Exhaust inspiration

289, FIA & Daytona topics
Johannes1
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Exhaust inspiration

Post by Johannes1 » Fri Mar 25, 2016 11:42 am

Hi at all + happy easter,
thinking about a different exhaust system. It would be helpfull to
admire which systems are fitted in your 289 Cobras. Pics/ideas are very welcome!
thanks
Johannes

peterc
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Re: Exhaust inspiration

Post by peterc » Fri Mar 25, 2016 7:41 pm

Johannes
I'm not in a position of posting any photos right now but my exhaust system was written about in an old club magazine. Hopefully you could investigate old copies on line. Internet too slow here for me to investigate!

Basically mine is a Hawk derived system but re routed from running down the middle to being tucked up close to the underside of the floor just in from the cills. The first bend attached to the headers was turned approx 45 degrees to aim towards the cill. Then the pipe runs just below the outriggers before joining to Hawks first box repositioned to be under the seats. Using swan necks on both inlet and outlet of the box to make the bottom of the box inline with the bottom of the pipe run. Heat shield on the underside of the floor avoids heat transfer from the box and the brake/ fuel lines also wrapped where the system crosses them.
It then ( unfortunately) has to dive down and in past the MGB spring mounts before curving up and over the Jag half shafts and then back down to use the 2nd Hawk box under the boot floor either side of the spare wheel well.
This route drastically improves ground clearance which was otherwise compromised with the system being low throughout the length of the car in the middle where any camber would cause the system to bottom out and grind away the U clamps.

The relevant new bends were purchased from a St Stl exhaust manufacturer and then tacked up by me. I subsequently persuaded them to then fully weld the joints properly.
Hope this assists.
Peter C

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Re: Exhaust inspiration

Post by Paul Blore » Sat Mar 26, 2016 10:28 am

Having followed quite a few Hawks on various road trips, ground clearance does seem to be a common problem with the exhaust, unless a custom system has been made.
Peter's is very good and Dave Woodward has also have a very nice system made up for his car.

Mine has side pipes and therefore has no such problems. :wink:

Paul

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Roger King
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Re: Exhaust inspiration

Post by Roger King » Sat Mar 26, 2016 11:29 pm

I was very pleased with the final system on my Hawk. It went in and out a bit, like this:

Image

But this allowed it to clear the Jag driveshafts yet look 'correct' from the side, giving the impression of a straight system going down each side of the car. With a single box on each side it sounded pretty authentic, too.*

Image

The section under the boot is important to look 'right' as it's very visible, as you can see.

This was done in one day, while I waited, in 304 stainless by Dean at Pipecraft in Basildon, cost around 5-600 quid. Never had any issues at all with ground clearance.

*This silencer size might be considered a 'post-IVA' modification, although the sound this car made was (is?) indistinguishable from that made by COB6029.

Johannes1
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Re: Exhaust inspiration

Post by Johannes1 » Mon Mar 28, 2016 11:14 am

Hi,
thanks for your ideas, one question Roger, is it not to hot under the seats?
But it looks great.
regards
Johannes

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Re: Exhaust inspiration

Post by Paul Blore » Mon Mar 28, 2016 11:19 am

If you zoom in on the area above the silencers on the under car photo, there appears to be heat insulation matting, but I'm sure Roger will confirm soon.

Paul

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Re: Exhaust inspiration

Post by Roger King » Mon Mar 28, 2016 12:26 pm

Yes, just a bit of aluminium heatshield from either DemonTweeks or CarBuilderSolutions, can't remember which. Not hot at all, wife always complaining the exact opposite.

Johannes1
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Re: Exhaust inspiration

Post by Johannes1 » Wed May 04, 2016 7:09 pm

Hi Roger,
Hi all,
next friday i´ll bring my HAWK to the Specialist in exhaust Systems, near Cologne, therefor one further question,
which diameter are the tubes? I have 2``mainfolds like the hole exhaust. Do you think ist works, 2``till the mufflers, then 2,25 or 2,5``to the end.
You know i have only a supersmall engine (Rover 3,5 l) and I like the exhaust configuration like Rogers HAWK is. It looks very authentic.
Thanks for your help.
Regards
Johannes

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Re: Exhaust inspiration

Post by Roger King » Wed May 04, 2016 9:54 pm

Johannes, my system is 2" as original, from memory.

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Re: Exhaust inspiration

Post by peterc » Thu May 05, 2016 6:17 pm

Jonhannes,
Just measured mine and its 2.125 O/D so assume its 2" bore. Connections are made by either expanding the tube or short section of next size up.
Only gets bigger on exit of rear silencer.
I think the benefit of Rogers system is that the hangers all have the rubbers in compression e.g. as preferred.
I'm running a 4.6 Rover. It's nice and quiet when needed through villages on small throttle but certainly makes plenty of noise when throttle is opened.
Peter C

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