2.5" or 3" exhaust on 72 Blazer - The 1947 - Present Chevrolet & GMC Truck Message Board Network

raptorgta · 08-19-2005, 12:40 AM

I'm trying to find out what would be my best option for an exhaust on my 72 4x4 blazer. Right now it has a 4" lift but I'm planning on putting an 8" on in the future. My question is can you run a 3" exhaust under it without hurting ground clearance? Or would I just be better off running a 2.5". Thanks

k-20 · 08-19-2005, 04:03 AM

i dont think 1/2'' is going to cxause you any trouble.

Mike C · 08-19-2005, 07:41 AM

Unless you are going for 500+ horsepower, the 2 1/2" will be easier to run and MUCH easier on your wallet.

raptorgta · 08-19-2005, 07:31 PM

Thanks for the replys. I don't think I'm anywhere close to 500 HP. I think I will go with the 2.5" I am also thinking about using the dynomax bullet mufflers. I know they will be loud but I only drive the blazer a few times a month.

Mike C · 08-19-2005, 10:45 PM

I have the Dynomax Hemi Turbos on my JImmy. They are NOT loud and still make good power, call me old, but powerful, high-flow AND quiet is where it's at. Ands at $40 each, affordable.

Russell · 08-20-2005, 01:51 AM

I have 2.5" on my truck, and they are a bit too big in my opinion. I put 2.25" on my 74, and she sounded real good. The 2.5" just sounds a bit too airy, while the 2.25 had a real crisp bark. Very nice

see ten · 08-20-2005, 06:58 AM

I have 2.5" to the muffler and 3" from the muffler on back. It sounds pretty aggressive I think. I had already tried 2.5" tailpipes and the turndowns before I settled with this.

raptorgta · 08-20-2005, 12:15 PM

That is a nice truck. I hope my Blazer will look that nice when I'm done with it. Thanks for all the replys. I kind of like the idea of going 3" after the mufflers.

Mike C · 08-21-2005, 09:18 AM

If you are going to do 3", no gain behind the mufflers. The gases cool as they go front to rear and take up less volume past the mufflers. 3" in and 2.5" out is probably the best power/noise trade off. And usuallay fewer bends from motor to mufflers than mufflers out the back. BUT it depends on a ton of other things like total exhaust length, total air flow (horsepower), driving style, cam design, etc.

See Ten has it right, though. You should turn the pipes and run out the side. A REAL 4x4 never has big giant chrome baloneys sticking straight out the back. When you have to rock forward and backwards to get out of a big stick you end up packing the exhaust with water and mud!

08-19-2005, 12:40 AM	#1
raptorgta Registered User Join Date: Apr 2004 Posts: 12	2.5" or 3" exhaust on 72 Blazer I'm trying to find out what would be my best option for an exhaust on my 72 4x4 blazer. Right now it has a 4" lift but I'm planning on putting an 8" on in the future. My question is can you run a 3" exhaust under it without hurting ground clearance? Or would I just be better off running a 2.5". Thanks

08-19-2005, 07:41 AM	#3
Mike C Registered User Join Date: Dec 1999 Location: Austin, TX, USA Posts: 7,715	Unless you are going for 500+ horsepower, the 2 1/2" will be easier to run and MUCH easier on your wallet. __________________ 44 Willys MB 52 M38A1 64 Corvette Coupe 68 Camaro 'vert LT1 & TH700 69 Z/28 355 12.6's @110 69 Chevy Short Step 4 1/2"/7" drop 72 Jimmy 4WD 4spd 4" & 35's 02 GMC 2500HD 4x4 Duramax

08-19-2005, 10:45 PM	#5
Mike C Registered User Join Date: Dec 1999 Location: Austin, TX, USA Posts: 7,715	I have the Dynomax Hemi Turbos on my JImmy. They are NOT loud and still make good power, call me old, but powerful, high-flow AND quiet is where it's at. Ands at $40 each, affordable. __________________ 44 Willys MB 52 M38A1 64 Corvette Coupe 68 Camaro 'vert LT1 & TH700 69 Z/28 355 12.6's @110 69 Chevy Short Step 4 1/2"/7" drop 72 Jimmy 4WD 4spd 4" & 35's 02 GMC 2500HD 4x4 Duramax

08-20-2005, 01:51 AM	#6
Russell Professional Grade Join Date: May 2003 Location: Fort McMurray, Alberta Posts: 7,915	I have 2.5" on my truck, and they are a bit too big in my opinion. I put 2.25" on my 74, and she sounded real good. The 2.5" just sounds a bit too airy, while the 2.25 had a real crisp bark. Very nice __________________ 1995 Chevrolet 2 Door Tahoe (6.6L LBZ Duramax / ZF6 / NP241 with 1 ton solid axle swap)

08-21-2005, 09:18 AM	#9
Mike C Registered User Join Date: Dec 1999 Location: Austin, TX, USA Posts: 7,715	If you are going to do 3", no gain behind the mufflers. The gases cool as they go front to rear and take up less volume past the mufflers. 3" in and 2.5" out is probably the best power/noise trade off. And usuallay fewer bends from motor to mufflers than mufflers out the back. BUT it depends on a ton of other things like total exhaust length, total air flow (horsepower), driving style, cam design, etc. See Ten has it right, though. You should turn the pipes and run out the side. A REAL 4x4 never has big giant chrome baloneys sticking straight out the back. When you have to rock forward and backwards to get out of a big stick you end up packing the exhaust with water and mud! __________________ 44 Willys MB 52 M38A1 64 Corvette Coupe 68 Camaro 'vert LT1 & TH700 69 Z/28 355 12.6's @110 69 Chevy Short Step 4 1/2"/7" drop 72 Jimmy 4WD 4spd 4" & 35's 02 GMC 2500HD 4x4 Duramax

08-19-2005, 04:03 AM	#2
k-20 Registered User Join Date: Jan 2005 Location: tasmania.australia Posts: 170	i dont think 1/2'' is going to cxause you any trouble.

08-19-2005, 07:31 PM	#4
raptorgta Registered User Join Date: Apr 2004 Posts: 12	Thanks for the replys. I don't think I'm anywhere close to 500 HP. I think I will go with the 2.5" I am also thinking about using the dynomax bullet mufflers. I know they will be loud but I only drive the blazer a few times a month.

08-20-2005, 06:58 AM	#7
see ten WTB this ad Join Date: Sep 2004 Location: Lafayette Georgia Posts: 5,073	I have 2.5" to the muffler and 3" from the muffler on back. It sounds pretty aggressive I think. I had already tried 2.5" tailpipes and the turndowns before I settled with this.

08-20-2005, 12:15 PM	#8
raptorgta Registered User Join Date: Apr 2004 Posts: 12	That is a nice truck. I hope my Blazer will look that nice when I'm done with it. Thanks for all the replys. I kind of like the idea of going 3" after the mufflers.



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