[TR] Inlet Manifold Question

[Tony Gordon]

I must admit I had thought the same ... and to that end I thought I'd look
at my collection of Triumph "history" books and looked at the design of the
various manifolds. At a glance, it seems that the 2000, Vitesse, and GT6
manifolds are all very stubby -- very short and it is difficult to see a
distinct runner -- and the 2500-TR250-6 manifolds are all somewhat similar
in shape with visible and longer runners.  I plan to call Chris Witor to see
if he can shed any light on the manifold design question in his article, but
I suspect you (and others) are right .. this applies to the 1.5" short
runner manifold design.

Moving on to the TR6 with its longer runner 3-1 manifolds in terms of
breathing, and from a purely bar-room mechanic view of how a one-to-three
manifold might work, I would guess that there has to be some flow
differences between 1 & 3 compared to 2 (and 4 & 6 with 5) since the runner
length is different.  Of course, I don't have a manifold to hand to look at
the runner I/Ds to see if they are smaller for any of the legs, or if there
are any flow shaping differences between the various legs of the manifold.
The differences in flow per cylinder will be less than that mentioned in
Witor's T2000 manifold tuning article, I'm sure, but I'd be interested to
learn what the difference was!

In terms of runner design, Kastner mentions in his tuning guide that the PI
and Weber cars really benefited from the nicely sculpted single runner per
cylinder design, and also showed that by lengthening the runners/trumpets,
you can increase the power: his work seems to show that (counter intuitively
...?) mounting the PI injectors as far away from the valves as possible
increased power and race performance.  The after-market EFI thinking seems
to assume that squirting the injected fuel at the back of the inlet valve is
the best approach, and so injectors are mounted very close to the valves.

**************************************
Tony Gordon
72 TR6
**************************************

----- Original Message ----- 
From: "Shawn J. Loseke" <sloseke at holly.colostate.edu>
Sent: Monday, May 19, 2008 2:16 PM
Subject: RE: [6pack] Inlet Manifold Question


> Its also specifically talking about manifolds and carburetors for a 
> 2000TC.
> Might have more in common with the GT6 than the TR6. Which always used 
> 1-/34"
> carbs (never 1-1/2) but did use two different intake manifolds (short 
> runner
> and long runner).
>
> The head numbers could be the same, other than thickness for compression, 
> but
> the manifolds could very well be apples and oranges.
>
> Shawn