Extractor/Header for 6cyl.

[michaeldavis39]

Here we go guys, this is an original Gareth Thomas exhaust- I'm sure he won't mind me posting this photo as he no longer comes on here and I know him well

 

 

[Malbaby]

Thanks for the replies...pity the RHD steering column limits the selection somewhat.

[Andy Moltu]

There were other manifolds with equal length primaries but not sold through the big TR retailers. I've got one that is less compact than the images above but gave a good boost to mid range torque than the bunch of bannanas that I had on before which made more of a benefit at the top end.

Interestingly some modern cars have variable length inlet trumpets that are controlled to optimise with the RPM. If you could do this with exhausts it could give you increased mid rang torque and top end power...

On the end the benefits of tuned manifolds are only worthwhile if you have done the other mods to get the benefit and if you actually use the car in a way that uses it.

I remember someone asking me which fast road cam he should fit in his 6. He said he never went over 3500 rpm. 4000rpm with foot to the floor would achieve the power boost far more effectively.

[super6al]

1 hour ago, Andy Moltu said:

There were other manifolds with equal length primaries but not sold through the big TR retailers. I've got one that is less compact than the images above but gave a good boost to mid range torque than the bunch of bannanas that I had on before which made more of a benefit at the top end.

Interestingly some modern cars have variable length inlet trumpets that are controlled to optimise with the RPM. If you could do this with exhausts it could give you increased mid rang torque and top end power...

On the end the benefits of tuned manifolds are only worthwhile if you have done the other mods to get the benefit and if you actually use the car in a way that uses it.

I remember someone asking me which fast road cam he should fit in his 6. He said he never went over 3500 rpm. 4000rpm with foot to the floor would achieve the power boost far more effectively.

Hi Andy

I remember Yamaha did something similar with their 'exup' valve in the exhaust pipe of some bikes. Don't know if it still used or ever been tried in a car

Alan 

[Peter Cobbold]

The problem with GT's flow-bench approach to exhaust design is that the exhaust gas is hot and his flow bench air was not. Gas temperature has a large effect on the speed of sound in the gas; in hot gas it is faster. That is one of the reasons why the ev can be made smaller than iv despite the much larger volume of exhaust gas compared with inlets. So gas-flowing an exhaust manifold  with room temperature air will compromise, even invalidate, the design.

https://www.engineeringtoolbox.com/air-speed-sound-d_603.html

 

Peter

[michaeldavis39]

Peter- do you know anyone who uses hot exhaust gases on a flow bench- in the late seventies early eighties when GT did all the hard work which nobody else had even thought of I think give credit where credit is due- all the rest have been copies for which GT got absolutely no compensation or recognition for so perhaps folks shouldn't be so critical of the man?

 

[Andy Moltu]

The concept of equal length primaries is not new - way before anyone made one fir a TR.

As Pete says temperature is a significant factor. No doubt those designing F1 engines and the like may well have the computer modelling to test their designs but that wasn't available back in the day. Thus his comments are valid and the jury is out on which of the equal length primary manifolds simply because there are too many variables. Exhaust gas temp and the use of the vehicle- road or race, top end or mid range?

[john.r.davies]

Surely there can be no argument that an  extractor manifold MUST have equal length primaries.  Thermal variation can only influence their length.

Anyway, "No doubt those designing F1 engines and the like may well have the computer modelling to test their designs but that wasn't available back in the day."   They certainly do, and I give you, Cordon D., Dean C.,  Steciak J., Beyerlein S, "ONE-DIMENSIONAL ENGINE MODELING AND VALIDATION USING RICARDO WAVE" 

"Ricardo WAVE" is just as suggested a system to model engines'  internal function.  Cordon et al derived this chart:

I've no details of the engine modelled  (the paper is behind a pay wall) but note the deep trough at 6K, except with 40 inch (!!!) primaries.    So clearly SOME effect!

And modern BMWs go the same 6-3-1 extent:

JOhn

Edited March 30 by john.r.davies

[Peter Cobbold]

17 hours ago, michaeldavis39 said:

Peter- do you know anyone who uses hot exhaust gases on a flow bench- in the late seventies early eighties when GT did all the hard work which nobody else had even thought of I think give credit where credit is due- all the rest have been copies for which GT got absolutely no compensation or recognition for so perhaps folks shouldn't be so critical of the man?

 

Michael, I also question the use of a flow bench for tuning exhaust manifold on the basis that the air flow is not pulsatile. Tuned exhausts rely upon those pulses 'co-operating' to improve scavenge. No flow bench can do that. The only way I know of designing exhaust manifolds (pre computers) is to run an engine on a dynamometer and measure torque for several different fabricated manifolds. That would have to be done to compare the various TR designs. Peter

[BlueTR3A-5EKT]

1 hour ago, Peter Cobbold said:

Michael, I also question the use of a flow bench for tuning exhaust manifold on the basis that the air flow is not pulsatile. Tuned exhausts rely upon those pulses 'co-operating' to improve scavenge. No flow bench can do that. The only way I know of designing exhaust manifolds (pre computers) is to run an engine on a dynamometer and measure torque for several different fabricated manifolds. That would have to be done to compare the various TR designs. Peter

Back when Terry Hurrell was introducing Triumph Tune product and developing the catalogue, he did do back to back rolling road testing of the product that was to go in the catalogue.   Notably the GT original manifolds were compared to others that were on offer.  

Exhaust manifolds and exhaust changes were always a challenge as too often the damn things did not fit in their original state and needed fettling before testing, then removing and shipping to the maker for jig changes.   Mike the Pipe was a primary supplier and got things just right, then they were sent for copying by a volume maker with cnc bending facilities. (Falcon)
 

The testing found improvements of course and demonstrated the need for fuelling/ignition changes on the Cox & Buckles workshop TR6 donkey car.   AKA ‘the racer’.   The other cars used were Terry’s own Spitfire, TR7 & V8 conversion.  Latterly of course MG items were developed.
One of the things found was how an aftermarket ?Peco? Perhaps, exhaust silencer performed less efficiently than a standard item. Ooops!

Terry would spend a lot of time fitting and removing parts from his cars to get them in the format he wanted testing.

There was a lot of swapping of cylinder heads, fuel systems and manifolds which took weeks and cost many hours of labour, to arrive at what were described as ‘plus-packs’    This was true development of some products, not suck it and see.

The actual test results & other figures from then  I do not have, they were broadly described in the Triumph Tune catalogue.   I think the test work was done at a rolling road near Luton.

[Andy Moltu]

That does illustrate the amount of time and expense it took back in the day to test tuning parts on the car and given the diminish size of the market, it’s not likely to be done again for the TRs.

John’s graph makes interesting reading.  Could it be interpreted that the shorter the primaries the more likely that (at least on that engine) the more likely you will hit dips in the torque curve? Rather than fancy manifolds achieving the effect of the beneficial scavenging being desired, could it be more a case of less less destructive being the aim . The much longer primaries seemed to perform better in mid range but all were pretty similar otherwise. A curve for 50 or 60 inch primaries would have been interesting.

 

[BlueTR3A-5EKT]

On 3/30/2024 at 7:17 PM, john.r.davies said:

Surely there can be no argument that an  extractor manifold MUST have equal length primaries.  Thermal variation can only influence their length.

Anyway, "No doubt those designing F1 engines and the like may well have the computer modelling to test their designs but that wasn't available back in the day."   They certainly do, and I give you, Cordon D., Dean C.,  Steciak J., Beyerlein S, "ONE-DIMENSIONAL ENGINE MODELING AND VALIDATION USING RICARDO WAVE" 

"Ricardo WAVE" is just as suggested a system to model engines'  internal function.  Cordon et al derived this chart:

I've no details of the engine modelled  (the paper is behind a pay wall) but note the deep trough at 6K, except with 40 inch (!!!) primaries.    So clearly SOME effect!

And modern BMWs go the same 6-3-1 extent:

JOhn

Thank you for the lead to 

https://www.researchgate.net/profile/Judi-Steciak/publication/267239110_ONE-DIMENSIONAL_ENGINE_MODELING_AND_VALIDATION_USING_RICARDO_WAVE/links/5460d2630cf27487b4526085/ONE-DIMENSIONAL-ENGINE-MODELING-AND-VALIDATION-USING-RICARDO-WAVE.pdf?origin=publication_detail&_tp=eyJjb250ZXh0Ijp7ImZpcnN0UGFnZSI6InB1YmxpY2F0aW9uIiwicGFnZSI6InB1YmxpY2F0aW9uRG93bmxvYWQiLCJwcmV2aW91c1BhZ2UiOiJwdWJsaWNhdGlvbiJ9fQ

 

An interesting article.

[john.r.davies]

60 inch primaries? Certainly, Sir!

That's one of Gareth Thomas', but as he never promoted it I suppose it wasn't that succesful.

John

[Andy Moltu]

That looks to be be an example of "Just because you can, doesn't mean you should!"

[Tom Fremont]

On 3/29/2024 at 1:10 PM, michaeldavis39 said:

Here we go guys, this is an original Gareth Thomas exhaust- I'm sure he won't mind me posting this photo as he no longer comes on here and I know him well

 

 

This is a work of art in its own right and it's obvious with circa (20) sections welded together it's not commercially viable.

Richard Good's " inability " to build it in stainless must mean " for an acceptable price ". 

From what I've seen on this thread the GOODPARTS design in coated mild steel is still the competitively priced best performance option. I would be quite surprised if he doesn't know whether the RHD cars will accommodate it, less surprised if they cannot.

I have no financial interest and provide this link just FYI:

 

https://www.goodparts.com/product-category/exhaust/

 

 

[michaeldavis39]

You are absolutely right Tom. Gareth told me his extractor manifold could not be made on a production line as each one has to be hand made hence expensive and very time consuming.

[Andy Moltu]

I guess it was too expensive for a road car and the benefits of mid range torque were less relevant to the racers for whom top end power is more important.

[dblenk]

On 3/29/2024 at 12:18 PM, stuart said:

What you want is this.

Stuart.

 

Bolognese sauce come with that !!!!! very nice i assume a well sorted engine

when i did my fast road grey car i did everything cam head flywheel etc etc 6-3-1 manifold but didnt get time to put a sports exhaust before lemans so the std went on and what a disappointment thought i had wasted all that money

got home and time to fit the sports exhaust

what a difference never thought the std exhaust throttled the engine so much ended up with 150bhp at the wheels on a rolling road which was enough for me 

i fitted a std clutch which didnt like quick get aways

David

[JohnC]

On 3/29/2024 at 11:18 PM, stuart said:

What you want is this.

Stuart.

 

And what is "this"?

[stuart]

Just now, JohnC said:

And what is "this"?

A very nice Manifold, running in a 2.5 saloon in your country somewhere. Leastways it was when that picture was taken many years ago.

Stuart.

[TRTOM2498PI]

On 4/6/2024 at 12:18 PM, stuart said:

A very nice Manifold, running in a 2.5 saloon in your country somewhere. Leastways it was when that picture was taken many years ago.

Stuart.

The car belongs to Andy Thompson. He still has it. It has a 2.7L motor now, with steel crank, rods, forged pistons, and now on EFI.

[stuart]

1 hour ago, TRTOM2498PI said:

The car belongs to Andy Thompson. He still has it. It has a 2.7L motor now, with steel crank, rods, forged pistons, and now on EFI.

Yes thats the one, couldnt remember his second name.That must be a beast now with the EFI as well.

Stuart.

[TRTOM2498PI]

4 hours ago, stuart said:

Yes thats the one, couldnt remember his second name.That must be a beast now with the EFI as well.

Stuart.

Yes, I think so. I think he is currently in the early stages of engine mapping and running it in actually.  Will try and obtain a current picture.