[6pack] Inlet Manifold Question

[John Macartney]

> 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!

Tony, if it helps, I've got a used Witor recommended manifold on my PI. It's the type I always 
recommend when this topic crops up as it's the 6-3-1 type. FWIW (and I believe the manifold in 
question is the former pattern from SAH and Triumphtune/Moss) the individual pipes are all (visibly) 
about the same length. Indeed, the pipe for #6 curves behind pipes 2 to 5 and snicks neatly in to 
#1. Many of us in the UK believe this design is arguably the best because the scavenging effect is 
best and with pipes of roughly equal length it can be argued the *bangs* all have to travel an equal 
distance before getting mixed up with all the other *bangs*. Certainly, this set-up makes a 
phenomenal difference to performance as a whole and makes an overall noise that probably isn't legal 
through just one main silencer and a tailpipe resonator. Gives me a splitting headache after a 
while - but what the hell, you can hear everything is working just fine!

Jonmac