Can any standard MFI - 2,4 thru 2,7 I guess - fit on a 83 911SC 3,0 engine? I'm trying to figure which way to go on a DE/track/HSR car. Used Webers or new PMOs are mucho $$$ and I like the looks of MFI. Whole MFI systems and bits and pieces from various years/displacements show up on eBay pretty often at very reasonable costs. I've got Wayne's 911 engines book and studied the Pelican site. I'm aware of the work required, I just haven't been able to pin down the inter-change range - mostly the intake port centerlines and whether head machining is necessary.
TIA
john (who now has a digital camera and WILL post a car pic soon)

 

The factory used MFI on racing engines in the 3.0L+ range, however, talk to Guy Pfister at Pacific Fuel Injection, since you'll want him to rebuild the MFI pump at some point. Check the phone number, last one I have is 415-588-8880 in San Francisco. (no affiliation).

 

Thanks. CIS just ain't me and I've heard horror stories about Veebers. I'm sure PMOs are great, but US$4k would buy me a lot of tyres and track time.
john

 

Nothing about the stock 3.0 SC engine is compatible with MFI. You will need the best people in the business to advise on cams, pistons, head modifications, MFI calibration, etc. Big, big bucks! This is not a bolt-on deal. Remember, when Porsche changes something (MFI to CIS) they change everything. It's a package deal, and to build a 3.0 MFI engine you might have to contract specialty shops to build you specific pieces. Once again, big bucks! Develop your suspension, and after you set a track record with the car put a big motor in it.
Pete

 

Well...I guess I've been told.

 

A 3L MFI motor can be a fanatastic thing (like 74 RSR), but they're quite different from SC motors as was pointed out already...

 

A 3.0 MFI engine is a great thing -- I know a couple of guys who've done it.

Because you'll want to use early S cams, you need to change your cam housings over to the early style (I forget whether it's 3 bearing to 4 bearing or vice versa). The heads have to be machined to accept the MFI injectors, but that's not a big deal at all. You'll need to get the magnesium MFI stacks (I forget which years they were used) and have them bored to 34mm, unless they're already 34mm (my memory is foggy on this). You may also wish to port your heads to the larger 39mm size of the Carrera 3.0 and '78-'79 SC engines and have the MFI stacks ported to match. Throw in a set of JE pistons of the desired compression ratio and you're good to go. I think it's a fine idea!

 

Hi:

Porsche did several 3.0 MFI motors (3.0 RS @ 230 HP and 3.0 RSR @ 335 HP) so the configuration is not totally custom. That said, most of the parts are NLA so one must be resourceful.

Having owned both versions of these engines, I have a good idea of whats needed to build one up again,....

Since the 3.0 RSR is now dreadfully expensive, all of the parts are no longer made, and its not really streetable, I'd suggest focusing on a 3.0 RS spec motor.

These can be done using an SC engine as the foundation and adding the various bits and pieces to get close. MFI pumps are matched to the cams and as Noah said, the 69-73 "S" cam is the one of choice. If you source factory "S" cams, you'll need to use early 3-bearing cam towers (SC ones are 4-bearing) and all the other MFI pieces; MFI pump mounting plate, oil lines, breather cover, MFI pump drive items, fuel filter console, left side, front engine sheet metal, etc.

After that, I'd get the early MFI stacks and throttle bodies ('69-'71) and have them modified to 3.0 RS spec; 38mm butterflies and the stacks taper bored to 44mm. Heads can be easily machined for the MFI injectors (we do these all the time) and they should be opened up and flowed to suit. A simple "port 'n polish" is no guarantee of proper head flow and Porsche did a great job of that. Thats a whole entire story for another day,........

I'd suggest the Mahle high compression 3.0 P/C's made for the SC engine instead of the JE's as they will last FAR FAR longer. You really do get what you pay for here.

This can be a fun project as long as one has the resources to do this properly.

 

Good stuff Steve!

Rick is building exactly the motor you describe using a Carrera 3.0 engine as a start. It's almost done. He bought the 3.0 MFI stuff from Jeff G already converted...

I can't wait to drive his car when he's done.

 

Thanks Steve & Noah, I appreciate the common sense replies rather than the dissing one, and hoped Steve would chine in. Because I've been around racing a while, I just couldn't figure why there hasn't been development of a variety of alternatives (I was also thinking 6 Stromberg 84s for you older guys) to CIS. EFI is neat, Kinsler would be cool. Tecalmet-Jackson should work. etc etc... I guess everyone is concentrating on soaking the waterboxer GT3 guys or putting $10k carbon-fibre 996 bodies on 77s. HSR rules call for the 930/1n cases and 3,0L max in the 911GTU cars - the ones from my day. My 83SC ('SchwartzMaus') is just a small rat rod to me anyway, so what the H---. I'm not after any 'track records' - been there, done that; bought the t-shirt, got the hat. If I still wanted to do that (and still weighed 150#) I'd get a shifter kart.
Thanks again
john

 

John: No dissing intended (if you're referring to me), I had no idea that you're a racer. I just wanted to lend some advice learned in the trenches; a great car with satisfactory horsepower, like the '83 SC, can deliver lot's of bang for the bucks, while a competition motor can make a great street car into an unpleasant one, and after the motor's done the whole car must be developed to that motor's ability. I'm sorry that I wasn't more clear...
Pete

 

Thanks Peter. I've been around race cars since 1950 (Watkins with my dad) and developed an affinity for Porkchops by auto-xing other peoples' 356B with an 1800 roller crank engine and very early 911s. I was with some (no name-dropping here) teams as crew and then team manager. I also did some testing and instructing in red 944s. Now I'm old and finally have my own 911, a garage, and time. I'm turning 'SM' into something I can have fun with - but you know as well as I: MORE POWER!!! My engineering curiosity led me to ask the Forum the lead-in question. After all, I'm the one who came up with the idea for a 928S4 GTO car with a 1100cfm Holley Dominator because it could run 100# lighter that an EFI 928. Holbert hated that one! =8->
Thanks, again
john

 

John: Whoa, that's freaky! My dad attended races at Watkins, also in the early '50s. I was just a tiny bit too young, and probably too big a pain in the butt, so I didn't get to go. He made the trip from our home in Jeannette, PA. It must be in the genes, because I started with slaloms (in my '58 Speedster) in '68, and it only took a year for me to find my way to Willow Springs Raceway (my dad moved us to SoCal in '55 - when sanity prevailed in CA). The rest is history... Have fun with your project, I hope you have a hoist at home!
Pete

 

My dad was on the ambulance crew at the stone bridge. The 'ambulance' was a hearse from the funeral parlor in my home town. They kept it out of sight of the drivers for some reason. FWIW, I got to meet Bill Milliken a couple of years ago - still sharp as a tack (him, not me). Nope, no hoist, I'll use the tractor bucket. Ha!
john

 

You can make S cams on new style billets and avoid swapping the carriers.
The 82+ billets have the bolt style snout and the mfi drive on the left camshaft.