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02-22-2009, 09:34 PM
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CC Member
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Join Date: Oct 2002
Location: Eagle,
Ne.
Cobra Make, Engine: 1966 Lone Star 427SC.
Posts: 4,310
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Not Ranked
Muffler size ?
I'm researching side pipes & mufflers. I have questions regarding muffler selection. By best friend Chad is a professional mechanic with his own shop, has a Mustang chassis dyno and we race sprint cars together.
He believes the 3" from Classic Chambered is too small for a engine that KC will be building for me. It will be a Pond aluminum and Edelbrock stage 2 heads alum. heads., with apx. 630-650 HP. The only 3.5" muffler I've seen is the Howe, but the problem is excessive noise. I do like the cobra fairy loud but, I don't want to piss off neighbors, getting nasty looks from other drivers, and MY wife, not wanting to ride in it. lol
We figure the 3" may restrict the flow, with this much HP & TQ.
So, how do I determine the needed size muffler with HP/TQ ratings ?
__________________
Regards,
Kevin
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02-23-2009, 01:39 AM
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CC Member
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Join Date: May 2001
Location: California,
Ca
Cobra Make, Engine: NAF 289 Slabside Early Comp Car with 289 Webers and all the goodies. Cancelling the efforts of several Priuses
Posts: 6,592
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Not Ranked
If the neighbors peek out he curtains when it's running, then their just about right. Otherwise they are too small.
__________________
Rick
As you slide down the Banister of Life, may the splinters never be pointing the wrong way 
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02-23-2009, 02:37 AM
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CC Member
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Join Date: May 2002
Location: Ashburton, New Zealand,
..
Cobra Make, Engine: UK Ram SC. KC-Yates 373, Jerico 5 speed.
Posts: 1,240
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Not Ranked
Muffler size
FUNFER2,
I am going through the same decision for my KC Yates 373 SBF which has similar hp to your engine, peaks on the dyno at around 7000rpm. I have a real nice merge collector which necks down to 3" and then back up to 3.5" I was intending on 3" perf tube stainless packed mufflers, which should be big enough I guess the only way is to find out on the dyno buts thats a hassle!
Apparently grouping several 4-5 small perforated tubes inside the main perf tube quietens them down significantly, so 3.5" main tube should work good but it may mean going to a 4.5" muffler case,to get a reasonable amount of stainless packing and space.
Quote:
Originally Posted by FUNFER2
I'm researching side pipes & mufflers. I have questions regarding muffler selection. By best friend Chad is a professional mechanic with his own shop, has a Mustang chassis dyno and we race sprint cars together.
He believes the 3" from Classic Chambered is too small for a engine that KC will be building for me. It will be a Pond aluminum and Edelbrock stage 2 heads alum. heads., with apx. 630-650 HP. The only 3.5" muffler I've seen is the Howe, but the problem is excessive noise. I do like the cobra fairy loud but, I don't want to piss off neighbors, getting nasty looks from other drivers, and MY wife, not wanting to ride in it. lol
We figure the 3" may restrict the flow, with this much HP & TQ.
So, how do I determine the needed size muffler with HP/TQ ratings ?
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__________________
A J. Newton
The 1960's rocked!
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02-23-2009, 05:21 AM
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Senior Club Cobra Member
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Join Date: Jan 2004
Location: McAlester,
Ok
Cobra Make, Engine: Lonestar LS427, Keith Craft 496 Genesis, 649 hp, 668 ft-lb, TKO-600, Dynatek Stack EFI
Posts: 204
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Not Ranked
Kevin
I have the 3.5" Howe's with a 496 c.i. KC, 650ish and don't thinks it's overly loud, but do have the outlets turned down slightly.
Here's the scoop
KC Engine dyno: 649 hp, 668 trq
Stock LS exhaust
2" headers
1.75" J-pipes
3" collectors
LS mufflers ?size
3" outlets
Chassis dyno: 427 rwhp, 415 rwtrq
Exhaust #1
2" headers
2" j-pipes
3.5" collectors
4" x 24" Lobek Auger Mufflers, don't remember auger size
3.5" outlets
Chassis Dyno: 506 rwhp, 535 rwtrq
Current Exhaust
2" headers
2" j-pipes
3.5" x 3" x 3.5" Merge Collectors
4" x 24" Howe Racing Mufflers (3.5" I.D.)
3.5" outlets
Chassis Dyno: 519 rwhp, 541 rwtrq
Brad W.
PS: Added photo to gallery that shows the current setup
__________________
A good friend will come and bail you out of jail...but, a true friend will be sitting next to you saying, "Damn...that was fun!"
Last edited by 2KWIK4U; 02-23-2009 at 05:48 AM..
Reason: more info
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02-23-2009, 06:03 AM
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Senior Club Cobra Member
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Join Date: Jan 2004
Location: McAlester,
Ok
Cobra Make, Engine: Lonestar LS427, Keith Craft 496 Genesis, 649 hp, 668 ft-lb, TKO-600, Dynatek Stack EFI
Posts: 204
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Not Ranked
BTW
John Ross has an LS with a 482 KC and Howe's, but had the mufflers turned around backwards with the outlets straight out and it's way louder than mine. By far the loudest Cobra I've ever heard.
Brad
__________________
A good friend will come and bail you out of jail...but, a true friend will be sitting next to you saying, "Damn...that was fun!"
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02-23-2009, 10:06 AM
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CC Member
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Join Date: Oct 2002
Location: Eagle,
Ne.
Cobra Make, Engine: 1966 Lone Star 427SC.
Posts: 4,310
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Not Ranked
Brad, please email me your number, I would appreciate talking with you.
And, I'll PM/email you my number.
__________________
Regards,
Kevin
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02-23-2009, 10:12 AM
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CC Member
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Join Date: Oct 2002
Location: Eagle,
Ne.
Cobra Make, Engine: 1966 Lone Star 427SC.
Posts: 4,310
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Not Ranked
A.J- what brand of collector do you have ?
__________________
Regards,
Kevin
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02-23-2009, 10:43 AM
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Senior Club Cobra Member
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Join Date: Oct 2006
Location: Orange Park,
FL.
Cobra Make, Engine: n/a
Posts: 1,596
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Not Ranked
One 3" mandrel bent pipe is good for 500hp according to IMCO EXHAUST out of Texas.They are one of the largest manufacturers of exhaust.....i2f
__________________
20mph is not fast, unless you are doing it in a 3/2, 1000sq. ft. house on 10 ft. waves! 
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02-23-2009, 10:48 AM
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CC Member
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Join Date: Oct 2002
Location: Eagle,
Ne.
Cobra Make, Engine: 1966 Lone Star 427SC.
Posts: 4,310
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Not Ranked
I'll be over 600 hp. I"ll try and find their website.
__________________
Regards,
Kevin
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02-23-2009, 11:01 AM
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6th Generation Texan
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Join Date: Feb 2002
Location: Devil's Backbone,RR 32,
TX
Cobra Make, Engine: Lone Star Classics #240,Candy Apple Red,Keith Craft 418w - 602 HP,584 TQ
Posts: 8,157
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Not Ranked
As far as ability of an exhaust system to flow enough air for a given amount of horsepower without causing significant back pressure, this is from one of David Vizard's books:
1. For avoiding significant restriction from back pressure, the pipe should flow at least 2.2CFM per horsepower produced.
2. A straight pipe will flow ~115CFM per square inch of area (using inside diameter of the pipe)
Here is some info on Primary tubing size...
http://victorylibrary.com/mopar/header-tech-c.htm |
02-23-2009, 11:05 AM
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6th Generation Texan
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Join Date: Feb 2002
Location: Devil's Backbone,RR 32,
TX
Cobra Make, Engine: Lone Star Classics #240,Candy Apple Red,Keith Craft 418w - 602 HP,584 TQ
Posts: 8,157
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Not Ranked
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02-23-2009, 11:43 AM
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CC Member
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Join Date: Oct 2002
Location: Eagle,
Ne.
Cobra Make, Engine: 1966 Lone Star 427SC.
Posts: 4,310
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Not Ranked
Very interesting. It's incredible, that increasing the diameter as little as
1/8" can make that much of a difference.
Thank you for the links !
__________________
Regards,
Kevin
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