6.0L exhaust tubing size? 2.5" 3" or ??

wizzo · Jun 23, 2011

plan is to cross over underneath the front of the oil pan and single exit out the side. pretty standard, but i'm wondering what size tubing to go with. engine is stock, i'm not doing any upgrades for a while, my headers have 2.5" collectors so should i just go with 2.5 the whole way? or will it be worth my time to go with something larger? i'm also planing on using a dynomax bullet muffler if it makes a difference.

thanks for any input

doctordick · Jun 23, 2011

According to Flowmaster, 2.5s into a single 3 should handle up to around 450 HP. Hope that helps

wizzo · Jun 24, 2011

thanks for the response MD

i haven't been able to find out a whole lot so guess i'm gonna try the 2.5" into 3" like you suggested. if it don't work out i'll just try something different i guess :dunno:

greenlion · Jun 24, 2011

2.5" into 3" will be plenty, won't hold you back. Muffler flows well also.

BamaTJ · Jul 2, 2011

Use the biggest you can fit but either will work fine.

hinton · Jul 4, 2011

all i could fit under my buggy was a single 2.5 and thats with a ls1 with 370 whp, it does not seem to hold it back

wizzo · Jul 5, 2011

thanks for the input! what mufflers are you guys using? i went with a dynomax race bullet but i'm think'n it's gonna be annoying loud, guess i'll just see

greenlion · Jul 5, 2011

I'm using the large case magnaflows in the 3" flavor. They are a straight through type and flow really well. The longer case ones are quieter but they come in a few lengths. I'm happy with them; I got plenty of noise, trying to keep it reasonable at idle which they do. Don't drone either and are plenty loud at WOT.
I think these are the ones I'm using:
http://www.summitracing.com/parts/MPE-12289/

98sierra · Jul 5, 2011

i would go 3", buddy of mine had a 6.0 vortec maxx and it had the 2.5" and it just sounded like it had a stopped up cat or somethin.. sure it didnt hurt the power delivery but just sounded weird. just do some research, its not about back pressure, that doesnt matter, its the flow you wanna pay attention to, to big and it tumbles through the pipes, too small and it cant get anough out

hinton · Jul 5, 2011

magnaflow

doctordick · Jul 5, 2011

98sierra said:
i would go 3", buddy of mine had a 6.0 vortec maxx and it had the 2.5" and it just sounded like it had a stopped up cat or somethin.. sure it didnt hurt the power delivery but just sounded weird. just do some research, its not about back pressure, that doesnt matter, its the flow you wanna pay attention to, to big and it tumbles through the pipes, too small and it cant get anough out

Back pressure doesn't matter? :wtflol:

All of the big block muscle cars of the sixties and seventies ran 2 1/2" exhaust with far more restrictive mufflers than are available today. Hell, up until the nineties you couldn't even find a shop that could bend 3" :****: Don't believe nuttin on the interweb, call magnaflow or flowmaster, they might just know what they're talkin' about.

98sierra · Jul 7, 2011

right, and the sixties big blockss ran waaaaaay better than todays big blockss...??? :gay:

doctordick · Jul 7, 2011

I haven't heard anyone say that sixties big blocks ran better than today's. That's dumb to think that fifty year old technology is equal to today's. That said, Any internal combustion engine is nothing more than a pump, 454 cubic inches will only pump in and out so many cubic feet of air at a given rpm (normally aspirated) even given better BSFC and intake Mach number, there is a limit called peak volumetric efficiency. Therefore, exhaust diameter and length has the basically same effect on a "68 Hemi or a 427 LSX. Just because you liked the way your buddy's engine sounded to you with 3" exhaust rather than 2.5" has absolutely no bearing on performance. Before you pull your **** out and step on it again, I've been building engines for 50 years and have made the effort to educate myself on what makes them work. Wizzo, Like I said, don't believe everything you read on the web, any of the aftermarket exhaust manufacturers will be glad to tell anyone what will work best on a particular combination based on mathematical calculations and actual dyno results. They're called engineers for a reason.

doctordick · Jul 7, 2011

Here's a good place to start educating yourself, that way you won't have to try to figure who's got his head up his ass on the internet. Go to Magnaflow Exhaust, click on FAQs and scroll down to the article on pipe size. Good information!!

P.S. When someone's post starts out "my buddy's..........." it's probably not to be taken as gospel to say the least.

wizzo · Jul 8, 2011

here's a link to the article md was talkn about http://www.magnaflow.com/07techtips/faq/question10.asp

pretty interesting. the chart at the bottom shows i should be alright w/ the 2.5 into 3 single exhuast, based on my motor factory specs. lq4 6.0L 370 cubic inch & 300 - 325 hp

CheapJ7 · Jul 8, 2011

doctordick said:
I haven't heard anyone say that sixties big blocks ran better than today's. That's dumb to think that fifty year old technology is equal to today's. That said, Any internal combustion engine is nothing more than a pump, 454 cubic inches will only pump in and out so many cubic feet of air at a given rpm (normally aspirated) even given better BSFC and intake Mach number, there is a limit called peak volumetric efficiency. Therefore, exhaust diameter and length has the basically same effect on a "68 Hemi or a 427 LSX. Just because you liked the way your buddy's engine sounded to you with 3" exhaust rather than 2.5" has absolutely no bearing on performance. Before you pull your **** out and step on it again, I've been building engines for 50 years and have made the effort to educate myself on what makes them work. Wizzo, Like I said, don't believe everything you read on the web, any of the aftermarket exhaust manufacturers will be glad to tell anyone what will work best on a particular combination based on mathematical calculations and actual dyno results. They're called engineers for a reason.

Big Rich for the Win! :woot:

98sierra · Jul 8, 2011

doctordick, "my buddy.." thinks you should go crawl back into TC's ball sack :tc

doctordick · Jul 9, 2011

The personal attack, always the refuge of a small mind. By the way, who's TC?

CheapJ7 · Jul 9, 2011

98sierra said:
doctordick, "my buddy.." thinks you should go crawl back into TC's ball sack

Haha, you have no clue who this is do you?

BamaTJ · Jul 9, 2011

The dynomax race bullets are very damn loud. They sound damn good when your in the gas. For a nice throaty sound but is not overly loud, go magna flow round style. If you want loud and nasty, go dynomax.