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 Cast iron headers vs small tube headers
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chupiw
Tribal Scout

USA
6 Posts

Posted - 29 Oct 2007 :  11:05:02 PM  Show Profile  Reply with Quote
Has anyone done a back to back test comparing the cast iron factory short style headers to small tube headers. I know that tube headers will work better, but I am curious as to what the real world difference between the two is. Say I build a 400 with 9.5 cr 6x heads ported to 240/200 cfm, factory cast iron intake with qjet and a comp cams XE 262 cam. With a combo like this or one similar, what kind of torque and power difference would there be. I hate to sound stupid, but I dont have acess to a dyno, of course I know headers do flow better, but I have never seen a dyno test showing a comparison between the two. I allways see tests of intakes and cams and even head swaps, but not much exhaust and header testing for pontiacs.

Phil
The Great White Buffalo

USA
6191 Posts

Posted - 30 Oct 2007 :  02:23:23 AM  Show Profile  Reply with Quote
Not stupid, actually an interesting question and one that comes up from time to time. I assume you are referring to the Hedman shorty headers with the stepped design?

They are decent and roughly equivelant in performance to good RA manifolds. Since full tube headers are not always in everyones realm, the Hedmans are a nice alternative to heavy cast iron RA manifolds IMHO.

FWIW, I can tell you from my personal experience with 5.0 EFI Ford truck motors that the JBA shorty headers really did nothing to enhance performance, just looked nicer than the rusty, ugly and factory cracked Ford exhaust manifolds.

However the MAC shorty headers did help. The MAC were the spider looking ones that were all equal length tubes, while the JBA's at the time were just simple tubes of various lengths to save space and keep it simple.

But nothing will outperform a good set of tuned full length headers.


"Chevy": even the name sounds cheap.
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hugh
Cochise

USA
430 Posts

Posted - 30 Oct 2007 :  1:08:31 PM  Show Profile  Reply with Quote
The key there is "tuned". This months Car Craft has a story about that. With a dyno, one can dial in the collector tube length in which adding an additional length to the collector can yield 15 - 30 extra hp. Several years ago, HPP did an in depth analysis on cast iron vs ra cast iron vs shorty headers vs full length headers. Going on memory, the ra cast iron and the full length headers performed about equal. Interesting, the Pontiac cast iron manifolds in general, have better flow than other factory style manifolds. fyi hh
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Cobrabill
Talking Dog

Aruba
2723 Posts

Posted - 30 Oct 2007 :  4:51:42 PM  Show Profile  Reply with Quote
If there is a header that has"roughly the equivalent" flow of a Long Branch header,there is ABSOLUTELY no reason to go with a header.


Ted Nugent/Phil Robertson in 2016.
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Randuss
Sitting Bull

USA
127 Posts

Posted - 30 Oct 2007 :  5:09:05 PM  Show Profile  Reply with Quote
Ram Air Restoration Ent. Says their Long Branch Manifolds will support up to 550 H.P.
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Phil
The Great White Buffalo

USA
6191 Posts

Posted - 31 Oct 2007 :  10:32:05 AM  Show Profile  Reply with Quote
Bill, I can think of one big reason for me: Weight. I just can't see bolting on heavy cast iron anything onto nice aluminum heads.

BTW, does anyone know if RARE ended up producing an aluminum version of the RamAir exhaust manifolds? I remember seeing samples of them several years ago, but the last thing I heard was there were some durability issues.

"Chevy": even the name sounds cheap.
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hugh
Cochise

USA
430 Posts

Posted - 31 Oct 2007 :  10:37:59 AM  Show Profile  Reply with Quote
The long branch cast iron manifolds require the offset oil filter adapter. I would not use cast iron manifolds with aluminum heads either. The original question was about 6X heads though.
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Cobrabill
Talking Dog

Aruba
2723 Posts

Posted - 31 Oct 2007 :  11:21:19 AM  Show Profile  Reply with Quote
True,and under the parameters of the original topic,i stick by the Long branch manifold.Your E-head comment does have validity,however.


Ted Nugent/Phil Robertson in 2016.
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Will
Cochise

Zimbabwe
285 Posts

Posted - 02 Nov 2007 :  02:44:22 AM  Show Profile  Reply with Quote
Full length 4-tube headers of the appropriate diameter and primary length for the application will outperform factory RA manifolds. In a 400 combo with an XE262 cam I'd guess the power differential to be roughly 10-15 HP with more torque in the lower RPM ranges. Such an engine would benefit from small (1-5/8") diameter primaries that are approximately 28-30" long.

As the cams get bigger and the RPMs increase the performance advantage of headers gets bigger and bigger.

The Long Branch style manifolds are the most efficient but can't be used on all chassis. They won't fit in '65 and later GTOs and '70 & later 'birds. For those cars you're stuck with the more compact and lower-flowing manifolds.

If an engine made 550 horses with long branches, I'd be willing to bet that it would pick up somewhere between 35 and 50 horses just by switching to appropriately sized 4-tube headers.

Not qualified to answer questions about engines over 425 HP.
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Total Jackass
Tribal Scout

0 Posts

Posted - 14 Jan 2014 :  04:22:03 AM  Show Profile  Reply with Quote
A. Swimming trunks.
http://www.wrotewatches.com/rolex.html

I'm a first class jerk and don't you forget it!
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