I am currently collecting parts/ideas/advice for two separate but very similar road race cars.I am maintaining(just so I can race it when I am bored) a friend's Gen 1 racer and collecting parts for a NASA PT-class rotary Miata.Both cars will run 12As and will be of similar tune(large streetport,possible bridge).We would like to start experimenting with programmable fuel injection so I scored 2 used MS units.Now the question is hat to do for manifolds/throttle bodies???Did I mention that this all has to done on the cheap as my GT1 car is sucking all the life/money out of my racing budget!I've been racing Spec. Miata for a few seasons and just want something different.A Miata chassis with some rotary power seems like a fun idea.
For a manifold I imagine there are 2 possibilities:expensive$$$$$$$$:TWM throttle bodies and IDA manifold or build a log-plenum type manifold with a single LS1-type throttle body.With the second option,since there will be 4 "runners" going into the plenum and an injector in each,will I have to stage the injectors due to the primary and secondary ports??Or will that not be needed if the street port is equal(both ports ported to the same template)??
Also a wildcard possibility could be to use motorcycle TBs(GSXR 1000a are 52mm) and fabb up some injetor ports in an IDA manifold(do I really need 4 injectors for a 12A rotary as some "experts say"??) Thanks, Dave D

 

A friend of mine 'squirted the 12A in his FB. IIRC he used a GM throttle body and an adapter to fit it onto the stock manifold (come to think of it he may have been using the Racing Beat manifold for the Holley Carbs).

(edit: a quick Google got me: http://www.affordable-fuel-injection.com/ )

I'll try and catch up with him and post back the results.

-b