964 3.6 MFI possible?

[Arlo911]

Would it be possible to convert a 964 engine to MFI?
What would be the biggest hurdles? Camdrive? Ignition?

[Utopia]

Yes, I understand that the pump needs to be recalibrated.

[Peter M]

Why would you want to?

Surely you could model the same limitations in a modern ECU setup at the fraction of the cost. But again why would you want to not exploit the capability of modern tech?

[clutch-monkey]

i'm sure it's possible but as above, why would you want to

[Jonny042]

MFI is awesome, I'm in the process of converting a 3.0 (actually a 3.2SS) to MFI. It's a pretty involved process, but the 3.0 block/heads still had some remnants that make it easy - the same basic outside dimensions including the pump mount, the height of the intake spigots, etc. that make it somewhat straightforward. Not to mention the intake bolt pattern is the same.

IMO the 964 genration of the engine is too far removed from the original architecture to make it practical, not to mention the breathing capacity of anything other than a full on high butterfly RSR intake system will be on the small side.

I'd say for a "retro" looking engine the sweet spot would be PMO itb's with a modern EFI system feeding the fuel and controlling the ignition. All the performance of the MFI with better tuneability. Not to mention the thousands (maybe even 10's of thousands) of dollars you'll save along with time and headaches.

[356RS]

The MFI pump can support engines up to 3.8 liters and some 3.9's. Custom re-mapping of the space cams are a little time consuming.

[Arlo911]

Well, I know EFI is better in many ways, but the engine is mounted in a 1972 S that was converted to RSR body and chassis back in the days for John Paul senior.
Back in the days there was a real RSR engine mounted in the car, but those are juuuuust a bit too expensive, so for the time being We'd like to convert it to MFI if it is physically possible to do so to keep it somewhat period correct.
The RSR throttle bodies are now being remanufactured in different sizes, I have a 010 pump that should be able to handle an RSR style spacecam, I would need new 3 bolt mounts made for the throttlebodies.
BUT, is it possible to mount the pump on the engine case, and would the camdrive work with the 964 camtowers without too much custom work?
If not we'll just put ITBs on it, but again, not very period correct.

[MBruns]

We ran an IMSA car that way for years, Hi butterfly ITB's and old school twin plug distributor,the pump drive just like the early cars, I have some oil seals left over, the pump mount stud holes are on the case, the injectors were in the manifolds, soft lines, Mark can do the pump mods for you, we built a custom 3.5 that Mark did for us we ran it on the dyno and made adjustments, sent the fuel data and the pump back to Mark he made some changes and we tested again and it was perfect, This was in a street hot rod for a customer of Kelly Moss.

Mike Bruns

[cmcfaul]

MFI injects the fuel higher pressure than modern cars. This gives better atomization of the fuel. It's like a blower for fuel

Chris
73 E

[Peter M]

Originally Posted by cmcfaul

MFI injects the fuel higher pressure than modern cars. This gives better atomization of the fuel. It's like a blower for fuel

Chris
73 E

Chris,
Whilst the old MFI system does operate at a higher pressure, I bet 40 years of subsequent development of the modern electronic fuel injector to meet ever stringent emission and fuel economy standards has surely surpassed the atomisation of the old MFI injector.

I don't have any actual data but am happy to bet you a beer or two on this.

[clutch-monkey]

Originally Posted by Peter M

Chris,
Whilst the old MFI system does operate at a higher pressure, I bet 40 years of subsequent development of the modern electronic fuel injector to meet ever stringent emission and fuel economy standards has surely surpassed the atomisation of the old MFI injector.

I don't have any actual data but am happy to bet you a beer or two on this.

it's easy to bump the fuel pressure on EFI also.. mine is double stock at the moment

[Jeff Alton]

^^^ what motor is the base and why are you running double the stock pressure? What pressure are you running and what is the set up?

[clutch-monkey]

Originally Posted by Jeff Alton

^^^ what motor is the base and why are you running double the stock pressure? What pressure are you running and what is the set up?

I double checked and it’s more like 50% extra, but we were planning on going higher if need be.
964 3.6L stock injectors
Jenvey itb’s
Speedflow fpr
Speedflow lines and fittings etc
Haltec ecu

Would like to go bigger injectors but no idea what to pick, this is just what we are doing in the meantime