Intake question

[Paul Lennemann <pjlenn@xxxxxxxxx>]

I read the "Crossram Chronicles" article that Gary added to the website. 
 It talks about a runner length of 15" being the magic number to 
scavenge the resonant pressure waves which result from the intake valve 
opening and closing.  And that this length was tuned to an engine rpm of 
5400. Giving the max wedge crossram manifold a distinct advantage over 
the earlier long ram  manifold which was tuned to provide more torque 
and power from rpm's in the low 2000's to @ 4800.

In reading general theory about intake manifolds it is stated that a 
single plane manifold generally works better at higher rpm than a dual 
plane which will give you more torque at lower rpm & better idle 
quality.  Since a dual plane has longer runners this would seem to put 
these two theories at odds with each other.  

I don't think any of the commonly available street type intakes have 
runner lengths anywhere near 15".  I'm thinking about The Holley Street 
Dominator and the Edelbrock Performer RPM in particular.  But since the 
Performer is a dual plane it should have the longer runners, making it a 
better intake for low end torque and the Street Dominator a better top 
end unit.  I am in the process of making some performance modifications 
to my 440 so I'm trying to understand this a little better.

Can anyone clear this up for me, Earl, Don, anyone?

Paul L.
'63 Sport Fury
440/727
http://www.1962to1965mopar.ornocar.org/ml-lennemann63.html


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