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| [GMCnet] EFI for GMC's [message #179957] |
Sun, 12 August 2012 13:08  |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Senior Member |
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G'day,
The PO of The Blue Streak installed a Holley Commander 950 and it goes like a "shower of $hit!"
Due to the vapor lock problems and total lack of performance at altitude I've decided to install an EFI system on the Patterson
engine I have sitting in Houston.
From where I sit there are two ways to go:
1) DIY with LOTS of help from the EFI group
2) Buy one off the shelf from Howell / Holley / MSD or ?
The one thing I really like about the commercial units is that they are 4 barrel units and if I understand it correctly the DIY
setups are only two barrel.
I also have a problem scrounging all the parts required to DIY as I don't live here.
Holley has a page on their website that you can fill in a lot of info on your vehicle and they review it and recommend which unit to
buy. I did that but haven't had the time to review their recommendation.
SteveF has suggested I look at MSD's Atomic EFI which I will do.
Comments please.
Regards,
Rob
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Regards,
Rob M. (USAussie)
The Pedantic Mechanic
Sydney, Australia
'75 Avion - AUS - The Blue Streak TZE365V100428
'75 Avion - USA - Double Trouble TZE365V100426
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| Re: [GMCnet] EFI for GMC's [message #179970 is a reply to message #179957] |
Sun, 12 August 2012 15:38  |
John Sharpe
Messages: 489
Registered: February 2006
Location: Texas
Karma: 1
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Senior Member |
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The Howell unit and the DYI's are mostly 2barrel throttle body systems. The only advantage of a 4 barrel is more air flow. At the rpms ours turn that is not an issue unless you are using a smaller throttle body designed for a smaller displacement engine, say a 350. In my opinion the simplest is the GM based TBI and with EBL it's hard to beat. I've been told by some that have had both, that difference between TBI and MPI is negligible.
John Sharpe
Humble,TX
'78 Eleganza TBI
'89 Spectrum 2000 MPI V-10
'40 Ford Panel Delivery TPI
johnasharpe@gmail.com
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| Re: [GMCnet] EFI for GMC's [message #179974 is a reply to message #179957] |
Sun, 12 August 2012 16:13 |
LYNN L
Messages: 140
Registered: March 2005
Location: Pearland TX.
Karma: 0
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Rob, there are several systems on the market now that simplify the whole install process. One of them is produced by a company called Fast. the beauty of it all is that the new systems tune themselves with the o2 sensor. I installed a system from a company out ot of Canada that you had to put in all the tuning parameters on the run. It ran good but I could never get the tip in at highway speed where I was happy with it. I was always tuning it while driving and would avert my attention from the road. Figured out that this was not very wise!!! I now run an edelbrock aluminum manifold with a edelbrock performer carb and am really happy with its perfomance on the Caddy motor.Check this site.
http://www.fuelairspark.com/ezefi/default.asp
Lynn L
76 Eleganza Cad.500
Pearland TX.
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| Re: [GMCnet] EFI for GMC's [message #180046 is a reply to message #180006] |
Mon, 13 August 2012 08:02 |
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Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
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| Robert Mueller wrote on Sun, 12 August 2012 21:10 |
John,
I reckon'd that the combination of two small primaries and two larger secondaries would provide better low RPM performance than just two large barrels.
Did I reckon wrong?
Regards,
Rob M.
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Rob,
Yes
Matt
Sorry, I just couldn't pass up that opportunity....
What you are thinking was completely true with a conventional carburetor. With anything close to a modern closed loop, self adapting system, it is not.
The simple fact is that carburetors are a technical upgrade of a 19th century device, but then so are many aircraft.
If you had the courses in engineering school, you were taught that the venturi is a mass flow device and pretty much linear (or at least simple function) over a wide range. When I was being taught this, I was already have problems with racecars not going as expected. This lead me to look at the investigate more thoroughly. What I was told was true only in a turn-down range of three ~maybe four.
Turn-down is an engineering description of how far you can get from the design operating parameter location until it quits working - like Cruise to Stall for an aircraft Or even VNE to stall (without variable geometry). That is not a real big window in terms of a road vehicle operation.
The computer controlled systems would appear to eliminate the issue, and in a practical sense they do. They do it with brute force calculating power. The processor 7747, uses an 8X8 matrix of LV8 (calculated air flow based on MAP) and Rev to determine how many pounds of air are being inhaled. It knows how many pounds of fuel the injectors spit per millisecond. The matrix cell tells it what it wants for F/A and timing. So, it just does the math... about 2000 times a second.
Now, the turn-down is now only a factor in each little tiny cell of the entire calibration matrix. So, it does what it needs to do to make it work and you go along your way.
I not sure if that makes a two barrel TBI more like an 8 barrel progressive carburetor or what. Have you noticed a distinct dearth of progressive multi-barrel throttle bodies in use?
To all those that bothered to read this all the way through, if I lost you along the way, please come back and say so. I will try to clarify any confusion I may have created.
Matt - again
Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
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| Re: [GMCnet] EFI for GMC's [message #180047 is a reply to message #180046] |
Mon, 13 August 2012 08:13 |
Dennis S
Messages: 3046
Registered: November 2005
Karma: 2
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Senior Member |
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Matt,
Should/could you include some comments on the design of the intake manifold and it's impact on the number of venturi?
Dennis
| Matt Colie wrote on Mon, 13 August 2012 08:02 |
| Robert Mueller wrote on Sun, 12 August 2012 21:10 |
John,
I reckon'd that the combination of two small primaries and two larger secondaries would provide better low RPM performance than just two large barrels.
Did I reckon wrong?
Regards,
Rob M.
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Rob,
Yes
Matt
Sorry, I just couldn't pass up that opportunity....
What you are thinking was completely true with a conventional carburetor. With anything close to a modern closed loop, self adapting system, it is not.
The simple fact is that carburetors are a technical upgrade of a 19th century device, but then so are many aircraft.
If you had the courses in engineering school, you were taught that the venturi is a mass flow device and pretty much linear (or at least simple function) over a wide range. When I was being taught this, I was already have problems with racecars not going as expected. This lead me to look at the investigate more thoroughly. What I was told was true only in a turn-down range of three ~maybe four.
Turn-down is an engineering description of how far you can get from the design operating parameter location until it quits working - like Cruise to Stall for an aircraft Or even VNE to stall (without variable geometry). That is not a real big window in terms of a road vehicle operation.
The computer controlled systems would appear to eliminate the issue, and in a practical sense they do. They do it with brute force calculating power. The processor 7747, uses an 8X8 matrix of LV8 (calculated air flow based on MAP) and Rev to determine how many pounds of air are being inhaled. It knows how many pounds of fuel the injectors spit per millisecond. The matrix cell tells it what it wants for F/A and timing. So, it just does the math... about 2000 times a second.
Now, the turn-down is now only a factor in each little tiny cell of the entire calibration matrix. So, it does what it needs to do to make it work and you go along your way.
I not sure if that makes a two barrel TBI more like an 8 barrel progressive carburetor or what. Have you noticed a distinct dearth of progressive multi-barrel throttle bodies in use?
To all those that bothered to read this all the way through, if I lost you along the way, please come back and say so. I will try to clarify any confusion I may have created.
Matt - again
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Dennis S
73 Painted Desert 230
Memphis TN Metro
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| Re: [GMCnet] EFI for GMC's [message #180096 is a reply to message #179991] |
Mon, 13 August 2012 12:24 |
roy1
Messages: 2126
Registered: July 2004
Location: Minden nevada
Karma: 6
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Senior Member |
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[quote title=Robert Mueller wrote on Sun, 12 August 2012 16:55]Lynn,
Double Trouble has a Patterson Q-Jet and a Patterson distributor. At sea level it runs great, the higher you go the worse the
performance gets.
What's the highest altitude you've had your GMC up to with the Edelbrock Performer Carb?
Regards,
Rob M.
-My stock quadrojet works just fine at 8,000 feet or Death Valley 200 feat below sea level. The performance droops of at higher elevations but any aspirated engine will suffer as the elevation increases.
Roy Keen
Minden,NV
76 X Glenbrook
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| Re: [GMCnet] EFI for GMC's [message #180097 is a reply to message #180096] |
Mon, 13 August 2012 12:30 |
habbyguy
Messages: 896
Registered: May 2012
Location: Mesa, AZ
Karma: 3
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Senior Member |
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| Robert Mueller wrote on Sun, 12 August 2012 16:55 |
-My stock quadrojet works just fine at 8,000 feet or Death Valley 200 feat below sea level. The performance droops of at higher elevations but any aspirated engine will suffer as the elevation increases.
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Does anyone out there have any feedback on how I should expect my 403-powered Royale to do at slightly over 12,000 feet (Cottonwood Pass in central Colorado, with my destination at about 10,000 feet). I've got a Lamey-tuned Holley carb that has been flawless for the places I've driven it so far, though I don't think I got over about 3,000 feet of altitude so far. I just don't want to get to 11,900 feet and find out I can't crawl the rest of the way over Cottonwood Pass...
Mark Hickey
Mesa, AZ
1978 Royale Center Kitchen
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| Re: [GMCnet] EFI for GMC's [message #180098 is a reply to message #180097] |
Mon, 13 August 2012 12:46 |
Neil
Messages: 271
Registered: July 2007
Location: Los Angeles and Magalia, ...
Karma: 1
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Senior Member |
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In my experience with a 455, so long as vapor lock is not an issue, and assuming that you are not towing or your tow is reasonable, a carb equiped coach can climb any interstate. Maybe you have to gear down and put the blinkers on, but you get there.
Neil
76 Eleganza now sold
Los Angeles
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| Re: [GMCnet] EFI for GMC's [message #180104 is a reply to message #179957] |
Mon, 13 August 2012 13:23 |
LYNN L
Messages: 140
Registered: March 2005
Location: Pearland TX.
Karma: 0
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Senior Member |
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Robert, I never go over 3,000 ft. Texas is flat and is really spread out. I used to run q-jets in my hot rod days and thought them to be one of the best designs on the market especially when well tuned on the vacuum secondaries. Since our Gmcs are more about torque than rpm, it makes perfect sense that 2 barrels will do the job. I have an origional 2-barrel throttle body from an early fuel injected cadillac 500 and it has rather large barrels to flow enough air into the beast.I had to make my own IAC with a fixed orfice and used a fuel selector solenoid for the choke. It worked great at some speeds but as I said before you needed a better way to tune the system I had. Matt, thank you for the dessertation on turn down. Kinda reminded me of the days before I retired and had to make engineers dreams into real world product. Turn down is sorta like putting something in a lathe and feeding the tool to fast. Reality sets in when the tool breaks!!! 
Lynn L
76 Eleganza Cad.500
Pearland TX.
[Updated on: Mon, 13 August 2012 13:24] Report message to a moderator |
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| Re: [GMCnet] EFI for GMC's [message #180154 is a reply to message #180097] |
Mon, 13 August 2012 21:00 |
roy1
Messages: 2126
Registered: July 2004
Location: Minden nevada
Karma: 6
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Senior Member |
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[
Does anyone out there have any feedback on how I should expect my 403-powered Royale to do at slightly over 12,000 feet (Cottonwood Pass in central Colorado, with my destination at about 10,000 feet). I've got a Lamey-tuned Holley carb that has been flawless for the places I've driven it so far, though I don't think I got over about 3,000 feet of altitude so far. I just don't want to get to 11,900 feet and find out I can't crawl the rest of the way over Cottonwood Pass...[/quote]
First I would make sure you have an electric pump plumed in in case you encounter vapor lock. If you have a toad it would be best to drive it up after you get 3/4 of the way up ,if the grade is steep. It sure would be nice to have low gears I wouldn't be without my 3:70's.
Roy Keen
Minden,NV
76 X Glenbrook
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| Re: [GMCnet] EFI for GMC's [message #180164 is a reply to message #180098] |
Mon, 13 August 2012 23:23 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Senior Member |
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I have been up and through the Eisenhower tunnel I-70 west bound in a GMC with a 403. I think that is a little over 11,000 feet. I have driven it in the reverse direction with a 455 powered GMC. They both handled it the same. I definitely was in second gear going up. The cars will pass you but you will pass the other RVs and trucks. I do not remember if I ever had to go to first gear. Both coaches had standard 3.07 final drives.
I have also driven up Trail Ridge Road (Highway 34) in the Rocky Mountain National park with my 455 powered GMC. I believe it is over 12,000 at the top. Again a lot of 2nd gear. I do not remember needing 1st, but I might have used it. 3.07 final drive.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: [GMCnet] EFI for GMC's [message #180165 is a reply to message #180046] |
Mon, 13 August 2012 23:25 |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Senior Member |
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Matt,
I understand what you've noted below, however, since the MSD Atomic EFI and the Holley EFI's both have four barrel throttle bodies
it appears that is more of a marketing ploy than a technical necessity.
Regards,
Rob M.
-----Original Message-----
From: Matt Colie
Rob,
Yes
Matt
Sorry, I just couldn't pass up that opportunity.... NO WORRIES MATE!
What you are thinking was completely true with a conventional carburetor. With anything close to a modern closed loop, self
adapting system, it is not.
The simple fact is that carburetors are a technical upgrade of a 19th century device, but then so are many aircraft.
If you had the courses in engineering school, you were taught that the venturi is a mass flow device and pretty much linear (or at
least simple function) over a wide range. When I was being taught this, I was already have problems with racecars not going as
expected. This lead me to look at the investigate more thoroughly. What I was told was true only in a turn-down range of three
~maybe four.
Turn-down is an engineering description of how far you can get from the design operating parameter location until it quits working -
like Cruise to Stall for an aircraft Or even VNE to stall (without variable geometry). That is not a real big window in terms of a
road vehicle operation.
The computer controlled systems would appear to eliminate the issue, and in a practical sense they do. They do it with brute force
calculating power. The processor 7747, uses an 8X8 matrix of LV8 (calculated air flow based on MAP) and Rev to determine how many
pounds of air are being inhaled. It knows how many pounds of fuel the injectors spit per millisecond. The matrix cell tells it
what it wants for F/A and timing. So, it just does the math... about 2000 times a second.
Now, the turn-down is now only a factor in each little tiny cell of the entire calibration matrix. So, it does what it needs to do
to make it work and you go along your way.
I not sure if that makes a two barrel TBI more like an 8 barrel progressive carburetor or what. Have you noticed a distinct dearth
of progressive multi-barrel throttle bodies in use?
To all those that bothered to read this all the way through, if I lost you along the way, please come back and say so. I will try
to clarify any confusion I may have created.
Matt
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Regards,
Rob M. (USAussie)
The Pedantic Mechanic
Sydney, Australia
'75 Avion - AUS - The Blue Streak TZE365V100428
'75 Avion - USA - Double Trouble TZE365V100426
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| Re: [GMCnet] EFI for GMC's [message #180167 is a reply to message #180154] |
Mon, 13 August 2012 23:52 |
habbyguy
Messages: 896
Registered: May 2012
Location: Mesa, AZ
Karma: 3
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| roy1 wrote on Mon, 13 August 2012 19:00 |
First I would make sure you have an electric pump plumed in in case you encounter vapor lock. If you have a toad it would be best to drive it up after you get 3/4 of the way up ,if the grade is steep. It sure would be nice to have low gears I wouldn't be without my 3:70's.
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Thanks Roy (and everyone else) for the input. I feel better about driving over Cottonwood Pass knowing that others have taken on similar grades and altitudes. I've got an electric fuel pump, and 3.42 Cinnabar gearing, and no toad, so I guess I'll be OK.
That's probably not going to stop me from going with fuel injection some day (and/or maybe that "altitude compensating blower") but based on what I've heard here, I won't hesitate to take on Cottonwood Pass (12,100 feet, packed dirt and gravel on one side) before any other modifications (other than non-ethanol fuel if I can find it). Unless it's raining, in which case I'll find another route altogether (somehow tight, muddy switchbacks at 12,000 feet doesn't sound like a good idea).
Mark Hickey
Mesa, AZ
1978 Royale Center Kitchen
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| Re: [GMCnet] EFI for GMC's [message #180171 is a reply to message #179957] |
Tue, 14 August 2012 02:43 |
George Beckman
Messages: 1085
Registered: October 2008
Location: Colfax, CA
Karma: 11
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| Robert Mueller wrote on Sun, 12 August 2012 11:08 |
G'day,
From where I sit there are two ways to go:
1) DIY with LOTS of help from the EFI group
2) Buy one off the shelf from Howell / Holley / MSD or ?
SteveF has suggested I look at MSD's Atomic EFI which I will do.
Comments
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Rob,
I cannot help much with the two-four discussion, but I certainly read Matt's comments. (I would like to hear Matt atGMCMI talk sometime about his views on combustion, cams and tappers, intakes and grades of oil viscossities as I alway learn something. And I have found some of my shade tree ideas are less than sound.)
I have a Howell with EBL. I have looked at some of the others and my only concern is total integrated control. In my mind you want one computer dealing with fuel and spark. Spark is an absolute must for me. Huge, huge improvement. By integrated, I mean spark based on fuel being supplied and only the EFI computer knows that. In my reading I have not been sure how spark is being handled by some companies.
I want:
1. Fuel controlled and checked by closed loop reports for th e O2 sensor.
2. Spark based in throttle, MAP and fuel being delivered
3. Fuel shutoff during coasting.
4. Lean cruise, leaning out fuel when driving flat ground and advancing the spark as this happens.
5. Power Enrichment that keeps my cylinders cool during hard pulls
6. A knock sensor that retards the spark when it begins to ping.
7. As a bonus, I want to Be able to adjust the above. (EBL for me)
And all the above integrated. So, make sure what ever you choose can do this, in my opinion. GM spent a zillion developing their EFI system that ran their vehicles for years and years. TBI is not as good as the modern stuff, but it is a very slick well designed system. I am not sure how much good a 2012 system would do with a combustion chamber designed in the 1960s.
'74 Eleganza, SE, Howell + EBL
Best Wishes,
George
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| Re: [GMCnet] EFI for GMC's [message #180175 is a reply to message #180097] |
Tue, 14 August 2012 06:23 |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
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Senior Member |
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Normally aspirated, it's gonna wheeze. Regardless of how the gas gets in, FI, stock carb, expresso carb ain't going to makwe much difference. The manifold absolute pressure will be near ambient at wide open throttle, and at 12K feet, ambient isn't nearly as high as at sea level. Less charge, less power. Low gear wil be Your Friend, but it ought to go over.
--johnny
'76 23' transmode norris
'76 palm beach
From: Mark <mark@habcycles.com>
To: gmclist@temp.gmcnet.org
Sent: Monday, August 13, 2012 1:30 PM
Subject: Re: [GMCnet] EFI for GMC's
Robert Mueller wrote on Sun, 12 August 2012 16:55
> -My stock quadrojet works just fine at 8,000 feet or Death Valley 200 feat below sea level. The performance droops of at higher elevations but any aspirated engine will suffer as the elevation increases.
Does anyone out there have any feedback on how I should expect my 403-powered Royale to do at slightly over 12,000 feet (Cottonwood Pass in central Colorado, with my destination at about 10,000 feet). I've got a Lamey-tuned Holley carb that has been flawless for the places I've driven it so far, though I don't think I got over about 3,000 feet of altitude so far. I just don't want to get to 11,900 feet and find out I can't crawl the rest of the way over Cottonwood Pass...
--
Mark Hickey
Mesa, AZ
1978 Royale Center Kitchen
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Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
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| Re: [GMCnet] EFI for GMC's [message #180178 is a reply to message #179957] |
Tue, 14 August 2012 07:43 |
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RF_Burns
Messages: 2277
Registered: June 2008
Location: S. Ontario, Canada
Karma: 3
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Senior Member |
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George,
I don't know that a modern engine would get that much better mileage.
I have 3 GM/Chev pickups (2005, 2010, 2011) and towing a single axle open trailer with a GVW of under 3,000lbs they all get about 19litres/100kms on the highway. That figures to about 12.5 miles per US gallon.
The 2010 & 2011 pickups are dog's to drive. They have 6 speed autos with DoD (Displacement on Demand, varies between 8 & 4 cylinders). On flat level ground @ 55mph cruise control it wants to shift to 4 cylinder mode and the tranny is in overdrive, engine at about 1300rpm. Of course the engine bogs, shifts to 8 cylinders and tranny downshifts to get to speed. Its a constant cycle. no power like having a mid 70's pickup with a 6 cylinder. I find myself switching to tow/haul mode.
The 2005 without that crap drives great and gets better mileage while carrying a 1000lbs of equipment and tools.
Bruce Hislop
ON Canada
77PB, 455 Dick P. rebuilt, DynamicEFI EBL EFI & ESC.
1 ton front end
http://www.gmcmhphotos.com/photos/showphoto.php?photo=29001
My Staff says I never listen to them, or something like that
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