Is a 4" exhaust to big for my power goals?
- Thread starter Ymh
- Start date
Ymh said:
When posting a thread please be more specific. Posting a title that says (4") doesn't tell the viewers anything. Is it that you have a 4" penis, 4" wire wheels on your ride?
Get my point :icon_conf
PS: I did however take the liberty to change the title for you.
To better answer your question, 4" is overkill. I run a 3.5" exhaust with big hp (see avatar)
Duane
JustAnotherVictim
Supramania Contributor
I thought the same thing, lol.upgradedsupra said:
IMO if you're not going for huge power 4" isn't necessary.
JustAnotherVictim said:
Unless you are planning on 1000RWHP, it is not needed.
I have 3.5" now but maybe I would need to upgrade. (depending on my goals)
Duane
You wont see too much gains over a 3" (10-30 hp? probably none for a 3.5")...
but.....
go baller and go 4"
but.....
go baller and go 4"
QWIKSTRIKE
475rwhp459torq an climbin
upgradedsupra said:
Hey Duane Blackdevilsupra made 562 RWHP on a 4" exhaust from the turbo back, and the gt4088 turbo at 21.7 psi
i got a 4'' cat back that i got at a decent price thats the only reason why, if not i would have gotten a 3''.
i thought it was a little overkill too. but on sean's sp67 there was a noticeable power increase going from 3" to 4". i dont remember the exact dyno numbers, cant search on supraforums.
i think he still has the dyno charts, i'll see if he will post them.
i think he still has the dyno charts, i'll see if he will post them.
QWIKSTRIKE
475rwhp459torq an climbin
dbsupra90 said:
Again blackdevilsupra made 562RWHP on a 7mgte with a gt4088 journal turbo at 21.7 psi witha 4" turbo back exhaust. All the flow chart theories in the world will not convince me that it is unsubstaciated. Paper flow theory, and real world applications don't always mix.:naughty: :biglaugh:
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On my 3.4L Toyota Hemi V8 with a pair of hi flo T04's I ran a short piece of 3" off the flange on each turbo then into twin 4" side pipes. (this builds in turbulant flow as it sets up a swirl effect and can benefit a turbo motor)
There is no such thing as "too big" on a turbo motor as long as it fits under the car, I'd run a 4>5" on mine but ground clearance is an issue in my drive way and this is why I have the 3.5" dump into twin 2.5" pipes. (also anything over 3" is a BITCH to silence and I like my 88db system)
There is no such thing as "too big" on a turbo motor as long as it fits under the car, I'd run a 4>5" on mine but ground clearance is an issue in my drive way and this is why I have the 3.5" dump into twin 2.5" pipes. (also anything over 3" is a BITCH to silence and I like my 88db system)
I have 4 inch exhaust on my car right now and I have three catback systems. One 4 inch, one 3 inch for local authorities, and one 4.5 inch drag pipe for the track. On my current set up dropping from the 4 inch pipe down to the 3 inch pipe and changing nothing else dropped 2.3 psi of boost and richened up the a/f's by 1.5. This changed horsepower on the car from 470 rwhp @ 16 psi to 430 rwhp @ 13.7 psi.This is with the boost controller off so it was off the wastegate on both runs. This info came from my logs on my AEM.
Current setup is a GT4202 74.3 mm inducer, 1000 cc injectors, AEM.
Sean
Current setup is a GT4202 74.3 mm inducer, 1000 cc injectors, AEM.
Sean
I think you could do well with both 3'' and 4'' exhausts. Obviously the 4inch will flow better, but you will have to accept the noise and ground clearance issues. I have seen 3" exhausts handle well over 700rwhp on MK4's with out any problems.
I had a similar instance as Sean when I swapped out my Random TECH "high flow" cat for a test pipe. With no boost controller change, I went from 18psi to 20psi.
I had a similar instance as Sean when I swapped out my Random TECH "high flow" cat for a test pipe. With no boost controller change, I went from 18psi to 20psi.
on our cars giant exhaust + lowered suspension = disaster.
why don't people go with cut-outs instead of a giant exhaust? my cut out is excellent, and when closed it runs through my 3" setup with cat and muffler to keep noise down for long trips. i'm even thinking of getting a silencer to reduce noise even more or going with an oval tubing setup.
i'd recommend getting that oval tubing, i posted this thread about it:
http://www.supramania.com/forums/showthread.php?t=34842
if i redo my exhaust (so i can get a new cat, muffler and silencer and run cleaner/quieter when the cut-out is closed) i'm going to get the 3-1/2" round equivalent (2-1/2" x 4" oval)
why don't people go with cut-outs instead of a giant exhaust? my cut out is excellent, and when closed it runs through my 3" setup with cat and muffler to keep noise down for long trips. i'm even thinking of getting a silencer to reduce noise even more or going with an oval tubing setup.
i'd recommend getting that oval tubing, i posted this thread about it:
http://www.supramania.com/forums/showthread.php?t=34842
if i redo my exhaust (so i can get a new cat, muffler and silencer and run cleaner/quieter when the cut-out is closed) i'm going to get the 3-1/2" round equivalent (2-1/2" x 4" oval)