Re: 427 FE engine, under car 'street' exhaust system?
 

Re: 427 FE engine, under car 'street' exhaust system?

Hi guys,
Does anybody run and able to recommend an off the shelf header, suitable for the above installation? Down pipe will be 3" diameter and thinking ceramic.
Clearly footwell clearance and heat are a big issue and I'm not clear if a tuned length primaries system is feasible, space wise.
I'd be grateful if anybody who's done it with success, could share their experiences.

Mickmate carries a header for FEs. No way to know if it would work in your car however.

Street Car Headers Mild Steel [] - $2,600.00 : Acton Custom Enterprises, Custom Metal for Cobras

Not sure if Superformance would work in your case but it might be worth a call. Also you might contact Firefly to see if they have any thoughts.

Specializing in Superformance after market

The MK IV footboxes are longer/wider than the 427 MK III units so I doubt that an "off the shelf" header will work without mods. Of course if Brian Angliss was still around and running the works he could have them supplied but that ship sailed....

Yes, it's so sad Brian is so off the scene. I know it ended badly and maybe there's some stuff he doesn't want to be reminded of, but in his way he altered the car scene, even those of us like me who are about to make a few changes.

And yep, the MK IV driver footboxes is massively over long (it covers the wing vents) probably because they used the Ford pedal boxes and cable clutch. Also the battery has to go rearwards as that covers the passenger vent!
Anyhow, I'm not just going to drop the engine and having it touch all the inner panels. When I'm finished it'll look factory and there won't be any evidence of tampering.
But we've sure got to get it right because there's not a 1/4" to waste....

Custom headers
 

Contact
Stainlessheaders.com
They can make anything and they have a jig for cobras they will send to you
Jon

My Kirkham has an undercar exhaust and the headers were fabricated by them. Couple of thoughts though:
Mickmate does make nice headers. I looked at them before I found out that Kirkham would make them for me.
Don't count on 3" downpipes and collectors. Very unlikely to fit 3" under the car. I have 2.5" to the mufflers and that's a squeeze.
Tuned length primaries?? You've got to be kidding! Have you looked in the engine bay of a Cobra with an FE before?:LOL:

Well, I've viewed two. Both had original iron 427s and the one I measured up in detail had a 3" dual system under the car. However couldn't get to the down pipe to measure that. Like I said, not sure if there was a way to make it feasible.
I presume your downpipes run in a formed area inside the inner footwells. How do you find the heat next to your right leg, assuming you're LHD? It's my biggest concern, although I'm RHD.
I'm also having a Pont block built by Lykins and am having custom crank to orig 3.78" stroke and orig 427 capacity. In fact engine will be near original, carbed but modern tech, Survival heads etc.
I'd be interested to know what you think of the combination you have in your Kirkham, because we have a lot of work to do with the footwell pedal box. Car is not designed for big block although has MK III type 427 twin rail chassis.
Trans wise I'm 3.54 at the back and wanted the vintage experience (barring front end weight) so ideally alum Kee w/r Toploader, but am thinking TKO 600 for practicality. Also what diff and overdrive ratio on your TKO? Again what do you think? Any regrets?
My car is already built, an alloy '93 Autokraft with 302 efi, so it's a big project, particularly here in the UK, where there's zero parts availability and only one specialist, who said don't do it, you'll never get rid of the heat!

With a 460 had custom headers built at Tubular Automotive ran 2 1/2" pipe through custom stainless mufflers. modified the frame in a couple places to keep good ground clearance. Before setting body on frame put thin plate steel in spaces over exhaust welded to frame to protect glass body. and floors.
On the CMC car footwells were not a problem and had to run a clutch cable.

ERA undercar headers are a little unconventional but basically the collectors are 2-1/2 inch and I ran 2-1/2 inch all the way to the rear bumpers with non-crush bends. A 2-1/2 inch exhaust system with low restriction mufflers will flow a lot of exhaust and support a lot of HP.

I would be leery of trying to run anything bigger than 2-1/2 inch as you are also compromising ground clearance. I used 2-1/2 inch deep mufflers by Spintech to maintain as much clearance as possible. If I were re-doing it I would have gone to 2-1/4 inch tail pipes from the mufflers back. By that point the exhaust temps have come down enough that a little smaller pipe won't compromise overall flow. It wouldn't have been so tight in the rear wheel wells either.

http://i125.photobucket.com/albums/p...ps75e04465.jpg

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Yes, very interesting: Cobra Kit Car Headers - Stainless Headers Mfg., Inc.

Also worth looking into is their oval tubing: Oval Exhaust Tubing - Stainless Headers Mfg., Inc.

And oval SS mufflers as well: http://www.racemufflers.com/category-s/2017.htm

Great installation. Sure looks cosy up by the rear tyre....but looked at you links and car looks and sounds fab. Can I ask how long it will tick over stationary in traffic for example on a warm day before boiling over? That and cockpit heat my only concerns.

So far heat has not been a problem - about the highest temp I've seen sitting at a light is 80C. The oil doesn't get much above that either. Sitting at a light I do start to feel a lot of heat welling up from under the car and spilling over the side of the doors but that is pretty much typical. I have weatherstripping around my hood opening to mimic the street roadsters and that is probably not a good approach. I think a few pieces of intermittent weatherstripping or hood bumpers would allow that area to help vent underhood heat a little. I do have ceramic coated headers, head pipes and mufflers and a lot of insulation in the cockpit. Those mufflers are right under the seat and about 1 inch off the floor board and when I've shot them after a drive they are somewhere around 500F. I have Lizardskin on the underside of the floors and B-Quiet and Kool It on the top side under the carpets. It's mostly the heat welling up from underneath at stop lights that I notice.

I saw a story in the April 2016 issue of Classic and Sports Car magazine about a firm called Taylor Automotive in East Sussex. They specialise in "difficult' engineering solutions. I don't know whether their expertise extends to headers but if not they'd probably be able to point you in the right direction. They're at www.taylor-automotive.co.uk

I am running a supercharged 6.2 litre LSA in my alloy-chassis Australian-made Pace 427SC. I had a custom made 2.5" stainless under car system with mandrel bends fabricated to fit the car by a local race shop that does work for some Australian V8 supercar teams.

My Cobra's design is a little different in that the exhaust can be located each side inside a frame rail channel on the outside of the car (but under the body). From the side of the car, you can only see about 10mm of the exhaust as most of it is tucked up into the channel. I am going to get that part powder coated in matt black. Had I run 2.25" tubing you probably wouldn't have seen it at all...but I needed the 2.5" for flow with the blower.

The exhaust runs into 2 x high flow 2.5" mufflers concealed under the body and the tips are turn-down type which sit flush with the body and are not visible from behind the car. Clearance is tight, but it all fits.

I am also running catalytic converters in the car as well just after the 4:1 headers so the system is fully emissions legal and tested/complied as such.

You guys know you can have custom NASCAR style flat rectangle pipe sections made for crossing under frame sections where needed a 1"X 4" = 4" pipe if you need that much exhaust. Or a 1"X 3"=3". NASCAR runs them from the header to the exhaust point & the flow is the same & so is the sound :) That is my plan; @ least under the frame points. But as usual, life's event have my conversion postponed. But I will get there one day soon. :) Just find a local muffler shop/ or just about any skilled fabricator/welder can make theses sections up for you with out huge cost either!

On rectangular you have to go quite a bit bigger than that I believe. The cross section of a 2-1/2 inch pipe is 4.9 sq in. So you would need a 1 x 5 to get equivalent area. But to get equal flow I think you would need to go even bigger since the boundary circumference on a 2-1/2 inch pipe is 7.85 inches and a 1 x 5 rectangular pipe would be 12 inches - creating a lot of boundary drag and restriction in the rectangular pipe. Someone who remembers their flow mechanics courses better than me would need to figure out an equivalent size. Oval piping is probably a better approach where ground clearance is needed. .

The area of a circle is diameter x diameter, divide that by 4 and multiply by 3.142.

Therefore the area of a 3" diameter pipe is 7.069 square inches.

That I am afraid equates to a much bigger rectangular section of 1" x 7" or 2" x 3.5".

However an oval section of 2" x 3.96" also equates to 7.07 sq in and is possibly the most practical alternative.......but very difficult to bend round a chassis.

What would really be beneficial, is for example with a 500hp big block, running 2" primaries, what is hp loss between 2.5 and a 3" collector pipes, if any?

Its generally not necessary to bend the oval sections around the chassis. They only need to be used under the frame - maybe with horizontal bends in a flat plane - where ground clearance is an issue. Oval to round adapters can be used to transition to header connections and tailpipe sections that need to bend over the rear suspension.

With a car like mine, it's not possible to run 3" downpipes adjacent to the footwells. I just feel there's just not enough space for a practical and serviceable installation. With a 2 x 3 oval downpipe there might be, but no point if you can't get it to transition to under car, where it would have to twist.

I think it's 2.5" or revert (sadly) to some side action.....or run the headers forwards, then loop under the car, so no downpipes in footwells, Only downside I can see, is increased engine bay heat and odd looks. TVR did this with the Griffith and Chimaera, if they are known in the US.