I have all the engines on the bench in front of me. 20B, 13B cosmo, 3rd gen,
and the rest! The 13B cosmo has the same housings as the 20B which are larger
than 3rd gen. I'm talking about the port runner actually where the manifold
bolts on. The cast iron housings are exactly the same as 20B's. Hope that
helps. I'm putting one together now with ceramic seals. I changed the inserts
in the rotor housings. They are just like the 20B except they say 13B. Just
like the 20B they are very restrictive. I ramped the exhaust port like Crissi
? was talking about. A pepsi can rattles around inside the exhaust port exit
where the header bolts to. Skip

I think lowering the exhaust port opening line is a bit counter
productive as it reduces the period of time the hot gases can expand
and do useful work.

Skip give us numbers. When does the exhaust port open and when does
it close relative the e-shaft angles?

Paul Lamar

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