Anybody here have a 6 with Bosch MFI? Does everything fit in the engine compartment? Is access to the pump for adjustment/maintenance possible without removing the engine? Anyone have pictures of such an installation?

I bought a complete MFI system with rebuilt pump but later was told that I might have to use a BFH on the back of the engine compartment to get it to fit. I have the original carbs but would rather have the extra performance of injection if it's possible without altering the bodywork. (I could have bought a later engine with CIS but I wanted to keep the original engine case number with the car)

CIS just barely fits, anyway. You'd at least have to lose the rain tray, and you have to hang the engine fairly low just to get the CIS to clear the engine cover. Plus, some alternative latch arrangement is called for.

As for MFI, can't give you any real answers there. I had mechanical injection on a pair of Italian cars (different pump, very similar principle), and when it's working, it's fabulous. It's hellfire expensive to rebuild one, however. I honestly don't think there's a huge performance difference between well-set-up Webers and MFI. Webers would be much easier to run in a 914.

Michel Richard has the setup in his Six conversion. I don't think he had to BFH anything to get it to fit, but I am not certain.

You will definitely have to run some sort of heat exchanger to get warm air to the pump, though. It has a thermostat gizmo in it that makes the mixture much richer when cold and leans it out when it warms up. Without a supply of warm air it will never warm up and you'll be running way over-rich all the time. Even moreso than MFI normally does.

--DD

DD,

Is Michel Richard on this board so I could pick his brain?

I was warned about the thermostat connection, but I think that could be fabbed without too much trouble.

Mike

A local (LA) guy named Marco has a 2.4S MFI engine in his six. I don't think he is on this board, but he hangs out on the Pelican 914 board sometimes. I don't remember his screen name over there but if you search the 914 BBS for "MFI" you may find something.

I thought about doing it myself, as I really like MFI, but my race group rules require "factory correct" 914-6 induction, i.e. carbs...

The thermostat can be modified easily on the pump to remove the warmup enrichment. The car will run funny for the first 5-10 minutes but you won't have to deal with the hoses etc. This is very common on race cars. Another trick is to put a lightbulb in the inlet for the thermostat, and adjust the wattage to give you the desired enrichment delay - they also did this in the 70s on MFI race cars (honest).

I have talked to someone who put MFI in their 914-6 before. Apparently you have to adjust the pump before the engine goes into the car, or make holes in the firewall so you can access the adjusters. The throttle body idle bypass screws are also a bitch to get to but it can be done. You cannot change the belt on the MFI pump or change the timing without removing the engine.

I know a little bit about MFI. I worked on it for 1.5 yrs trying to get my last car to run right. It was never perfect.

MFI was rated 10 hp more than carbs on the 1972 911T, official Porsche spec.
The short answer is better fuel atomization due to 220 psi blowoff pressure, I do not know how true this really is. But I have driven a car with MFI and I will never, ever forget what it was like.

Hey! I can quote!


I've heard this from several people. MFI when well adjusted is really nice! I really don't want to drill holes in the body for access to the adjustment though.

Not that I know of. But M-A (si3tm2 or something like that--his avatar is the very nice set of 914 panties!!) knows him. He has shown occasionally on the Bird board, but the last time I remember was several years ago. He sometimes pops up on the 914 Rennlist, but that's about it.

I think he's gotten heavily into the Spridget that he is building for his youngest daughter. Dad wanted a car she'd like that wouldn't go over 70 MPH, I think... Or wanted to be able to claim that to his wife...

--DD

HUH, What????

You talking to me Dave???



I'll get Michel to come and hang over here.

Dave, Michel's Bugeye project is finished. Last summer I drove his bugeye for a ride while he took my six. That bugeye is dying for a V8 conversion!!! You think a 914 is small, wait till you drive a bugeye... I don't think Michel's daughter want's to drive the bugeye...

Marc-André

I'm here !

I did get sidetracked a bit, building an early bugeye sprite for my youngest daughter. That is now running and I am now looking at the 914 with fresh eyes.

Bugeye = 40 hp. 2.2 E = 165 hp (IIRC)

4 times the power, 1.5 times the weight. 914 rocks

Putting an MFI engine in the 914 is a bit of an adventure, but if I can do it, most people can too.

The engine fits, but a few things don't: the air cleaner assembly needs to be replaced with K&N raintrays; new provision needs to be made for the squirters that spray raw fuel when cranking; the fuel filter console needs to be provided for (I hung mine off the battery tray); the relay board needs to be replaced and a lot of re-wiring done; a special heat-exchanger needs to be organized (although it appears that there are stock 914-6 heat exchangers that have a fitting for the air blled to the thermostat); and you need to make provision to adjust the idle mixture while the enigne is in the car. It might actually be possible to do this with only a small hole (say 1/2 diameter) if it is in exactly the right place.

That's the few things I can think of right now, and is in addition to all the other /6 conversion things.

This being said, and even if mine is not completely dialed-in yet, you end up with an exhilarating free-revving glorious engine.

HTH

Michel Richard

HEY WHAT TOOK YOU SO LONG!

Just look at a 916 for inspiration. Got one hanging around? Great. There's your solution.

Wasn't aware of the air cleaner issue. You sure that it won't fit? The stock air cleaner just touched the engine lid on my Richard Johnson-mounted weber carbureted conversion, but that's with the short manifolds. No way would it work with tall PMO manifolds.

What's the complication on the relay board?

I like the idea of an MFI 914-6. Might do it myself one day.

For the air cleaner:
If I recall correctly, when you install the air cleaner on a carbureted 914-6, you have to turn in around. But you can't do that with the MFI because the underside of the cleaner then fouls the pump.
If there is a way to use the stock cleaner, I missed it.
Oh, and the rain shields have to be modified for the right-hand side one clears the pump.
Michel

And for the relay board:
an MFI relay board contains a lot of wiring that is not there on the stock 914-4, to control the overun shutoff of the fuel and the cranking enrichment. That's what I remember right now, at least.

Michel

Just got my RS MFI throttle bodies and stacks back from Harry Bieker. $1350.00

Pump goes off to Gus Phister next week. $1600.00

Price for MFI alone can easily exceed the value of a lot of 914's

My 914-6/GT project will get Webers and S-Cams on top of the 2.5 SS motor. Cheaper that-a-way... (sorta)

Sounds very cool Eric! You won't beleive the throttle response that engine will have. Nothing pulls like MFI! Some of the best factory race cars used MFI (including most all race turbo'd engines up through the mid to late 80's) for a reason.

I had Gus do a pump almost ten years ago and it was $750 then, but that was a stock rebuild on a 2.2E pump.

Last summer I got lucky and found a core 2.2E engine with about 2500 miles on a set of new intakes.

If you have a 914-6 relay board with the RPM transducer, it should work to activate the idle pull down solenoid on the pump. The 914-6 transducer was a factory recommended replacement for later MFI 911's with balky idle pull down. The way it works is when the engine drops below a specific RPM it activates the solenoid on the pump to pull back to the idle position.

You can use the stock air cleaner, but you have to modify the snorkle, the airbox, and the engine lid. On a six conversion, I guess you could mount the engine a little lower, and that would help too. I gave up on Watershields, but I'd probably do like Michael and massage them to work the next time.

The Ed Villela strut kit for the rear lid would be a good idea too. The factory torsion springs are very close quarters installing the engine.

The other biggies I remember are the fuel pump (what I call the supply pump, not the MFI pump), and the fuel filter console. The system requires the correct Bosch supply pump, that looks like a stock 914-6 and 914 pump, but has a different output. The fuel filter console uses a filter the size of an oil filter (and runs about $30) and also has the (WWI vintage) fuel enrichment solenoid, where you shoot raw fuel down the barrel of the injection stack for cold starting. I just hooked up a momentary contact switch on the dash and hoped it wouldn't burst into flames. The factory cold start system has a thermo-time switch that supposedly did the same thing.

Don't know if any of this helps. I did make out a wiring diagram for the MFI/ignition curcuitry. I've done two plug and play wiring harnesses for 914-6's with MFI. I'd probably trade one for some white panties with a 914 on them

PK

PK,

The MFI is going on a 930/07 motor (3.0 SC block) with JE's. Goes in the 911RS clone. Should be weeeeeallly fun.

I'll rummage up some panties if you make me a harness for my carb'd six conversion

Holy crap, the pump rebuild Gus did for me a couple years ago was under $1K IIRC; are you having new space cams fabbed or is Gus just trying to give his retirement fund a kick in the ass?

The MFI 914 projects sound cool. Not sure I would try it at this point as I have "done" the MFI thing already so I would like to try an EFI next (Tec3, MoTEC or whatnot).

FYI I found here in SoCal that the fuel squirters at startup were really not needed. It maybe took one extra crank of the engine to fire, no big deal, so I eventually just plugged-off the lines to ease any fuel spill concerns.

The preheat/thermostat hose is a bigger deal as any kind of street car would be pretty bitchy without that circuit; probably the first 15 minutes of each drive would suck and that would get old fast. I think most racecars do away with it though.

According to Anderson, in one of his "Excellence" columns, the race cars had a lever on the pump that a mechanic would hold while the car started. The mechanic would hang onto that lever to keep it in the "warmup" position for extra enrichment for about five minutes. Then he'd flip it to "normal" as soon as the engine would run without the extra enrichment. Not very street-car-friendly. Oh, I think this was an RSR pump he was talking about.

BTW, my understanding is that the greatest number of factory Turbo race motors (934s and 935s; there were a lot of those!!) actually used CIS. Why? Because they were homologated with it, and legally could not run anything else. And as soon as Porsche had the chance to ditch the CIS (due to a rules change), they went to MFI.

--DD

There's a guy (Walt I believe) at a shop in S. Cal. that makes the enrichment lever from a hand-throttle. Can't recall the name of the shop... SuperTech or something??

Works for guys that want to run a tricked out motor with headers. I'll be using John's SSI's made for MFI. I'm putting the old style shorter studs in the heads.

Close. It shuts off fuel on overrun only and restores it when the throttle is released back to the idle stop AND the engine RPMs go below some value (1200 or so). There is a solenoid on the pump that does this and it is activated by the RPM transducer and the idle stop switch. Some people claim the car will backfire on overrun unless you have this system working. I ran with it and without it for months at a time and never really noticed a difference.

I think that these engines were tuned to run quite a bit leaner than where we run them today. When they were that lean, they would apparently backfire all the time, especially on overun. My has been running a little fat and I have'nt used the overun shutoff either, without a problem.

Michel