Exhaust Pipe SIZE? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

elks · 02-14-2013, 02:54 PM

So I am running a pretty build 350. Has intakes, cam, worldproducts head, etc. The headers are flotechs with a 3" collector. I am running dual exhaust out the back and probably looking a super 40s, or the likes. But I am not sure if I should run 2 1/2 pipes etc. or 3"pipes.

I want a good throaty type of sound and have set the motor up for more low end power/pull.

Just not sure what size to run out...

CC69Rat · 02-14-2013, 03:32 PM

2.5 would be fine.. Just my opinion. Have you looked into an X pipe ? Talk about a wicked sound. Have you ever heard the old Sterling Marlin #4 Kodak Nascar from the late 90's ? .. I don't know how to describe it but it would sound very unique.

You'll lose a little off the line if you run 3" just from back pressure .. but 3" would out flow 2.5" on the higher rpm range. It just depends on your plans for it IMO.

96blazr · 02-14-2013, 03:45 PM

Quote:

Originally Posted by elks

So I am running a pretty build 350. Has intakes, cam, worldproducts head, etc. The headers are flotechs with a 3" collector. I am running dual exhaust out the back and probably looking a super 40s, or the likes. But I am not sure if I should run 2 1/2 pipes etc. or 3"pipes.

I want a good throaty type of sound and have set the motor up for more low end power/pull.

General rule of thumb is: anything less than 400HP it would be best using 2 1/2". Anything above 450HP you could use 3".
I would like to recommend you look into Hooker Aerochamber Mufflers. They sound REALLY good. I have a set on my truck and I have 320HP and they sound BETTER then Flowcrappers.

AirSpeed · 02-14-2013, 04:03 PM

I can't help you with the performance end but I have flowmaster 40s on my truck with a stock 350 and 2.5" pipes and it sounds really nice, it's a very mechanical sound (if that makes any sense), it sounds like its got more of an engine than it does and I have people asking me all the time what I did to the engine.
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Zoomin · 02-14-2013, 04:04 PM

For low end, definitely 2-1/2.

**Ol Blue K20** · 02-14-2013, 04:10 PM

Quote:

Originally Posted by Zoomin

For low end, definitely 2-1/2.

x2

1970 C10 MJW · 02-14-2013, 04:16 PM

I HATE MY FLOWMASTER!! it costs almost as much as a borla for my dual in dual out thats on my 97 as a borla dual in dual out, and the flowmaster is always giving me headaches, and it seems to be getting louder, like its breaking down inside, and its only about 18 months old, and I drive almost 20 miles each way to work everyday so its not from too much moisture build up, borla and dynomax are my two favorites by far!!!

AirSpeed · 02-14-2013, 04:20 PM

Do you guys know if an X or H pipe make any difference as far as perfomance, mileage or sound? I've heard mixed opinions and was wondering if I'll notice anything real?
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OTIS HURTS · 02-14-2013, 04:20 PM

agree on the 2 1/2

**dennislbrooks** · 02-14-2013, 07:49 PM

I am sold on at least an H pipe. It evened out the sound thru the Flowmaster 50's. From what I hear a xover is even better. Guys on this forum suggested it to me to give a better more even sound and it did. I have 2 1/2 from short headers to the 50's in front of the axle with 2 1/2 inch back to the bumper. I welded in a 2" crossover at the end of my 208 transfer case --- it can be removed without dropping exhaust. if I redo will use a 2 1/2 inch H pipe but not sure it would make a diff. I run a 268 cam in my 350.

brad_man_72 · 02-14-2013, 08:07 PM

Quote:

Originally Posted by elks

So I am running a pretty built 350. Has intakes, cam,....

I hope its fully built, they don't run very good when they are missing parts. Maybe trade one of those intakes for some connecting rods.

I prefer the sound of 3" myself.
After having flowtech headers on my sbc I would recomend anything else they didn't even come close to fitting and the ceramic coating was so thin that they rusted within 6 months.

Be sure to have the exhaust shop run the exhaust through the frame, you don't want that stuff hanging down.
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**70cst** · 02-14-2013, 08:22 PM

2 1//2 is what I'm using with my 402

CC69Rat · 02-14-2013, 08:51 PM

Have you considered Magnaflow? Maybe some of the longer round ones?
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69GWC · 02-14-2013, 09:04 PM

I have Magnaflows on my 06 sounds better the flowmaster I put on it first go around.
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big mike71 · 02-14-2013, 09:43 PM

Everyone bags on flowmasters, I have headers, H-pipe and flowmaster 40's and I think my truck sounds good.

cubber · 02-15-2013, 01:02 AM

383 stroker, shorty headers, 2.5 pipe into 3 inch JEGS mufflers with turndowns.

http://www.youtube.com/watch?v=OpUICoZ8oL8

luvbowties · 02-15-2013, 01:27 AM

Quote:

Originally Posted by elks

So I am running a pretty build 350. Has intakes, cam, worldproducts head, etc. The headers are flotechs with a 3" collector. I am running dual exhaust out the back and probably looking a super 40s, or the likes. But I am not sure if I should run 2 1/2 pipes etc. or 3"pipes.

I want a good throaty type of sound and have set the motor up for more low end power/pull.

Just not sure what size to run out...

The smaller pipes should definitely give you more torque in the lower RPM range. In my experience even 2 1/4" sounds and feels better on a mildly built 350 than a bigger pipe in the useful, daily driving ranges. Another thing, if you run pipes to the rear, the smaller ones can produce much neater bends plus give better clearances. Again, just my experiences!

CC69Rat · 02-15-2013, 10:56 AM

New one to consider. Spin Tech

Big Block Chevelle w/ Spin Tech mufflers & X...

original-71 · 02-15-2013, 11:03 AM

Quote:

Originally Posted by CC69Rat

New one to consider. Spin Tech

Big Block Chevelle w/ Spin Tech mufflers & X pipe - YouTube

wish my alarm clock sounded like that

CC69Rat · 02-15-2013, 11:31 AM

Cell phone ring tone maybe? Just the idle..

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Lattimer · 02-15-2013, 11:47 AM

I went 2-1/4 behind my 327. I have long tube headers, a short pipe to a Flow Tech muffler on each side, the the pipe turns out in front of the wheels. I'm about to add in some resonators to tone it down some. Has a good tone but just too loud in the cab.

**TBONE1964** · 02-15-2013, 12:06 PM

http://www.angelfire.com/my/fan/Exhaust_Pipe_Size.htm

There are many web sites with exhaust caculators and I attached one for you.

As others have mentioned, to get optimum power, you need to consider back pressure. If your pipes are to big, it is like blowing air into a bag that has a hole in it, it does nothing. The 3 inch stuff looks and may even sound good but it kills low end throttle response.

As the chart shows, 2 1/4 is the best for a dual with 400 hp. Also consider the price of the pipe as the bigger the ID the more it cost.

**70cst** · 02-15-2013, 02:10 PM

Quote:

Originally Posted by CC69Rat

New one to consider. Spin Tech

Big Block Chevelle w/ Spin Tech mufflers & X pipe - YouTube

That is what I am using.

c10srule · 02-15-2013, 03:19 PM

2 1/4 is good to 400 hp, 2 1/2 is good to 500 hp, then you need to go 3", i put 2 1/2 pipes with stainless glass packs on my wifes with a 375 hp vortech head 350 and she won the rackoff contest, we did the same setup on our boys with 2 1/4s and it was pretty loud and sounded pretty good as well, now ive got 3" on mine with summit mufflers 30 degree bend with 4 1/2 stainless tips in front of my rear tires but it has a 580 hp 477 and im telling you its really loud, but it sure sounds good,

02-14-2013, 02:54 PM	#1
elks Registered User Join Date: Mar 2009 Location: NW, Colorado Posts: 285	Exhaust Pipe SIZE? So I am running a pretty build 350. Has intakes, cam, worldproducts head, etc. The headers are flotechs with a 3" collector. I am running dual exhaust out the back and probably looking a super 40s, or the likes. But I am not sure if I should run 2 1/2 pipes etc. or 3"pipes. I want a good throaty type of sound and have set the motor up for more low end power/pull. Just not sure what size to run out... __________________ Confidence is the feeling we have before we fully comprehend the situation

02-14-2013, 03:32 PM	#2
CC69Rat Registered User Join Date: Jan 2011 Location: Chattanooga TN Posts: 6,208	Re: Exhaust Pipe SIZE? 2.5 would be fine.. Just my opinion. Have you looked into an X pipe ? Talk about a wicked sound. Have you ever heard the old Sterling Marlin #4 Kodak Nascar from the late 90's ? .. I don't know how to describe it but it would sound very unique. You'll lose a little off the line if you run 3" just from back pressure .. but 3" would out flow 2.5" on the higher rpm range. It just depends on your plans for it IMO. __________________ Chad 1967 C10 SWB - Project Savannah - 6.0/4L80 Currently underway 1968 C10 SWB - TOTY 2018, 50th Anniversary Tribute Project * Sold * Pride and Joy 1986 Silverado Short Fleet - Scarlet Sold 1985 Silverado Short Fleet Sold 2022 Jeep Gladiator Mojave 2001 Jeep Cherokee XJ 4x4 - Lifted, Built 1992 Jeep Cherokee XJ 4x4 - Lifted 2013 Honda Accord EX-L v6 Coupe 6spd (wife's ride)

02-14-2013, 04:04 PM	#5
Zoomin Man of Mini-Talents Join Date: Sep 2009 Location: Oklahoma City, OK Posts: 4,295	Re: Exhaust Pipe SIZE? For low end, definitely 2-1/2. __________________ Steve Project - Ruth 66 Skylark Project - Lola 60 Biscayne Project - Iron Ox 54 GMC 100 Project - Darth 69 Camaro

02-14-2013, 04:16 PM	#7
1970 C10 MJW Registered User Join Date: Aug 2012 Location: Indiana Posts: 470	Re: Exhaust Pipe SIZE? I HATE MY FLOWMASTER!! it costs almost as much as a borla for my dual in dual out thats on my 97 as a borla dual in dual out, and the flowmaster is always giving me headaches, and it seems to be getting louder, like its breaking down inside, and its only about 18 months old, and I drive almost 20 miles each way to work everyday so its not from too much moisture build up, borla and dynomax are my two favorites by far!!! __________________ 70 C10 working on a LSx swap 4.8L MS3 edelbrock pro flo intake, pacesetter long tubes, 4l60e 2500 stall hoping the tranny holds up lol Last edited by 1970 C10 MJW; 02-14-2013 at 04:17 PM. Reason: clarifying my statement

02-14-2013, 04:20 PM	#8
AirSpeed Registered User Join Date: Jul 2007 Location: Fall River California Posts: 2,026	Re: Exhaust Pipe SIZE? Do you guys know if an X or H pipe make any difference as far as perfomance, mileage or sound? I've heard mixed opinions and was wondering if I'll notice anything real? Posted via Mobile Device __________________ http://smg.photobucket.com/albums/v655/aaronhero/

02-14-2013, 04:03 PM	#4
AirSpeed Registered User Join Date: Jul 2007 Location: Fall River California Posts: 2,026	Re: Exhaust Pipe SIZE? I can't help you with the performance end but I have flowmaster 40s on my truck with a stock 350 and 2.5" pipes and it sounds really nice, it's a very mechanical sound (if that makes any sense), it sounds like its got more of an engine than it does and I have people asking me all the time what I did to the engine. Posted via Mobile Device __________________ http://smg.photobucket.com/albums/v655/aaronhero/

02-14-2013, 04:20 PM	#9
OTIS HURTS Registered User Join Date: Dec 2012 Location: TN Posts: 31	Re: Exhaust Pipe SIZE? agree on the 2 1/2

02-14-2013, 07:49 PM	#10
dennislbrooks Senior Member Join Date: Feb 2004 Location: Williamsburg, Ohio Posts: 1,766	Re: Exhaust Pipe SIZE? I am sold on at least an H pipe. It evened out the sound thru the Flowmaster 50's. From what I hear a xover is even better. Guys on this forum suggested it to me to give a better more even sound and it did. I have 2 1/2 from short headers to the 50's in front of the axle with 2 1/2 inch back to the bumper. I welded in a 2" crossover at the end of my 208 transfer case --- it can be removed without dropping exhaust. if I redo will use a 2 1/2 inch H pipe but not sure it would make a diff. I run a 268 cam in my 350.

02-14-2013, 08:22 PM	#12
70cst Senior Member Join Date: Feb 2001 Location: New Madison, Ohio Posts: 21,365	Re: Exhaust Pipe SIZE? 2 1//2 is what I'm using with my 402 __________________ A husband can be right...or...A husband can be happy. 67-72 Chevy and GMC Trucks...The Classic Truck for the Classic Folk. 1970 CST Two tone green, 402BB, 400 Automatic, Tach, Buckets, AC, AM-FM, Tilt, GM CB, GM 8 Tract, LWB, etc JOHN 17:3...The better side of "LIFE" Remember: Everyday is a good day...Some are just gooder!

02-14-2013, 08:51 PM	#13
CC69Rat Registered User Join Date: Jan 2011 Location: Chattanooga TN Posts: 6,208	Re: Exhaust Pipe SIZE? Have you considered Magnaflow? Maybe some of the longer round ones? Posted via Mobile Device __________________ Chad 1967 C10 SWB - Project Savannah - 6.0/4L80 Currently underway 1968 C10 SWB - TOTY 2018, 50th Anniversary Tribute Project * Sold * Pride and Joy 1986 Silverado Short Fleet - Scarlet Sold 1985 Silverado Short Fleet Sold 2022 Jeep Gladiator Mojave 2001 Jeep Cherokee XJ 4x4 - Lifted, Built 1992 Jeep Cherokee XJ 4x4 - Lifted 2013 Honda Accord EX-L v6 Coupe 6spd (wife's ride)

02-14-2013, 09:04 PM	#14
69GWC Registered User Join Date: Jun 2012 Posts: 1,089	Re: Exhaust Pipe SIZE? I have Magnaflows on my 06 sounds better the flowmaster I put on it first go around. Posted via Mobile Device

02-14-2013, 09:43 PM	#15
big mike71 Registered User Join Date: Mar 2009 Location: independence mo Posts: 2,111	Re: Exhaust Pipe SIZE? Everyone bags on flowmasters, I have headers, H-pipe and flowmaster 40's and I think my truck sounds good. __________________ I'm not as good as I once was, But I'm as good once as I ever was.

02-15-2013, 11:31 AM	#20
CC69Rat Registered User Join Date: Jan 2011 Location: Chattanooga TN Posts: 6,208	Re: Exhaust Pipe SIZE? Cell phone ring tone maybe? Just the idle.. Posted via Mobile Device __________________ Chad 1967 C10 SWB - Project Savannah - 6.0/4L80 Currently underway 1968 C10 SWB - TOTY 2018, 50th Anniversary Tribute Project * Sold * Pride and Joy 1986 Silverado Short Fleet - Scarlet Sold 1985 Silverado Short Fleet Sold 2022 Jeep Gladiator Mojave 2001 Jeep Cherokee XJ 4x4 - Lifted, Built 1992 Jeep Cherokee XJ 4x4 - Lifted 2013 Honda Accord EX-L v6 Coupe 6spd (wife's ride)

02-15-2013, 11:47 AM	#21
Lattimer Registered User Join Date: Jan 2013 Location: Mickleton, NJ Posts: 1,776	Re: Exhaust Pipe SIZE? I went 2-1/4 behind my 327. I have long tube headers, a short pipe to a Flow Tech muffler on each side, the the pipe turns out in front of the wheels. I'm about to add in some resonators to tone it down some. Has a good tone but just too loud in the cab. __________________ Shawn 1970 Chevy C-10 SWB, 350, TKO 600 5 speed My build http://67-72chevytrucks.com/vboard/s...d.php?t=559881

02-15-2013, 12:06 PM	#22
TBONE1964 Cluster King Join Date: Nov 2012 Location: Junction City, OR Posts: 5,263	Re: Exhaust Pipe SIZE? http://www.angelfire.com/my/fan/Exhaust_Pipe_Size.htm There are many web sites with exhaust caculators and I attached one for you. As others have mentioned, to get optimum power, you need to consider back pressure. If your pipes are to big, it is like blowing air into a bag that has a hole in it, it does nothing. The 3 inch stuff looks and may even sound good but it kills low end throttle response. As the chart shows, 2 1/4 is the best for a dual with 400 hp. Also consider the price of the pipe as the bigger the ID the more it cost.



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02-15-2013, 03:19 PM	#24
c10srule Registered User Join Date: Oct 2012 Location: oran,mo. Posts: 171	Re: Exhaust Pipe SIZE? 2 1/4 is good to 400 hp, 2 1/2 is good to 500 hp, then you need to go 3", i put 2 1/2 pipes with stainless glass packs on my wifes with a 375 hp vortech head 350 and she won the rackoff contest, we did the same setup on our boys with 2 1/4s and it was pretty loud and sounded pretty good as well, now ive got 3" on mine with summit mufflers 30 degree bend with 4 1/2 stainless tips in front of my rear tires but it has a 580 hp 477 and im telling you its really loud, but it sure sounds good,

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