Huh? MFI is archaic and not better than EFI. Sorry.....

There is none......

Agreed. We have now, however, finished the first lap. Gone full circle. This was covered earlier in this very thread. We are now getting down to the most sacred of Pelican traditions - "last wordism".

Yes, there is. Again, already discussed right here, in this very thread. I'll simply agree to disagree, and sign out.

For those still wondering, all I can say is "drive one". Like Superman did. Don't listen to us, make your own decision. It took Superman very little time to do that. It probably won't take any of you all that long either. It really is that noticeable. But don't take my word for it. Just drive one...

See ya... SmileWavy

I have. If you compare MFI to CIS or any other single throttle body setup, yes, the throttle response difference is huge. Compare MFI to a well setup EFI setup with ITBs and I would hate to have to live off the difference because there isn't any.

The higher fuel pressure of MFI atomizing fuel better is negated by modern injector technology.

MFI does nothing better than EFI with ITBs except rigidly not adapt to anything. Oh, MFI will give you more headaches too....

Look, if you want or need MFI, go for it. But let's not spread fairy tails about how MFI has better throttle response than a well setup EFI system with ITBs.

I agree with everything Winder said. Why don’t we have a shoot out. Get some MFI and some EFI/ITBs together and pick a back road. Have some fun and a great excuse to drive our cars.

MFI for historic reasons yes. For cool factor sure.
EFI/ITBs for driveabilty and flexibility.

http://forums.pelicanparts.com/uploa...1630473919.jpg
http://forums.pelicanparts.com/uploa...1630473919.jpg
http://forums.pelicanparts.com/uploa...1630473919.jpg

There is none. Butt dyno stuff. You could overfuel on throttle opening to get the same smell and feel. It’s neat to think that a cable and pump system can react faster than a microprocessor but it’s just not true. Modern Efi can do millions of calculations per second. Modern injectors are very precise.

your MFI work is the stuff of legends Jeff.

Theoretically the scan times of a modern processor should be fast enough to work faster than you can move your foot, but in practice there are always built-in delays to smooth input signals. On top of that, even as memory becomes cheaper and processors become more capable and faster the temptation is to load them down with data-logging every signal channel so the advantage of more modern processors might be lost.

On an MFI system, if you move your foot to introduce more air into the system, the amount of fuel will increase on the very next intake stroke with NO delay. At 5000RPM you are never more than 4 milliseconds from this happening - which is pretty quick even by modern standards.

Why is it some people on this forum are always trying to pick a fight? It’s tiresome.

I still play tube guitar amplifiers, when for 1/10th the cost I can buy a software modeling amp for my laptop...

Enjoy the ride
 

I'm not saying one is better than another. I really would like to get some guys together and have some fun. Feel the difference back to back. For that matter lets get some Turbos, CIS and Carbed cars out too.

Heck, I'm in my sixties, still listen to Vinyl played back on stereo's from the 70's. But, like the ease of streaming media. Majority of my carpenter and mechanics tools are cordless. Even moving away from pneumatics. Worked on all my cars and bikes. Owned around 90 vehicles, 4 and 2 wheeled. I'd like to think we're all on this forum to share ideas, learn and have some fun.

I have great respect for guys who maintain their cars to original factory. Also respect guys who push the limits of todays innovations. We have a smorgasbord of exiting cars both past and present.

As far as my car. Just wanted to have the convenience of EFI and be able to jump in and drive. Simplicity and easier to maintain. I haven't had to do a thing to the motor since finishing it 3 years ago. Just change the oil and filters. Changed the plugs before final tune and then checked the plugs after the break in. No fouling. I had a '76 and couldn't do anything with it out here in Calif.

Modern EFI with ITBs is better than MFI. That doesn't mean I am saying you should not use MFI. All I am saying is this idea that MFI has magical throttle response that no other system has is not true.

I use a tube pre-amp and a tube amp in my 2 channel stereo system. I did give up on vinyl though as I can't deal with the required rituals anymore....

Agree 100%

Below is from someone else but I’m in agreement...

I consider myself a hard-core hard-a$$ about running old cars --- especially old Porsches. I'm not really interested in performance or usability or comfort in any absolute sense. If I was . . . I have lots of other choices. But I chose an old Porsche, and I specifically sought mine out for, among other things, its MFI. I'm interested in driving and living with and understanding something that I view, not just as a car, or a possession, but as an artifact --- something from another time.

So I don't really care if the car is difficult or flawed . . . as long as it's still what it started out as, still authentic . . . still the car that Porsche built.

http://forums.pelicanparts.com/uploa...1630547029.jpg


Above is a spark plug from my 2.7RS with 1600 miles of 95F degree highway driving this last weekend. 22 mpg at 3500-4000rpm, 80-90 mph. Dialed in right from the factory manual....

http://forums.pelicanparts.com/uploa...1630548381.jpg


Possibly a better pic.....

Hey, if you want to run MFI for any or all of these reasons, go for it:

1. It came with your 911
2. You think it is cool
3. You had the parts lying around
4. You want or have to be period correct with fuel injection
5. You want the best throttle response while being period correct
6. You just want to run MFI

I think everyone here agrees….

You guys think MFI and EFI are good, you should try CIS.





And if you don't like CIS how about KFC.





.

Winner winner Chicken dinner

I hate you guys. I recently fell down the MFI rabbit hole after deciding $5k+ for a set of PMO's wasn't worth it to me and if I was going to start with a blank slate rebuild there may be another way. This thread is making me want to go this direction even more.

I've been reading all of Jeff Higgins old posts and started to put together a spreadsheet of things I need to start accumulating. Henry Schmidt's builds are the stuff dreams are made of and also provide a lot of inspiration.

For me EFI isn't even remotely a consideration. One of the things I love most about my car is the lack of computers, having to tune it with a laptop would ruin the experience, I'd rather sell the car.

That is one clean running machine! What spark plugs are you using?

Bosch W3DPO, spec for all MFI cars except 911T. Also for 930.

Works in winter or summer, city or highway.

Thanks Jeff, I'll try that spark plug on my 70 911S

And here I was starting to worry about you... ;) I haven't given up on vinyl yet, though...

Yup, I check all of those boxes. And yes, I readily acknowledge all of MFI's shortcomings, and still prefer it.

At the end of the day, this is all about having fun. Some of us enjoy discovering how archaic old systems work and trying to make them work for us. I think one thing our little community has learned in these modern times is that MFI is not the mystery some had thought it was. With the benefit of modern instrumentation and test equipment, we can now make these systems run far better than when they were new. To me, that has been the challenge, and the enjoyment. I can see the same satisfaction in getting modern EFI/ITB systems working on these old motors.

I find it interesting that those work so well in your application. Every time I stray away from plain old single fat electrode style plugs, the really primitive bargain basement ones, I run into trouble. My car lives on NGK BP6ES's, while my son'e likes the BP7ES's. Any of the multi electrode plugs, or the ones with the really fine electrodes like the one you show, simply foul. Of course neither of our motors are any kind of original Porsche factory spec, and are running custom space cams, so they do run a bit dirtier in spots.

Which ignition are you running? My car uses the old Electromotive crank fire with six split coils, my son's uses the stock distributer (recurved by Barry Hershon) with a Pertronix Ignitor and a Bosch 6AL. Plenty hot spark from both, but they still foul the "fancy" spark plugs.

Ignition is Bosch 3 pin and Bosch coil from, I think 74-75. I’ve also used the original Permatune blue box and blue coil that Porsche used on 74 CIS 911s when they ran out of Bosch parts in late 73. They seem to perform equally well on this car with no discernible difference.

Yeah, vinyl, to sound great, needs to be real clean and cared for well. Plus, it is getting super expensive to obtain quality vinyl. I spent a bunch of time finding the best masterings of the albums I have on CD and SACD. Then, I rip these and play them through Roon. Roon integrated wonderfully with Qobuz so I can explore music I don't own. I don't have to get out of my listening chair to change albums.

I am all for people using MFI if that is what they want to do. If I were to pick up a pre 1974 911, I would want one with MFI and I would be happy to deal with the system. If I were building a restomod on a 1974 or later chassis, I would be using EFI.....there is no way I would try to make MFI with the modern engine build I would use.

Let's keep in mind that my only point of contention in this thread has been the idea that MFI has superior throttle response to a modern and well setup EFI ITB setup.

Wait, you use MFI because you enjoy the old systems yet you use Electromotive crank fire with six split coils?

Twisted....

The Electromotive crank fire stuff sucks.....

Yes, indeed. Quite the contradiction, I know. The problem was, about 15 years ago when I built the thing, twin plug distributers were virtual unobtanium. Originals would have set me back the cost of the entire rest of the motor build. Cap and rotor sets were in the neighborhood of $1,500 each. Just not a viable option at the time, for a street car that was meant to be driven. A lot.

My real world experience says otherwise. 15 years of absolutely trouble-free operation. It will roll over on its first 100,000 miles before the end of this year. It has averaged 10-12 DE events per year. The motor regularly sees in excess of 7,000 rpm with nary a misfire or bobble of any kind. The system is eminently tunable, with individual control over idle, mid range, and high RPM advance, with a high RPM retard available as well. I literally set this thing and forgot it 15 years ago, although I do check it once a year with a timing light.

So, yeah, 15 years of real world, hands-on experience with the Electromotive crank fire ignition system, and over 20 with MFI. My opinions are based upon actual experience. There are, of course, other ways to form opinions, some more valid than others.

I guess it works for street cars....I see failures at the race track way more often than I should considering the limited number of people running them.

That speaks more to the quality of people running them than the quality of the components themselves.

If anything, these components lead a much harder life on a street/DE car than on any race car. They see a lot more mileage, a lot more duty cycles, a far broader range of climatic conditions (my car regularly sees, with the changing seasons, anything from bone dry 110 degree Eastern Washington high desert to the snow and ice in single digit temperatures of our Cascade Range to our infamous Pacific Northwest rain).

Beyond that, this car gets driven every bit as hard on our local race tracks as any race car. My lap times would put me out in front of our local SOVREN (Society of Vintage Racing Enthusiasts) C/Stock class, wherein our local vintage 911 continent runs. Alas, I am "cheating" - my 3.0 displaces too much for the class (2.4 limit), has newer aluminum cases, and is twin plugged. Oh, and I run "Wide A" calipers on the front, also illegal for the class. Even though it is purely my equipment advantages speaking, I do lap faster than they do...

So, I guess I'm unclear on how Electromotive "sucks" (but only on race cars...). Race cars are prissy, pampered pussies compared to cars used on the street. Race cars typically get far more love and attention, they get far, far fewer miles (hours), and get to operate under far more controlled conditions. If someone cannot get Electromotive to work under these conditions, he must be rather inattentive or incompetent. It's a fantastic system.

Maybe. The competent race engine designers and builders I know recommend against it.....of course these are people mostly using MoTec with EFI. I guess their combined 100+ years of experience pales in comparison to your experience...and what I have seen.

Yeah, you are so fast I tremble in my racing shoes....jeez. Oh, doing a few laps at a time at race pace is not the same as running 40 minutes to 90 minutes at race pace.....

Here is my crappy MoTec setup not using Electromotive:

http://forums.pelicanparts.com/uploa...1605733094.jpg

Interesting. You began this little sidebar by flatly exclaiming that "Electromotive sucks". I responded by saying I have had great luck with it. You responded by saying "I guess it works for street cars....I see failures at the race track way more often than I should considering the limited number of people running them".

I went on to explain why I believe these systems lead a harder life in street car, particularly street/DE cars that do double duty. Essentially, they are faced with the harsher environment of street use, plus the same duty on track as any race car.

I guess I'm not sure why you would respond to that with a simple argument from (others') authority, a childish insult, and a flash of your wallet. Do you honestly believe any of that furthered your argument, or answered any of mine? :confused:

Again, why is it some people on this forum are always trying to pick a fight? It’s tiresome.

Come on, Jeff. Your argument is more fallacious than mine. Just because you have had success with Electromotive does not negate what I have seen at the track or heard from high performance engine designers and builders. Also, my photo was not a flash of my wallet anymore than your lap time comment was a flash of your ego.

I am glad you have Electromotive working for you. But don’t try to suggest that one positive case cancels any and all negative cases. Street engines see a different kind of environment than race engines. Race engines won’t last 100,000 miles….so that argument is flawed too.

Please post that same comment a few more times as I might have missed the last two in this thread.

The behavior continues and yet still no answer to my question.

Oh, you mean the part where someone has an opinion that is contrary to another person’s opinion? Oh, you want a forum where no opinions or statements are challenged. Boring….and not at all educational.

Is it really (more fallacious than yours)? Do you honestly believe my experiences represent an "example of one", or some kind of an anomaly? There are literally thousands of these systems in daily use in everything from our 911's to American muscle cars. A great number of "high performance engine designers and builders" use it as their first choice. My first hand experience is merely representative of their outstanding reputation.


Hardly. I took pains to point out that the only reason for my lap times is the fact that I'm "cheating" and have a distinct equipment (mainly power, some braking) advantage over what is allowed under class rules, thereby ruling out any possibility it is my "skill". Hardly any sort of a display of "ego". My only intent was to illustrate that the car is operated under the exact same conditions as "race cars", in addition to leading a much more demanding life when not on the track. Instead of just sitting in a garage, awaiting the next race day.

Again, do you honestly believe I'm suggesting my "one positive case cancels any and all negative cases"? There are thousands of these on the road. Thousands.

Race engines do, indeed, see a different kind of an environment. An environment that is much harder on some mechanical components - rod bearings, valve springs, and that kind of thing. Reciprocating, moving parts. These modern ignitions systems have no moving parts. All they "see" is how many times they are asked to provide a spark. In a race motor, they see no RPM induced loads nor stresses that they do not see in a street motor. In a race motor, they are not exposed to the extreme environmental conditions I noted earlier. Coupled with a fraction of the number of duty cycles on a race vs. street motor, these electrical components actually lead a much easier life on a race car than they do on a street car. They are simply not experiencing systems failure due to the added stresses of racing - there aren't any with these kinds of components.

These are all points I made earlier, none of which you were able to address - hence your response. I think you must have some image of everything on a race motor (or race car as a whole) somehow leading a much tougher life, somehow being much more highly stressed, than a similar component on a street car. While that is absolutely true for some components (tires, brakes come to mind) it is absolutely not true for others. Electrical components come to mind, including ignition components.

So, yeah, if they are seeing failures on race cars, it's due to faulty installation, neglected maintenance, inattention, or incompetence. And I'll bet the truly competent have chosen not to run it because other systems give them other advantages, like full engine management integration with the EFI system. Not because Electromotive is failure prone.