Thank you to the gents who responded to my query on the shortening of tubes- I did not completely clarify my thinking, so please read and comment again. It seems as if the gap or space between the top of the tube and roof of plenum box is quite small and the shortening will be done only to allow an easier "turn" for the gases to get into the tubes, not more than 10 to 15mm, or 1/2". A bit like cutting the choke tower off a Holley to increase space between body of carb and ceiling of 14"air cleaner.
Thank you,
Johan
Your theory seems sound but without a means of testing it is unlikely someone could give you a definitive answer. You could try cutting them down about 1/4" at a time and see what improvement you get.
JB
If I had the means, I'd also test variations of the flare itself: increasing the radius and continuing the arc further around.
I'm in with Curtis.
Testing has shown vast differences in flow over the lip of the stack horn.
A fully radiused edge seems to have a huge advantage.
I have seen a marked improvement in stability on various carbed motors. And while not verified, an improvement in torque #s on fuel injected motors.
From a purely physics standpoint. An engine doesn't really suck in air. It's pushed in.
If you look at an intake system from that perspective everything changes.
Think of the engine as a valve allowing the air to enter rather than a device sucking it in.
Once you truly grasp that idea the power, so to speak, is yours.
Cheers
Fred
Johan, Back on March 26th on your other thread, same subject, I suggested looking at what the "specialist" have accomplished. These mod's have all been done and verified. There is no mystery here. Good Luck, roverman.