| 3.5 inch exhaust??? [message #103680] |
Thu, 21 October 2010 11:23  |
g.winger
Messages: 792
Registered: February 2008
Location: Warrenton,Missouri
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Any body thought about it?? Any one try it. 3"=7sq.in. area. 3.5"= 9.3sq. in. area. Pretty big increase percentage wise. Would only need .25 inch bigger hole, 1/4 inch all the way around of course.??????,,,,PL
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| Re: 3.5 inch exhaust??? [message #103682 is a reply to message #103680] |
Thu, 21 October 2010 12:16  |
Keith V
Messages: 2337
Registered: March 2008
Location: Mounds View,MN
Karma: 0
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| g.winger wrote on Thu, 21 October 2010 11:23 |
Any body thought about it?? Any one try it. 3"=7sq.in. area. 3.5"= 9.3sq. in. area. Pretty big increase percentage wise. Would only need .25 inch bigger hole, 1/4 inch all the way around of course.??????,,,,PL
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Not even close to worth it.
2.5" is plenty, 3" is overkill.
Keith Vasilakes
Mounds View. MN
75 ex Royale GMC
ask me about MicroLevel
Cell, 763-732-3419
My427v8@hotmail.com
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| Re: 3.5 inch exhaust??? [message #103704 is a reply to message #103680] |
Thu, 21 October 2010 17:07 |
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Here is a major consideration. The 3" exhaust will fit through the existing holes in the cross members along the RH side. 3 1/2" will not fit.
I have the 3" - I don't know if it improves performance or not but I grew up adopting the philosophy that if a little bit is good then too much is just enough. But 3 1/2"? I'd say it isn't worth the hassle.
Bill Brown - '77 Buckeye Cruiser
Coshocton OH
carguybill@sbcglobal.net
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| Re: [GMCnet] 3.5 inch exhaust??? [message #103720 is a reply to message #103684] |
Thu, 21 October 2010 19:58 |
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mike miller
Messages: 3576
Registered: February 2004
Location: Hillsboro, Oregon
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| KRDietz wrote on Thu, 21 October 2010 10:22 |
... You won't increase the mileage. You probably won't have a
noticeable increase in power. You WILL get a louder exhaust. ...
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From all my reading (and not much experience) I even question a 3" all the way to the rear. Seems you CAN have to large of an exhaust for "torque proposes." It has something to do with "exhaust scavenging." Exhaust in a long "too large" pipe cools and contracts... slowing down in the pipe. (Note that a 3 inch exhaust DOES increase horse power a small but measurable amount.)
How do you know if your pipe is to large/small for your installation? I have read about spraying paint (regular, non-high temp) in places on your exhaust. Where it burns off you could use a larger pipe. NOTE THAT I haven't tried this... and it might not be that accurate near the engine.
BUT
I do have experience with the loader exhaust. Two of my coaches have 3 inch exhausts (and 455's) and one has 2.5 inch (and a 403). The "3 inch" coaches are MUCH louder... but I am not sure if the exhaust size is the ONLY reason.
Mike Miller -- Hillsboro, OR -- on the Black list
(#2)`78 23' Birchaven Rear Bath -- (#3)`77 23' Birchaven Side Bath
More Sidekicks than GMC's and a late model Malibu called 'Boo'
http://m000035.blogspot.com
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| Re: 3.5 inch exhaust??? [message #103788 is a reply to message #103742] |
Fri, 22 October 2010 12:13 |
roy1
Messages: 2126
Registered: July 2004
Location: Minden nevada
Karma: 6
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Thanks Scott that confirms my thoughts on the Walker Dynomax mufflers I have been running for the past 20 years. I always felt they were pretty good and also not too loud at a reasonable cost. It's good to see a test showing all of this.
Roy
Roy Keen
Minden,NV
76 X Glenbrook
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