MFI vs Webers

My '70E came to me with a set of nicely running Webers that were put on by PO 2.
What are the upsides and downsides of finding an original to this car MFI setup and installing. I am interested in originality, but concerned about performance and maintenance.

Will any of the setups for 2.0s to 2.4s retrofit? What is cost of a rebuild?

Thanks,
Mark

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Mark B. Wilson
http://www.marksobsessions.20m.com/

What are the chances that the PO kept the
E MFI stuff and will forward it on
to you now that you asked?

MFI works great if all of the components
are in top shape and within spec. Otherwise
it can be very problematic. I am speaking
from personal experience. My MFI T ran
like a turd for several years before
I had a MFI guru here in Denver tune it.

On restoring your original MFI, first you need to determine whether you still
have the left side cam drive. As this
cam drives the MFI injector pump. If you
do, and there has been no mods to the engine
except for removal the MFI stacks, then
all you need to do is locate an 70 E spec
MFI system and slap it on. However, be prepare to pay some bucks. Every system is
tuned to the cam profiles of the engine,
so a T pump would hobble an E engine, and
so on. There are a lot more T pumps out
there than E or S too.

Any injector pump can be made to work with
the right space cam added. Stacks, fuel lines
and injectors are available from dismantlers and internet P buds. E and T stacks are the
same, and S stacks are bigger and rare. Early
MFI systems such as your missing one, had
mag stacks which are pretty cool. Plastic
came with the 72 and later MFI systems.

Your fuel pump will have to be reset to MFI specs from carb setup as well (different pressures). There is more but this gives you an idea. Probably around $2K in parts alone. Finally you need to have an MFI mechanic available if you need help. MFI capable wrenches are rare and are retiring too. The Porsche MFI manual is helpful but not straight forward.

Good luck. Oh MFI rocks over carbs when
it works...

Bill
72T-->S

ps There is proverbial lock on MFI Porsche
parts and pump rebuilders, Gus at Pacific Fuel Injection and some outfit back east called (I believe) Euromotion. No way around the two, Bosch will not resale parts
to others rebuilders, as couple years back I
tried to work with a Bosch diesel mechanic in Seattle on getting some work done and he told me that was the situation no wiggle room. HTH

Not too sure offhand about the retrofitting, but I tell you what: MFI is a nice luxury.
Once you have the sustem sussed out it's great! Just takes a while to learn its quirks and work out how to set it up and tune it, then yeeehaaaa!!

MFI is a mechanical oddity nowdays, and it's nice to pop the engine lid and explain the system to interested people. Plus it is extremely reliable in day to day service, doesn't need constant tuning and adds to the cacophany under full throttle!

The higher pressure of the system results in extremely fine fuel atomisation, and I'd say that's its advantage over carbs for power. Plus you get near instant throttle response. Nice. But at a Price (as always). Sure beats a Holley.....

------------------
'72 911 TE

My advice to any MFI wary people out there is to become your own Guru! With exception of the pumps themselves (and even parts of these are repairable by a keen enthusiast), the system is reasonably user friendly and sets up logically. You'll need a few tools, but nothing too fancy and all are explained in the MFI Check Measure Adjust factory manual available here on the Pelican site. A Unisyn or similar throttle balancer will be needed too.
The rarer S stacks Zotman mentions are I believe the same as the T&E ones only bored out a bit and fitted with matching larger thottle butterflies. I also understand you could get away with a T pump on an E engine, richen it out a bit on the part load mixture adjustment and it should be workeable.

Read up, work carefully and learn as you go!

I saw a complete 'T' MFI system for sale the other day for $400 ... I think it was here on Pelican ... add $700-$100 to rebuild the pump to 'E' specs, and you've got it! But, buy a 'wounded' 2.7, rebuild it to 'RS' specs and you've got a monster disguised as an 'E' ... a set of brand-new 'S' MFI cams can be had for $1000!!! Dream a little about 210 DIN hp! New RS 2.7 piston/cylinder sets can be found for $1500 ...

------------------
Warren Hall
1973 911S Targa

Everyone early with MFI should also keep Wes Ingram in mind for rebuilds. He is a master with Alfa SPICA injection pumps. Little know is that he also does Bosch and Kugelfischer pumps.

karl

Thanks to all for your input.
Mark

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Mark B. Wilson
http://www.marksobsessions.20m.com/

I'll show you how much of a Porsche enthusiast (and nice guy) that I really am - I'll GIVE you the complete MFI off my '73T if you think you can make it work for you.
The system was working well when removed (several years ago). I did a headers and Weber conversion. Quite honestly I did not understand the MFI and after a few frustrating phone calls decided to ditch it before something went wrong. The throttle bodies, pump, plumbing, lincage, and assorted hoses and lines are all there. I am sure that all will need cleaned and maybe rebuilt after sitting so long. As with most things Porsche, getting the system will be only be the begining of your cash hemorrhage.

I agree with the post that a fella can
tune his MFI on by himself. Bob Spindel
up in Seattle is one such a wizard. Spindel
and others have posts on this site and others
on how to tune MFI systems.
The Porsche MFI manual is a must. The system is not all that different from Bosch diesel system found on VWs and other German cars, aside from the stacks.
Once my MFI system was sorted out, I was
admonished never to touch it again by my
wrench. Now building an S motor, I will
have this same mechanic (Eisenbud in Denver)
set it up and I will leave it alone. What is surprising to me is that deals do come
along for needed parts through our electronic community. My S stacks
and cams came from Rennlist/Pelican
individuals.

Expatriot, with regard to Rarly8's generous
gift/offer, I would suggest you jump all over it, as the injectors alone are over $80 a pop new. A T MFI system can be made to
work on an E as described. Just do not let
some PCA concours weanie check your pump
serial number! 8)

Bill

Oh and your sport muffler will sound
better with a MFI system, that is a given!



[This message has been edited by zotman72 (edited 02-27-2001).]

Bill,

Your car has a special place in my heart because I never thought I'd part with those stacks!

Carlo

------------------
Carlo
http://bigblue111c.tripod.com/dec2000/

expatriot,

I am sure that you can tune a mech. MFI if you have to. I had mine rebuilt when I got my 911 T engine rebuilt by G&W Motorworks. After the rebuild(which included 911 S cams), the engine developed a slight sputter. I read the Bosch manual(Check, Test, Adjust), bought the adjustment tools, and went to work. A few clicks here, a few clicks back, and I was on my way. I think my car is running a little rich now, but runs great. I may still purchase a CO meter to get everything 100%, but for now I am extremely happy. The guys on the board will be really helpful to you.

Bill

------------------
William Armentrout
1973 911T
2.7 carerra rs specs
www.geocities.com/william_armentrout

RarlyL8,
You are a generous guy. I sent you an email this morn. Lets talk.
Thanks,
Mark

------------------
Mark B. Wilson
http://www.marksobsessions.20m.com/

RarlyL8,
You are a generous guy. I sent you an email this morn. Lets talk.
Thanks,
Mark

------------------
Mark B. Wilson
http://www.marksobsessions.20m.com/

DOH!!!

[This message has been edited by expatriot98 (edited 02-28-2001).]

Jon Eisenbud in Denver truly is an "MFI Guru". I would recommend him to anyone with this system within a 1000 mile drive. I unfortunataly am too far away! Zotman, please give them my kindest regards. Bill (yellow '73)

Originally posted by zotman72:
I agree with the post that a fella can
tune his MFI on by himself. Bob Spindel
up in Seattle is one such a wizard. Spindel
and others have posts on this site and others
on how to tune MFI systems.
The Porsche MFI manual is a must. The system is not all that different from Bosch diesel system found on VWs and other German cars, aside from the stacks.
Once my MFI system was sorted out, I was
admonished never to touch it again by my
wrench. Now building an S motor, I will
have this same mechanic (Eisenbud in Denver)
set it up and I will leave it alone. What is surprising to me is that deals do come
along for needed parts through our electronic community. My S stacks
and cams came from Rennlist/Pelican
individuals.

Expatriot, with regard to Rarly8's generous
gift/offer, I would suggest you jump all over it, as the injectors alone are over $80 a pop new. A T MFI system can be made to
work on an E as described. Just do not let
some PCA concours weanie check your pump
serial number! 8)

Bill

Oh and your sport muffler will sound
better with a MFI system, that is a given!

[This message has been edited by zotman72 (edited 02-27-2001).]

Mark, got your e-mail. I can't send from this terminal so I'll post.
The offer is genuine and I don't want any money for the items. If you want to trade something I need an SC rear black letter reflector. Mine was stolen when my SC was apart, that is why the later model red one is on the back of it now. The MFI has been in my garage for some years now so it's not going anywhere.
I'm a packrat when it comes to car stuff. I will probably never use this unit and would rather it go to someone who needs or wants it than for it to just be part of an ever growing pile of Porsche history. This is no bargain - I think it may be quite costly to rebuild and modify.

Just to ad. You definately are going the right way with the MFI. Those "T" throttles and stacks may need to be enlarged to go with your inlet ports but that can certainly be done easily, and seeing your starting at zero cost cheaply. Also you'll have to get warm air up to your warm up regulator. Personaly I think there is something awsome about seeing that big honkin injection pump running of the cam.

I have a 72 911 w\ modified t cams and 2.7 rs p&c's which is great for autocrossing. Kind of a slug when it comes to time trialing though. I had mine rebuilt by pacific fuel injection. Gave him the specs on my t grind and away he went. Installed myself and brought it down to a local guru who tuned it while i watched. learned a hell of allot. it's not that hard to adjust if you heve the tools and the patience. It takes a good area to drive your car hard and do the adjusting by trying what works best for your setup. Took me an entire day to get it to run right. These things love to run fat-more gas than less.
Get some good plugs.
I run my car at the local NASA events. I have seen and talked with a few racers who run there cars 3.2, 3.6, motors with MFI. These are 300-500 hp machines. They love it and the ones who have got it right will not go to carbs.

"your sport muffler will sound better with the MFI"

You bet! These systems are supposedly sensitive to exhaust tuning. Perhaps. What I've found is that there is sooo much scope for adjustment in the mixture (idle & part load) that you can get just about any situation covered. The space cams tailor the mixture to the requirements of the cams etc further in the three specs; T,E,S (whoops- 4 including the renegade RS) to get it factory precise. I agree, they do like to run a little fat, but that can affect the wallet!

I've got mine tuned to where a single click either way on the part load mixture will lean it/ richen it enough to suit any climate/ performance requirements. It's really very simple, just a rather steep learning curve. Fortunately, all the resources you will need are HERE on Pelican, so you don't need to be duped by an overly confident but useless mechanic trying to make a quick buck.
I have a stainless sports system, which although verging on antisocial, emits a thunderous chainsaw BLAAAAAP on hard acceleration, and a harmonious GURGLE on part throttle. You can just about hear those injectors squirting away surplus gas and spitting it out angrilly.
Maybe not a very PC system nowdays, but what the heck; I dig it, and so does every passenger I've had so far if their silly grins are anything to go by!

------------------
'72 911 TE

This is all very cool. I found John Hunt's site that has loads of info also. I now feel like MFI is the way to go.

There is a guy on Reenlist that has a '70 2.2E pump that he wants $75 for. Opinions on using that pump with the rest of RarlyL8s hardware?
Mark

------------------
Mark B. Wilson
http://www.marksobsessions.20m.com/

Mark,

Direct swap, no problem ... assuming it isn't locked-up solid or something!

------------------
Warren Hall
1973 911S Targa