Re: Headers vs HP Manifold
[Re: ramman5600]
#1106833
11/04/11 11:25 AM
11/04/11 11:25 AM
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Joined: Apr 2005
Posts: 15,134 Kelowna, B.C. Canada
DPelletier
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Ahhhh, the old headers vs. manifolds discussion. OK, why not? - yes headers will usually show a gain over manifolds. how much depends on the motor/build. Expect maybe 10-15 on a street RB. BUT - most people fail to consider that the exhaust system is a SYSTEM and the motor doesn't really care WHERE the restriction is. I am positive that my HP manifold/2 1/2 " mandrel bent TTI/Dynomax Ultraflow system flows better than a set of cheapie headers mated to the stock exhaust system. - People tend to look at this two ways; one person will say why give up the hp using manifolds and another will say that you can get whatever hp you are after using manifolds with the right build. Both are usually correct: it depends on your perspective. Headers vs. Manifolds pros - flow better, usually pick up some hp, lighter cons - most leak, higher underhood temps, full headers can drag, doesn't look stock. As was said; 500hp can easily be had with manifolds....how much power are you looking for? Dave
1970 Super Bee 440 Six Pack
1974 'Cuda
2008 Ram 3500 Diesel
2006 Ram 3500 Diesel
2004.5 Ram 2500 Diesel
2003 Ram 3500 Diesel
2006 Durango Limited
[url] http://1970superbee.piczo.com [/url]
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Re: Headers vs HP Manifold
[Re: dogdays]
#1106835
11/04/11 01:50 PM
11/04/11 01:50 PM
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Joined: Apr 2005
Posts: 15,134 Kelowna, B.C. Canada
DPelletier
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Quote:
A common misconception is that headers only influence the top end. Another common misconception is that headers only reduce power by reducing restrictions in the exhaust system.
Dyno tests have shown that shorty headers make more power than manifolds and long tube headers make more power than shorties. It has to do with the length of time the exhaust pulse travels in its own tube. A good long tube header will not only increase power above the torque peak, but it also increases torque below the torque peak. This low rpm increase clearly has little to do with flow restriction.
The oldsmobile head is an example. The center two exhaust ports are run together in the head and come out as one wider port which should lower restriction for those two ports. However, it is always advantageous to divide the ports. There is significant cross-talk between the two which interrupts something, probably scavenging during overlap. Flathead fords also had the center two exhast ports run together. In the flathead crowd it was a well-known modification to run a piece of sheet metal up that center port to divide the sides and increase performance.
There's more to an exhaust system than restriction.
R.
I am aware of all that, yet my observations are still correct. I presume that you meant to say "increase power by reducing restrictions". Restriction isn't the ONLY part of the equation.....but it is the most important part, esp. when comparing relatively restrictive stock exhaust systems.
Dave
Last edited by DPelletier; 11/04/11 01:56 PM.
1970 Super Bee 440 Six Pack
1974 'Cuda
2008 Ram 3500 Diesel
2006 Ram 3500 Diesel
2004.5 Ram 2500 Diesel
2003 Ram 3500 Diesel
2006 Durango Limited
[url] http://1970superbee.piczo.com [/url]
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Re: Headers vs HP Manifold
[Re: DPelletier]
#1106836
11/04/11 01:56 PM
11/04/11 01:56 PM
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Joined: Jan 2003
Posts: 16,376
dogdays
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I Live Here
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Re: Headers vs HP Manifold
[Re: DPelletier]
#1106842
11/04/11 02:31 PM
11/04/11 02:31 PM
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Joined: Nov 2004
Posts: 2,825 Sk. Canada
RemCharger
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master
Joined: Nov 2004
Posts: 2,825
Sk. Canada
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Quote:
Quote:
Whats even scarier is a f.a.s.t car with real headers.
Yeah, you're right; a 383 with headers is the shiznit!
Dave
Sorry wasn't talking about my car. Reread the quote.
fastest I've gone with my motor is 130 ,, so I'm hardly in the same ranks
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Re: Headers vs HP Manifold
[Re: DPelletier]
#1106844
11/04/11 03:22 PM
11/04/11 03:22 PM
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Joined: Nov 2004
Posts: 2,825 Sk. Canada
RemCharger
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Quote:
Quote:
Quote:
Quote:
Whats even scarier is a f.a.s.t car with real headers.
Yeah, you're right; a 383 with headers is the shiznit!
Dave
Sorry wasn't talking about my car. Reread the quote.
fastest I've gone with my motor is 130 ,, so I'm hardly in the same ranks
I did reread your quote; you changed it from "fast" to "f.a.s.t." which changes the meaning......and of course there AREN'T any F.A.S.T. cars with headers......against the rules and all that.
anyway, have a good day.
Dave
Well I agree, when you have lemons, you make lemonade. Here's to hoping your day is as good as mine
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