Add these numbers to the fixed runner lenght. Short memory Jerry? :)
Max torque at a given RPM is max HP at that RPM.
Paul Lamar

"Weinstock, Rob" wrote:

What are the relevant equations for runner lengths?

Thanks,

Rob

There are some around. I don't have them however. What you see here
has been verified
on a dyno. Just copy this exactly and you should get exactly the same
HP.

Paul Lamar

Paul,  can your friend with Anvil, take a look at the Powersport engine
(photos on their web site) and tell us how long the runners are?  Also
their diameter?    Since their dyno info is published on the site, we
may get data we can analyze.

There is still the question of how "should" we tune the engines? Not
very many will want to run their engines at peak h.p. all day .  Should
we tune for cruise?   For those using the 2:85 drive, the difference
between max performance rpm and slow cruise rpm will be considerable,
perhaps as much as 3000 rpm.   Half that for the 2:17.  The thing is Ed
and I have to choose a number and go with it.  Or maybe we will have to
choose two numbers one for each drive.  Help with this would be most
appreciated.

   Also,  there is looking at this from the other point of view, i.e.
what is possible given that we have to run the runners over the engine,
we want an air cleaner, we want ram air, we have to fit it under a
tight cowl, we want the fuel on the cold side.

   Some of the data is counter intuitive.  For example I have watched  p
ported street rods  accelerate strongly from fairly low rpm.  I would
assume these had very short intake runners but they still ran damn
strong when the throttle was pushed.     Who has a p ported car who can
give us some performance data?  Lynn,  how did you tune your p ported
race car.  Did you try different runner lengths?    What advice can you
offer?    Thanks  Jerry

Tuning for peak torque at a lower RPM with longer runners will result in 
better BSFC at that lower RPM. I doubt however you will do much better 
than the Leman engine's BSFC of .47 at 6000 RPM. However you will be running
the engine at a lower RPM so the HP will be down and so too the fuel burn.

Paul Lamar

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