3.5" or 4"?
3.5" or 4"? Ok i've decided to scrap my 2.5" true dual side exit boom-tube idea. Everytime I see someone with a side exit setup, it seems like they took it off due to bad ground clearance. I've decided to have custom mufflex style setup built, with a custom 3" y, flowmaster merge, and a single magnaflow race muffler with a dump behind the axle. Should outflow my side exit idea by quite a bit, tuck up loads better, and probably run less. It will be much like in this link. My question is should I go with a 4" or 3.5" setup? My car just has full bolt-ons now, but i have plans to go heads/cam in the next few years sometime after I graduate college. I can get a flowmaster merge either 3" to 3.5" or 3" to 4" and theyre the same price so that's not a big deal. I'm thinking the 3.5" is plenty for stock cubes, but it probably won't cost much more for 4". Any thoughts?
Here's the link I saw that gave me the idea...
https://ls1tech.com/forums/generatio...aust-pics.html
Here's the link I saw that gave me the idea...
https://ls1tech.com/forums/generatio...aust-pics.html
Haha, I was going to post a link to my exhaust.
3.5" should be plenty even if you up the cudes down the road and if built correctly it should have great ground clearance also. I love my system, still get compliments a lot even from people who have heard it before.
3.5" should be plenty even if you up the cudes down the road and if built correctly it should have great ground clearance also. I love my system, still get compliments a lot even from people who have heard it before.
Go 4 inch for sure.
This is Detroitmuscle's custom exhaust set up. His car uses a stock catback and made something like 408 threw the exhaust and 441 with the 4in cutout open. Plus the ground clearance is amazing.
Stenod Performance did all the exhaust work. I must say they did a damn good job also.
This is Detroitmuscle's custom exhaust set up. His car uses a stock catback and made something like 408 threw the exhaust and 441 with the 4in cutout open. Plus the ground clearance is amazing.
Stenod Performance did all the exhaust work. I must say they did a damn good job also.
I might just see what kind of price difference it is. If its not much more i'll go 4" if they want much more i might just go with 3.5". Main factor is good flow with good ground clearance.
Do you guys think it will be any problem running this though a stock tunnel brace? I'm not sure how much more an aftermarket brace adds for clearance.
Last edited by Gordo78; Dec 26, 2009 at 08:31 PM.
I don't know how much more a 4" pipe will flow than a 3.5" one. I've seen the flow charts several times but never saved them. 4" piping is BIG, the clearance over the axle is going to be very tight. There's a lot of people running big cube motors with a 3" system and a cutout. I don't see why 3.5" wouldn't be enough for almost anything you throw at it and if you have a cutout it would make even more sense. I went with 3.5" because I wanted a bigger exhaust than the norm and I didn't want a true dual system. Clearance is still tight over the axle and it does bang occasionally but it's never scraped over bumps.
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Do yourself a favor and do the 4" all the way back. people who have done it will never regret it. Still tucks fine and sounds amazing. And a 4" will outflow most setups available. I gained all across the board going from 3" to 4" while changing rear from 10 bolt to 9". let me know if you needs pictures. Also if someone needs me to explain the flow rates of 4" compared to 3.5" or dual 3" let me know.
i realize there is more to flow than just cross sectional area, fluid dynamics is a bitch...buffer layers etc...but here is the jist...
cross sectional area of tubing (sq inches):
2.75" = 5.94
3" = 7.01 (15% increase over 2.75")
3.5" = 9.62 (27% increase over 3")
4" = 12.57 (44% increase over 3", 23.5% over 3.5")
dual 2.5" = 9.82 (28.5% increase over 3", only 2% over 3.5", still 22% behind 4")
dual 3" = 14.02 (10% over 4")
cross sectional area of tubing (sq inches):
2.75" = 5.94
3" = 7.01 (15% increase over 2.75")
3.5" = 9.62 (27% increase over 3")
4" = 12.57 (44% increase over 3", 23.5% over 3.5")
dual 2.5" = 9.82 (28.5% increase over 3", only 2% over 3.5", still 22% behind 4")
dual 3" = 14.02 (10% over 4")
I had that 4" setup for a while. You can find pics in the staff showcase from it. I loved it. Had a 3.5" collector and went into a nice magnaflow muffler. Let me check on pictures.
i realize there is more to flow than just cross sectional area, fluid dynamics is a bitch...buffer layers etc...but here is the jist...
cross sectional area of tubing (sq inches):
2.75" = 5.94
3" = 7.01 (15% increase over 2.75")
3.5" = 9.62 (27% increase over 3")
4" = 12.57 (44% increase over 3", 23.5% over 3.5")
dual 2.5" = 9.82 (28.5% increase over 3", only 2% over 3.5", still 22% behind 4")
dual 3" = 14.02 (10% over 4")
cross sectional area of tubing (sq inches):
2.75" = 5.94
3" = 7.01 (15% increase over 2.75")
3.5" = 9.62 (27% increase over 3")
4" = 12.57 (44% increase over 3", 23.5% over 3.5")
dual 2.5" = 9.82 (28.5% increase over 3", only 2% over 3.5", still 22% behind 4")
dual 3" = 14.02 (10% over 4")
Do yourself a favor and do the 4" all the way back. people who have done it will never regret it. Still tucks fine and sounds amazing. And a 4" will outflow most setups available. I gained all across the board going from 3" to 4" while changing rear from 10 bolt to 9". let me know if you needs pictures. Also if someone needs me to explain the flow rates of 4" compared to 3.5" or dual 3" let me know.
