TR6 Exhaust fumes / airflows over bodywork.

[OAF939M]

I have done around 140 miles today half with hood down and half hood up due to rain.

There were no exhaust fumes noticeable up or down ,and my passenger could not smell them either.

Nothing has been done to the car so it is very strange and rather confusing ,but pleasing also.

The only thing different is that today with hood up I had the fresh air blower switched on.

[barkerwilliams]

OAF939M,

 

Very pleased you had a good day out. Please for your own safety under no circumstances do not associate smell with fumes. For example today you could have pushed your choke fully home and would not have that rich smell, but if the exhaust fumes are coming back into the cockpit, they still will be and just as dangerous, perhaps more so if you cannot smell them.

 

That is the reason I would like to insert smoke into my exhaust to see where it is going, not just relying on my aging sense of smell which nowadays is only used to appreciating a decent red wine.

 

Take care and good driving,

 

Alan

[OAF939M]

Thank you Alan,

A valid point, and I think to fit a small carbon monoxide warning indicator, same as we had in boats and small aircraft.

[BlueTR3A-5EKT]

Slightly off thread here..

When working for Heritage/Rover/BMW I saw a video of wind tunnel tests of the MX5 with and without the hood and different design accessory wind breakers. It was interesting to see the stream of smoke passing over the car and not being sucked back into the cockpit area when the wind breaker was fitted. Solid, as in plexiglass wind breakers were not as good as the mess type items for stopping the cockpit air turbulence. The ultimately developed accessory wind breaker was a mesh item that is almost full cockpit width and no higher that the seated occupant, interestingly it improved the vehicle Cd at the test airflow speeds compared to soft top down only.

This test knowledge was used by the factory to develop the wind breaker for MGF.- which was also a mesh item.

 

So maybe your dad's old airtex vest on a couple of lovingly fashioned wire coat hangers strung between the seat will solve the stink in the cockpit.......

 

Peter W

[OAF939M]

I do have the mesh windbreaker fitted, it was on the car when I bought it.

I will be out in the car later on with hood up to dry before stowage ,so will see what happens today.

[PaulAA]

Alan

 

Interesting thread you've started. I've been blighted by varying degrees of fume ingress into the cockpit since I bought the car just over two years ago. I too have a two-pipe system, which discharges either side of the number plate. I've made sure that the usual suspects are eliminated - exhaust pipe checked for leaks, front bulkhead seals all replaced, steering column shroud sealed, floor pan checked, rear lights sealed, boot lid seal checked with the oil smear test - leaving just the kamm effect as the most likely culprit.

 

Logic would suggest that the lowest pressure is likely to be in the centre of the kamm - it would certainly account for the original exhaust pipe design discharging to the side of the vehicle and, discounting cars in poor repair with tub penetrations, my unscientific straw poll suggests that the greatest problem occurs with after-market exhausts.

 

I was therefore speculating that, short of wholesale replacement of the exhaust, an alternative to the endpipe downturn might be a swan neck in the final section behind the rear box, so that both pipes discharge as far into their respective corners as possible, thus:

 

 

Any thoughts?

 

Cheers

 

Paul

[barkerwilliams]

Paul,

 

You seem to have the same setup as me. Truth is I'm just a TR driver with a cough; what you suggest seems logical but moves metal (i.e. weight and leverage) further out from the centre line of the silencer box mounting and will put a greater load on the seam / end of the silencer box that it was not designed to cope with. I wonder if the proposed tail pipes will rip off the box after a few encounters with decent potholes and might need an additional mounting from the rear valance - side panel seam.

 

However I have not seen any problem reports from drivers with a "standard" transverse rear box and it may be better to go with what was known to work, better than spending probably a similar sum on "hopeful" modifications. Unless of course the mods can be done cheaply out there. I think my car exhaust system would only need a rear box not a whole system - check yours out.

 

There is nothing intrinsically different about the TR6, look to see what solutions other makers have, particularly on older classic cars before aerodynamic testing moved into car production.

 

If you do make any modifications you will then run into the problem of proving that your changes have made a difference; that is the tricky bit. It might seem to have improved but how do you really know, how can you quantify the change?

A couple of drivers have reported being dizzy from the fumes, so on a long run what damage is being done?- Read Peter Cobbold's bits on the very nasty petrol additives, even good old fashioned CO poisoning would not be too much fun at speed.

 

I will say the http://www.ebay.co.uk/itm/161523251404 £4.20 each, tail pipe trim, which I fitted that lengthens and deflects the exhaust "seems" (just can't prove it) a great improvement - it just looks - well different.

 

Please let us know what you decide and how you get on.

 

Alan

[Peter Cobbold]

I have a single outlet where Paul's offside tail pipe is located. But ending flush with the lower edge of the rear valence , and no bumper.

No fumes - at least none I'm sensitve to. I wonder if the exhaust velocity leaving the tail pipe is involved? Twin pipes will share the gas and the velocity will be halved. The upkick on Paul's pipes also wont help eject the gas from the backflow, so repositioning the outlets to eject sideways might be better - leave out the second bend?

Peter

[PaulAA]

Alan

 

The truth is that the welding can be done cheaply here and the only real cost would be in acquiring additional sections of stainless steel pipe. However, I agree with your reservations about unscientific experimentation and differential loading on the remainder of the system. The downturn end pipe would seem to be an easier option to try first - thanks for the link.

 

Cheers

 

Paul

[PaulAA]

Peter

 

Our posts crossed - interesting thought. Are you able to estimate the angle to horizontal that your final section describes? A simple realignment might be the first step.

 

BTW and at the risk of pedantry, the gas velocity would be halved in a two pipe system if the sectional area of each was the same as a single pipe system. So could you accelerate the gas exit velocity by reducing the diameter of the end pipe?

 

Cheers

 

Paul

[Peter Cobbold]

Peter

 

Our posts crossed - interesting thought. Are you able to estimate the angle to horizontal that your final section describes? A simple realignment might be the first step.

 

BTW and at the risk of pedantry, the gas velocity would be halved in a two pipe system if the sectional area of each was the same as a single pipe system. So could you accelerate the gas exit velocity by reducing the diameter of the end pipe?

 

Cheers

 

Paul

Paul, My mid-section is standard twin pipes merging into one short 'silencer', whose outlet is near as dammit horizontal. I think its 2.5inch bore. Peter

[JJC]

Just followed an Élan. Exhaust pipe centre of car inclined slightly up. Not quite a Kamm tail but not far off. Do they get the smell? If not why not? JJC

[Cew]

Just followed an Élan. Exhaust pipe centre of car inclined slightly up. Not quite a Kamm tail but not far off. Do they get the smell? If not why not? JJC

 

Not being as knowledgeable as other sages on here ,who will no doubt have a correct answer, I wonder if the underneath of the Elan is "smoother" then the TR6 which could contribute in some way to the overall airflow,just a thought.

[Guest ntc]

To put things into perspective first run in a fully rebuilt car today totally standard and there was no smell anywhere,even the wife commented . Look elsewhere

[PaulAA]

Paul, My mid-section is standard twin pipes merging into one short 'silencer', whose outlet is near as dammit horizontal. I think its 2.5inch bore. Peter

 

Thanks, Peter. For the sake of a weld, I give it a try.

[JJC]

Interesting that the underside of the Élan might be smooth. Presumably that would mean lamina flow, lack of turbulence, and hence no smell. So, if you jump in the TT and wait till the spoiler pops up do you then get fumes? JJC

[Tim D.]

Having had an elan +2 (not quite the same I know) the underneath is smooth compared to the tr.

Also pretty sure the fumes can sometimes be an issue in the soft top.

Tim

[re-hiker]

As promised earlier, here the Pictures of my Version which eliminated the Exhaust Fumes in the Car, Dizzyness and Headache. Supplementary Effect, the rear Lights and Bumpers stay cleaner. Cost USD 7.50 plus two M3 x 10 mm.

 

During my time with the BL Importer in Switzerland, Emil Frey AG, we modified all A 40 Farina as well as Austin Cambridge Exhaust End Tubes with a supplementary Pipe of maybe 70 mm, fully out to the left rear Corner. Otherwise the Customers complained about Exhaust smell in the Car

 

Robert

Edited July 12, 2015 by re-hiker

[barkerwilliams]

Robert,

 

I am pleased that your exhaust tips have eliminated fumes from your cockpit, I have fitted something similar and have also noted the improvement in air quality. It seems that an unmodified twin exhaust on the TR6 poses a real threat to health especially when so many cars seem to be running on fuel additives. On the TR6 forum Peter Cobbold warns of the dangers of the contents of some fuel additives and not breathing high concentrations of fumes for extended periods can only be good.

 

Alan

[jean]

I well remember that in the 60th it was the number 1 solution for committing suicide. Lock your self in in the garage with engine running.. a very soft death.

[OAF939M]

I bought some small CO indicator patches from Maplin, stuck one at top of screen out of sight from outside the car.

No indication of fumes or CO after 150 miles trip this weekend.

[PaulAA]

I bought some small CO indicator patches from Maplin, stuck one at top of screen out of sight from outside the car.

No indication of fumes or CO after 150 miles trip this weekend.

 

For absolute certainty, might be worth repeating with the indicator stuck somewhere around your collar or upper chest, to overcome the influence of swirl.

[OAF939M]

This was with the hood up, in fact the fumes stopped when we found a slightly loose silencer a couple of weeks ago ,we fixed that and had no fumes since.

So maybe worth checking something simple like that first.

But will try fixing a detector around my face area.

Edited July 14, 2015 by OAF939M

[PaulAA]

I didn't realise that the car actually works with the hood up - I thought it was a parking precaution

 

I haven't had the opportunity to try the downturn pipe-end option yet, but the whole exhaust system was re-set and re-sealed when the engine was reinstalled last month. I also replaced the boot seal as a precaution (despite establishing that the old one achieved a complete seal with old cooking oil smear test). The result is a significant improvement and, ironically, I am only aware of fumes when standing in traffic and, more profoundly, when reversing into my garage space...

[WWT338J]

Another solution?

 

http://www.ebay.co.uk/itm/Triumph-tr6-full-exhaust-manifold-/221825794392?pt=LH_DefaultDomain_3&hash=item33a5d90158

 

Not mine.

David