MFI or Webers pros and cons?

[rgunson]

Hi HalM

I wasnt suggesting you, or anyone else on this post were implying that webers were superior, but it is a comment that I hear frequently & I feel it is misplaced.

I am not so sure that carbs are 'cheaper' though, especially as this guy already has MFI (I agree they are expensive to acquire separately). Carbs incur labour cost to retune frequently, in my experience. MFI is tricky to set, but once done that's it. As for fuel economy, I would expect MFI to be considerably better than carbs, if the engine is in good condition (this was one of the primary reasons for developing fuel injection - efficiency).

If your engine is getting a bit tired & you do not wish to embark on an expensive rebuild, then I agree that webers are the way to go. This is the real reason why they are so prevalant - which you hear a lot less often. I am sick of hearing (again outside of this forum) that MFI is inferior to carbs.

Rant over

Kind regards




Reiss.

[roblav]

I have a 2.2S that came with webers, and I'm going through a LOT of effort to return to MFI. Never, ever, get rid of ANY MFI components you have that belong to your particular car. MFI is really neat - I loved it on my previous 70E - it is more fun than webers.

[SandyI]

I have the original stock MFI on my '69E. Runs great. I would NEVER trade it for carbs. And it's a major value point for resale.

[rs911t]

I "reverted" my 2.8S to MFI from Webers this year. Stated with a 2.2S pump and mag throttle bodies and stacks. Rebuilt the pump to RS spec, rebuilt the throttle bodies, bought new linkage pieces. The net cost was <$2000, including selling the carbs. I couldn't be more pleased! Throttle response is telepathic, the car pulls strong from standing stop to redline and the induction noise is marvelous! The key is starting with a system in good condition. I used an AFR meter to set the mixture. My engine is 10.3:1 CR and I wanted a sufficiently rich mixture at redline!

It may be easier to find a Weber mechanic, but Porsche was using MFI on their race cars. I'm content with my decision!

[ttweed]

5. Originality
It would be a crime not to retain the MFI.

This is really the best (and probably, only) argument for MFI on these older cars.

Finally, if webers are really superior to MFI why did porsche invest so much time and money in race development of the system for the 917s, and then transfer it to their road cars if it was an inferior system.

And they are still using it on which of their race cars???? C'mon, MFI is an antiquated, obsolete system that has been left in the dust by modern EFI systems. Yes, MFI was superior to carbs, but that was 30 years ago, for crying out loud. Modern EFI systems are so much better in both performance and efficiency, there is no comparison. I have PMO 50 carbs on my hot-rod 3.4 right now, but there is no way I would convert it to MFI. If I had the funds, it would go straight to Steve Weiner for a modern, ITB/EFI system, dialed in and dyno-tuned. No question about it.

TT

[Steve@Rennsport]

Great thread!

Lots of fun reading this one,....

Many good points raised here and plenty of incorrect ones, too.

I've seen plenty of both systems and when the MFI system & its engine are in PERFECT condition, its a neat system.

I'll also tell you that I've not touched the Webers on my own twin-plug 2.7 since 1979. IF,...........IF they are installed and setup properly by someone who truly knows what they are doing, they are VERY reliable and do not "require constant fiddling". Thats precisely what happens on a poor setup and cars with issues,.....

Tom said it best though,...nothing beats a properly programmed EFI system. It makes the same sounds, with better HP everywhere in the RPM range.

Just one person's opinion, tho

[rgunson]

Tom Tweed

At what point did EFI enter the discussion? What you are saying is patently obvious, but wasn't in the frame of the discussion as far as I was aware.

All I was trying to illustrate is that MFI is a more advanced system than carbs, is more economic, runs better when cold, compensates for changes in air density, and most importantly stays in tune & needs little intervention once correctly set.

Furthermore, unlike many mechanical FI systems of the day the Bosch MFI was, and still is, regarded as an engineering gem (again, for its time).

The logical conclusion of your argument would have us ripping out our early air cooled engines & installing water-cooled 997 turbos with EFI, ABS, etc on the grounds that the engine is more advanced, which I am sure we all agree with, but it seems to miss the point of our discussion.

If you want the most advanced engineering buy the newest 911 you can afford. Leave the old 911s unmolested for those of us who appreciate them for what they are - examples of the finest automotive engineering of their time.

Or have I misunderstood you?

Kind regards





Reiss.

[roblav]

Agree Reiss.

The thread changed direction. For a while there, I had debated using Suzuki motorcycle throttle bodies and a megasquirt EFI on my 70S, but decided to return to MFI because that's the way it was back then - a neat design for the time period. If my car was a 911T, I would have done EFI.

[ttweed]

At what point did EFI enter the discussion? What you are saying is patently obvious, but wasn't in the frame of the discussion as far as I was aware.

I guess it entered the discussion when I suggested it, which wasn't a big leap off topic, actually, since it is "patently obvious", as you say, that if the original poster (Tommy) is considering replacing his MFI with carbs, he should also consider replacing it with EFI, as it is superior in every way (except originality, which he will lose going to carbs anyway.)

My intention was simply to point out that MFI vs. carbs are not the only two choices available for his situation (worn out induction system.) Your extrapolation of my suggestion to it's "logical conclusion" that we should all "rip out our air-cooled engines and replace them with water-cooled 997 turbos" is specious, to say the least.

TT

[rgunson]

Hi Tom

I guess you guys must do things a little differently in the US

To put EFI in a nice early 911 in Europe would be considered something of a heresy as early 911s in an unmodded state are now rare

Isn't it all the little nuances of the old cars, albeit inferior to modern technology, that attracts us to them?

IMHO if you want convenience go & buy a new 911

I mean, where do you draw the line otherwise? Why don't we add modern suspension as well, because it is also far superior. What about climate control, traction control, etc?

I really can't see the point in owning any car that is 'collectable' then adding your own 'improvements'. Doesn't this defeat the purpose?

911's seem to particularly susceptiable to 'modding' - you do not see it to any extent with other marques such as ferrari.

I don't know, perhaps this is the attraction of a 911 to many people, the ability to mix & match bits.

Ciao.