<... According to the graphs Ed distributed after the presentation, on the 1990 Turbo and street ported 1991 Turbo II  their primary and secondary runners can be identical lengths...>
So (to go back to the original question) why do we need separate primary and secondary runners?  Why not a single runner for each rotor?

<... should be about 4 inches longer than the primaries ... presumably is for a non-street ported ...porting will dramatically alter the required lengths...>
To closer to the same length, or greater difference?  If the "paths" were close (from, say, the mid point of a manifold that "straddles" the ports) it would seem that DIE would work "pretty well".  Maybe even better since the duration of the overpressure on one port before it closed would be a little longer.

Is keeping primary and secondary paths the same length might be more trouble than it's worth ... Jim S.

Finn Lassen wrote:

Jim Sower wrote:

<... a simple way to cut down on the amount of fuel/air mixture during idle ... yet have plenty of reserves at redline rpm ...>
So why do I need primarys and secondarys with different lengths that screw up DIE and generally make life more difficult?
There must be more to this than meets the eye ... Jim S.

According to the graphs Ed distributed after the presentation, on the 1990 Turbo and street ported 1991 Turbo II  their primary and secondary runners can be identical lengths.

On the 1988 NA the secondary port runners should be about 4 inches longer than the primaries. This presumably is for a non-street ported engine. Any porting will dramatically alter the required lengths.

Come on, Ed. Help me out here!

Finn
 

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Jim Sower
Crossville, TN; Chapter 5
Long-EZ N83RT, Velocity N4095T