PMOs and altitude changes, Questions and experience |
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PMOs and altitude changes, Questions and experience |
914forme |
Jun 17 2018, 04:56 PM
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#1
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Times a wastin', get wrenchin'! Group: Members Posts: 3,896 Joined: 24-July 04 From: Dayton, Ohio Member No.: 2,388 Region Association: None |
I am working on getting the 2.7L redone for dad's 914-6 project. Plan is to drive it to Okteenerfest, and take dad for a beautiful run in the Georgia Mountains. I am not as good as I would like to be with carbs, more of an EFI guy. For some reason PMOs carbs are calling my name.
My one question comes into elevation changes. I really don't want to build the car and then hate the drive if they can't transition well with elevation changes. Any one with experience and know they won't frustrate running up the mountain roads? Are the PMO carbs worth the price of admission? |
Mike Bellis |
Jun 17 2018, 05:50 PM
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#2
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Resident Electrician Group: Members Posts: 8,345 Joined: 22-June 09 From: Midlothian TX Member No.: 10,496 Region Association: None |
I don't know PMO. But no carbs adjust to elevation. It's a factor of oxygen density. Higher elevation is less oxygen. Less oxygen requires less fuel. Less fuel requires a jet change. Carbs should be tuned for your primary elevation. I'm sure some work better than others but if you travel through a bunch of elevations changes, EFI is a better choice.
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mb911 |
Jun 17 2018, 06:31 PM
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#3
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914 Guru Group: Members Posts: 6,811 Joined: 2-January 09 From: Burlington wi Member No.: 9,892 Region Association: Upper MidWest |
Lots of jetting fun..
. I will do efi some day just doing carbs now so I can get the car running and driving. |
rhodyguy |
Jun 17 2018, 06:53 PM
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#4
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Chimp Sanctuary NW. Check it out. Group: Members Posts: 22,060 Joined: 2-March 03 From: Orion's Bell. The BELL! Member No.: 378 Region Association: Galt's Gulch |
What kind of elevation changes do you expect to see?
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porschetub |
Jun 17 2018, 07:53 PM
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#5
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Advanced Member Group: Members Posts: 4,697 Joined: 25-July 15 From: New Zealand Member No.: 18,995 Region Association: None |
Depends if you have rebuilt the Webers so they work great no need to go to PMO's if you have already spent the $$$ on them.
If you retain the Webers you could just fatten up the idles and mains a touch because they were jetting lean from day one so you won't have serious issues @ the higher altitude ,keep a close eye your oil temp you should be ok. |
JmuRiz |
Jun 17 2018, 08:51 PM
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#6
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914 Guru Group: Members Posts: 5,423 Joined: 30-December 02 From: NoVA Member No.: 50 Region Association: MidAtlantic Region |
If planning on new PMO money, might as well spring a bit more on EFI.
Check with Al Imolska (sp?) for some ideas on any budget in that range and above. |
914forme |
Jun 17 2018, 09:02 PM
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#7
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Times a wastin', get wrenchin'! Group: Members Posts: 3,896 Joined: 24-July 04 From: Dayton, Ohio Member No.: 2,388 Region Association: None |
Jim you talking about theseX-Factory?
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SirAndy |
Jun 17 2018, 10:54 PM
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#8
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Resident German Group: Admin Posts: 41,606 Joined: 21-January 03 From: Oakland, Kalifornia Member No.: 179 Region Association: Northern California |
you could just fatten up the idles and mains a touch because they were jetting lean from day one so you won't have serious issues @ the higher altitude ,keep a close eye your oil temp you should be ok. I'm pretty sure higher altitude with *less* oxygen requires *less* fuel, not more fuel ... (IMG:style_emoticons/default/shades.gif) |
EdwardBlume |
Jun 18 2018, 05:31 AM
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#9
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914 Wizard Group: Members Posts: 12,338 Joined: 2-January 03 From: SLO Member No.: 81 Region Association: Central California |
I've done some research on EFI and can tell you that the pros outweigh the cons. The people who have done this conversion on the 911s seem to report back that its reliable amongst many other benefits.
The biggest issue is cost. Some of the kits are from hobbyists who deserve every penny for their efforts. Other company kits are higher than that. For me, I have to solve oil cooling and the cost of other components to switch from a 2.4 to a 3.0 EFI, which is kind of frustrating because the 3.0 has a working CIS on it already, but given the leap in years and technology, the kits are the way to go. Bitz Racing has a MS based system which uses the 3.0 intake which I would likely go with. I would have to get a new Kennedy flywheel and clutch, $700. Oil lines, cooler and thermostat $1500, cut the front out $???, and install the kit, including dyno time. The 2.4 when sold will pay for all of this, but I need to get it running and compression verified first. |
mb911 |
Jun 18 2018, 05:53 AM
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#10
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914 Guru Group: Members Posts: 6,811 Joined: 2-January 09 From: Burlington wi Member No.: 9,892 Region Association: Upper MidWest |
I've done some research on EFI and can tell you that the pros outweigh the cons. The people who have done this conversion on the 911s seem to report back that its reliable amongst many other benefits. The biggest issue is cost. Some of the kits are from hobbyists who deserve every penny for their efforts. Other company kits are higher than that. For me, I have to solve oil cooling and the cost of other components to switch from a 2.4 to a 3.0 EFI, which is kind of frustrating because the 3.0 has a working CIS on it already, but given the leap in years and technology, the kits are the way to go. Bitz Racing has a MS based system which uses the 3.0 intake which I would likely go with. I would have to get a new Kennedy flywheel and clutch, $700. Oil lines, cooler and thermostat $1500, cut the front out $???, and install the kit, including dyno time. The 2.4 when sold will pay for all of this, but I need to get it running and compression verified first. You could always use the mfi ports in the heads for injectors and the carbs as throttle body's.. Thats my plan some day with my 2.4.. |
JmuRiz |
Jun 18 2018, 07:30 AM
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#11
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914 Guru Group: Members Posts: 5,423 Joined: 30-December 02 From: NoVA Member No.: 50 Region Association: MidAtlantic Region |
I've done some research on EFI and can tell you that the pros outweigh the cons. The people who have done this conversion on the 911s seem to report back that its reliable amongst many other benefits. The biggest issue is cost. Some of the kits are from hobbyists who deserve every penny for their efforts. Other company kits are higher than that. For me, I have to solve oil cooling and the cost of other components to switch from a 2.4 to a 3.0 EFI, which is kind of frustrating because the 3.0 has a working CIS on it already, but given the leap in years and technology, the kits are the way to go. Bitz Racing has a MS based system which uses the 3.0 intake which I would likely go with. I would have to get a new Kennedy flywheel and clutch, $700. Oil lines, cooler and thermostat $1500, cut the front out $???, and install the kit, including dyno time. The 2.4 when sold will pay for all of this, but I need to get it running and compression verified first. You could always use the mfi ports in the heads for injectors and the carbs as throttle body's.. Thats my plan some day with my 2.4.. (IMG:style_emoticons/default/agree.gif) jpnovak from the Pelican board did this and it looks good, just get a good controller (MS or something) and you're in the game! If I didn't already have a good set of carbs I got a long time ago for cheap, I'd do EFI....maybe if/when I sell off all my old parts I'll have some $ to splurge |
Mark Henry |
Jun 18 2018, 10:17 AM
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#12
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that's what I do! Group: Members Posts: 20,065 Joined: 27-December 02 From: Port Hope, Ontario Member No.: 26 Region Association: Canada |
If you can DIY then you can build an FI system for around the price of the PMO's If it has to be bolt on and take it for tuning then it could cost double PMO's
PMO TB's are the same price as the carbs. If you can and have the time to DIY triumph TB's work. MFI stuff is getting spendy like all porsche goodies. Dyno time isn't cheap, FI tuning has a learning curve. Yes you can make a plenum FI system cheaper than ITB's, but that's comparing apples to oranges. PMO carbs will make more HP than a plenum system. |
mlindner |
Jun 18 2018, 12:31 PM
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#13
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Senior Member Group: Members Posts: 1,512 Joined: 11-November 11 From: Merrimac, WI Member No.: 13,770 Region Association: Upper MidWest |
Give Richard at PMO a call. He'll have the answer for you. Having a extra set of jets to handle high elevation should not be a problem. Best, Mark
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EdwardBlume |
Jun 18 2018, 04:51 PM
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#14
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914 Wizard Group: Members Posts: 12,338 Joined: 2-January 03 From: SLO Member No.: 81 Region Association: Central California |
If you can DIY then you can build an FI system for around the price of the PMO's If it has to be bolt on and take it for tuning then it could cost double PMO's PMO TB's are the same price as the carbs. If you can and have the time to DIY triumph TB's work. MFI stuff is getting spendy like all porsche goodies. Dyno time isn't cheap, FI tuning has a learning curve. Yes you can make a plenum FI system cheaper than ITB's, but that's comparing apples to oranges. PMO carbs will make more HP than a plenum system. Good point. With stock 3.0 cams I figured using the stock plenum would be safe. |
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