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Old 03-20-2013, 09:46 PM   #1 (permalink)
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Case Study: 45% above EPA?

A friend of mine is skeptical of the influence my hypermiling techniques have on my gas mileage, and stated that he wouldn't believe it worked unless I could achieve 26 MPG (45% above EPA) on a tank. I thought, challenge accepted! My problem? So far I can't get better than 22.5 MPG on any one tank (25% above EPA), and I'm out of ideas on how to improve. Here's the situation:

My car is a 2000 Lincoln LS 3.0L V6 Auto Transmission, 213k on the odometer.
EPA: 16 city, 18 combined, 23 Highway.

What I've done:
Tires to 50 PSI
Folded in passenger-side mirror
I don't want to do any extensive ecomods because I plan to sell the car in a few months (when I finish rebuilding my mustang). Any other cheap, easy, reversible ecomods I can do?
50-55 highway speeds, steady speed
minimize brake use in city, timing lights, engine braking when appropriate (e.g. when engine is cold)
Goal to stay in bottom of top gear as much as possible.
coast in neutral whenever I can do so for more than 15 seconds ( my tranny does high rev's when re-engaging to drive mode, and when in neutral, rpm gauge often shows higher rpms than when in drive at the same speed. I think it's to keep the tranny pump at the right speed. Anyway, point is I don't often go into neutral).
Neutral at lights. (I used to turn off the engine, but then once when I did so the electrical system failed and I couldn't restart the engine. After bugging a few dozen cars, I got mine to the side of the road and fiddled with it until it started working. I'm not turning my car off at lights after that)
Low RPM's, try to stay below 2500 at all times.

On a side note, I tested P&G with 75% throttle with 1500-2000 RPM from 50 to 60, then coast to 50, on several tanks, then steady speed on the same routes on several tanks, and I always got 20.5-21 MPG with P&G, and 21.5-22 with steady speed. Perhaps the car is old enough that compression losses at high throttle decrease efficiency. And I can't EOC because of the Auto Tranny.

Do you think it's possible for me to get 26 in combined driving with this car? Is there anything I'm missing that I could do?

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Old 03-20-2013, 09:48 PM   #2 (permalink)
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tell your friend that 25% is a highly significant difference and is quite impressive for an automatic.
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Old 03-21-2013, 12:05 AM   #3 (permalink)
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I suggest you accelerate slower and keep the load on the engine low; If you have a ScanGauge II or other on-board gauge this is easier/quicker to learn. Try to keep the load under 20, 15-20 at the highest (Though YMMV depending on the vehicle, I'm basing this on the Caravan I drive.) You may also attach pizza pans to the hubcaps though they might start rusting quickly if not painted. Also, 50 PSI may or may not be the most fuel-efficient tire PSI for your car; It may be best to test the FC for various tire pressures.

Edit/Update: Find what works for you and your car and locality while staying safe.

Last edited by 101Volts; 08-14-2013 at 08:22 PM..
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Old 03-21-2013, 01:32 AM   #4 (permalink)
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Quote:
Originally Posted by 101Volts View Post
I suggest you accelerate slower and keep the load on the engine low; If you have a ScanGauge II or other on-board gauge this is easier/quicker to learn. Try to keep the load under 20, 15-20 at the highest (Though YMMV depending on the vehicle, I'm basing this on the Caravan I drive.)
Actually, most BSFC maps suggest that IC engines are most efficient around 80% load, with rpms around max torque.
The BSFC chart thread
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Old 03-21-2013, 05:49 AM   #5 (permalink)
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Quote:
Originally Posted by Piwoslaw View Post
Actually, most BSFC maps suggest that IC engines are most efficient around 80% load, with rpms around max torque.
The BSFC chart thread
I've been able to test that. My average consumption on the flat at 75 km/h is 3,05 l/100. On a 2,5% average slope, at the same speed, the consumption didn't exceed 3,50 l/100 (5th gear, 1900 rpm, throttle pressed at about 75%). After calculating the power needed in both cases, the engine efficiency is 21% on the flat and 35% on that slope.
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Old 03-21-2013, 07:49 AM   #6 (permalink)
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This might be cheating but... maybe see if you can find a more efficient route. Without a manual and DFCO going up and down hills in an auto wastes a lot of fuel....
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Old 03-21-2013, 08:37 AM   #7 (permalink)
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Quote:
Originally Posted by Piwoslaw View Post
Actually, most BSFC maps suggest that IC engines are most efficient around 80% load, with rpms around max torque.
The BSFC chart thread
I was speaking from my experience, I did manage some decent FE by keeping low but perhaps it can be improved yet. I haven't tried using the engine at its most efficient load (Though I exceeded it,) Thanks.

Austin

Last edited by 101Volts; 03-21-2013 at 08:43 AM..
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Old 03-21-2013, 09:18 AM   #8 (permalink)
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Quote:
Originally Posted by 101Volts View Post
I was speaking from my experience, I did manage some decent FE by keeping low but perhaps it can be improved yet. I haven't tried using the engine at its most efficient load (Though I exceeded it,) Thanks.

Austin
In my experience older autos seems to do better if you apply enough throttle for brisk acceleration then let off at the appropriate speed to lock up the converter then keeping a steady throttle to keep the converter locked. So what you say is correct.
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Old 03-21-2013, 04:46 PM   #9 (permalink)
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Quote:
Originally Posted by razor02097 View Post
In my experience older autos seems to do better if you apply enough throttle for brisk acceleration then let off at the appropriate speed to lock up the converter then keeping a steady throttle to keep the converter locked. So what you say is correct.
I need to be more specific, I meant that I've tried accelerating very slowly to the speed limit or just under it (Which worked pretty well in some cases, IMO but perhaps that's due to not P&Ging most efficiently yet) and that I've also tried mashing the pedal to the floor to try P&Ging. But, I don't always do the latter one and I certainly exceeded the best operating engine load when mashing the pedal; I haven't yet learned a more fuel-effieient P&G method. Thanks for mentioning that about the converters in older cars, Though.

Was I straying off-topic?

EDIT:

When I was accelerating I was scarcely holding the pedal down. The HPR gauge would read at 6-7ish or so when I wasn't holding the pedal down and I only pressed it down enough to go to about 8 HPR and that would not exceed 20 on the TPS (Throttle Position Sensor). When the throttle isn't held down at all it's at 16.

- Austin

Last edited by 101Volts; 09-18-2013 at 09:30 PM..
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Old 03-21-2013, 05:45 PM   #10 (permalink)
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If your route has areas where you'll be driving at 50 mph or so, grille blocking would probably help. Every time I've tried it, there's been a significant improvement (like 2 mpg). Definitely get a ScanGauge, or something that shows you what kind of results your getting from your different ideas you try.

When I tried to P&G or hold a good BSFC load going up a hill in my Jimmy with auto trans, I couldn't do it - mashing the throttle enough to get the engine load up there would always cause it to downshift & also shoot up right past my best fuel economy speed. So I found that just trying to hold it at best fuel economy speed did the best.

And 50 mph might be too high for your car. I was assuming it would be around 50 mph for my Jimmy - that lower speeds might be "lugging" it. But nope, turns out 40 mph was actually the best speed. (and I checked it a couple times to make sure). Too slow for the freeway (I tried it & got honked at a lot ), so then I found NON-freeway routes where the speed limit was closer to 40. With the ScanGauge, I found that coasting up to stops from half a block away in neutral really boosted the average mpg, too. It was weird getting used to acceleraing off a green light & then throwing it into neutral and coasting before even getting up to the speed limit, but if you see the light 3/4 of a block ahead turn yellow, that's what you do - and it works!!!

But do a grille block - that should help a lot.

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