Cool air induction

[Koncretekid]

I posted a couple of photos of a cool air induction system I have made for my bike.  I have an airbox approximately 4 times the size of my motor with two 2" inlets on the sides.  Today I bent some 2" aluminum tubing (1.9" I.D.) which will hook up with ABS inlet tubes at the front.  The inlets are currently 1-1/2" I.D.(1.6" actually) ABS.  My options are as follows:
1.) Just hook up the 2" aluminum to the 1-1/2" ABS with an adapter.
2.) Make some short transition pieces that taper from 1.6" out to 1.9" I.D.
3.) Cut out the old 1-1/2' ABS stubs and put in 2" ABS stubs to make a continuous 2" inlet

A gradual transition is probably the best way, but with over 30" of induction tubing, two sides, I'm going to get some line losses anyway, so I'm thinking 2" throughout might be just as good.

Does anyone have positive or even negative experience with such an induction system?  I'm thinking I won't run it at Loring, but it may help in the two mile acceleration zone at Bonneville.

[fredvance]

I think I would go with the 2" all the way. Why wouldn't you run it at Loring? I would run it a the Drags, if I did that sort of thing.

[Koncretekid]

Fred,
Thanks for the reply.  Woody has volunteered some pressure and velocity analysis on my build diary which is the answer I needed, even if I can't make it exactly like he has suggested.  As for Loring, I'll try to get some dyno time in June, but what I fear is that the added restriction of the airbox and the induction system may hurt performance at lower speeds.  If I have time I will run it both ways.
Tom

[1212FBGS]

I have developed pressurized air boxes for Yoshimura, Vance & Hines, and American Honda... Road race, Drag race, and LSR bikes, ive done em all.... you don't want to run a continuous size tubing, period..... your 2" tubing 30" down stream will have the air flow of a pencil.... surface friction and drag will make flow almost non existent.... 30" run is crazy long... that 2" funnel needs to dump into a 4" tube to slow the air speed down, 18" later that tube needs to increase 20% to reduce internal surface drag.... the inside of the tube needs to be smooth, I sell smooth bore duct hose for compound bends.... by the way 4 times motor size of air box will never pressurize...

[Stan Back]

Good to hear from you again.  Hope someone listens.

[Elmo Rodge]

Good to hear from you again.  Hope someone listens.

I'm trying. But, as an itinerant door to door dog food taste tester it's a bit rough. Wayno