gathermewool
Site Donor 2023
I too use a Scan Gauge. It shows 9999 MPG on my Ford Escort from about any speed until it's down to a specific RPM around 1100 RPM if I recall correctly.
Isn’t that field programmable?
I too use a Scan Gauge. It shows 9999 MPG on my Ford Escort from about any speed until it's down to a specific RPM around 1100 RPM if I recall correctly.
I think so.Isn’t that field programmable?
Or a 25,000 ton frieght train.Why should vehicle size relate to concern about fuel economy?
What really matters is how much the vehicle is used.
A cabbie driving a Prius might be as watchful of fuel use as one driving a 17 passenger van or a pilot flying a 100 ton jetliner.
Drove one of those as a work truck along the northern 1/3 of the Trans-Alaska Pipeline System (TAPS), maintaining the fiber-optic network along it. Put 20K miles on it along the same stretch of road the Ice Road Truckers did and liked it. The only thing I disliked was the front suspension didn't have enough travel -- I bottomed it out many many times on potholes along the Dalton Hwy, otherwise known as the "Haul Road" to the North Slope oil fields. Also drove F-350 and Chevy 2500 diesel trucks as needed. All were good trucks as they were properly outfitted and expertly maintained by fantastic mechanics at pump stations #1 and #5.Lady at church still drives that original Excursion diesel …
I can remember when it was full of Little League players.
Conditions and safety permitting, rpm @45-50% of red line is the most efficient engine speed to run at (or torque peak).
Drove one of those as a work truck along the northern 1/3 of the Trans-Alaska Pipeline System (TAPS), maintaining the fiber-optic network along it. Put 20K miles on it along the same stretch of road the Ice Road Truckers did and liked it. The only thing I disliked was the front suspension didn't have enough travel -- I bottomed it out many many times on potholes along the Dalton Hwy, otherwise known as the "Haul Road" to the North Slope oil fields. Also drove F-350 and Chevy 2500 diesel trucks as needed. All were good trucks as they were properly outfitted and expertly maintained by fantastic mechanics at pump stations #1 and #5.
Bar none, for a good living I drove and operated the most remote and loneliest stretch of road in North America. No services of any kind for 241 miles between Coldfoot, Alaska and Deadhorse, Alaska... no services, no lights, no fences, no sign that Man has ever been there except for the pipeline and a few related pump stations, associated remote gate valves and the gravel road highway. It was absolutely a vast and beautiful sub-arctic and arctic wilderness full of mountains, tundra and animals.
Note that as a Alyeska pipeline contractor, I had access to services at every Alyeska pump station positioned about every 60 to 70 miles along the pipeline. Fueled up and ate like a king at those along the way. Your average civilian didn't have any access to those.
Every fluid used in North Slope-related vehicles sports cold-rated synthetic oils, greases, and other fluids. They are typically changed ahead of the severe schedule. My driven trucks had fluids changed once a month! One cannot afford a mechanical breakdown in such an austere and severe environment.I had to look up Deadhorse Alaska as I thought it was in the Yukon. That would be Whitehorse.
My iPhone says it is -22F in Deadhorse. Time for 0wxx
That depends on how much output (power / torque) you need from the engine. At full throttle, peak torque is the RPM having maximum BMEP, but that is not the same thing as minimum BSFC (peak efficiency), which varies depending on load or power output. On most gasoline engines, peak torque RPM is not the most efficient for low power cruise. Peak torque RPM can be pretty high (like 4,000 RPM in my Mazda). I can guarantee you that cruising down the freeway at 4,000 RPM in my Mazda means being in 4th gear where it gets much worse fuel economy than in 6th gear.Conditions and safety permitting, rpm @45-50% of red line is the most efficient engine speed to run at (or torque peak).
Thanks. Interesting. That BMEP is the point where fuel efficiency is greatest per horsepower and is independent of wide open throttle position?That depends on how much output (power / torque) you need from the engine. At full throttle, peak torque is the RPM having maximum BMEP, but that is not the same thing as minimum BSFC (peak efficiency), which varies depending on load or power output. On most gasoline engines, peak torque RPM is not the most efficient for low power cruise. Peak torque RPM can be pretty high (like 4,000 RPM in my Mazda). I can guarantee you that cruising down the freeway at 4,000 RPM in my Mazda means being in 4th gear where it gets much worse fuel economy than in 6th gear.
Part of what you say is correct: the RPM at which the engine achieves max efficiency is near peak torque at wide open throttle. But that's more power than you need. To cruise at 60 mph you need to dial back the power. There are 2 ways you can do that:
1. Keep the engine at peak torque RPM and dial back the throttle.
2. Use a taller gear to reduce RPM and keep the throttle open.
When the amount of power you need is less than what the engine can deliver, method (2) is a more efficient way to reduce power. That's why cars have tall overdrive gears for freeway driving. And why CVTs in "normal/economy" mode keep the engine at revs far below peak torque.
I think I did the opposite - Durango Richmond to Charlottesville.“Also on moderate hills, if you can keep the pedal steady and bleed off some speed to reach the top, this saves quite a bit compared to maintaining your speed exactly.”
Years ago I kept the cruise control on while on the highway thinking it would give me the best MPG. Wrong. It’s OK for straight and level. I found that slowing loosing some speed going up a grade then slowing getting back up to speed on the downhill side gave better fuel economy in hilly areas.
Yeah, that's how I interpreted what you said....I spoke of max efficiency regardless of what is needed or appropriate -no preconditions. Just max efficiency. Period
Ay, there's the rub. It's not independent, it is very dependent. Peak efficiency, or minimum BSFC, depends on load or power output. If the engine produces 100 HP at its peak torque RPM at full throttle, then this is the most efficient combination of RPM and throttle that produces 100 HP, which is minimum BSFC for 100 HP. But if all you need is 30 HP, it is most efficiently produced at a much lower RPM.Interesting. That BMEP is the point where fuel efficiency is greatest per horsepower and is independent of wide open throttle position?
Thanks for the link. Interesting read. Much better than "what is the best oil" or "I'm tearing my hair out: 5-30 or 10-30" LOLYeah, that's how I interpreted what you said.
Ay, there's the rub. It's not independent, it is very dependent. Peak efficiency, or minimum BSFC, depends on load or power output. If the engine produces 100 HP at its peak torque RPM at full throttle, then this is the most efficient combination of RPM and throttle that produces 100 HP, which is minimum BSFC for 100 HP. But if all you need is 30 HP, it is most efficiently produced at a much lower RPM.
A constant power curve can be useful for illustrating this, as discussed here.
RIP, Joy.Every fluid used in North Slope-related vehicles sports cold-rated synthetic oils, greases, and other fluids. They are typically changed ahead of the severe schedule. My driven trucks had fluids changed once a month! One cannot afford a mechanical breakdown in such an austere and severe environment.
Here's an example of a competitor's (AT&T) diesel Excursion on the North Slope. Note the woman pictured was killed in a rollover accident on the Slope. She was known as a careful driver and was missed within the Slope work community.
View attachment 50268
This summertime picture was taken at a pulloff in the Brooks Range.
That is a dead link and google search found nothing. Do you have an accessible source ?Thanks for the link. Interesting read. Much better than "what is the best oil" or "I'm tearing my hair out: 5-30 or 10-30" LOL
Thanks. Interesting. That BMEP is the point where fuel efficiency is greatest per horsepower and is independent of wide open throttle position?
You are correct but I spoke of max efficiency regardless of what is needed or appropriate -no preconditions. Just max efficiency. Period.
Fuel economy is calculated by distance traveled / fuel consumed. Driving a vehicle less will simply accumulate fewer miles on that vehicle, and does not necessarily change the vehicle's calculated fuel economy. In fact, letting the vehicle sit with fuel in the tank is likely to cause increased evaporative emissions and actually reduce the fuel economy. But I appreciate the attempt at humor.The best way to get the most fuel economy out of any vehicle is to drive it less. Use public transportation, car pooling, hitchhiking, ride a bicycle, or stay home because you're working remotely anyway.