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Old 08-17-2008, 04:46 PM   #11 (permalink)
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Originally Posted by bgd73 View Post
torque is the work . non-japanese inline four bangers find it naturally.
I made a funny. anybody get it?

your foot finds it for your car: the slowest rpm to get what you want. Screaming weirdos enignes don't understand and called it moderate to heavy acceleration...

a big diesel at 40 tons loaded is getting 224 mtpg (mile tons per gallon) all while never seeing much more than 2k rpm. The ultimate workers has no concept of this "perfect throttle".It is never a concern. all else who ask have pansy driveline. "Statistics" you seek will only reveal the most common driveline. Most likely that dumbo inline four cylinder...and those are in the moderate to heavy acceleration to get a thing called torque doing the work...
the concept of hypermiler would not exist if we had real engines....

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Old 08-18-2008, 07:30 AM   #12 (permalink)
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Quote:
Originally Posted by bgd73 View Post
torque is the work . non-japanese inline four bangers find it naturally.
I made a funny. anybody get it?

your foot finds it for your car: the slowest rpm to get what you want. Screaming weirdos enignes don't understand and called it moderate to heavy acceleration...

a big diesel at 40 tons loaded is getting 224 mtpg (mile tons per gallon) all while never seeing much more than 2k rpm. The ultimate workers has no concept of this "perfect throttle".It is never a concern. all else who ask have pansy driveline. "Statistics" you seek will only reveal the most common driveline. Most likely that dumbo inline four cylinder...and those are in the moderate to heavy acceleration to get a thing called torque doing the work...
the concept of hypermiler would not exist if we had real engines....
"Glorious sunset of my heart was fading. Soon the super karate monkey death car would park in my space. But Jimmy has fancy plans... and pants to match. The monkey clown horrible karate round and yummy like cute small baby chick would beat the donkey." - Jimmy James
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Old 08-18-2008, 08:55 AM   #13 (permalink)
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The "best acceleration" is also complicated by real conditions. You only need to accelerate downhill enough to prevent the onset of road rage in people behind you. Going uphill, you just need to punch it. Crawling uphill means staying in low gears for longer. The name of the game is getting into high gears as soon as possible.
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Old 08-18-2008, 10:01 AM   #14 (permalink)
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I've been accelerating with loads between 70 and 80 and I'm seeing better or rather more efficient use of my MPGs by the time I reach 4th gear. I might have broken 43mpg on my last trip if I wasn't stuck with traffic. Had to settle for 41.
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Old 08-18-2008, 02:27 PM   #15 (permalink)
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Daox:

As I stated I've read that BMW recommends this, but so far I have yet to find it as a direct source. I have read it from a gentleman who posts on Dodge Truck forums and lists who has spent much time experimenting with fuel efficiency on his truck and researching efficiency and aerodynamics. The feet/minute number is a rule of thumb as far as I know so it may not be optimized for any specific engine design, but all of us here probably lack the means to determine the optimum number.

I find that the 1200 fpm target correlates well with my personal experience. My engine, with a 3.40" stroke, hits 1200 fpm at 2117 RPM. I have gotten my best fuel efficiency lately shifting at 2100. I get my best steady-cruise efficiency at 2100 in 5th (75 mph) with another "island" of efficiency ~1800-1900 in 5th (65 mph) both achieving identical MPGs. If I wound out to 1500 fpm that would put me at 2647 RPM and I know it's not worth my while to drive that fast on the interstates (would have to put me near 95 mph), when accelerating from a stop up a hill I will let it rev to 2500 before shifting and find that not only does it work better in the elevated torque band, it keeps me out of open-loop enrichment under the load of uphill acceleration.

There is a direct correlation between an engine's stroke and the speed at which that engine will naturally produce a torque peak. As noted above the engine's stroke directly correlates an engine's speed to a mean piston velocity. As engines produce more low-speed torque they need to be run slower to maintain efficiency, and as engines produce more high-speed torque then can be run faster and still be efficient. All you folks out there with Honda b16s with a 3.05" stroke should let 'er rev up to 2360 instead of dogging it down below 2000 rpms (Wiki says the D16A3 in a Civic HF has a 3.405" stroke, putting you guys at 2100 rpms like me).
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Old 02-18-2009, 08:37 PM   #16 (permalink)
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I found this thread via Google, and wish to share my tactics for fuel efficient acceleration. What I've done is through experimentation, found the lowest speeds my car will shift at (2001 Toyota Echo AT: 15km/h, 25km/h, and 46km/h OR 9mph, 16mph, and 29mph) and do some 'upshift coaxing' to get my car to shift at these points.

However, I have found that by doing this over time, shifts seem much rougher than before, especially when doing regular and smooth acceleration. This point was driven home when I had to drive the company van, and couldn't even feel the thing shift unless I accelerated REALLY slowly.

I'm currently trying to accelerate slowly AND smoothly to get it to shift as close to these speeds as possible without coaxing. I'll report back next time I fill up.

This is my suggestion: Drive about a week trying to find when your car shifts. Once you have an idea of where it does, use upshift coaxing to try and get it to shift even earlier. Once you've determined all the slowest speeds your car shifts at, accelerate slowly to get it to shift as close to these points as possible.

Another note: When doing 'smooth and slow acceleration' it may not always be able to recreate the same shift points. If I accelerate VERY slowly, I find the transmission will be struggling to upshift, thus using more fuel probably. You want to accelerate slowly, but you also want it to shift without struggling either. If it is struggling, you need to give it more gas so it can shift. I find with my car it isn't a problem for it to shift into 2nd at 15km/h, but will shift at 30km/h and 50km/h unless I upshift coax, regardless of how slow I accelerate.
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Old 02-20-2009, 08:16 AM   #17 (permalink)
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UPDATE: Well, my economy dropped significantly by accelerating slowly and smoothly. I went from a solid 35-39MPG down to about 33MPG!!! I guess I was tempted to try this because of my experience driving another vehicle (Toyota Sienna), but if I had spent more time with it I'm sure I would have found its shift points.

Also, try accelerating a different speeds to determine shift points. Sometimes its easier to hear the car shift when giving it more throttle.
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Old 02-20-2009, 10:04 AM   #18 (permalink)
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heres my method:

i have a slightly louder exhaust (and a decent sized motor), so i can "hear/feel" the motor pretty well. while my truck is an automatic, it has 5 gears that are actually pretty close in ratio (not much rpm drop in between gears).

its kinda hard to explain in words, but i'll try my best. there are 2 main "feelings" i get from my engine.

-when i accelerate really slowly, the engine "feels" like it wants to go faster, but i'm holding it back. makes it stay in lower gears, and the shifts aren't "crisp". it shifts like i get out of bed in the morning; slow, tired, and sluggish. small variations in accelerator pressure don't seem to make any difference (in speed).

-when i give it more (like 3000 rpms+ ), i get excessive noise, the engine "feels" like its doing way too much work for the speed i'm traveling.

so my "sweet spot" is around 2000-2300 rpms. when it shifts, rpms only drop a couple hundred, and are short and crisp. i reach higher gears in moderate time. the engine just "feels" happy. that seems to get me the best mileage.

yeah i know, i haven't updated my fuel log in awhile. i do have it saved (in excel) at home. my "mpg tracking" process is always filling up from almost empty, at the same time of day, at the same gas station. my excel program corrects my mileage from bigger tires automatically.
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Old 02-21-2009, 10:53 AM   #19 (permalink)
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"Glorious sunset of my heart was fading. Soon the super karate monkey death car would park in my space. But Jimmy has fancy plans... and pants to match. The monkey clown horrible karate round and yummy like cute small baby chick would beat the donkey." - Jimmy James
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Old 02-25-2009, 11:39 AM   #20 (permalink)
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it depends...

I judge my accel on location and how heavy traffic is...

If the distance between lights is long, I will accel faster to get to a good cruzin' speed. Shorter distance between lights, slower accel.

And as always, I judge all that with how heavy traffic is...

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