EFI on 911 race motor

[kanna]

Here's my moment of pondering......
I am building a pair of short stroke 3.2's and the plan was to use TWM 52's.
I would like to hear from those who have used them or any others. I am actually contemplating possibly using a highly modified 3.2 stock intake and repositioning the injectors further up on the runners. I am sure this would result in lower HP figures on the dyno, but the simplicity would be tough to top.
The cars are being built for SCCA GT2, and slide valves are not allowed so that is not an option.
Management was going to be Motec, but a sponsorship deal is in the works with Haltech and that may be the route.

[Steve@Rennsport]

A few thoughts,......


1. 52mm throttles are far too big for a 3.2

2. Any engine using aggressive cams will not run with a single-throttle system. One needs individual throttles for each cylinder to handle the natural reversion that takes place.

3. Intake length is just as important as injector position so those should not be compromised for each other.

Here is what we do:

[89turbocabmike]

Jeeez Steve

please warn us before you post a pic like that......nearly wet myself

[Steve@Rennsport]

Hey Mike:

Thats my job,.....

[914efi]

I have built an intake manifold for a 2.2 with the injectors positioned as you describe for the reason you describe (simplicity). I'm not sure if it is worth moving them from the stock location unless you plan on very high RPM. I ended up redesigning my manifold to move them to the ports since I was having street driveability problems and though it would be better to have them close to the ports. I was surprised how much some of my programming had to change, but it did not really result in any major improvements. I was using an SDS controller, so not very sophisticated for a relatively cammy engine (E cams).



CAD rendering shows final version with low injectors

[kanna]

well if you want stuff to drool over.....

[Jeff Alton]

Efi, somebody say efi with ITB's?





48mm Jenveys with port matched manifolds, custom fabbed linkage (though no where as neat as Steve's stuff). 3.4, 10.5, twin plug.

Kanna, show us some more detailed pics of that car!


Cheers