Velocity pipe revisited.

[Anonymous]

Sup Hometowns...

I started to hate how the long tube was looking. Didn't like it much...so I decided to shorten the length...TORQUE has increased noticeably and I'm glad I went with my hunch, although it was not what I was thinking. Now with it more or less tuned...I will be sending back the torque converter to Phoenix for more stall...can't wait.

I posted 3 pix.

www.fungusworks.com/TheShow/html/engine.html

It kinda makes sense now when I think about it. All the aftermarket pipes for GM trucks are short. Guess the 'ol 6 was sucking through a looong straw that's been shortened

Later days.

chevytooooooown

 

[StrangeRanger]

C'town,
The theory is that the intake efficiency and therefore the torque is optimized when the reflected pulse from the intake opening arrives at back at the valve approx 90° after opening.

The equation is L = T*V/ RPM

where:
L is the length in inches from the valve face to the tip of the air horn
T is the valve opening = 90°
V is the speed of sound = 1100 FPM

For 4000 RPM the length is 24.75"
For 3000 it's 33"
For 2000 it's 49.5"

I suspect you are correct that your old system was so long that you were optimized for some speed well below usable.

 

[Anonymous]

Kewl deal on the formula SR.

I'll see if I can input the data correctly with some "backyard" measurements and see what comes out.

It's a different animal all together. I'm figuring it's also acting like a cold air box. It has a certain amount of air to take in before it starts taking in air entering the cone filter...

Gracias again for the formula. It will be interesting to see where it lands between 24.75"-33". It hasn't felt this strong/with ease down low since I swapped cams for the EFI system.

Ctown