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Old 08-18-2014, 12:21 PM   #1 (permalink)
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Question What RPM range do I accelerate and shift for best fuel economy?

Hello all!


This is my first post here and I'm happy to say that I found this website.

I've been researching online for hypermiling tips and while most are straightforward, others are more complex.

The one that I need the most help understanding and putting into practice is:
How should I accelerate??? Meaning at what speed, time and intensity.
I've read many findings that some receive better mileage while accelerating slowly while others find that accelerating more quickly yet smoothly yield better results.

*NOTE: If anyone could tell me how to shift efficiently that is specific to
this vehicle's layout, then that would be even better.*

Here are the estimated shift points that I have witnessed in my 5 years of ownership:

1st Gear: 17 MPH
2nd Gear: 27 MPH
3rd Gear: 37 MPH
4th Gear: 47 MPH

-At what RPM should I accelerate before allowing the automatic transmission to shift?

- What Engine Load should I use whilst accelerating?: this term CONFUSES me! (Example: 70% load)
Gauges aside, how does one measure how much load to use while accelerating
for the best fuel economy just with the feel of your foot on the pedal?


If I am missing something here, please do not hesitate to let me know







I have a 2001 Toyota Camry LE.
Here are the specs:

2.2L 16 valve DOHC I-4 cylinder
4 speed automatic transmission w/OD
.3 drag coefficient
3,100 curb weight
136 HP @ 5200 RPM
150 lb.-ft. @ 4400 RPM
18.5 gallon tank
Cruise control
DFCO @ 1400 RPM

RECENT UPGRADES:
New WIX air filter
New 15 inch Michelin Primacy tires
Oil changes every 4,000 miles

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Old 08-18-2014, 12:37 PM   #2 (permalink)
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There is a spreadsheet often called a map that the engine management uses that has load listed as one of the variables. With my old Subaru it had engine RPM starting at upper left and going down to the max toward the bottom. Then going across the top starting at the top left going toward the right was columns called load like an excel spreadsheet. For example, if you were idling at 850 rpm it would highlight a cell across from 850 rpm in the column that had say zero or 10% load. If I were climbing a steep hill at 850 rpm with the gas pedal all the way to the floor it would highlight a cell across from 850 rpm in the 100% load column. The software uses the highlighted cell that dances around the spreadsheet to manage the engine parameters. As you can image it would use less fuel at idle in the zero column as opposed to the 100% load column where it will need to add as much fuel as it can use for the amount of air available in the cylinder. Load is much like how hard you'd be straining to do a job. I hope that helps.
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Old 08-18-2014, 01:01 PM   #3 (permalink)
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Quote:
Originally Posted by kafer65 View Post
There is a spreadsheet often called a map that the engine management uses that has load listed as one of the variables. With my old Subaru it had engine RPM starting at upper left and going down to the max toward the bottom. Then going across the top starting at the top left going toward the right was columns called load like an excel spreadsheet. For example, if you were idling at 850 rpm it would highlight a cell across from 850 rpm in the column that had say zero or 10% load. If I were climbing a steep hill at 850 rpm with the gas pedal all the way to the floor it would highlight a cell across from 850 rpm in the 100% load column. The software uses the highlighted cell that dances around the spreadsheet to manage the engine parameters. As you can image it would use less fuel at idle in the zero column as opposed to the 100% load column where it will need to add as much fuel as it can use for the amount of air available in the cylinder. Load is much like how hard you'd be straining to do a job. I hope that helps.
Where do I find the map for my specific car?
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Old 08-18-2014, 01:04 PM   #4 (permalink)
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Quote:
Originally Posted by Old Tele man View Post
I try to shift between gears, while accelerating, at the RPM coninciding with the engine's torque peak (≈70-75% of RPM @ maxium HP), so as to NOT force the carburetor/FI to go into 'fuel enrichment' (old accelerator pump)
My torque peak is 150 lb. ft. @ 4,400 RPM.

So 70-75% of 4,400 RPM would mean that I should accelerate around 3,000 RPMs? That seems a bit high to me, but then I could be wrong.
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Old 08-18-2014, 01:05 PM   #5 (permalink)
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Since my Festiva "L" doesn't come with a tach, I'd have to purchase one to know the rpms, but there's no way I'm shifting over 2K rpm ever.

I shift at:

1st - 7 mph
2nd - 15 mph
3rd - 24 mph
4th - 33 mph

I bump start at:

greater than 5 mph - 5th gear, halfway out on clutch to start it, then quickly switch into appropriate gear

less than 5 mph - key start in neutral
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Old 08-18-2014, 01:10 PM   #6 (permalink)
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In my SUV I have a mpg gauge. When I'm climbing a hill or accelerating it may read 8 mpg (heavy "load" or strain). When I'm on a smooth flat road maintaining my speed I may see 60 mpg (light "load"). I may be running 3000 rpm but the engine is not working very hard so its not using very much fuel. My car is geared to spin pretty fast on the highway. I don't have a choice to change my RPM if I want to maintain my speed, but I can request more fuel with the gas pedal. It may not go any faster but it will make more noise. Its under more of a load. It takes practice to find the best spot for your vehicle. It's kind of like riding a 10 speed and finding the right gear to keep your legs from burning. Sometimes pedaling faster makes it easier sometimes not.
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Old 08-18-2014, 01:14 PM   #7 (permalink)
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Quote:
Originally Posted by kafer65 View Post
In my SUV I have a mpg gauge. When I'm climbing a hill or accelerating it may read 8 mpg (heavy "load" or strain). When I'm on a smooth flat road maintaining my speed I may see 60 mpg (light "load"). I may be running 3000 rpm but the engine is not working very hard so its not using very much fuel. My car is geared to spin pretty fast on the highway. I don't have a choice to change my RPM if I want to maintain my speed, but I can request more fuel with the gas pedal. It may not go any faster but it will make more noise. Its under more of a load. It takes practice to find the best spot for your vehicle. It's kind of like riding a 10 speed and finding the right gear to keep your legs from burning. Sometimes pedaling faster makes it easier sometimes not.
My car must have taller gearing because when I'm driving 55 MPH, it's right at 2,000 RPMs.

Hills are my biggest challenge because I still have not mastered the hypermiling techniques for them yet.
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Old 08-18-2014, 01:17 PM   #8 (permalink)
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Quote:
Originally Posted by cowmeat View Post
Since my Festiva "L" doesn't come with a tach, I'd have to purchase one to know the rpms, but there's no way I'm shifting over 2K rpm ever.
I usually try to keep my shifts at 1,800-2,200 RPMS but I may be doing it incorrectly, I'm not sure. I just like to baby my car.
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Old 08-18-2014, 01:50 PM   #9 (permalink)
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With that low of shift rpm, your probably accelerating for a long time, by dragging it out, you are staying in 1st and 2nd a long time where mpg are terrible, accelerate faster to get into D/OD and lock up the torque convertor.

With my Stratus with a 2.4 3,000 rpm worked well, 1/2-3/4 throttle to 3,000 rpm, left off to get it to shift, back on as hard as I could without making it to down shift. With my auto tranny it is real hard to get 70% load after 1st gear because it will down shift. So thinking about % load has no value.

Shift light on my Cobalt is at 2k, but it's a manual, so I can load the engine for greater efficiency, but sometime like accelerating up hill, it think it's better to get to 55 in 3rd and then jump to 5th than take 2x long to get to 55 if I shifted by the light. 55 rpm = 2k.

Best mpg gains are really on the other end of the road when you need to stop, a good coast = better mpg and brakes last longer.
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Old 08-18-2014, 02:25 PM   #10 (permalink)
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Quote:
Originally Posted by roosterk0031 View Post
With that low of shift rpm, your probably accelerating for a long time, by dragging it out, you are staying in 1st and 2nd a long time where mpg are terrible, accelerate faster to get into D/OD and lock up the torque convertor.

With my Stratus with a 2.4 3,000 rpm worked well, 1/2-3/4 throttle to 3,000 rpm, left off to get it to shift, back on as hard as I could without making it to down shift. With my auto tranny it is real hard to get 70% load after 1st gear because it will down shift. So thinking about % load has no value.
I usually accelerate like a granny, it probably takes me 10-15 seconds to get from 0 to 45 MPH on flat to slightly elevated terrain.

I've been averaging about 30 MPG using this method, however I want to increase that number.

How do I know how much throttle I am using??

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