Ed, here's a highly theoretical question (as I have no plans to take apart my engine again):
will street porting the 1986 NA narrow the intake runner length curves on the graph?

On another note, I somehow have the idea that it's a bad idea to combine the runners. For example Jim Mosur had big problems splitting the water flow between his two radiators when he ran them in parallel. Tracy has argued that it doesn't matter because on an intake system you have a vacumn sucking in the air which would split it evenly. However, not so with the DIE pulses. I could even imagine that the pulse, preferring on path (one port) could even start to push out the air/fuel charge out the other port.

Over to you...

Finn

Ed Anderson wrote:

I believe (but have no data to support the belief) that if you want the DIE effect at only one rpm, then given all else is equal (which it seldom is) then it may make sense to port an engine to give the same timing on both primary and secondary.  I think this would be hard (and not necessarily good) to do on the 6 port as there is a wide difference between say the secondary and aux timing.  I think it is easier to get the two ports on a turbo block equal in timing without major challenges.

 

I will be merging my primary and secondary runners shortly after they exit the engine block on my next manifold.  My ports are already equal in timing.  So hopefully with in the next month or two, I will have this new intake fabricated and can provide some data on the results.

 

Hope this addresses your question.

 

Best Regard

 

Ed Anderson