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12-30-2018, 12:41 AM
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#1 |
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Registered User
Join Date: Jan 2010
Location: Here
Posts: 5,411
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327 exhaust pipe size
I have a 1967 327 300hp I'm going to have completely rebuilt for my short bed 67 truck. May do a roller cam but it will stay close to stock. It's an 400 auto, gear vendors 3:55 rear so it won't be a really high spinner. I have a set of Vette 2.5" ramhorns and my exhaust guy recommended I use them (he says he can make the tight bend work off the manifolds) and do full 2.5" exhaust. Now my question is will this hurt the engines performance? This is a full frame off new build so the exhaust will be new stainless steel mandrel bent. If the stock ones with 2.25" would be better I'd rather do what's right 1st time around. No towing or racing, just a cruiser.
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12-30-2018, 12:58 AM
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#2 |
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Senior Member
 
Join Date: Jan 2001
Location: Orem, Utah
Posts: 7,794
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Re: 327 exhaust pipe size
Free flowing exhaust is not going to hurt performance.
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I have sworn upon the altar of God, eternal hostility against every form of tyranny over the mind of man. - Thomas Jefferson |
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12-30-2018, 08:25 PM
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#3 |
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Fabricate till you "puke"
Join Date: Jun 2002
Location: Ill
Posts: 9,403
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Re: 327 exhaust pipe size
I would go 2 1/2, all the way out back....add an H-pipe to the system, to help with low/mid tork & it will also take the sharp rapp off the duel pipes
 Best of fun....Longhorn
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69 longhorn,4" chop,3/5 drop, 1/2 ton suspension/disc brakes,1 1/2" body drop,steel tilt clip, 5.3/Edelbrock rpm intake/600 carb, Hooker streetrod shorties,2 1/2" exhaust/ H pipe/50's Flows , 6 spd Richmond trans,12 bolt/ 3.40 gears.... |
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12-31-2018, 12:36 AM
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#4 |
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Registered User
Join Date: Jan 2010
Location: Here
Posts: 5,411
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Re: 327 exhaust pipe size
Yes he said put an H or X pipe as well. Ok. I just heard that may hurt my down low torque but if it's not a big issue I'll just go with 2.5s all the way thru! Thanks.
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12-31-2018, 09:49 AM
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#5 |
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Registered User
Join Date: Jan 2000
Location: Wyoming USA
Posts: 2,445
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Re: 327 exhaust pipe size
Wont hurt a thing to run either 2.25 or 2.50 don't think you could tell a difference in either with or without a balance pipe besides sound wise. Seat of the pants dyno says you wont but if you put it on a real dyno you will see it on paper then. JUST MY OPINION
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2001 Silverado K-1500 2005 FXDWG stage3 69 CHEVY Short/Step 327/4L60 373 posi 63 IMPALA 327 |
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12-31-2018, 03:14 PM
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#6 |
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driving is in my blood
Join Date: Dec 1999
Location: Mesa AZ
Posts: 5,691
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Re: 327 exhaust pipe size
They put dual 2.5" exhaust on little 4.0L v8's oem these days, you want at least that with a 5.3L.
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-78 c10 short/step: 388cid, M20, 5/5 drop, lots more. Playtoy and first vehicle. -98 c1500 x-cab: 5.7L, 17" rims, 5/6 drop, flowmaster, helper bags,NBS rear disk brakes. -02 Suburban 4x4: leveled front -CBR600F4i, CBR600RR, CBR1000RR, and standup skis DISCLAIMER: I cant spell for the life of me. |
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12-31-2018, 07:21 PM
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#7 | |
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Senior Member
Join Date: Jan 2001
Location: Orem, Utah
Posts: 7,794
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Re: 327 exhaust pipe size
Quote:
Where tube size does matter is in building headers - you need an appropriate size for proper scavenging. With rams horns, you're fine to run 2.5 and you won't suffer any loss of torque.
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I have sworn upon the altar of God, eternal hostility against every form of tyranny over the mind of man. - Thomas Jefferson |
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01-01-2019, 04:07 AM
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#8 |
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Registered User
Join Date: Jan 2014
Location: Indpls. , IN
Posts: 797
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Re: 327 exhaust pipe size
2.5" headpipes to 2.5" "H-pipe" and 2.5" mufflers then you can drop to 2.25" out thru the tailpipes without a loss. 327, 350 , or small cam 400. Just a suggestion, I built alot of my exhausts in alot of yrs, racecars (2.5" ramhorns) to muscle cars & worktrucks (headers).
Mandrel bends only !
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Tim K. 84 K30 srw Silverado 454 auto 85 C20 350 C6P auto flatbed 94 K1500 lifted shortbed 350 4 bbl NV4500 Last edited by 68post; 01-01-2019 at 04:17 AM. Reason: yes |
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01-10-2019, 01:58 PM
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#9 | |
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driving is in my blood
Join Date: Dec 1999
Location: Mesa AZ
Posts: 5,691
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Re: 327 exhaust pipe size
Quote:
__________________
-78 c10 short/step: 388cid, M20, 5/5 drop, lots more. Playtoy and first vehicle. -98 c1500 x-cab: 5.7L, 17" rims, 5/6 drop, flowmaster, helper bags,NBS rear disk brakes. -02 Suburban 4x4: leveled front -CBR600F4i, CBR600RR, CBR1000RR, and standup skis DISCLAIMER: I cant spell for the life of me. |
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01-10-2019, 04:09 PM
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#10 | |
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Registered User
Join Date: Jan 2014
Location: Indpls. , IN
Posts: 797
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Re: 327 exhaust pipe size
Quote:
It can help maintain a little more velocity and be easier to find tailpipes (should cost less too).
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Tim K. 84 K30 srw Silverado 454 auto 85 C20 350 C6P auto flatbed 94 K1500 lifted shortbed 350 4 bbl NV4500 |
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