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| [GMCnet] Gas Mileage ??? [message #259798] |
Fri, 22 August 2014 21:27  |
Arthur Mansfield
Messages: 290
Registered: April 2010
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I just completed a ~2000 mile trip. I tow a Geo Tracker. I got ~7.5 mpg. I change the jets in my Q-Jet since I always ran hot. The power is much better and I run normal temperatures now (180 to 190). Before I changed the carb I had to run the fan in direct drive to keep it from over heating (220+). I guess my question is will fuel injection improve my gas mileage. The other side of the question is will a computer controlled disturbed also help gas mileage. I know this subject has been discussed before but I do not know what to do.
Art & Doris
76 EL
Decatur AL
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| Re: [GMCnet] Gas Mileage ??? [message #259800 is a reply to message #259798] |
Fri, 22 August 2014 21:40  |
jknezek
Messages: 1057
Registered: December 2007
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7.5 towing isn't bad at all. You seem very much in the normal range. You will never realize enough fuel savings from going to fuel injection to cover the project costs. When this topic has come up before those who have switched to efi reported no or almost no measurable gains in fuel economy. There might be some special cases related to altitude where you might see marginal gains.
Thanks,
Jeremy Knezek
1976 Glenbrook
Birmingham, AL
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| Re: [GMCnet] Gas Mileage ??? [message #259805 is a reply to message #259801] |
Sat, 23 August 2014 07:05 |
Ray Erspamer
Messages: 1707
Registered: May 2007
Location: Milwaukee Wisconsin
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What jets did you change and why would this affect running
temperature? Just curious here.
On Fri, Aug 22, 2014 at 10:15 PM, Dan Gregg wrote:
> Art, I have towed 3000 pounds running a Holley Pro Jection fuel injection system for 10 years. I get about the same mileage that you report with carb.
> I have never had any kind of heat problems though and run the aluminum radiator.
> Dan
> Spent a good bit of time hanging out in Decatur with a girl before Teri came along.
> --
> 3 In Stainless Exhaust Headers
> One Ton All Discs/Reaction Arm
> 355 FD/Quad Bag/Alum Radiator Manny Tran/New eng.
> Holley EFI/10 Tire Air Monitoring System
> Solarized Coach/Upgraded Windows
> Satelite TV/On Demand Hot Water/3Way Refer
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Ray Erspamer
78 Royale - "The Great Lakes Eagle"
Center Kitchen TZE368V101144
Wauwatosa, Wisconsin 53226
Email: 78GMCRoyale@gmail.com
414-484-9431
Web Site: http://ray-lisa.page.tl/
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Ray Erspamer
78 GMC Royale Center Kitchen
403, 3.70 Final Drive
Holley Sniper Quadrajet EFI System,
Holley Hyperspark Ignition System
414-484-9431
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| Re: [GMCnet] Gas Mileage ??? [message #259835 is a reply to message #259805] |
Sat, 23 August 2014 15:13 |
Keith V
Messages: 2337
Registered: March 2008
Location: Mounds View,MN
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I second the question on jets.
I run a wide band O2 and an egt
I run 67 jets at get about 15:1
after I put in the 3:70 gears the mix got fatter at cruise ( ~14.4:1), may try 66 jets
If you are running hot you have cooling issues you shouldn't need a fan on the highway...
Keith Vasilakes
Mounds View. MN
75 ex Royale GMC
ask me about MicroLevel
Cell, 763-732-3419
My427v8@hotmail.com
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| Re: [GMCnet] Gas Mileage ??? [message #259880 is a reply to message #259798] |
Sun, 24 August 2014 03:26 |
George Beckman
Messages: 1085
Registered: October 2008
Location: Colfax, CA
Karma: 11
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Arthur Mansfield wrote on Fri, 22 August 2014 19:27I just completed a ~2000 mile trip. I tow a Geo Tracker. I got ~7.5 mpg. I change the jets in my Q-Jet since I always ran hot. The power is much better and I run normal temperatures now (180 to 190). Before I changed the carb I had to run the fan in direct drive to keep it from over heating (220+). I guess my question is will fuel injection improve my gas mileage. The other side of the question is will a computer controlled disturbed also help gas mileage. I know this subject has been discussed before but I do not know what to do.
Art & Doris
76 EL
Decatur AL
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There may be no perfect answer. However, Randy Van Winkle and I did some pretty extensive tests. We both have EBL Throttle Body fuel injection. EBL lets you see and instant and elapsed mpg and easily change mixtures and spark.
We laid out a run that was hopefully 1) level and 2 a two way run, meaning we went East and then West. We never shut of the engine during a set of runs. We used the cruise control (Delphi Electromotor) to try and make each run equal. (62 mph)
We had two goals: 1) what gas mixture gave the best MPG and 2) what spark gave the best MPG.
After one morning of runs, we decided the air to fuel ratio was not getting us much results. Now, please underdstand the EFI was keeping things pretty even. We were running in Lean Cruise which means the computer was leaning the mixture from 14.7:1 to 16.4:1, 16.4 was what the internet said was best for MPG and we soon thought that was good enough. I now push the mid 17s to one.
Lean burns take longer to ignite so modern vehicles advance the spark when they lean the mixture. EBL is not modern but is good solid Mid 90's technology. Some features are more modern.
We learned that spark makes a big difference. in MPG. If the carb or EFI is doing around 14:1 spark must stay around 38 or 39 degrees advanced but during the lean runs we found the 455 taking around 50 degrees. Randy's 403 handles 52 advance. We also saw an oddity in that around 38 did worse than 36 or 42.
The 403 is running 370 gears. My coach at the time had a stock Final Drive.
I could never get the MPG Randy got. Later that year I had the engine rebuilt due to valve train failure.
Randy can get mid 9s mpg towing. He can get mid 10s not towing. On a 5200 mile trip I did speedo correction and pumped gas and averaged 10.7 for the trip. For almost comical reasons I had ended up with at 2.73 FD and did not tow. (Yes, that is right.) The coach lugged terribly and developed transmission problems. I got rid of that FD and now have a 3.21. Never got close to 10.7 since, but the the coach is much more driveable.
Both Randy and I installed Exhaust Gas Temperature gauges. Lean cruise does not cause cylinder heat. 14.7 (normal) can cause a 150 degree rise in 30 seconds It is very, very important that carb and efi users do NOT delay the power valve or Power Enrichment. An engine could be brought to catastrophic temperatures in 30 seconds at less than 1/2 throttle. (Yes 14.7 the perfect burn can raise temps 150 degrees in 30 seconds on a slight slight grade.) The Power valve or Power Enrichment in EFI needs to bring the mixture to at least 12.8.
Randy took the tests a bit further, trying at 45, 55, 65, 75 mph. You want good mileage.... slow down. I have found I can get about the same mileage towing a Geo Metro at 58 mpg as I ca driving 65 and not towing. Most MPG is lost pushing a big hunk of air out of the way.
SO EFI can help. A well tuned Q-Jet does a really nice job. Fiddling with Power Enrichment on EFI or jets and springs on a Q-Jet, without checking exhaust temperature results could be a very expensive game.
EFI that knows what fuel and spark are doing can get the most benefit out of spark advance.Will you every pay for EFI in gas savings. At the current prices, you better 1) drive lots of miles and 2) be fairly young. If gas goes to $8 like many countries, then you may see more payoff.
Fiddle with this jets or EFI settings too much, then don't whine if you loose valves or melt pistons. There was never, never a 120 mpg carburetor. Chevron did not buy it. Anything above about 19:1 air fuel and you cannot get a spark plug to light the mixture. It wont fire. New engines that can get richer mixture near the plug an leaner in the rest of the cylinder do pretty well. No matter what, we still have to lug 11K+ pounds and push a big square of air.
Do I like EFI? Sure. No run on at key off, Starts good in the mountains and every place else.Lean Cruise engaging increases MPG by one (1) every time. Trouble is, Power Enrichment on hills decreases MPG by about six mpg.
'74 Eleganza, SE, Howell + EBL
Best Wishes,
George
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| Re: [GMCnet] Gas Mileage ??? [message #259939 is a reply to message #259880] |
Sun, 24 August 2014 16:08 |
Arthur Mansfield
Messages: 290
Registered: April 2010
Karma: 0
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Senior Member |
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Thanks for the info. I do not have a way to check the exhaust. I went to larger jets because of having trouble with over heating. I also reduced the power valve spring to the weakest spring. I drive at 65 GPS speed. My speedometer reads just over 60. Radar agreed with the GPS. I started looking into the fuel injection when I changed the jets and got 5 mpg on the first trip. Before this trip the engine quit and when I opened the hatch I found the top of the engine full of gas. I changed out the float valve. Then my gas milage was 7.5 over about 2000 miles without correcting the mileage.
As to best milage I got was when my carb filter plugged up. I could get to 45 and run easy. I did not realize at the time the carb had the small filter. I get over 12mpg during that time. Running slow and running easy sure helps the gas milage. I know it is hard to check milage on one tank but I average between 8 and 7 for each fill up during my NY trip. So if you take your time you can get fairly good refills each time. I do need to fix my vent since it does not work.
Will the over all engine performance be improved if I go to fuel injection. The performance greatly improved when I changed the jets. Before I changed the jets I had seen engine temperature go over 230F while climbing hills. No my trip from Decatur AL to Oswego NY going western route and eastern route I never got over 200F even on the long climbs while running the Q jet wide open at times.
I guess I need to have an oxygen sensor installed in my exhaust. Getting a read out to see what my mixture is. I do not know what would be a good read out to purchase.
Thanks again George.
Art & Doris
76 El
Decatur AL
On Aug 24, 2014, at 3:29 AM, George Beckman wrote:
> Arthur Mansfield wrote on Fri, 22 August 2014 19:27
>> I just completed a ~2000 mile trip. I tow a Geo Tracker. I got ~7.5 mpg. I change the jets in my Q-Jet since I always ran hot. The power is
>> much better and I run normal temperatures now (180 to 190). Before I changed the carb I had to run the fan in direct drive to keep it from over
>> heating (220+). I guess my question is will fuel injection improve my gas mileage. The other side of the question is will a computer controlled
>> disturbed also help gas mileage. I know this subject has been discussed before but I do not know what to do.
>>
>> Art & Doris
>> 76 EL
>> Decatur AL
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
>
> There may be no perfect answer. However, Randy Van Winkle and I did some pretty extensive tests. We both have EBL Throttle Body fuel injection. EBL
> lets you see and instant and elapsed mpg and easily change mixtures and spark.
>
> We laid out a run that was hopefully 1) level and 2 a two way run, meaning we went East and then West. We never shut of the engine during a set of
> runs. We used the cruise control (Delphi Electromotor) to try and make each run equal. (62 mph)
>
> We had two goals: 1) what gas mixture gave the best MPG and 2) what spark gave the best MPG.
>
> After one morning of runs, we decided the air to fuel ratio was not getting us much results. Now, please underdstand the EFI was keeping things pretty
> even. We were running in Lean Cruise which means the computer was leaning the mixture from 14.7:1 to 16.4:1, 16.4 was what the internet said was best
> for MPG and we soon thought that was good enough. I now push the mid 17s to one.
>
> Lean burns take longer to ignite so modern vehicles advance the spark when they lean the mixture. EBL is not modern but is good solid Mid 90's
> technology. Some features are more modern.
>
> We learned that spark makes a big difference. in MPG. If the carb or EFI is doing around 14:1 spark must stay around 38 or 39 degrees advanced but
> during the lean runs we found the 455 taking around 50 degrees. Randy's 403 handles 52 advance. We also saw an oddity in that around 38 did worse than
> 36 or 42.
>
> The 403 is running 370 gears. My coach at the time had a stock Final Drive.
>
> I could never get the MPG Randy got. Later that year I had the engine rebuilt due to valve train failure.
>
> Randy can get mid 9s mpg towing. He can get mid 10s not towing. On a 5200 mile trip I did speedo correction and pumped gas and averaged 10.7 for the
> trip. For almost comical reasons I had ended up with at 2.73 FD and did not tow. (Yes, that is right.) The coach lugged terribly and developed
> transmission problems. I got rid of that FD and now have a 3.21. Never got close to 10.7 since, but the the coach is much more driveable.
>
> Both Randy and I installed Exhaust Gas Temperature gauges. Lean cruise does not cause cylinder heat. 14.7 (normal) can cause a 150 degree rise in 30
> seconds It is very, very important that carb and efi users do NOT delay the power valve or Power Enrichment. An engine could be brought to
> catastrophic temperatures in 30 seconds at less than 1/2 throttle. (Yes 14.7 the perfect burn can raise temps 150 degrees in 30 seconds on a slight
> slight grade.) The Power valve or Power Enrichment in EFI needs to bring the mixture to at least 12.8.
>
> Randy took the tests a bit further, trying at 45, 55, 65, 75 mph. You want good mileage.... slow down. I have found I can get about the same mileage
> towing a Geo Metro at 58 mpg as I ca driving 65 and not towing. Most MPG is lost pushing a big hunk of air out of the way.
>
> SO EFI can help. A well tuned Q-Jet does a really nice job. Fiddling with Power Enrichment on EFI or jets and springs on a Q-Jet, without checking
> exhaust temperature results could be a very expensive game.
>
> EFI that knows what fuel and spark are doing can get the most benefit out of spark advance.Will you every pay for EFI in gas savings. At the current
> prices, you better 1) drive lots of miles and 2) be fairly young. If gas goes to $8 like many countries, then you may see more payoff.
>
> Fiddle with this jets or EFI settings too much, then don't whine if you loose valves or melt pistons. There was never, never a 120 mpg carburetor.
> Chevron did not buy it. Anything above about 19:1 air fuel and you cannot get a spark plug to light the mixture. It wont fire. New engines that can
> get richer mixture near the plug an leaner in the rest of the cylinder do pretty well. No matter what, we still have to lug 11K+ pounds and push a
> big square of air.
>
> Do I like EFI? Sure. No run on at key off, Starts good in the mountains and every place else.Lean Cruise engaging increases MPG by one (1) every time.
> Trouble is, Power Enrichment on hills decreases MPG by about six mpg.
> --
> '74 Eleganza, SE, Howell + EBL
> Best Wishes,
> George
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
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| Re: [GMCnet] Gas Mileage ??? [message #260063 is a reply to message #259939] |
Mon, 25 August 2014 18:49 |
George Beckman
Messages: 1085
Registered: October 2008
Location: Colfax, CA
Karma: 11
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Senior Member |
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Arthur Mansfield wrote on Sun, 24 August 2014 14:08Thanks for the info. I do not have a way to check the exhaust. I went to larger jets because of having trouble with over heating. I also reduced the power valve spring to the weakest spring.
Will the over all engine performance be improved if I go to fuel injection. The performance greatly improved when I changed the jets. Before I changed the jets I had seen engine temperature go over 230F while climbing hills. No my trip from Decatur AL to Oswego NY going western route and eastern route I never got over 200F even on the long climbs while running the Q jet wide open at times.
I guess I need to have an oxygen sensor installed in my exhaust. Getting a read out to see what my mixture is. I do not know what would be a good read out to purchase.
Thanks again George.
Art & Doris
76 El
Decatur AL
Art,
Measuring exhaust gas temperature (EGT) can be a frustrating and expensive endeavor and I am not sure it is for everyone. Ken Henderson has been working with new EGT gauges and sensors and it has not been the easiest of projects for him. My setup was more than I wanted to spend, but I got them because anytime we mentioned Lean Cruise or any EFI tuning we heard over and over we were going to burn up pistons and valves.
So I try to pass on what I "think" we learned. 1) when cruising, leaning the mixture cools the exhaust. Makes sense, more air, less fire. 2) a regular (not enriched) mixture will produce quick excessive heat in seconds and 3) Rich mixture will keep EGT from getting hotter but don't necessarily do much to lower existing temperatures. So you don't want to have the power valve engaging late.
While Wide Bands are also pricy, I believe mine saved the day. WHen your gas filter was plugged you would have been helped in your diagnosis. One time in Utah on 80, I was starting up a grade. The EBL has a red bar that appears across the bottom of the trip screen showing Power Enrichment. Out of the corner of my eye I say it flash on. I also noticed that the engine seemed flat and powerless. I gave it more throttle and it was like stepping on a grapefruit.
I decided it was time to look at the Wide Band because I was loosing speed. A glance there showed 19:1. Power Enrichment should be at least 12.8. As you did, I thought filter, as I pulled over. I heard an odd noise and left it idling as I walked back to the kitchen. I could hear the electric fuel pump grinding as if it had rocks in the gas. End of diagnosis. I swapped it out and all was well. (I always have a spare ignition module, fuel pump and filter. They are light.)
I know you want to ask, "What did the EGT gauges say?" All happened so quickly I didn't think to look. I was making sure that if it stopped, I was not in the middle of the road. When I saw I had no fuel mixture I let off right away. Pushing them when they are flat because of the lack of fuel could be a very bad thing.
My Wide Band is an Innovate. It has worked since 2008. I think, because I have EBL fuel injection I would probably buy one of BobR's. Most use a standard Bosch sensor. Bob's EBL site is dynamicefi.com I don't have a gauge any more as this all appears on the Whats Up Display. I did have a digital and frankly O2 in the exhaust jumps around so fast it was actually hard to read sometime. Perhaps a damped needle gauge would be easier. Maybe the Q-Jet doesn't jump as much as the computer that keeps adjusting several times a second. I think that part of the jumpiness also has to do with trying to light a fire with a momentary spark... all explosions are not created equal. (Maybe the Model T trembler coils were not such a bad idea... first MSD ignition. Ha)
'74 Eleganza, SE, Howell + EBL
Best Wishes,
George
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