for the sidepipes:
headers into crossover
crossover into 3 inch pipe (duals)
CATs if required (duals,3 inch in/3 inch out)
Flowmaster mufflers (duals, 3 inch in/3 inch out)
twin 3 inch pipes out the rear
for a street car you should not really need to worry about the weight, but if for a race car--who needs CATs and mufflers?
--Russ
headers into crossover
crossover into 3 inch pipe (duals)
CATs if required (duals,3 inch in/3 inch out)
Flowmaster mufflers (duals, 3 inch in/3 inch out)
twin 3 inch pipes out the rear
for a street car you should not really need to worry about the weight, but if for a race car--who needs CATs and mufflers?
--Russ
Last edited by largecar379; 12-14-2008 at 02:26 AM.
#27
Nordschleife Master
MSDS headers into straight pipes that merge into 1 3" pipe that have a 2 chamber 40 series flowmaster at the end.
http://youtube.com/watch?v=uTI6-YV-fCU
http://youtube.com/watch?v=uTI6-YV-fCU