Volocity stack design considerations??, for my mickey mouse ITB's Options

[Mueller]

Slightly warmed up /4 motor applications...I'm thinking just about any design better than none at all....I'd like to metal spin these myself, however if I can get a good price on 8 from a fellow non-club member, I'll go that route (IMG:http://www.914world.com/bbs2/html/emoticons/smash.gif)

[Thorshammer]

Since I worked for Suzuki for 5 years, I thought I might comment on this particular situation.

Yes, the slot in the rubber velocity stack was to reduce the intake reversion on this model, The 2003 had different cams that caused some minor fuel distribution issues we worked out by doing this simple mod. It does not work in all applications. The intake port velocity on this engine is completely different than that of the 914 4/6engine. Also a GSXR1000 will regularly spin to 12,600 rpm. None of us ever will, or at least we will not have any straight valves after that.

This mod would be an R&D affair. For GSXR 1000 race engines I build, we remove these stacks and install a stack that is a touch shorter, with a 12mm rounded edge which increases flow and changes the torque peak. The stack is also void of all slots unlike the standard piece.

As far as 4D to determine the correct radius for the velocity stack bellmouth, this would be a good starting point, I checked some of the ones I have and they range from 3.5D to 5D. Interesting. I wish I could give you a reason why I arrrived at the sizing I did, but I don't.

This is one area we have not discussed, and I have a trial set for my next dyno run. I really think aircleaners are very important, But I have glued a upside down top shaped piece of plastic to the under side of the air box pointed towards the carb velocity stack. I am hoping to guide some more air into the carb without restricting it. Stole the idea from Buell motorcycles. We'll See!


Erik Madsen