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This is a free download of the Bernoulli Principal. Fun to play with and educational.
The amount of fuel air entering the chamber is a function of runner cross section, velocity and time.
The depression, or vacuum generated is a function of displacement and RPM. So the depression is about fixed by the 2606CCs and say, 6,000 RPM. The "M" in RPM is the time. So............
That leaves only Porting to increase intake open and closing time, (lengthen time period) and manufacturing the ideal intake runner set/ Throttle body combination.
In my mind the runner size would be identical the the port opening for 4 to 6 inches out from the port opening. Then blend into one "D" shaped pipe for the 180 bend over the engine top. Then taper to a larger pipe of about 2 1/2" to blend into a plenum just big enough to fit the throttle body mounting plate.
So, the cross section would be reduced gradually from the throttle body to the end of the "D" shape, then remain constant right up to the port opening.
I would upset the inside radius of the "D" shape with a number of burs stood up with a three corner punch, to generate some tubulance.in order to keep flow attached.
Just a guess. I could be completely wrong.
Later, I tried a 75MM at one point and while it did nothing to improve engine power and performance, in my case it had an undesirable down side – now to be fair it could have been partially the results of having all 4 injectors back near the throttle body – but in any case, if you suddenly opened the throttle like in a panic go-a-round – the engine would bog and hesitate for a fraction of a second (seemed like minutes {:>)), the engine never stopped, but I just didn’t like it. So I went back to the 65mm.
So the important thing is to match your induction system to your real operating regime – NOT what you would in your wildest dream like for it to be {:>).
Ed Anderson
You are only 70??
Run hard and put away wet comes to mind..............
Lynn E. Hanover
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