Exhaust performance question
Thread Starter
Instructor
Joined: Jan 2018
Posts: 229
Likes: 31
From: Finger Lakes area NY
Exhaust performance question
Performance wise, which is better
header side pipes with reverse flow inserts or stock exhaust manifolds with top quality exhaust out the back?
I have 68 conv. 427 with Doug’s headers-side pipes with spiral bagels. They are too loud. The car is a daily driver for me in the summer. (Maybe I’m getting older....)
so I am considering either reverse flow inserts or going back to a stock setup.
which system would give the best performance?
header side pipes with reverse flow inserts or stock exhaust manifolds with top quality exhaust out the back?
I have 68 conv. 427 with Doug’s headers-side pipes with spiral bagels. They are too loud. The car is a daily driver for me in the summer. (Maybe I’m getting older....)
so I am considering either reverse flow inserts or going back to a stock setup.
which system would give the best performance?
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From: Sunshine Coast, Queensland, Australia
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I'm pretty sure that the answer is good long tube headers with a good high flow system out the back.
I'm running stock manifolds with a good high flow system out the back. My car makes good power. My manifolds never come loose. (I've heard of troubles with headers). All my standard chrome ignition shielding covers and heat shields fit, look good and do there job. The trade off is more power with headers. I've always wondered just how much power? And where in the power band. On a Street driven car. How much difference really would one feel with headers?
I ask because, when I was young, like over 40 years ago. I put headers on my Mustang. Ya know, it made more noise, the bolts did work loose and blow the gaskets, more than once. And I really can't say that I really noticed a difference in power. Of course I was 18 at the time and my tuning skills weren't what they are today.
I'll be watching this thread.
I'm running stock manifolds with a good high flow system out the back. My car makes good power. My manifolds never come loose. (I've heard of troubles with headers). All my standard chrome ignition shielding covers and heat shields fit, look good and do there job. The trade off is more power with headers. I've always wondered just how much power? And where in the power band. On a Street driven car. How much difference really would one feel with headers?
I ask because, when I was young, like over 40 years ago. I put headers on my Mustang. Ya know, it made more noise, the bolts did work loose and blow the gaskets, more than once. And I really can't say that I really noticed a difference in power. Of course I was 18 at the time and my tuning skills weren't what they are today.
I'll be watching this thread.
Dr. Detroit
Joined: Mar 2012
Posts: 10,097
Likes: 4,027
From: New Braunfels Texas
Rams horn manifolds with the 2.5" out let and a premium 2.5" exhaust will flow better than the sidepipes with reverse flow inserts.......
The factory 2" outlet manifolds were kinda pathetic.
2.5" manifolds were used on C2's......365hp, 350hp L-79, 375 FI, etc......
Of course I urge you to go all the way with headers and exhaust......
Jebby
The factory 2" outlet manifolds were kinda pathetic.
2.5" manifolds were used on C2's......365hp, 350hp L-79, 375 FI, etc......
Of course I urge you to go all the way with headers and exhaust......
Jebby
Thread Starter
Instructor
Joined: Jan 2018
Posts: 229
Likes: 31
From: Finger Lakes area NY
I have a 427.... Rams horns do not apply. The stock 427 manifold actually looks pretty clean. I have a set on the shelf....
Because of the larger displacement and greater volume of air, do headers make a bigger difference?
Because of the larger displacement and greater volume of air, do headers make a bigger difference?
Race Director
Joined: May 2006
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I have reverse flows and have had Spiral Turbos, Sweet Thunder, and Hooker glass packs. The shortblock is a 70 LT-1, early Chevy angle plug heads, RPM Airgap, 780 Holley VS, roller tip rockers, recurved distributor. There is a massive power reduction running the reverse flows.
Last edited by MelWff; Apr 25, 2020 at 06:52 PM.
Le Mans Master
Joined: Apr 2011
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From: Hermosa
I have reverse flows and have had Spiral Turbos, Sweet Thunder, and Hooker glass packs. The shortblock is a 70 LT-1, early Chevy angle plug heads, RPM Airgap, 780 Holley VS, roller tip rockers, recurved distributor. There is a massive power reduction running the reverse flows.
Dr. Detroit
Joined: Mar 2012
Posts: 10,097
Likes: 4,027
From: New Braunfels Texas
The BBC angel wing manifolds are not horrible.....but people forget it is the pulse scavenging from a long tubes collector that creates the power.
On a stock L-88 open to open the headers were worth 40+ horsepower compared to manifolds.....but this is an engine with a shitload of overlap too....
I know just going to a 2.5 from a 2 inch exhaust on my 69’ 427/400 freed up at least 40 horsepower.....but that engine was .060 and had a 268 Comp cam.....the difference was staggering though.....
Jebby
Le Mans Master
Joined: Oct 2002
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From: Las Vegas - Just stop perpetuating myths please.
Well if your looking for performance and the open (spiral baffles) side pipes are to loud then you want long tube headers with magnaflow mufflers. And a H balance tube near the collectors. You want performance but want to save some $$ with stock exh manifolds is not how it works. You buy and use quality parts that compliment each other. You want to run stock exh manifolds and have someone tell you that will improve performance and what you will get is BS.
Choice is yours and sorry if it rubs you but the truth can hurt.
Choice is yours and sorry if it rubs you but the truth can hurt.
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Last edited by MelWff; Apr 25, 2020 at 11:38 PM.
Drifting
Joined: Jun 2010
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From: Richmond Texas
I don't wish to hijack this thread but I have Hedman Long tube headers going to a 3" dual exhaust out the back. 460 C.I. BB. I REALLY like the look of side pipes. Will the side pipes really kill a lot of power?
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How modified is the engine? How high do you typically rev it when "playing around"?
The Vette manifolds are much better than most. You can gain a lot with some serious porting. If you search Steve Barker (632C2) threads here you'll see he's making well over 700 RWHP and running high 9's with cast iron manifolds on a 548" engine. They are certainly giving up some power, but he ported them like crazy and mated them to 3" pipes.
That said...headers are a good thing overall. A set of headers and a full exhaust of at least 2.5" mandrel would be great. 3" would be better. Mufflers will determine what you get for sound and noise. I like my Pypes Race Pro's. I also like the Flowmaster sound even though they don't always make as much power.
Choking up the side pipes is a bad combo. Kills power and just makes more heat.
JIM
The Vette manifolds are much better than most. You can gain a lot with some serious porting. If you search Steve Barker (632C2) threads here you'll see he's making well over 700 RWHP and running high 9's with cast iron manifolds on a 548" engine. They are certainly giving up some power, but he ported them like crazy and mated them to 3" pipes.
That said...headers are a good thing overall. A set of headers and a full exhaust of at least 2.5" mandrel would be great. 3" would be better. Mufflers will determine what you get for sound and noise. I like my Pypes Race Pro's. I also like the Flowmaster sound even though they don't always make as much power.
Choking up the side pipes is a bad combo. Kills power and just makes more heat.
JIM
Safety Car
Joined: Oct 2007
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From: South Florida
Best performance is a turbocharger with a huge downpipe
Then you can stop worrying about the things NA people worry about, such as header diameter & length, exhaust scavenging, helmholtz/resonance effects, etc...
otherwise I would stick to stock
Then you can stop worrying about the things NA people worry about, such as header diameter & length, exhaust scavenging, helmholtz/resonance effects, etc...
otherwise I would stick to stock
Is my vette stock?? HAHA
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3" pipes out the back is the best of the available choices whether you use a new Hooker manifold or headers. If you watch Engine Masters on motortrend, they did a bunch of different tests that answer all your questions. The winner is always headers and big pipes, but the amount you gain with the headers is sometimes only at he top of your RPM range. If your not revving past 5500, you may not even notice. If thats the case, good manifolds and 3 inch pipes. you might find them on youtube