Well I was at a local motorcycle place today and I am searching for some stuff for my 6 port when I noticed kind of a trap door. I think it is vacuum operated. Anyways I got a better Idea than a butterfly valve to help shut off the aux ports and maintain port velocity.



BTW does anyone know about how much CFM a 4 pack of these would flow?



If it is above the target number it might be worth the effort.

isnt that an aptly named constant depression carb?

how big is that inside diameter?

A set of 4 carbs of a 650cc or up bike should be in the ball park. Twin 2.25 SUs used to be very in vogue here in the UK.



However getting progressive opening that you want is not what they were designed for, so unless you are already an expert on those sort of carbs you will not get what you want.



The EFI throttle bodies off bikes are great though...light and cheap.

Ive got a set of GSXR TB's sitting on my desk beside me waiting for a manifold. 4 x 42 mm https://www.nopistons.com/forums/pub...#>/biggrin.png

I have 600s and 1000s in the garage so I can hedge my bets.



Also waiting on getting my ar5e into gear to sort out fly-by-wire onto them.

In japan they make those for cars they are called FCR (flat carberator) The hachi roku guys use them alot. They make this interesting rattling sound when you use big cams with them.

I've seen some motorcycle carbs used on a rotary engined airplane before. But the requirements for an airplane engine at a constant throttle is entirely different than a car.



I've got a set of the GSXR throttle bodies also. Such a nice package to start with and the price can't be beat.

Ill be making the manifold for mine next week https://www.nopistons.com/forums/pub...#>/biggrin.png

Show us all the pics when done as I'd be interested to see how you do it. I've got some thoughts but always open to seeing if someone else has a more elegant solution.

Hey Bill, are the newer Bike TB's butterflys or are they like the slide carbs?

I only have experience of GSXR TBs and they are all butterflies. 2001 on they all have secondaries that are controlled by the ECU as a sort of pseudo fly by wire.

A set of roller barrel TB's would be even better.



Progressive opening and zero restriction at WOT.

Errm, no they wouldn't. Roller barrels are notoriously bad on part throttle and cause all sorts of fuel mixing problems due to stagnation on the port walls.