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Rear airflow


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For many years our 6 had a wheelbarrow exhaust system, it also suffered from fumes in the cab and consequently smelly clothes. At the last rebuild a few years ago I fitted a standard exhaust and no longer suffered from fumes. So I was curious about airflow. Made up a set of wool tell tales hanging from the boot. RVWP (of this parish) observed then we swapped over. The wool only goes up to horizontal possibly because it’s a bit heavy so unable to say anything about airflow back up over the boot which was what I was looking for. What I did notice was that at both sides the airflow goes out beyond the car sides. Right over where the standard exhaust comes out. Have a plan for modifying the kit to make it more sensitive so sometime might have another go.  JJC

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Keep us in the picture, there was someone on the forum a while ago who was proposing to do some aerodynamic modelling on air flow around the back end of the TR6....
Thanks
Ian

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I've read a fair bit of anecdotal evidence that exhausts that exit in non-stock locations can lead to exhaust odor in the cabin.  Triumph Engineers likely had a good reason for including the dog-leg on the terminal exhaust pipes.  Those bends don't come free.

Ed

Edited by ed_h
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I have a single pipe exiting on the drivers side. I just put a chrome tip on the end with a turned down outlet. This extended the exhaust length and put the fumes down into the airflow (I assumes) and seemed to end the fumes issue.

 

Simon

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1 hour ago, kiwican said:

I have a single pipe exiting on the drivers side. I just put a chrome tip on the end with a turned down outlet. This extended the exhaust length and put the fumes down into the airflow (I assumes) and seemed to end the fumes issue.

 

Simon

Do you have a picture of that?

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2 hours ago, kiwican said:

I have a single pipe exiting on the drivers side. I just put a chrome tip on the end with a turned down outlet. This extended the exhaust length and put the fumes down into the airflow (I assumes) and seemed to end the fumes issue.

 

Simon

I fitted a couple of those on a 5 in the late seventies. I think that it used to take out the shins of those passing close across the rear of the car.

Tim

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4 minutes ago, Tim T said:

I fitted a couple of those on a 5 in the late seventies. I think that it used to take out the shins of those passing close across the rear of the car.

Tim

I think mine stops about level with the bumper, it will spit on your foot if standing in the right (wrong?) spot when loading the boot. I will check tonight and take a picture as was requested.

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JJC,

I had the same problem years ago and also made wool tell-tales. I had a loop of elastic which went around the boot lid with wool tell-tales attached every six inches. I found that after about 30 mph the airflow over the centre of the boot lid reversed and came forwards. I also swapped from wheel barrow exhausts back to the original position of exhaust and the fumes stopped.

Alan

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On the General Forum there’s a post about mesh wind deflectors. Peter W says that wind tunnel tests on (I think) an MG showed a reduction in drag coefficient with the mesh present. Would be interesting to know if a mesh deflector stops the air flow over the boot lid reversing. Can we persuade a mesh owner to do the experiment?  JJC

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Does anyone have a picture of a standard exhaust showing the exit angle for the gasses and how far it extends in relation to the rear bumper. I have a stainless system fitted (when I bought the car), it ends almost in line with the rear bumper and points slightly upwards, and wondered if this might be making things worse?
Thanks
Ian

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1 hour ago, cvtrian said:

Does anyone have a picture of a standard exhaust showing the exit angle for the gasses and how far it extends in relation to the rear bumper. I have a stainless system fitted (when I bought the car), it ends almost in line with the rear bumper and points slightly upwards, and wondered if this might be making things worse?
Thanks
Ian

Like this Ian

Stuart.

 

Marko 012.jpg

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Marko 023.jpg

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1 hour ago, stuart said:

Like this Ian

Stuart.

 

Marko 012.jpg

Marko 022.jpg

Marko 023.jpg

Thanks Stuart, exactly the same system as mine, but appears to extend a little further beyond the bumper than mine and slightly less inclined.
Ian

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1 hour ago, cvtrian said:

Thanks Stuart, exactly the same system as mine, but appears to extend a little further beyond the bumper than mine and slightly less inclined.
Ian

Heres another Ian this is a standard steel system. It does have stainless finishers on it though which might be an idea for yours.

Stuart.

 

Marko 064.jpg

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Edited by stuart
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32 minutes ago, stuart said:

Heres another Ian this is a standard steel system. It does have stainless finishers on it though which might be an idea for yours.

Stuart.

 

Marko 064.jpg

Marko 065.jpg

Thanks Stuart, I'm all for easy solutions!
Stay away from the hoards invading Cornwall.................
Cheers
Ian

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13 minutes ago, cvtrian said:

Thanks Stuart, I'm all for easy solutions!
Stay away from the hoards invading Cornwall.................
Cheers
Ian

Dont remind me, its absolutely rammed with self entitled w*****s

Stuart.

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Going back a bit to screens behind the seats, I have a breeze breaker (mesh) that works fairly well as is evidenced by the accumulation of rubbish on its rear surface.  By rubbish, I mean black'grime' that accumulates as you drive along, presumably from the exhaust and general traffic fumes, etc.  My 6 has the standard NS twin pipe exhaust.  My understanding is that the airflow down there near the side is more turbulent than in the middle and therefore more likely to disperse the exhaust fumes than any centre mounted pipes.   Obviously the breeze breaker is not 100% effective at stopping the muck, as becomes clear if you go on a tour and cover several hundred miles each day- the need to wash hair soon arises.  Just one word of caution though.  My breeze breaker is immediately behind the seats and gets in the way of the headrest if you are wearing a crash helmet (eg on a track day).  Also, as the air rushes forward from over the boot, it meets the breeze breaker and then tries to enter the cabin from between the seats or between each seat and the doors.  In the winter, these draughts can be very cold indeed.  The curtain that hangs from the breeze breaker is not on its own enough to stop this chill wind, even when lengthened, the air pressure is too great for the material.  You need to fill the 'shelf' volume behind the seats with stuff to stop the air flow.

Apologies for the rambling input, but that type of rambling I can do all day long, as opposed to the more physical type of rambling!

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5 hours ago, cvtrian said:

Does anyone have a picture of a standard exhaust showing the exit angle for the gasses and how far it extends in relation to the rear bumper. I have a stainless system fitted (when I bought the car), it ends almost in line with the rear bumper and points slightly upwards, and wondered if this might be making things worse?
Thanks
Ian

Bolt on some stainless pipe trims with Downturned exits and try it.

Mick Richards

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When Triumph were developing the TR6 they had a lot of problems with exhaust soot being drawn onto the rear of the TR6 and their solution was to weld on extension pieces to the TR5 tail pipes to make them coincident with the rear face of the bumper and also to paint the rear valence matt black to disguise the soot. The first image shows the welded on extensions and the second image shows the soot and the TR5 exhaust

Derek  

77097 towing bracket.jpg

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Excellent photos Derek!

i too added a stainless finisher to extend the mild steel ‘big bore’ single pipe that came on my car, and this fixed the fume issue

i then found and fitted the correct stainless back box for the system, this has a longer outlet and no fume issue

Steve

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