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Join Date: Mar 2007
Location: Colorado
Posts: 67
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MFI @ Mountain Elevation
I have searched the archives and found little on this specific subject as I am sure I am in a distinct minority. Since I live at 9,000’ and drive between 5,500’ and 12,000’ I wanted to know your experience with MFI at these diverse elevations. Is MFI as quirky as carbs?
I have wanted an MFI car for years but need to know before I make a final decision on a potential car what I am signing up for. Can I get it tuned for this range of elevations? What experience or recommendations do you have? Is there anyone in the Denver area that knows MFI you would trust to work on these cars? For reference we are talking 2.2E that is mechanically sound and refreshed but never completely rebuilt. It runs great at sea level currently. |
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11-30-2019, 03:55 PM
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Been here a while
Join Date: Apr 2004
Location: East coast, west coast, typ. 35,000 ft
Posts: 2,451
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Steve Rowe is a magician and a superb gentleman.
I brought my 72 mfi, twin plug 2.7 from socal at sea level to denver and drove 1000 miles up to 13,000 feet, it ran rich but ran well up to the highest elevations...within reason.
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looking for 1972 911t motor XR584, S/N 6121622 |
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11-30-2019, 04:28 PM
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Join Date: Oct 1999
Posts: 8,673
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John Eisenbud (Eisenbud's) in Denver is good with MFI.
303 825-0322 |
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11-30-2019, 04:31 PM
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Join Date: May 2006
Posts: 287
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I believe the gold can that sits on top of the pump is a barometric pressure compensator. I'm not exactly sure how it works, but would expect it has some kind of air bladder attached to an adjuster that richens/leans the rack as pressure changes.
So at least the MFI system has air pressure compensation built into it that might give you some shot at tuning to your conditions. Edited to add: see this thread for more info: http://forums.pelicanparts.com/porsche-911-technical-forum/544158-mfi-barometric-cell.html
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Jeff Jensen 1973 911 Last edited by mobius911; 11-30-2019 at 04:45 PM.. |
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11-30-2019, 04:38 PM
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Registered
Join Date: Oct 2008
Location: Denver, CO
Posts: 3,505
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second the eisenbud's recommendation -- john and jim know their 911 MFI and live/work at the right altitudes
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11-30-2019, 05:19 PM
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Join Date: Dec 2008
Location: San Antonio, Texas
Posts: 3,591
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You need to run a bit more ignition advance at higher altitudes. A couple of clicks lean helps too. At least these are both things I did at 7200ft.
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1973 911S (since new) RS MFI specs 1991 C2 Turbo |
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11-30-2019, 05:29 PM
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gearhead
Join Date: Nov 2007
Location: Loverland, CO
Posts: 23,639
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Quote:
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1974 914 Bumble Bee 2009 Outback XT 2008 Cayman S shop test Mule 1996 WRX V-limited 450/1000 |
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11-30-2019, 05:33 PM
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Functionista
Join Date: Jul 2011
Location: CO
Posts: 7,717
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Get them in spec and you’ve nothing to worry about as far as quirkiness. I’ve driven mine right up to the top of Pikes Peak 14,115 feet. No rough running or trouble re-starting. With real time monitoring of air/fuel mix you can get it super close to even factory specs which for years people have said are too lean. No issues here but I will say the meaning of “in spec” is super important.
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Jeff 74 911, #3 I do not disbelieve in anything. I start from the premise that everything is true until proved false. Everything is possible. |
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11-30-2019, 06:17 PM
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Registered
Join Date: Oct 2004
Location: S California
Posts: 7,997
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Contact Mark Jung at MFI Werks. He'll get your pump dialed in.
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1970 911E Sportomatic Albert Blue 1971 911T Sunroof Coupe w/ Twin Plug 2.5 MFI 1973 911E Glacier Blue 1973 911E RSR Tribute Viper Green w/ 3.5 Twin Plug MFI |
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11-30-2019, 08:43 PM
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Join Date: Jul 2001
Location: mt. vernon Wa. USA
Posts: 8,756
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+1 for Mark Jung....
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[B]Current projects: 69-911.5, Previous:73 911X (off to SanFrancisco/racing in Germany).77 911S (NY), 71E (France/Corsica), 66-912 ( France), 1970 914X (Wisconsin) 76 911S roller..off to Florida/Germany RGruppe #669 http://www.x-faktory.com/ |
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11-30-2019, 09:32 PM
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Join Date: Jun 2009
Posts: 1,251
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The can on top is for barometric pressure. If it is not up to the job, I live a 1000ft, so don't have experience with how they perform in the mountains, you can remove it and put a mech adjuster in its place. I have 3 MFI setups and I really like it. Bob
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12-01-2019, 04:26 PM
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mfi and altitude
The MFIis designed to work under any altitude.
The barotric compensator will adjust from below sea level to about 25000 though i have read it can go to 40000" Caveat: the pump needs to be set up properly
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1975 911S Targa Silver Anniversary Edition |
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12-03-2019, 02:29 AM
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MFI will compensate for altitude . If still running too rich, a turn or two on the main MFI linkage will lean it out over the whole spectrum a bit. Easy to reverse when back a lower elevations. Linkage, not the MFI enrichment screws (dont touch these).
Chris 73 E |
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12-03-2019, 12:49 PM
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Registered
Join Date: Mar 2007
Location: Colorado
Posts: 67
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Thank you so much for the information. I feel much more confident MFI will work in my situation when the elevation has complicated things in the past.
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12-03-2019, 01:18 PM
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Registered
Join Date: Dec 2008
Location: San Antonio, Texas
Posts: 3,591
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Quote:
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1973 911S (since new) RS MFI specs 1991 C2 Turbo |
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12-03-2019, 04:05 PM
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