simplest MFI system?

[haycait911]

Originally Posted by jcge

This is the simplest MFI implementation I can find..

Maybe a 901/21 4 cam ??

No baro cell
No thermostat
No flyweights (speed independant !!)

Fuel delivery just governed by throttle position


(C) unknown

now THAT'S simple. I don't mind giving up easy warm-up and I don't even mind popping on decelleration. just hate a bunch of extra cr*p in the engine compartment.

[Flieger]

Originally Posted by GrantG

My problem is more serious than the box rattling - there is no box at all

My car has no transducer (the whole console is missing and was never on my car - originally a 73.5 911T with CIS). I was told the racecars never had this feature and since my car is mostly a track car that I wouldn't miss it. Most of the time I don't, but I fear that I'm leaving a little power on the table by running the motor rich to avoid backfires (with nice flames out the exhaust if I run it leaner). Is it worth the effort to add the transducer and microswitch? Any potential harm if I lean out the motor (to the proper level) and increase backfires?

Yes, I had the same problem: no box. I bought an old used unit here on Pelican as a core. I opened it up and repaired it. I had the schematic and I think you could change some components to more modern ones to simplify the box or make a substitute. Rebuilt boxes are available but not cheap. They are hard to find.

The RPM transducer's fuel shutoff effects drivablility greatly. Crisper throttle response, mostly. I detailed my repair of the speed switch in an MFI thread a while back. "MFI Gurus... and friends of Warren" was in the title.

So, I would get the speed switch if I were you.
Hope that helps.

[GrantG]

Thanks, Flieger!

[Flieger]

replied to your PM.

For everyone else's benefit, here is the RPM transducer schematic: