Cast iron exhaust manifold flow


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By DANIEL TINDER - 16 Years Ago
The "Blue Thunder" thread had led to this inquiry;



Disregarding the futility due to back pressure inherent in any street-type exhaust system, aside from "Extrude Hone" type modification (not likely available?) and port/gasket matching, is there any practical way (ceramic internal/external coating perhaps?) to improve the flow of OEM manifolds?
By bird55 - 16 Years Ago
Not sure of your question, but?

Why not consider extrude honing of the exhaust manifold? with porting. It would seem like a very viable solution. Then one could also change the size of the entire exhaust pipe to the muffler and out by at least 1/2" larger. This would help, some. And would look almost stock. Don't know exactly what you're after here.
By Ted - 16 Years Ago

Actually extrude honing use to be available for exhaust manifolds.  Talk to these people about it as I’ve had them perform their magic on intake manifolds.

 

Extrude Hone Corporation

1 Industry Blvd

Irwin, PA.15642

Ph: 724-863-5900  or 1-800-367-1109

http://www.extrudehone.com/ 
By pegleg - 16 Years Ago
And it works well enough that it's banned in the pure stock classes, and some "roundy round" racing classes in the Midwest. 
By Hoosier Hurricane - 16 Years Ago
Daniel:

I believe Pegleg's car made around 370 horses breathing through a pair of stock manifolds and 2 1/2" pipes and mufflers.  How much flow is required for that power level.  Frank, am I correct on the horsepower figure?

By DANIEL TINDER - 16 Years Ago
Had tried to contact Extrude Hone in the past, but never got a response. I assumed they were fully engaged with industrial NASCAR/R&D type work, and not interested in small jobs.



Am I barking up the wrong tree in thinking a slick internal ceramic coating (if proved durable) would not only increase cold flow, but hold in more heat and thus improve efficiency?



The high cost of custom-built T-Bird headers/simplicity of installation/appeal of OEM appearance might tend to suggest practicality of manifold modifications?
By Ted - 16 Years Ago
DANIEL TINDER (1/21/2009)
Had tried to contact Extrude Hone in the past, but never got a response. I assumed they were fully engaged with industrial NASCAR/R&D type work, and not interested in small jobs.

When contacting companies in general, do not use email as many companies do not respond to that venue of communication.  Phone contact is always recommended.  For Extrude Hone Corporation, my contact was Rick Miller at ext. 277 but it’s been awhile now so that may no longer be a valid contact.

Am I barking up the wrong tree in thinking a slick internal ceramic coating (if proved durable) would not only increase cold flow, but hold in more heat and thus improve efficiency?

Coating the insides of header tubes works so there's no reason to believe that coating the insides of the exhaust manifolds would not also be beneficial.  It would also make sense to clean up the insides of the manifolds as much as possible before coating.

By DANIEL TINDER - 16 Years Ago
Finally got a quote from Extrude Hone ($750). Price of custom headers now looking more reasonable.
By charliemccraney - 16 Years Ago
Pretty nice headers, at that. Wow. I guess, if you need maximum performance with a stock look it's the way to go, though.
By pegleg - 16 Years Ago
John you're right on the number. It was hooked to a set of 2 1/2" turbos on the dyno. Also was running out of fuel because I fell for the "6 valve" pump that turned out to be a standard 2 valve. So that was at 5200 rpm. It now goes into the low 6's and pulls pretty hard all the way up there.       

       Mummert has told me that he sees very little difference between the factory log manifolds and the Rams horns on the dyno. So in other words, unlike the FE's and early small blocks, these manifolds work pretty well.