Bought this on Ebay, it's from a Polaris snowmobile...

 

don't think they will flow enough air to feed a bp. any idea what the cfm rating of each is? custom intake wont be cheap.

 

anything will work anywhere...............if you have enough money!!

Seriously you should do more research...if big enough, it would look cool on a 3 rotor!

 

What are the sizing on those? I hear of people using motorcycle ITBs.

 

I don't have any idea about the flow, but I think they are 40mm (1.617") dia.
That's 37.7 sq cm (5.843 sq inch) on 3 Throttle bodies.

If I look at a normal 2x48mm throttle body that equals 36.19 sq cm or 5.610 sq in.
And a 2x52mm would be 39.27 sq cm (6.087 sq inch).

So a 2x50mm Weber or 2x50mm throttle bodies would be about the same size, but much more expensive.

The intake will have to be custom made by myself. I want the butterflies to be as close to the rotors as possible to prevent backpulses. The engine will be built and balanced for 11000rpm.
I will also togheter with the BP on the 13B sideplates make a semi PP (30-45mm dia, not sure how big I will make them) on the 12A housing I'm going to use. :-) The engine will be a hybrid between a 1984 12A (excentershaft, rotors and housings) and 1989 6-port 13B (side and middleplates).
The P-ports will have two smaller throttle bodies or one big, but separatet from the ones on the sideplates. I want them to open att full load and together with the secondary injectors.
The primarys will be the two injectors in the middleplate. The secondary the three on the Polaris Throttle body.

 

This would be a cool project if you could adapt them to work!! Hope you can make it work and keep us in tune with the buildup!

 

84 has the O ring grooves in the rotor housings, 89 has them in the irons. can't use them together unless u fill the grooves in one or the other. u have to use either pre 86 housings together or 86 and later housings together. and i think a really short intake kills low end. someone with more knowledge in this area can verify this tho.

 

Yes I know I have to fill the grooves... Or make custom o-rings with double thicknes!
The low end is not what I'm looking for... Long airhorns will help a bit, but I'm aiming for a high figur horsepower 12A. I don't care about low end tourqe...
What's driveability?? :P

 

My personal opinion with a bridgeport engine is to use either 2 throttle plates (1 for each rotor) or 4 (1 for each runner).

 

Lifting this old tread... I'm on to the project agan! :-)

What would be the difference using two, three or four plates?

 

Haha 3 year thread, I'll contribute. This would be awesome to see completed, I hope it works out for you!

 

I had great results on a half bridge 12A last year. The reason it worked is because the early intake manifold had true separated runners and the carb had an air screw and a fuel screw making idle tuning actually possible. Basically the best parts for this were available, so I went for it and it turned out well.