Ecodriving.org suggests shifting between 2000-2500 rpm to save gas. This is much lower than what's recommended in the Fit manual (which comes out to about 3300 rpm).

1. Is shifting this low "safe" for the USDM Fit MT engine or will the engine or transmission wear it out quicker?
2. Are they right that it's better to press down all the way on accelerator in a higher gear, even when climbing a hill?
3. What does it mean exactly for all this that the Fit is deisgned for higher rpm's compared with many other cars like the Yaris, Corola and Civic?

thanks!

http://www.ecodrive.org/The-golden-rules-of-ecodriving.250.0.html :
"Shift to a higher gearShift up between 2.000 and 2.500 revolutions. For both petrol and diesel fueled cars.
Part of the power of a passenger car's engine is lost by internal friction. These losses increase with engine speed. By driving at low engine speeds these losses remain limited, which reduces fuel consumption. The efficiency of a car engine also increases when a high engine load is used (giving more gas at low engine RPM (revolutions per minute)). Under these conditions the engine power is generated more efficiently. During acceleration the most efficient way of driving is therefore to shift up as soon as possible (at low engine speed) and to apply a relatively high load on the engine. Driving in a high gear automatically requires a high engine load to keep up with traffic.
In order to use the efficiency of a car engine in an optimal way, a maximum engine speed of 2500 RPM for shifting is recommended for petrol/LPG engines. ... The recommended way of shifting is in no way harmful to a properly maintained .
Travel on a hill
In mountainous regions, it is very important to command the right acceleration and brake manipulation to save considerable fuel.
Uphill: The target is to travel in the highest possible gear with almost full pressure on the accelerator pedal. It is frequently argued that this level of pressure with low revolutions is too much. Car manufactures build the car in a way that you can travel constantly at 1,000 rpm at full load.
"

 

I dont' believe that HOnda's are like Alfas. The reason Alfa's need to be shifted at a higher RPM is becasue the engien RPM determines teh amount of oil the engine gets. THE higher RPM, the more lubrication.

 

That sounds pretty low to me. I'm certainly not an expert, and I usually drive pretty green, but I woudn't be driving up a steep hill fully loaded with the pedal to the floor at 1000 rpm. The DBW of the fit is pretty sensitive - if you have to floor it to get acceleration, I'm pretty sure you're asking too much of it.

I don't know if there is a really solid answer to this, other than the obvious one of "don't lug the engine". If you feel it bucking or straining, you're in too high of a gear. If not, and you feel some acceleration with slight additional gas pressure, you're probably fine ; If it really jumps with slight pressure, feel free to upshift...

The bit about driving in "the highest gear possible" should really be read "the highest gear the engine will run smoothly in".

If I'm on a flat or downhill surface and not accelerating, my Fit seems comfortable in 5th in as low as 40 mph. But if I encounter a hill at that speed I'll downshift.

If there's any kind of real load, the Fit seems pretty unhappy below 2k. For normal driving at steady speed, I shift so I'm as close to 2k without going under, and shifting as necessary if I hit a steep hill or need to accelerate quickly.

If I'm way off I'm sure somebody will let me know

 

As long as it doesn't cause undue engine engine wear I'm going to try the exeriment. But can you clear up something for me: What exactly happens inside the transmission and/or engine when you "lug"? And wouldn't too low rpm put undue strain on internal parts like bearings even if you couldn't hear anything?

 

Agree. If you feel/hear either of the above, it's time to downshift. Usually you'll feel the lugging first. However, if you're in at low rpm at a steady speed w/no lugging and then either go up a hill or try to accellerate, you may get some pinging - cue shift....

I haven't had this happen on the Fit yet, but my Harley, with it's ever so sophisticated drivetrain, will ping like crazy when accellerating from too low rpms, especially in the higher gears.

 

The Fit wont go anywhere at those RPMS.
Ive been trying to shift at 3000rpms and even thats hard for me. And when the AC is on. Yea right!

 

Shifting at 3300rpm would keep the car in the flat area of the torque curve around 2400-3400rpm (before VTEC kicks in yo); some people don't like having a noticeable torque drop when they shift up.

In my daily driving (small city) I usually shift around 2Krpm; there's always a car or a light in front of me anyway. I've never had lugging or pinging, but if I remember I'll try running slower while watching the ignition timing.

 

Just out of curiosity, I tried this on the way home from work tonight. Yeah, it works -- the car will shift and run smoothly at ~2000 rpm, but there's no way in heck that I think it's safe to drive like this with traffic around. I never accelerated so slowly in my life, and 2000 rpm in 4th doesn't even hit 40mph. I understand wanting to save gas and be green and all, but this just doesn't seem worth it to me. I normally shift at 3500-4500 rpm regularly (often higher) and I'm still getting over 30mpg in daily use, so what's the point? The amount of gas and money saved doesn't seem to outweigh the disadvantages of having to drive like this, at least to me.

 

Wow. Climb a hill at highest gear with full gas? I heard the opposite... I don't even know if the fit can climb a hill like that cuz of its engine.

 

Is there a chart that shows the torque at various rpm's or are you just going on feel?

At 2k shifts, what mpg you get?

 

Honda recommends being in the highest gear possible when cruising but still be able to accelerate smoothly.
Being in such a high gear when driving isnt really a good idea, you are making the engine work harder than it needs to and that wastes gas/
I dont believe we should floor the gas peddal when climbing a hill because at wide open throttle the ecu doesnt read AF ratios,egr and all that junk so the ecu would be dumping all this fuel in the engine but the car is barely moving plus you're making the engine work harder...

 

The TOV L-series article has one, in the VTEC section near the end.

At best, in decent weather, I've had several 39.X tanks -- never quite broke 40mpUSg; maybe in spring when I remove the steel wheels. At worst (all city driving at -20°), 33mpUSg. I probably shift the low gears closer to 2500, but do shift into 5th for city cruising at around 2000rpm.

Everything I've read says gas engines are more efficient at higher load.

Actually, I tried last fall and never actually saw it running open loop except for a few seconds after starting.

Claymore is correct -- certainly don't let the car lug or ping.

I did a quick test a couple nights ago. When lugging begins (at far lower rpm than you'd ever get by shifting at 2K) there's no sign of pinging -- I didn't hear any, and the timing didn't retard, so the knock sensor didn't either. (My previous car started pinging under acceleration in its old age, so I'm sensitive to it.)

[edit] I should add that I don't know yet whether shifting in the low 2000s is ideal for efficiency with this engine. I haven't seen any results elsewhere, and since I only got my car in the fall, I haven't had stable enough weather conditions to test it myself. It might well be better to stay in the flat spot.

It is generally more efficient to accelerate to cruising speed quickly, assuming you will be cruising and not pissing away the energy by braking immediately. "Quickly" usually means as much throttle as possible without going open loop, but I don't know how VTEC affects this in this car.

 

After 20,000km of "green" driving, meaning we (my b/f and I) shifting ~2krpm, we've averaged ~6.2lt/100km (~36mpg, I think). Before it got cold we were averaging 5.9lt/100km (38+mpg?).

Generally speaking, we accelerate carefully (but not slowly enough to piss of people behind us) and shift between 1,800rpm on flat/slight downhill and ~2,200 to 2,500 up hills. On the highway we try not to get much over 3,500rpm in 5th. The speed depends on weather/wind, but usually is around 90-110kmh. We're very careful not to lug the engine. This meant, too, that the maintenance minder didn't come on for the first oil change (15%) until 9,900km and the second one (in the winter) until ~18,500km.

Not to sound like an old granny... We still really enjoy the corners and on occasion I get in the fast lane and enjoy how easily the Fit does 140kmh. But in general, to save some money and wear on the car, driving it easy is all good and really does make a big difference in the fuel economy. We're hoping to keep our Fit for ten years at least. One of my last cars was a '91 Lumina APV that lasted from '91 to '03 and went to the wrecker with 466,000km on it.... and it was a domestic! I want this Fit to last long enough to beat that record!

The Fit is a car that lets you have fun, but really rewards you when you take her easy.

Digi

 

 

Dont think higher rpm means your using more gas, the farther you press the gas pedal, the more gas you burn.
Do your Fit a faver and dont let the RPMs drop below 2000 RPM unless its idleing.

 

What's the Y unit? That's a fuel map, i.e. fuel per ignition, right? So for a fixed load fuel consumption per unit time (or distance, for a single gear) increases linearly, or a little more than linearly, with rpm, and the question is whether the MAP factor decreases more than that. I suspect not. But then, the car doesn't normally run open loop anyway.

 

I’m not really sure but I thought, in the modern cars, the engine management CPU is deciding how much gasoline is injected into the piston and not my foot.
What I really can imagine is that every rotation some gasoline is injected, and if the rpm is doubled there are also double as much injections.
That means I need to inject more then double as much gasoline into a piston by halve the rpm’s to get a higher usage then with double the rpm’s.
Maybe anybody here can explain correctly how it works with the injection in the Jazz/Fit.

 

Yes. When you have half as many injections to do the work of moving the car, you need more fuel per injection. But you don't usually need twice as much fuel per injection, because not all the energy actually goes into moving the car; for instance, the wasted part that goes into engine friction is basically the same per injection, so it goes up with rpm.

 

There is NO way in any shape or form that you can shift at 2,000 through 2,500 RPMS in So Cal. You will either get run over by a tractor trailer or cut off left and right......while people flip you off! Shifting at 4,000 is a great point...very smooth...still gets good gas mileage. There is a difference between trying to save gas n endangering you and others on the road. These are my thoughts.

Best Regards,

 

Yeah Honda's like to REV baby!