Exhaust manifold TR6

[nylen]

When I search for exhaust manifold I find that there at two different main types. From Racetorations and Revingtons the have the figure 6-2-1. This is also what Kas Kastner recommend in his book. Triumph Preparation manual.

Both Phoenix types on Moss website has figure 6-3-1.  Primaries joined together in pairs at 180 degrees interval. That make sense but I can not understand the principal for 6-2-1.

Can anybody explain?

 

[BlueTR3A-5EKT]

This was a good discussion at the time

 

[TRseks]

On 6-2-1 the pipes from the 3 rear cylinders goes in to 1 and the 3 at the front to another, then into 1.

I got the Racetorations, no problems with clearances even with standard starter.

 

I wrapped the starter in “heat shield material”, and made a heat shield under the carburettors as the heat is higher from the SS manifold.

 

Magnus

Edited September 4, 2021 by TRseks

[nylen]

Thanks but I still don´t understand the principal for 6-2-1.

[TRseks]

I did not fit the racetorations system because I have a highly tuned engine, my car is a US model and had the original single outlet pipe (not the dual outlet) and I wanted a SS system that would last a long time and with added nicer sound. The racetorations manifold is made of high grade 308 stainless steel and sounds great, big bore system with a phoenix muffler. I have heard the 6-3-1 is better for the TR6 as it gives a better “pulse from each cylinder”? and helps better at higher revs but it does not really matter as I hardly ever rev the engine up. I have not wrapped the exhaust either as this will probably make it rust.

 

Magnus

Edited September 4, 2021 by TRseks

[YankeeTR5]

The principle behind the 6-2-1 is, I believe, is that there may not be much principle behind it (other than the simplistic things like packaging, ease of mfg and the fact that cars need some type of exhaust manifold).  For the dual pipe exhaust using a 6-2-1 header you can almost make the case that each of the two branches would have its own exhaust pipe.

The 6-3-1 at least has some thought re: resonance scavenging etc. that make sense. 
Basis some other comments....the beauty of the 6-3-1 is that the largest benefit  to power is mostly on the lower end.  

[nylen]

It is funny that no one ever made a test of a 6-3-1 system compared to a 6-2-1 system. For example- Phoenix race performance system against  Ractorations or Revingtons. You have thousand of TR5/TR6 in UK and no one had made a rolling road test to compare!!

[DRD]

1 hour ago, nylen said:

It is funny that no one ever made a test of a 6-3-1 system compared to a 6-2-1 system. For example- Phoenix race performance system against  Ractorations or Revingtons. You have thousand of TR5/TR6 in UK and no one had made a rolling road test to compare!!

I think people have but there are always so many different variations its difficult to compare directly.

You would need to do it on the same car on the same RR on the same day etc. etc.