George Lendich wrote:

Paul,
Why is it not an option to run two manifold tubes (and  have 2 into one closer to the motor inlet
area) instead of the four that most are using.
Is there a performance penalty, does one tube rob the other or something.
I notice a 20B has a fancy tube manifold with the 2 into one concept - I've always wondered !?
George (down under)

You never see two into one near the engine. What you are seeing in the
case of the 13B and it only works with a two rotor is a series
of dynamic chambers. These in essence are tuned at two different RPMs
Usually about 3000 and 6000 RPM. The stock 20B had six long tuned
runners opening into one plenum. Probably tuned around 6000 RPM.

Its like the end housing coatings. Mazda spent a billion dollars
finding out what works best.

Paul Lamar
 
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