Well..
Im doing my saab setup, and trying to pick out a new exhaust while im at it. For now it will just be a stock saab turbo setup but in the future I do plan on upgrading the turbo compressor housing and such.
Is 3" to large even with the upgraded turbo housings?
I know stock 2.5" would be perfect since people say its good to about 250hp after that go to 3".
Will I lose some power with to large a exhaust on this setup?
Thanks..Phil
You wont lose power you might gain a tab of spool up with the bigger exhaust. You'll have a hard time making it sound good without cats.
1994 Saturn SL2 Home Coming Edition: backup car
2002 Chevy Cavalier LS Sport Coupe: In a Junk Yard
1995 Mazda Miata R-package Class=STR
Sponsored by:
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Ill be putting a cat and a resonator in..really dont want it to sound like @ss for the sake of a few hp.....but function over form.
Well there are a few ways to get function and forum. The Evo guys now love the new Dynomax VT mufflers. And for a turbo app be sure to get the over 4 litre one.
1994 Saturn SL2 Home Coming Edition: backup car
2002 Chevy Cavalier LS Sport Coupe: In a Junk Yard
1995 Mazda Miata R-package Class=STR
Sponsored by:
Kronos Performance
WPI Class of '12 Mechanical Engineering
WPI SAE Risk and Sustainability Management Officer
Could just buy my 2.5" and be all good to go
I feel 2.5 may be small for the future plans...Really trying to avoid doing it twice.
Also I just read up on those vt mufflers and hell no! Great idea but I have read nothing but complaints about them rattling.
Did you read anything from oh say mid to late 2010? The Evo guys had huge issues until about July when all the 1st gen ones were recalled and they got the new ones with zero rattle.
1994 Saturn SL2 Home Coming Edition: backup car
2002 Chevy Cavalier LS Sport Coupe: In a Junk Yard
1995 Mazda Miata R-package Class=STR
Sponsored by:
Kronos Performance
WPI Class of '12 Mechanical Engineering
WPI SAE Risk and Sustainability Management Officer
I know a 3" is better for a turbo as it allows it to spool quicker but saying 250 is the most power you can have on a 2.5" exhaust is not true. My truck has a 2.5" exhaust and it has 300hp and it has a lot bigger displacement than a cavalier (5.3L). Saying that I know with a bigger exhaust will allow more air to flow which will yeild more power but saying "2.5" would be perfect since people say its good to about 250hp after that go to 3". If your going through the trouble of putting a new exhaust on your car I would go 3" then its done and you don't have to worry about it. I wish I had put my 3" exhaust on my car before I rebuilt it to see the dyno graph between the difference of a 2.5 and 3.0".
Reading on the subi forums....guys with a stock td04 are getting 10-20 hp from going from 2.5" to 3". Thats what made me wonder since it is such a little turbo...and not sure if the subie td04 is similar to the saab td04.
I think im going to go 3"...but with cat, resonator and muffler to keep it quiet....er.
Matthew Jollymore wrote:I know a 3" is better for a turbo as it allows it to spool quicker but saying 250 is the most power you can have on a 2.5" exhaust is not true
i just put down 322 on a mustang dyno with my 2.5"
Ill have new numbers in the spring with the 3".
I understand you can have any amount of power with any given size of pipe, but...Im trying to get the most out of this little thing. Ive redone my car a pile of times and want this to be the last exhaust I have to put on it.
I just don't know the theory behind exhaust sizing with turbos since ive read conflicting stuff, some say 3" is always ideal and some say its to big.
But it sounds like it may be a bit big for the stock saab but perfect for the upgraded turbo.
You can't go too big after the turbo. The larger the diameter and shorter the pipe, the better. Scavenging does not occur after the turbo. Different theory when compared to naturally aspirated cars.
BuiltNBoosted wrote:Matthew Jollymore wrote:I know a 3" is better for a turbo as it allows it to spool quicker but saying 250 is the most power you can have on a 2.5" exhaust is not true
i just put down 322 on a mustang dyno with my 2.5"
Ill have new numbers in the spring with the 3".
Glad you proved what I was saying.
I would go 3" regardless. Turbo motors love flow and the bigger exhaust will be less restrictive which is good (as for N/A a little backpressure is good). Even with a small turbo setup it will probably yeild some gains. The mp45 s/c that I had on my car probably flowed less than your turbo and I bet if I had a 3" exhaust I would have had some small gains.
3" it is then.....
Now what to make it sound good.....thinking magnaflow cat, magnaflow resonator and dynomax super turbo muffler
I'm not very good in that department....gutted cat and race series magnaflow muffler for me. Oh and a turbo for a resonator haha
put some videos of your exhaust when you get a chance matt. I'm trying to decide if crush bent would be ok.
i dont have a cat, and used a 28" thrush glasspack for a resonator, and dynomax super turbo.
For my 3" im going to use the longest thrush resonator I can, and no cat, and once again, the dynomax super turbo again.
I gotta run a cat though here in Van bc. We get e-tested.
Oh, thats no fun. Guess you could have a good cat to throw on for safety inspection haha.
Philly D wrote:I gotta run a cat though here in Van bc. We get e-tested.
id bet i could get it to pass without a cat. its all in the tune... but to be safe, any cat will do.. they claim high flow but any cat will do...
As long as you dont have a tail pipe sniff test you dont need a cat to pass emissions, I'll leave it at that.
1994 Saturn SL2 Home Coming Edition: backup car
2002 Chevy Cavalier LS Sport Coupe: In a Junk Yard
1995 Mazda Miata R-package Class=STR
Sponsored by:
Kronos Performance
WPI Class of '12 Mechanical Engineering
WPI SAE Risk and Sustainability Management Officer
Sometimes they do sniffers and sometimes they dont. Not something im going to bank on. I also want the cat to help with sound.
Like I said ill be going with the magnaflow cat, magnaflow 18" resonator and dynomax superturbo muffler all in 3"
this just might make some of you think twice about 3'' pipe.
Exhaust System
The goal of a good exhaust system is to minimize back pressure. Back pressure prevents the turbocharger from spooling up freely creating lag and a loss of power. The key to minimizing back pressure is to use straight through mufflers, mandrel bent piping, and larger than stock diameter pipe. The turbocharger itself acts as a good muffler, removing as much as 1/3 of the noise from the exhaust system. The first component that requires consideration are the mufflers. Mufflers that have a straight through design do not have internal baffles. The ideal straight through design will have a perforated core instead of a louvered one. Louvers protrude into the exhaust flow to muffle the noise. Perforated cores have holes in the center pipe that do not inhibit exhaust flow. Another thing to look for in a good muffler is stainless steel packing. Stainless packing will not burn out of the muffler like fiberglass (which is used in most aftermarket mufflers) will. MagnaFlow makes excellent universal mufflers that meet these requirements. Of course the best muffler in the world will not make any difference if the pipe diameter is small, restricting gas flow. Two factors effect exhaust flow, the type of bend used and the diameter of the pipe. Two types of pipe bend are crush and mandrel. Crush bending works by crushing the pipe at the bend, in effect, putting a kink in the pipe, reducing the diameter of the pipe at that bend. Mandrel bending works by stretching the pipe as it is bent. The result is a bend that does not reduce the diameter of the pipe. As far as diameter goes, bigger is better, but up to a point. The Corkey Bell book "Maximum Boost: Design, Testing, and Installing Turbocharger Systems" suggests that the full benefits of 3" diameter pipe will not be fully realized until 700 horsepower! To learn more about why, pick up the book. Clearance with the rear suspension can also be an issue with 3" pipe, especially if the car is lowered. If you choose to have a custom exhaust system made and crush bending is the only option (mandrel bending machines are expensive so a lot of shops do not have them) then 3" would be the way to go. The extra diameter will compensate for the diameter you lose when crush bending. If you have access to mandrel bending services then 2.5" diameter pipe is ideal to use. The 2.5" pipe is good to 500 horsepower.
The only option for a prefabricated, bolt-on, exhaust system that is suitable for use on a turbocharged car is from Thermal Research & Development
The catalytic converter is a significant flow restricter in the exhaust system, even presumably 'high flow' cats. You can expect as much as a 30 horsepower gain by removing the cat. Having the cat in the system will also contribute to extremely sluggish low RPM performance. However, removing the cat in most areas of the country is illegal and results in a heavy fine, remove it at your own risk. One option to reduce the chance of being caught it to have a fake heat shield that looks like a cat's heat shield welded onto a straight pipe, making it look like a cat (I'm not telling you to do this, I'm just telling you what some people have done).
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Where did you copy and paste that from?
Oh and btw OEM also sells a 3" mandrel bend exhaust for the J-bodies. His is just made from welding mandrel bends into the piping rather than actually making a 1 piece setup on a mandrel bender.
ps there's also a 3rd kind of bend, the compression bend. It sitll reduces the diameter of the pipe, but the inner radius is smooth and the decrease is not as bad.
1994 Saturn SL2 Home Coming Edition: backup car
2002 Chevy Cavalier LS Sport Coupe: In a Junk Yard
1995 Mazda Miata R-package Class=STR
Sponsored by:
Kronos Performance
WPI Class of '12 Mechanical Engineering
WPI SAE Risk and Sustainability Management Officer
