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barkerwilliams

TR6 Exhaust fumes / airflows over bodywork.

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John L,

 

No, no additives. But even if car is running rich and therefore could be better, I would rather not be breathing in sweeter smelling fumes if I can avoid it. I never thought of he bumper being too involved in this, but I do not know what I'm doing, or where I am going with this, so yep I will put it on the list.

 

I think I need either (or both) to lower the low pressure behind the car, or to raise the pressure in the cockpit. The exhaust gasses cannot then flow from a very low pressure to a higher pressure. That would also stop any fumes penetrating the boot which others have issues with.

 

I just might have found Mercedes drivers solution to the problem:-

 

http://www.duramaxforum.com/forum/attachments/exterior/56930d1351103161-stupid-stacks-pics-imageuploadedbyag-free1351103162.352617.jpg

 

 

 

Alan

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That was a great exposition of a well known factor of aero - there is a lot more drag with the top down, or even with the windows open!

But it shows how possible it is to do CFD on a PC today; the labour is obtaining a suitable model of the car.

 

But I don't think it demonstrates that exhaust gases will be entrained forwards - there may be equally low pressure areas at the back and behind the windscreen, but flow goes from a high pressure to a low.

What you need is the next CFD step-up, flow lines.

Try http://www.mentor.com/products/mechanical/events/cabin-comfort-cfd-webinar

 

John

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Phil,

From your thumbnail you have a different style of tailpipe. I have twin tailpipes and twin silencers, and I believe all those other with issues have twin tailpipes as well. They are mounted symmetrically closer to the centre line of the car than yours, perhaps by only 2 to 3" each side. I am working on the belief that it is the proximity to the centre line of the car that is the issue. The exhaust gasses are venting / accumulating centrally behind the car and then flowing up over the boot and into the cockpit.

 

I expect you have a silencer fitted left to right across the width of your car, with a twin exhaust system there are two silencers mounted front to rear, these may deflect air from entering under the rear of the car and disrupt the turbulent airflows that are created by your transverse silencer, creating a more laminar flow.

 

I would post a picture of my setup but it never seems to work on here for me so here is a stock photo I found on google - not my car.

 

http://farm6.static.flickr.com/5121/5242522998_7a2bb90e94.jpg

 

 

Alan

Edited by barkerwilliams

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John,

 

Thanks for that I will have a play. I did notice the first words on that site "thermal comfort in passenger cabins", surely that can't apply to a TR6? Comfort and Triumph are not words that sit easily together!

 

 

Alan

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post-11647-0-85914100-1433600113_thumb.jpg

Phil,
From your thumbnail you have a different style of tailpipe. I have twin tailpipes and twin silencers, and I believe all those other with issues have twin tailpipes as well. They are mounted symmetrically closer to the centre line of the car than yours, perhaps by only 2 to 3" each side. I am working on the belief that it is the proximity to the centre line of the car that is the issue. The exhaust gasses are venting / accumulating centrally behind the car and then flowing up over the boot and into the cockpit.

I expect you have a silencer fitted left to right across the width of your car, with a twin exhaust system there are two silencers mounted front to rear, these may deflect air from entering under the rear of the car and disrupt the turbulent airflows that are created by your transverse silencer, creating a more laminar flow.

I would post a picture of my setup but it never seems to work on here for me so here is a stock photo I found on google - not my car.

http://farm6.static.flickr.com/5121/5242522998_7a2bb90e94.jpg


Alan

You are correct - here is an image I just took

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Phil,

 

Managed to attach my car photo. You can see fore & aft mounting of silencers which will influence the airflow in some way down there.

 

Alan

Edited by barkerwilliams

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Phil has the standard side exhaust which I reverted to to improve the situation. Also as its a USA car he will likely be on carbs and running less rich than a PI car.

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When we went down to Cornwall last year, a 300 mile trip, everything carried in the boot reeked of exhaust fumes, vile.

All clothing had to be washed before it was wearable, didn't spoil the holiday though.

A return to a standard set up is on my mind.

 

winston

Hi Winston

I had the same issue at Le Mans last year with things in the boot smelling, I just replaced the boot seal and all was sorted ;):D

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Sounds like it's worth a shot, thanks Clarkey.

I've put it on my list of things to get around to doing!

 

Winston

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i replaced my boot seal also but made sure the seam was at the front by the fuel filler.

 

i recently read elsewhere that the license plate lights can let in fumes to the boot. it might be worth trying to seal them too.

 

c74

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I am driving my TR6 since 20 years with a twin SS exhaust System. Only two small boxes at the rear and then the end Pipes go up at about 30°. End is shortly before the rear of the Bumper. On Long Trips I was getting dizzy from the Exhaust fumes so something had to happen. I bought while in the US two simple chromed 45° bent End-tubes. Shortened them to about 30mm longer then the Bumper and pushed them over the Original pipe. It looksow like the Setting on a E-Type which has the same End-Pipe. No more fumes, no smell. Can post Picres if needed.

 

Robert

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I am driving my TR6 since 20 years with a twin SS exhaust System. Only two small boxes at the rear and then the end Pipes go up at about 30°. End is shortly before the rear of the Bumper. On Long Trips I was getting dizzy from the Exhaust fumes so something had to happen. I bought while in the US two simple chromed 45° bent End-tubes. Shortened them to about 30mm longer then the Bumper and pushed them over the Original pipe. It looksow like the Setting on a E-Type which has the same End-Pipe. No more fumes, no smell. Can post Picres if needed.

 

Robert

 

Hi Robert

 

Please do - would be interesting to see.

 

Cheers

 

Paul

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I too have suffered with horrid smells from the exhaust. Whenever I return from a journey, my wife says I stink of fumes. The car would also be very smelly. However, last weekend I fitted an unused old stock air manifold box (oil free), the existing one fitted had a mess of oil inside and running underneath it.

 

What a marked improvement. I returned from my run out and my wife commented how little I smelt and I have to say the same about the car.

 

Is the oil from the airbox heating up and getting into the engine and out the back and even getting smelly in the engine bay and leaking out through the clutch master cylinder rubber boot and into the car where the pressure is low.

Cheers Peter

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All,

 

I have spent some time working with my Tr6 to kill the exhaust fumes in the cockpit before they kill me. Using tell-tales and a camera as a basic car I cannot find a speed above 15mph when fumes are not being drawn into the cockpit, even in heavy crosswinds.

 

I have fitted the usual "behind the seats screen" and tried again, this has some effect, the fumes splitting and either coming around the screen or flowing down into the space behind the seats and thence under the newly fitted screen.

 

At the moment I have purchased two SS exhaust extension / bends http://www.ebay.co.uk/itm/161523251404 at £4.20 each. These seem to work well, perhaps 3" longer and a 90' bend to throw the fumes down and out. These particular extensions come with fittings for smaller diameter exhausts which I discarded, and I triple-slit the rear of the new fittings which have a 59mm internal diameter, and attach beautifully to the 58mm exhaust trims with a jubilee clip.

 

I cannot admit that they look as nice as the original, but the alternative was looking to be the transverse silencer at about £200, or an early death. Still considering a wind deflector between the two front-to-rear mounted silencers.

 

 

Alan

Edited by barkerwilliams

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I also have the fumes problem with a twin box systems.

Does the transverse box fit a twin exhaust system?

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OAF939M

 

Did you get / have a copy of the TR Shop 2015 leaflet sent out with the TRF magazine this year? On Page 3 at the bottom are two exhaust systems identical apart from the back box.

 

Now what system is fitted to your car and your pipe diameters I do not know, but there is a strong possibility that your second pipe can be repositioned and a transverse box could be fitted. But first it's on your back with a tape measure to check what you have. A back box is £200'ish so perhaps you should also consider the extravagant £10 on a couple of exhaust trims/deflectors.

 

I have been surprised by the response to this thread I started and I wonder if anyone with twin boxes does not have the problem of fume ingress. It was not apparent to me until I started driving longer distances at higher speed on motorways, my first symptom was noticing "TR cough" after using the car.

 

I'm still thinking of an underbody spoiler between the rear boxes and the rear valance which projects down and appears to disturb the underbody airflows. This space is filled by the transverse silencer. I am having difficulty in "proving" which route the fumes are taking so that I am able to determine if something I change makes a quantifiable difference. I can only think of injecting coloured smoke into the exhaust as per the Red Arrows - difficult to justify Your Honour on a public road. And of course the exhausts exit nearer the centre line and point upwards into the low pressure behind the car.

 

Alan

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Thanks ,I have got the advert insert as I ordered some new mirrors from it.

 

Under the car to investigate further ,the tailpipe extension deflectors seem worth trying.

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Thanks ,I have got the advert insert as I ordered some new mirrors from it.

 

Under the car to investigate further ,the tailpipe extension deflectors seem worth trying.

Interesting to see your registration come up as its a Cornish registration, our local group web page has a gallery of pictures of Cornish registered cars and yours appears in it though somewhat different from your avatar presumably shows it now.

Stuart.

25-OAF939M.jpg

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Thank you Stuart, I knew the car was originally Red but not sure when it was totally restored and painted.

I would be interested to find more history.

I bought the car from a garage owner and everything has been quite fastidiously done, body, chassis, engine with mild tuning. giving 136 bhp at the flywheel and loads of torque.

Recently I sold a 1974 MGB GT V8 ,and the TR is just so much better to drive .

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Well I had my exhaust modded! so Basically I put a level line straight now, cut 3 inches of the tail pipe off, turned it around to face down to the ground and stainless welded it up....I tell you what chaps what a difference!! I could smell two cars in front was a smoker whilst driving at 50! I no longer stink of fumes, my wife is some what a little happier too! Now the only down side is it looks a bit odd but man so worth doing!! I'll try to upload a few pictures

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All

I have been following this whole topic with great interest, it's yet another TR6 learning curve!

 

As you can see from my picture, my car has, what I believe to be, a std exhaust system exiting on the NS.

 

As there have never been issues with fumes in the cockpit, I was unaware of the problem, until thd start of this thread.

 

So, questions;

Does anyone know why there are an apparent range of different exhaust configurations on the 6?

I have seen twin NS, twin centre and twin single exhausts

 

Would I be right in assuming that ST did no testing of the effects of differing configurations?

 

How come there has been no discussion until now?

Have owners just put up with it on the basis that, 'this is how it is'?

 

I have been facinated by the effects just moving the tailpipe(s) can have on such a simple, clean, body design

 

Good luck with your efforts to obtain gas free driving

Edited by wjgco

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