All motor exhaust options

gsr_nikhil

Member
Since I own a shop, I like to play around with different exhaust setups. Currently I have a Type R header welded to a 2.5" pipe that is custom bent to follow the OEM design and it ends with a Magnaflow muffler. But I'm wondering, can I just weld a straight pipe from the header to just before the gas tank and have it down fire right there? In my mind it will decrease resistance because that 'S' curve in the exhaust will no longer be there. Instead the exhaust will just end right before the gas tank. Is this ideal? Let me know if you need a better explanation as I just woke up and my have been unclear
 

Muckman

Not a M0derator
I don't think there is any measurable resistance from the bends downstream of the fuel tank. And this is assuming we are talking about mandrel bends. Did you mean you would eliminate the muffler if terminated before the fuel tank? If so that would be a better argument for reducing resistance than removing a few smooth bends.

Any flow system is only as good as its most restrictive point. And that's going to be the catalytic converter or the header (if you dont have a cat). I think you should focus on the header.
 

gsr_nikhil

Member
Muckman said:
I don't think there is any measurable resistance from the bends downstream of the fuel tank. And this is assuming we are talking about mandrel bends. Did you mean you would eliminate the muffler if terminated before the fuel tank? If so that would be a better argument for reducing resistance than removing a few smooth bends.

Any flow system is only as good as its most restrictive point. And that's going to be the catalytic converter or the header (if you dont have a cat). I think you should focus on the header.
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Thanks for this man. And no they aren't mandrel bent because we aren't a high end shop haha just a regular pipe bender. And yes I would be eliminating the muffler. I do need a new header because mine is cracking but since the new exhaust would be free, I was just going to run a straight pipe until I save up for a new header
 

Aussie

Zoom-Zoom
I'd also be careful about having hot exhaust exit on your fuel tank
 


xZachTheRipper8

New Member
I think it would be cool to try but if im not wrong with a straight pipe you wont have any back pressure which could result in burning your valves which is no bueno, correct me if im wrong.
 

Muckman

Not a M0derator
Buy some mandrel bends and weld yourself a new exhaust. It will flow so much better and you can still keep the muffler.
 


Charly[horse]

Name = John
A lot of truck guys "dump" their exhaust where you are explaining. I did it to my dakota and felt a small difference in power and all I deleted was pipe, I still have a muffler and cat.
 

NemesisCBR

Boredest Member
Don't over think street applications. Maintain a sufficient size all the way back with a high flow cat and a straight through muffler or one of the other two options if you have lower decible needs/wants.

To simply say you want or dont want back pressure is outdated.

Charly, gotta remember a lot of people do it simply because it makes it sound aggressive.
 

gsr_nikhil

Member
NemesisCBR said:
Don't over think street applications. Maintain a sufficient size all the way back with a high flow cat and a straight through muffler or one of the other two options if you have lower decible needs/wants.

To simply say you want or dont want back pressure is outdated.

Charly, gotta remember a lot of people do it simply because it makes it sound aggressive.
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So if I don't care about noise then its okay (meaning it won't damage my car) to just dump it right before the fuel tank. Keeping in mind to avoid letting the gases go directly to the tank
 

96LSteg

Jemel
What exactly is the purpose for dumping the exhaust before the tank?

Street? Drag?

The reason I ask is because your car is going to be extremely loud for no reason and you probably wont see that much of a gain from it without making the entire system flow better (intake, head work, exhaust) as previously stated. Like muckman said I would start with the header. Find a good one and then decide on whether or not you are going to keep your cat or go with a test pipe and then go with MANDREL bent piping not crush bent piping. Then I would look into a good intake manifold and other supporting modifications. After all of this is done and properly tuned, only then will you see any noticeable gains.
 

Muckman

Not a M0derator
Back in "the day" I dropped the cat from my exhaust to run open header at the track, which is essentially what you are proposing. It was unbelievably loud. My friend with the RSX in the lane next to me said it hurt his ears so much that he was trying to cover them with his shoulder while driving. lol

[youtube=Stock GSR engine, CAI, open header, gutted interior.]OUQ6Xqygqks[/youtube]
 

gsr_nikhil

Member
Great responses guys I appreciate the insight. And I already deleted my cat so now its just a pipe crush bent from the header all the way back to a magnaflow muffler. I need to find a shop that does mandrel bends.

I'm not 100% sure on the exact model of the magnaflow but do you guys think that is restricting air flow too much? I just want the best flowing exhaust possible. I don't mind noise too much bit I've driven open header before and it just sounds nasty
 

96LSteg

Jemel
gsr_nikhil said:
Great responses guys I appreciate the insight. And I already deleted my cat so now its just a pipe crush bent from the header all the way back to a magnaflow muffler. I need to find a shop that does mandrel bends.

I'm not 100% sure on the exact model of the magnaflow but do you guys think that is restricting air flow too much? I just want the best flowing exhaust possible. I don't mind noise too much bit I've driven open header before and it just sounds nasty
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I would imagine that it wont be too restrictive with you setup for the simple fact that you have not made any mods that allow you engine to take in a substantial amount of air (i.e. intake manifold, valves, head work...) you exhaust is only gonna flow out what flows in and nothing more. Like i stated earlier you will need to make the ENTIRE system flow "better" to have any true gains. Atm you shouldnt have to worry about any restrictions
 
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