Extractor vs Standard Cast Exhaust Manifold

[colin3511]

Hi,

 

I have a fast road cam and ported and polished head. I have the stainless extractor manifold fitted with single bore exhaust. It generates a lot of heat and I am considering changing back to a standard manifold through to a single big bore system.

 

Will I notice any performance change as a result?

 

Thanks,

 

Colin

[DRD]

Hi,

 

I have a fast road cam and ported and polished head. I have the stainless extractor manifold fitted with single bore exhaust. It generates a lot of heat and I am considering changing back to a standard manifold through to a single big bore system.

 

Will I notice any performance change as a result?

 

Thanks,

 

Colin

 

Quite possibly - why don't you wrap it?

 

Also it sounds much better as well

[john.r.davies]

Colin,

you appear to have a 6-1 manifold, with all the primaries joining low down at the level of the final tail pipe. This may have advantages at high revs, but in the usual range does not act as a 'scavenger' or extractor.

A 6-3-1 manifold, with primaries 17" long, allows the exhaust pulse of paired cylinders to resonate as negative waves back up the opposite primary to reinforce extraction, inproving performance over the 6-1 and the cast manifold.

 

 

The 6-1, with longer primaries, has a greater surface area than the 6-3-1 -and a very much greater area than a cast manifold - and will radiate more heat, but I doubt if you will find your under bonnet any cooler with either alternative. That vast majority of that heat comes from the radiator. Once I built a Triumph (Vitesse) with a rear radiator - it was a cold car to drive, even in warm weather!

 

Jiohn

[Fireman049]

Hi Colin ~

 

I sprayed the inside of my extractor manifold with special heat resisting paint from Frost's.

I also sprayed the outside with heat resisting paint before wrapping the manifold with heat wrap.

This was also sprayed with heat resisting paint. The front pipe is double wrapped to protect the alternator

as are the twin pipes adjacent to the starter motor.

 

Tom.

Edited July 31, 2018 by Fireman049

[Fireman049]

Hi again Colin ~

 

I also heat wrapped my high inertia starter motor.

 

Tom.

[john.r.davies]

For a long thread on wraps, ceramic coatings, heat resistant paints, see: https://www.tr-register.co.uk/forums/index.php?/topic/64128-manifolds-wrap-or-ceramic-anyone-interested-in-a-comparison/page-6?hl=manifold&do=findComment&comment=575537

 

John

[BlueTR3A-5EKT]

Colin,

you appear to have a 6-1 manifold, with all the primaries joining low down at the level of the final tail pipe. This may have advantages at high revs, but in the usual range does not act as a 'scavenger' or extractor.

A 6-3-1 manifold, with primaries 17" long, allows the exhaust pulse of paired cylinders to resonate as negative waves back up the opposite primary to reinforce extraction, inproving performance over the 6-1 and the cast manifold.

 

manifold length.jpg

 

The 6-1, with longer primaries, has a greater surface area than the 6-3-1 -and a very much greater area than a cast manifold - and will radiate more heat, but I doubt if you will find your under bonnet any cooler with either alternative. That vast majority of that heat comes from the radiator. Once I built a Triumph (Vitesse) with a rear radiator - it was a cold car to drive, even in warm weather!

 

Jiohn

Help please John, and excuse my ignorance.

Your 'manifold length.jpg' has induction pipe length (m) up the left side. Is induction pipe length same as exhaust primary length, or am I missing something in the graph?

Cheers

Peter W

[john.r.davies]

I took the graph from Stone's "introduction to Internal Combustion Engines". The physics of "tuning " the lengths of induction or exhaust ducts, so that they resonate is the same. So while that chart represents i duction, a similar one would do for the exhaust.

 

John

[harlequin]

Colin

I swapped from a phoenix stainless manifold back to a standard cast manifold because of the under bonnet heat and didn't notice any difference in performance. Although not a very technical answer I should add the car seemed smoother and quieter.

An added bonus is I can now remove the starter without first removing the manifold and should the manifold need removing the nuts are way more accessible.

 

George

[oldtuckunder]

I have a fast road cam and ported and polished head. I have the stainless extractor manifold fitted with single bore exhaust. It generates a lot of heat and I am considering changing back to a standard manifold through to a single big bore system.

 

Will I notice any performance change as a result?

 

 

 

As John hinted unless you are going racing, NO. and in all probability in regular fast road driving you may even see an improvement. The Standard cast TR6 manifold isn't bad, and not all bolt on performance goodies are good.

 

Alan

[michaeldavis39]

Nobody here mentioned that there were two cast iron manifolds- the early single outlet and the later twin outlet. The twin outlet is the better of the two from my research online from TR forums.

[PodOne]

If you are concerned about heat and for normal road use I'd use a ceramic coating such as Zircotec. I've used it on cast maifolds and turbo housing's etc and has made a noticable/measurable difference along with reflective heat foil on starters etc which helps.

 

There might also be some mileage is using a polyprop isolation inlet manifold gaskets if available to keep the throttle bodies/plenum cooler but given they are on the same side as the exhaust I'm not too sure if there would be any benefit.

 

As said not all mods are worthwhile and in a lot of cases make matters worse from my experience. With regard to tubular manifolds/exhausts yes they might sound good but with a detimental effect on performance unless dyno proved against oem. In reality they might only give 3-5bhp lift and head work is likley to be a better option. But if your into racing then even 3-5bhp is worth having!

 

Andy

[lightningburns]

Nobody here mentioned that there were two cast iron manifolds- the early single outlet and the later twin outlet. The twin outlet is the better of the two from my research online from TR forums.

As far as i am aware the twin outlet was installed on all the PI tr5/6. TR250 and earlier TR6 carb cars had the single outlet, but as you say the standard PI twin outlet is the one to go for.

 

John

[oldtuckunder]

If you are concerned about heat and for normal road use I'd use a ceramic coating such as Zircotec. I've used it on cast maifolds and turbo housing's etc and has made a noticable/measurable difference along with reflective heat foil on starters etc which helps.

 

 

 

No idea about Turbo Housings, but as one of the few people who has actually back to back tested wrap and ceramic on headers in the same car, I'll declare that it is snake oil, Pretty, but useless for heat.

 

https://www.tr-register.co.uk/forums/index.php?/topic/64128-manifolds-wrap-or-ceramic-anyone-interested-in-a-comparison/

 

Alan

[john.r.davies]

Snap! That's the one I linked to, and Alan's comparison.

 

Also mentioned therein by me and others is the weird corrosion that occurs under the wrap. When you remove it, the matal surface comes away in large flakes. I don't think we identified what was happening, but several others confirmed the same effect.

 

JOhn

[DaveR]

Also mentioned therein by me and others is the weird corrosion that occurs under the wrap. When you remove it, the matal surface comes away in large flakes. I don't think we identified what was happening, but several others confirmed the same effect.

 

JOhn

 

 

I too have used wrap and had corrosion take place. As a result I don't use it anymore.

 

Dave

[colin3511]

Interesting comments - thank you.

 

You have confirmed what I thought. The tubular manifold is generating a lot of heat, noisier in the engine bay and a pig to remove.

 

I have the standard twin pipe PI manifold so I'll swap it over when I put the original engine back.

 

Thank you.

 

Colin

[Bodiam]

Colin,

 

I exchanged a manky tubular manifold for a standard twin pipe cast iron job about 5 years ago and noticed no loss of performance.

 

I did have it media blasted then aluminium sprayed and it still looked as good as the day I fitted it when I sold the car in February.

 

The firm who did it for me are in Wolverhampton - if they are near enough for you to get it to them, send me a PM for the address.

 

John

[YankeeTR5]

Not to go down the rabbit hole or to be contentious....BUT, Kas Kastner, Triumph's race team director in the states did very extensive testing on the six cylinder engine including different cam's, induction (standard & modified ZS, Webers & PI) etc and wrote a manual on how to make a 6 pot go faster - for street and for all out race. The manual is full of comparative graphs showing differences of bolting on different parts to the same engine as a baseline. Good read really.

 

Given his results (TR's were very successful, if not dominant, from TR4-6's under his direction) he called out under the exhaust section that the best performance, other than for all out race, to be achieved was with a single pipe exhaust with a slightly larger diameter pipe. He found no benefit to fitting the dual manifold/dual pipe exhaust. Just sayin....

 

He did not however ever test a 6-3-1 manifold, as the idea wasn't around back then. From my understanding, this style if correctly done (equal length primaries, etc) provides a nice bump in HP and torque on a street car.

Edited August 1, 2018 by YankeeTR5

[Tom Fremont]

 

 

He did not however ever test a 6-3-1 manifold, as the idea wasn't around back then. From my understanding, this style if correctly done (equal length primaries, etc) provides a nice bump in HP and torque on a street car.

 

I have one of these in a GOODPARTS which has equal length primary and secondary tubes. The contortions to bring this about within the envelope make it difficult to render in stainless, so they're ceramic coated mild steel. Converting from a 6-2-1 to this filled a persistent hole in the mid range on a wildly cammed Webered engine ( 1/2"+ lift at valves ), and I was surprised that several sizes leaner in the main jet stack were needed to settle things afterward. So I am convinced manifolds can have a considerable effect and switching may require re-tuning the fuel system.

 

If the engine runs well and heat is the only objection I'd keep what works and have it ceramic coated. The specialists claim dramatic reductions in surface temps though I reckon that applies to low load, cruising conditions.

 

Cheers,

Tom

[BlueTR3A-5EKT]

 

I have one of these in a GOODPARTS which has equal length primary and secondary tubes. The contortions to bring this about within the envelope make it difficult to render in stainless, so they're ceramic coated mild steel. Converting from a 6-2-1 to this filled a persistent hole in the mid range on a wildly cammed Webered engine ( 1/2"+ lift at valves ), and I was surprised that several sizes leaner in the main jet stack were needed to settle things afterward. So I am convinced manifolds can have a considerable effect and switching may require re-tuning the fuel system.

 

If the engine runs well and heat is the only objection I'd keep what works and have it ceramic coated. The specialists claim dramatic reductions in surface temps though I reckon that applies to low load, cruising conditions.

 

Cheers,

Tom

It's alright for you Tom, we have a steering column in the way of the exhaust manifold on UK cars.

[Tom Fremont]

It's alright for you Tom, we have a steering column in the way of the exhaust manifold on UK cars.

 

Won't it work on these too? It would be good to know.

 

If not, there may be a TT version which accomplishes the same thing and ought to work for RHD cars.

 

Tom

[DRD]

 

Won't it work on these too? It would be good to know.

 

If not, there may be a TT version which accomplishes the same thing and ought to work for RHD cars.

 

Tom

 

The Phoenix one fits OK and is a 6-2-1 extractor manifold.

 

Also can't say I've noticed any heat issues either compared with the original cast one.