Dual Exhaust ???
Thread Starter
Melting Slicks
Joined: Feb 2003
Posts: 2,330
Likes: 6
From: Long Island NY
Dual Exhaust ???
I'm planning on converting from the 2-Y's & cat, to true duals with no cats. 2 shops recommend 2 1/4" not 2 1/2" + 'H' pipe (I have a 4 spd). Because it's a low compression motor (motor will be kept stock). I see other guys went with 2 1/2". What do you think...
Race Director
Joined: Apr 1999
Posts: 11,520
Likes: 13
From: CORVETTE 77 385 C.I. TEXAS
Re: Dual Exhaust ??? (mvftw)
Yes, do it. See Why Exhaust is problem for HP on 75-81
what many refer to as my Exhaust topic. http://www.corvettefaq.com/c3/ganeyexhaust.htm
Some ex. pipe size guidelines. You want flow not turbulance.
DUALS
2" .... 200 BHP
2.25" 320 BHP
2.5 .. 400 BHP
3.0 .. 600 BHP
what many refer to as my Exhaust topic. http://www.corvettefaq.com/c3/ganeyexhaust.htm
Some ex. pipe size guidelines. You want flow not turbulance.
DUALS
2" .... 200 BHP
2.25" 320 BHP
2.5 .. 400 BHP
3.0 .. 600 BHP
Race Director
Joined: Jul 2002
Posts: 13,858
Likes: 0
From: A 12/8 man in a 4/4 world
Re: Dual Exhaust ??? (Ganey)
Gainey,
Thanks for the numbers. My father and I put Headers and dual exhausts on back in 1980. 23 years and the custom bend work is showing its age. Indesisive on what to do with exhaust. but think now ill keep headers and dual exhaust. the ceramic coated ones sound cool (pun intended)
Thanks for the numbers. My father and I put Headers and dual exhausts on back in 1980. 23 years and the custom bend work is showing its age. Indesisive on what to do with exhaust. but think now ill keep headers and dual exhaust. the ceramic coated ones sound cool (pun intended)
Le Mans Master
Joined: Sep 2000
Posts: 6,036
Likes: 2
From: Westfield Indiana
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Re: Dual Exhaust ??? (Ganey)
Ganey, I found a page on dynomax's website that has slightly different info. They say 2.25 for 250HP and 2.5 for 300-400 HP.
Scroll down the page: http://www.dynomax.com/techsupport.stm
Either way, I think 2.25 will be plenty of exhaust for a stock 78 engine. Also, the H-pipe size should be at least 70% of the size of other pipes. No harm in making the H-pipe the same size as exhaust pipes.
Scroll down the page: http://www.dynomax.com/techsupport.stm
Either way, I think 2.25 will be plenty of exhaust for a stock 78 engine. Also, the H-pipe size should be at least 70% of the size of other pipes. No harm in making the H-pipe the same size as exhaust pipes.
Race Director
Joined: Apr 1999
Posts: 11,520
Likes: 13
From: CORVETTE 77 385 C.I. TEXAS
Re: Dual Exhaust ??? (Captain Morgan)
Captain Morgan
An excellent link which includes C.I. The guidelines I posted were from Racing Head Service. Comparison below.
Racing Head Service..... Dynomax
DUALS
2" .... 200 BHP...............100-200
2.25" 320 BHP................250
2.5 .. 400 BHP................300-400
You are ahead of this topic & have already answered the next issue which is whether he intends to remain basically stock in which the 2.25 should be fine w/ rec. high flow mufflers. If he intends to go for more HP, then 2.5.
Suggest Increase Power.
:cool:
An excellent link which includes C.I. The guidelines I posted were from Racing Head Service. Comparison below.
Racing Head Service..... Dynomax
DUALS
2" .... 200 BHP...............100-200
2.25" 320 BHP................250
2.5 .. 400 BHP................300-400
You are ahead of this topic & have already answered the next issue which is whether he intends to remain basically stock in which the 2.25 should be fine w/ rec. high flow mufflers. If he intends to go for more HP, then 2.5.
Suggest Increase Power.
:cool:
Melting Slicks
Joined: May 2001
Posts: 2,700
Likes: 3
From: Lebanon KY
Re: Dual Exhaust ??? (Ganey)
Yes, do it. See Why Exhaust is problem for HP on 75-81
what many refer to as my Exhaust topic. http://www.corvettefaq.com/c3/ganeyexhaust.htm
what many refer to as my Exhaust topic. http://www.corvettefaq.com/c3/ganeyexhaust.htm
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Race Director
Joined: Apr 1999
Posts: 11,520
Likes: 13
From: CORVETTE 77 385 C.I. TEXAS
Re: Dual Exhaust ??? (corvettemaster)
The link to that thread has been posted many times by many. Did that topic for you guys. The new guys need to see it. Would prefer not to post it myself.
You are approaching 300.
You are approaching 300.
