variable Trumpet Length?

[Birel99]

since the intake trumpes move up and down to alter the air speed.
how much do they move to make a difference?
would 7mm make a difference to the power band? lets say the trumpet was stationary 7mm up from the bottom how much would peak torque and HP be altered if the trumpet was stationary at the bottom?
if my question is worded poorly, please let me know...
Thanks,

[Birel99]

also,
what variables within the engine effect air speed?
Bore stroke Etc?
what type of airspeeds do V8 F1 engines see at 17K Rpm?
how do these speeds compare to the speeds of a 125cc Engine at 17K RPm?
Thank you,

[Carlos]

Intake tract length is not altered to change the speed of the incoming charge - rather the varible length is calculated to take advantage of wave pulse dynamics to assist in optimizing cylinder charge volumetric efficiency If you should have the interest for a more detailed discussion of this extensive subject - Links below offer a short description of each book.

Scientific Design of Exhaust and Intake Systems by Philip H Smith
(Search Title/Author - specifically read 3rd reader review)
http://www.amazon.com

Design and Simulation of 4 Stroke Engines by Gordon P Blair
http://www.sae.org/technical/books/R-186

SAE papers # 2002-01-0001 and #2002-01-0002

[Jersey Tom]

I still think variable length exhaust would have a much more noticeable effect.

[Carlos]

Jersey Tom I agree with you. This paper is about that specific subject. SAE paper #2002-01-001

Experimental and Computational Analysis of a High Performance Four Stroke Motorcycle Engine with a Variable Geometry Exhaust System

Authors - M Badami, F Millo and G Giaffredia If I should have mispelled an authors name - apologies.

[Birel99]

ok so, i was talking to my science teacher (a 10th grade chemistry teacher, so take his anwer for what its worth)
he said that for any given tube, the longer the tube is, the more resistence the air will have going in and coming out of it. do you agree with this statement?
and if their is more resistence, wont the air slow down?
Thank you,

[ruud.]

there is a bit more resistence, but that isnt what intake length is about, its making use of pressure waves, and make them fill cilinders better. With a longer intake the pressure wave must travel a longer time before it gets back in to the cilinder, so the engine will run at lower rpm. ( to keep it simple). Ive done some testing with intake length at some 4 strokes, and it has a amazing effect .

[Belatti]

has someone got any data about speeds and pressures inside there?
and what are the lenght and diametres variations along lenght?
i´m eager to make some calculations.. jeje