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Old 03-02-2007, 07:12 AM   #11
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Or it could be just that you hit everything just right. Try the technique a few more times and see what happens. I have 2-3 MPG changes on my commute just by hitting one light wrong or traffic. Ric might be right about the torque.
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Old 03-02-2007, 03:40 PM   #12
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Going from the top

Toecutter,
I wish I had the fuel map for my engine. Would give a better idea of where it is happy compared to guessing.

Peakster,
That was my understanding as well. Usually when getting on the highway I use about a quarter throttle, 2k shifts and take a mile or two to get it up to 65. My instantaneous reads around 18-20 that way, so I figured that was better. Where as flooring it was consuming around 6.5 GPH MPG was ~ 7-9 instantaneous.

omgwtfbyobbq
My engines output is similar to the 1MZ-FE though I hit peak torque at 3k vs 4.4k so it makes sense 2-3k at 2/3s throttle

caprice,
I'm thinking that I'm consuming more energy over time accelerating slowly rather than blowing a lot of energy over a short period. I was at a cruising speed of 65 by the end of the on ramp which was a a little less then a quarter mile.

cfg83,
It could be that. During the acceleration portions of the trip back I was in the 3-4k range, while passing the trucks I was around 2250-2500 rpm

rh77
Pedal to the floor, open loop acceleration initially. Backed off once I reached 65, jumped to about 40-50% throttle on the sprints. The Jeep goes into open loop under any bit of acceleration. Since it was ignoring my O2s for a while, maybe one of them are on their way out. Which would suck royally.

So end result I'm going to do this for the remainder of the tank and see what happens. Though factoring in a trip I took earlier in the year in which I did 70 over mountainous terrain and averages 20 something MPG, it seems like rather than gearing down my cruising RPM, gearing it up could help. And driving like a bat out of hell on on ramps.
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Old 03-02-2007, 04:24 PM   #13
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If you hit peak torque earlier your peak BSFC may be from 1-2k rpm at high load, so flooring it and shifting at ~3k rpm is definitely what you should do from stops, like a bat outa hell. Gearing up will never help your cruising mileage... Occasionally there are engines that will see the same or better mileage at higher speeds, but that has more to do with vehicle design compared to the BSFC maps. With efficiency, lower gearing is always better for gasoline engines imle, at least for mass produced autos.
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I think if i could get that type of FE i would have no problem driving a dildo shaped car.
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Old 03-02-2007, 04:29 PM   #14
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Remember accelerating hard at 2-3k rpm is generating about 25% of the peak engine output so it is not really accelerating at full power. Less revolutions of the engine results in less losses per distance traveled so the quicker you get up to top gear the better without over reving the engine. And as can be seen in the graph operating below 1500rpm is pretty poor so lugging it is not good.
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Old 03-02-2007, 06:04 PM   #15
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Quote:
Originally Posted by JanGeo View Post
Remember accelerating hard at 2-3k rpm is generating about 25% of the peak engine output so it is not really accelerating at full power. Less revolutions of the engine results in less losses per distance traveled so the quicker you get up to top gear the better without over reving the engine. And as can be seen in the graph operating below 1500rpm is pretty poor so lugging it is not good.
But turning over 1.2-1.5k during city cruising (35mph) can net 25-30 MPG, keeping the Jeep inside its 2-3k range only generates around 18-20 MPG
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Old 03-02-2007, 06:34 PM   #16
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From my experience with our F150, for steady cruise speeds, assuming no P&G, the lower the rpm, the better. Acceleration however seems most efficient at about 1/2 throttle. Any less than that seems to impose a time penalty before minimum cruise rpms can be attained.

Experiments with 1/2 throttle P&G net us about 2 mpg more than the egg-under-foot technique in 35-40mpg zones.
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Old 03-02-2007, 07:04 PM   #17
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Welcome to the board Snax, its great to see another truck

Is your F-150 an auto or manual?
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Old 03-02-2007, 07:38 PM   #18
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Quote:
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But turning over 1.2-1.5k during city cruising (35mph) can net 25-30 MPG, keeping the Jeep inside its 2-3k range only generates around 18-20 MPG
Ahh but that puts you back into the higher rpm lower throttle position which is on the graph. It only matters to get the most power per kg of gas when accelerating and need the power. After that you want the lowest RPM possible - the only way to improve FE is to get the engine into the heavier load range giving the most torque per kg of gas for that speed with a change in gearing. The problem is you probably have more power at the most efficient load at 35mph than you need to maintain that speed - now you get into the pulse and glide operating mode - pulse at peak efficiency and then glide in neutral. You would do better climbing a hill and then coasting down the other side. The way to figure it out is to know the torque to maintain the 35mph speed and then plot that line on the engine graph to intersect the most efficient load - rpm curve to calculate the gearing needed.
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Old 03-03-2007, 12:46 PM   #19
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Back when I first got my HCH and began learning how to drive more efficiently the only "real" hybrid or hypermiling website was Insight Central. They suggested WOT as the most efficient way to accelerate due to the effects of pumping losses. Their theory and explanations were quite convincing.

I used that advice and took an afternoon to test it out in my new car. Under identical conditions I ran my car 5 tests each for WOT, moderate and extremely slow acceleration.
In all cases the slowest, but constant acceleration was more efficent- and in all runs WOT burned roughly twice the amount of fuel vs slowest.
Considering the kind of car I drive, I also have to consider that my electric assist is weakest and intermittant for light acceleration, while the electric boost is at 100% WOT.

The tests that afternoon convinced me that slowest is more efficient: and I've had great results over my last 89,000 miles.
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Old 03-03-2007, 04:13 PM   #20
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Quote:
Originally Posted by Snax View Post
From my experience with our F150, for steady cruise speeds, assuming no P&G, the lower the rpm, the better. Acceleration however seems most efficient at about 1/2 throttle. Any less than that seems to impose a time penalty before minimum cruise rpms can be attained.

Experiments with 1/2 throttle P&G net us about 2 mpg more than the egg-under-foot technique in 35-40mpg zones.

I was wondering what year your F-150 is, does she have the 5.0 liter engine? I know with my 5.0, I get the same gas mileage through almost all speeds on my only long trip I've taken since installing my tripminder. I don't see why my engine would be doing this? unlses it has to do with EGR only kicking in at certain rpms? It was excpetionally stormy and windy when i got these numbers, but just curuios how yours compare.

MPH MPG
30 25-35
45 20-27
55 17-20
65 18-21
70 20-22
75 18-21
85 14-17
+85 14-16
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