Speaking of MFI, Man that sounds good.. Options

[redshift]

What are the limitations of it?

I am planning a /6, had considered a 2.7RS, guffawed at the video of that 2.8 RSR, but I like the 3.0-3.2s running forever, AFAWK...

Negativity will be ignored in favor of zooming noises, and high-pitched whining descriptions. (with pictures and exuberant hand gestures)

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[tryan]

i have mfi on a 2.4t in a tail dragger.

sounds fast ( three brand new SLOW signs on the 1/2 mile home stretch to the house after i bought the car. heheh), but any 914 will drive circles around any 911.

2.8 would be the largest space cam for the pump, but the slide vavles might cost more than a good teen. i would go 3.2 with cis for any easy, drivable conversion.

[airsix]

This will sound wild and impractical (HA! That got everybody listening!) but I don't think it's as impractical as it sounds.

MIF as I understand it, provides mixture as a function of RPM and throttle possition. Pretty straight forward isn't it? Your first though is "How crude". All the modern systems of EFI use manifold pressure or mass-air-flow in combination with rpm to measure load. While this is a more refined and precice method of getting the mixture right, don't think MFI type sytstems aren't capable of getting the job done well.

A MODERN MFI:
Most of the programable ECU's on the market (even the megasquirt) are capable of running in alpha-n mode, meaning they don't have a reference to manifold pressure and just use RPM, temperature, and throttle possition to meter fuel. I ran and tuned my PEFI system in alpha-n mode just as an experiment to see how well it would run and I was totally amazed. I was able to make it run great, and I wouldn't be afraid to set up a hot six to run this way. You might not be able to keep the mileage and emissions as good as running EFI with MAP (manifold absolute pressure) or mass-air-flow metering, but you'll be able to make power. I think you could also make it every bit as "drivable" or even more-so than a MFI setup.

You would need:
ECU
Manifolds & Throttlebodies
Airfilters

The ECU could be as simple as a $200 megasquirt, or as fancy as a $3k+ Motec.
The manifolds and TB's could be carb manifolds and gutted carbs. Even cooler would be to use motor-bike TB's. Many of the late bikes have individual TB's with a bosch injector bung in the manifold. Several of the .9 and 1.0 litre bikes apear to have good sized TB's for a 2.7-3.0 six. The hard part would be adapting the bike manifold and the throttle linkage. You'd of course have to use two sets of bike intakes, and lop off one of the TB's from each set of four to end up with two sets of three.

I know it sounds nuts, but I think it would be pretty awsome. MFI power & sound with EFI reliability & drivability. Ok, the drivability part will still be a compromise, but the SOUND, MAN, THE SOUND! (IMG:style_emoticons/default/wink.gif)

-Ben M.

ps - I was told that that 2.8RSR made 250hp at the wheels at it's post-build dyno session (not pump gas though).
pps - There is a guy out there with a Lotus Europa (sp?) running individual bike TB's and I think an SDS ECU. He says it's awsome and he couldn't be happier.

[redshift]

(IMG:style_emoticons/default/huh.gif) How much is a good teener?

If I understand what you are saying, CRAP. I can't seem to find much about it on the web, and PET doesn't really help.. -g-

The 'build your own fake mfi' sounds like a job for Seom O. Neelse, the famous FI builder.

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[Aaron Cox]

i thought that with MFI in a teener you need to cut an access panel in the firewall? MFI was used on lots of porsche racecars- so it must be good (IMG:style_emoticons/default/smile.gif)

[DNHunt]

Something to consider. Alpha-N since it isn't dependent on a vacuum signature will work better with a wilder cam. Also you don't need to synchonize the manifold atmosheric pressure in each throttle body.

Dave

[campbellcj]

I think somebody should put one of these in a 914 (maybe I will, if I win the lottery, LOL)

If I recall correctly, 2.8RSR twin-plugged slide-valve throttle body MFI. I would guess you'd drop $5K+ on the injection setup alone; if you were lucky enough to find one.

[redshift]

Yeah, that's what I want, but 3.0+..

Anyone?



M

[Mueller]

redshift Posted on Jul 19 2003, 11:26 AM
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What are the limitations of it?

the only limitation is the flow of money from your wallet (IMG:style_emoticons/default/smile.gif)


There are still a few people that know how to tune them.
For your average mechanic, MFI is fine on a stock engine, since so many have BTDT, but when you want to install the MFI on a tweaked engine, the sources are limited.

It won't be cheap, so make sure you are commited and have a nice fat budget

[Aaron Cox]

in the book "porsche 911 ; performance handbook" - they show numerous thinks relating to super duper MFI setups- cool. i like the flat fans that blow air down to the motor-

[mightyohm]

There actually was an MFI setup for a 3.0 for a special edition SC. I think it had some more advanced electronic controls than the early units did.

And also didn't the 74 Euro Carerra have a 3.0 with MFI?

There has been talk on the PP 911 BBS before about doing electronic versions of MFI using alpha-N. One guy was using Motec and stock MFI throttle bodies. Electronic injectors went in place of the MFI ones and there was a TPS on one end of the cross bar.

[redshift]

Yeah, there is a factory 3.0 version of that motor, I was thinking a system could be retrofitted to something bigger..

and another thing..

Rotax engines.. have you seen the TPS on that? They are like $200... and that got me to thinking..



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