6spd MT, what is the optimal RPM to shift for best mileage
06-04-2009, 01:45 PM
#43
I used to be disappointed in our city mpg --it was around 12-14mpg in town. I usually shifted around 3K. The motor is obviously a lot more responsive in that range.
After driving a couple of loaners from the dealership I noticed the AT versions shifted pretty early. I decided to try it out and started shifting way earlier - keeping the shift points at or under 2K. The difference was dramatic. Now I'm getting 20-22mpg in town. It takes a little discipline and you run up through the gears pretty fast. I find myself in 6th gear around 40 mph. The performance isn't as zippy - but it is well worth it considering the milage improvement.
After driving a couple of loaners from the dealership I noticed the AT versions shifted pretty early. I decided to try it out and started shifting way earlier - keeping the shift points at or under 2K. The difference was dramatic. Now I'm getting 20-22mpg in town. It takes a little discipline and you run up through the gears pretty fast. I find myself in 6th gear around 40 mph. The performance isn't as zippy - but it is well worth it considering the milage improvement.
06-04-2009, 01:56 PM
#44
Im not surprised by your experiences since there are a lot of unexpected stops in the city. Driving like a grandma here would really help fuel economy as well as save your brakes a bit too.
06-04-2009, 03:28 PM
#45
Ryan Christopher
I did an experiment with mine at one point to see what gave me the best fuel economy. I was at 500+ on the tank with 34mpg. I shifted no later then 2.5k in all gears and took my time getting up to speed and I did not travel faster then 60 mph. This was a mix of highway and city driving as you can tell from the average MPH (38). I babied the hell out of it the entire time. Each person is different and it takes some learning of your car to figure out what is best for you in the area where you drive.
06-04-2009, 06:31 PM
#48
If I'm crusing, I will shift just above 2k. If there is a sense of urgency on where I need to be, I will shift just above 3k and if I'm really mixing it up, I play in the VTEC zone but gas mileage really suffers so I don't do that often. Normally I shift in the 2-2.5k range. The car has plenty of torque so there is no lugging.
06-04-2009, 06:46 PM
#49
some like it stock
mine only lugs around 1500 or lower, usually shifting at 2k is enough to keep it out of that range. but i prefer 2.5-3k most of the time for initial accelerating.
06-04-2009, 07:19 PM
#50
REDLINE EACH GEAR BABY!!
(... well it sounded good)
I read a thing in road & track recently about getting the most mpg; they said to accelerate fast off the line, then maintain your speed on the freeway. The logic behind it is that yes, you use a little bit more gas getting up to the speed, but it uses less gas to get up to speed fast and then maintain a steady speed than it does to get up to speed at a slow rate.. so even tho its more gas to start, it takes less time to get to the cruising speed thus saving fuel
Sometimes I shift at 3k RPM.. usually 4500 though (when getting on the freeway)
(... well it sounded good)
I read a thing in road & track recently about getting the most mpg; they said to accelerate fast off the line, then maintain your speed on the freeway. The logic behind it is that yes, you use a little bit more gas getting up to the speed, but it uses less gas to get up to speed fast and then maintain a steady speed than it does to get up to speed at a slow rate.. so even tho its more gas to start, it takes less time to get to the cruising speed thus saving fuel
Sometimes I shift at 3k RPM.. usually 4500 though (when getting on the freeway)
I read the same thing. Accelerate up to speed faster, upshift to the next gear and coast. = best gas mileage.
06-04-2009, 07:43 PM
#51
good info. Especially the guy with 34mpg, that's impressive with mixed city driving. But shifting before 2k rpms, it seems like the car would be bogging and you'd be using the clutch a lot more in city driving.
BTW you guys don't know crappy traffic till you drive in los angeles. going 10 miles on the freeway may take like 10x as long as it should.
BTW you guys don't know crappy traffic till you drive in los angeles. going 10 miles on the freeway may take like 10x as long as it should.
06-04-2009, 07:53 PM
#52
some like it stock
06-04-2009, 09:31 PM
#55
Needs wheels
I enjoy driving too much to hold myself to any of these ridiculous shift points and slow acceleration. If I wanted to drive like a granny I would have gotten an auto, but to each his/her own.
06-05-2009, 04:52 PM
#57
some like it stock
06-08-2009, 08:18 PM
#59
There is so much bunk being spread around here...
An engine is most efficient at around 75% throttle. What this means is you should probably stay at 75% throttle as long as you can while not exceeding your target speed and while in the highest gear possible and staying above your preferred minimum RPM to prevent lugging (I choose something around 1500).
So don't floor it if you don't have to.
http://www.ecrostech.com/prius/origi...Combustion.htm
However, it would be different if the engine in the TL is like this one.
http://world.honda.com/news/2005/4050705_a.html
So don't floor it if you don't have to.
http://www.ecrostech.com/prius/origi...Combustion.htm
However, it would be different if the engine in the TL is like this one.
http://world.honda.com/news/2005/4050705_a.html
06-09-2009, 08:33 AM
#60
06-09-2009, 12:20 PM
#61
hi
Yes, that is why I added, "while not exceeding your target speed."
This is why cars with smaller engines are more efficient. Their "little" engines are worked harder.
You can also get similar benefits with Honda's VCM.
This is why cars with smaller engines are more efficient. Their "little" engines are worked harder.
You can also get similar benefits with Honda's VCM.
06-09-2009, 12:37 PM
#62
I have a hunch its more because
1) less displacement
2) lighter cars
3) less air resistance
I recall a recent experiment where a toyota prius was raced around a track as fast as it could go and an e92 m3 tailed it around the course. In the end, the M3 got better mpg than the prius.
06-09-2009, 01:58 PM
#64
well
#1 is key
#2 and #3 can be shown in cars where different engines are offered. For example, you can get a Camry with a 2.5L inline 4 or a 3.5L V6. The one with the inline 4 gets better mileage.
#2 and #3 can be shown in cars where different engines are offered. For example, you can get a Camry with a 2.5L inline 4 or a 3.5L V6. The one with the inline 4 gets better mileage.
06-09-2009, 03:00 PM
#65
1) the car with the smaller engine will weigh less, although not substancial
2) the car gets better mileage due to less displacement, not because people will drive it harder since its a 4 cyl.
I'm not seeing how 4cylinders get better gas mileage because people drive them harder though. Please explain.
06-09-2009, 05:16 PM
#66
some like it stock
the engine works harder but there are fewer cylinders using gasoline. going from 4 to 6 cylinders is a 150% increase. if a person is driving the same way, and the 4 cylinder does not have to put forth more than 150% of the effort then it will get better gas mileage.
on a straight and level road, at constant speed, you can see there's a clear advantage to fewer cylinders since you just have to keep the car rolling. for acceleration, loads or going uphill, there's clearly less to the point of a disadvantage (i.e., prius vs. M3 on the track). however most people spend the majority of their time at constant speed during normal driving, even city driving (stopped = constant speed) although much less so.
on a straight and level road, at constant speed, you can see there's a clear advantage to fewer cylinders since you just have to keep the car rolling. for acceleration, loads or going uphill, there's clearly less to the point of a disadvantage (i.e., prius vs. M3 on the track). however most people spend the majority of their time at constant speed during normal driving, even city driving (stopped = constant speed) although much less so.
06-09-2009, 10:30 PM
#67
engine efficiency
Efficiency goes up as compression ratio goes up. In a larger engine, you don't have to open the throttle as wide to get the same amount of power. This results in a lower compression of the intake charge.
Your 11:1 compression ratio might be a measly 2:1 while the car with the small engine is compressing that same mixture 4:1 (numbers not real - only for illustration).
Therefore, in a smaller engine, you will get more power out of the power stroke because the mixture is compressed to a greater degree.
The smaller engine also suffers less from pumping losses because the throttle is open wider. It doesn't have to pump against as much of a vacuum.
And it's not because people purposely drive it harder. It's because they HAVE to drive it harder. The smaller engine will have to work harder to keep the same car moving at the same speed. It's not as powerful as the bigger engine. The throttle will HAVE to be open wider for the same power output.
Does any of this make sense? The closer you are to WOT, the more efficient your engine. Or course if you reach a point where your computer enriches the mixture for maximum power, you won't benefit from the increase in efficiency as far as fuel mileage is concerned. And if you reach an RPM where your engine spits out unburned fuel, you will lose efficiency.
Your 11:1 compression ratio might be a measly 2:1 while the car with the small engine is compressing that same mixture 4:1 (numbers not real - only for illustration).
Therefore, in a smaller engine, you will get more power out of the power stroke because the mixture is compressed to a greater degree.
The smaller engine also suffers less from pumping losses because the throttle is open wider. It doesn't have to pump against as much of a vacuum.
And it's not because people purposely drive it harder. It's because they HAVE to drive it harder. The smaller engine will have to work harder to keep the same car moving at the same speed. It's not as powerful as the bigger engine. The throttle will HAVE to be open wider for the same power output.
Does any of this make sense? The closer you are to WOT, the more efficient your engine. Or course if you reach a point where your computer enriches the mixture for maximum power, you won't benefit from the increase in efficiency as far as fuel mileage is concerned. And if you reach an RPM where your engine spits out unburned fuel, you will lose efficiency.
yes, but
1) the car with the smaller engine will weigh less, although not substancial
2) the car gets better mileage due to less displacement, not because people will drive it harder since its a 4 cyl.
I'm not seeing how 4cylinders get better gas mileage because people drive them harder though. Please explain.
1) the car with the smaller engine will weigh less, although not substancial
2) the car gets better mileage due to less displacement, not because people will drive it harder since its a 4 cyl.
I'm not seeing how 4cylinders get better gas mileage because people drive them harder though. Please explain.
Last edited by robocam; 06-09-2009 at 10:33 PM.
06-10-2009, 01:52 AM
#68
I see what youre saying, but do you really think that because the engine needs to be pushed harder to achieve the same output that it achieves better efficiency? Youre only considering times of acceleration and not cruising speeds, which people spend the majority of their driving. At these times the engine need only to over come wind resistance and mechanical friction forces to keep the car moving. This requires very little engine effort depending on the speed of course. This is the idea that cylinder deactivation feeds off of - the fact that you dont need 8 or even 6 cylinders for 50+mph cruising speeds.
06-10-2009, 02:32 AM
#69
hi
The harder an engine works, the more efficient it is. So yes, an engine needs to be pushed harder to achieve a higher efficiency.
What happens when you deactivate half of the 6 cylinders? The remaining 3 have to work twice as hard. Therefore, it is as if you had a 3 cylinder engine working twice as hard as if you had a 6 cylinder engine with twice the displacement.
You are right that cruising is low load, but there IS a load and it is that load that the engine has to drive. The smaller engine will be working harder to drive that load than the larger engine. Because the smaller engine is working harder, it is more efficient.
What happens when you deactivate half of the 6 cylinders? The remaining 3 have to work twice as hard. Therefore, it is as if you had a 3 cylinder engine working twice as hard as if you had a 6 cylinder engine with twice the displacement.
You are right that cruising is low load, but there IS a load and it is that load that the engine has to drive. The smaller engine will be working harder to drive that load than the larger engine. Because the smaller engine is working harder, it is more efficient.
I see what youre saying, but do you really think that because the engine needs to be pushed harder to achieve the same output that it achieves better efficiency? Youre only considering times of acceleration and not cruising speeds, which people spend the majority of their driving. At these times the engine need only to over come wind resistance and mechanical friction forces to keep the car moving. This requires very little engine effort depending on the speed of course. This is the idea that cylinder deactivation feeds off of - the fact that you dont need 8 or even 6 cylinders for 50+mph cruising speeds.
Thread
Thread Starter
Forum
Replies
Last Post
SidhuSaaB
3G TL Problems & Fixes
18
05-30-2020 12:40 AM
DerrickW
3G TL Performance Parts & Modifications
9
11-15-2015 05:52 PM
