Introducing "LOG"

[California98Civic]

Originally Posted by busypaws

Anybody have a rule of thumb for difference in speed at start and end of pulse. It seems to me that anything less then 10mph makes it inefficient. I.E. I try to top out at 60mph and then glide down to 45mph. This on a 65mph road with little traffic. Only coasting down to 50mph seems ineffecient. If I pop the clutch put the throttle where I think the LOD should be about 75 -- by the time the SG starts reading its back to 60 and time to glide again.
Any community wisdom here?

Talking only about freeways here. I pick the minimum legal speed (10mph under posted limit) as my bottom. I use 10mph and 5mph differences. 10 on flats and down-hills, and 5 on inclines because I'm not confident that speeding up the hill is good for FE. The load % to seek will vary from engine to engine because we are trying to optimize for the BSFC map (even though many of us have never seen the map for our cars).

[SentraSE-R]

Originally Posted by busypaws

Anybody have a rule of thumb for difference in speed at start and end of pulse. It seems to me that anything less then 10mph makes it inefficient. I.E. I try to top out at 60mph and then glide down to 45mph. This on a 65mph road with little traffic. Only coasting down to 50mph seems ineffecient.

My experience parallels yours, busypaws. A 15 mph delta works better than 10 mph at higher speeds, and 20 mph is even better. I use the same 60 mph upper limit with my boxy xB, so the only roads where I can use the wider delta are non-interstate, lightly traveled highways. 40 mph is illegally slow on most highways.

I P&G with 10 mph deltas in 2nd and 3rd gears. What's really important is the ratio between pulse time & glide time. It's something like this:

Gear  pulse time  glide time  ratio P:G  speeds  mpg
5th      8-10        8-16        1:2      45-60   50  
4th       8           24         1:3      25-40 55-60
3rd       6           40         1:7      20-30 60-70
2nd       3           30        1:10      10-20 80-95

[PaleMelanesian]

I agree that 15 is good. Sometimes 20 can be good, but it's tough to get that right at the top and bottom end in a single gear. You lose a bit if you have to shift during a pulse. I try to do single gear pulses so 15 generally works better.

There's some inefficiency at both ends of the pulse. There's the idle time before you engage the gears, and again after you release as the engine spins down. To minimize that loss, do fewer pulses and make them count for more.

[redyaris]

I have been doing much more EOC lately and have been astonished at how much it improves mpg. As I gain experience I find more and more situations when I can turn the engine off and coast, even in the city I find more and more places/times to turn the engine off. The difference between the scanguage distance and the odometer distance can be as high as 20%. which is the distance the engine has been turned off! This is fun, maybe I can get the kind of numbers that PaleMelanesian get for mpg.

[PaleMelanesian]

You really really really need to turn it back on as soon as the engine has stopped. You'll actually count for those missing miles. Even more important, all the electronics will be working. Little things like ABS and airbags. Be safe.

Mine is off more than it's on. Default mode is off and coasting. I turn it on when I need a boost, then it's off again.

[redyaris]

I do in fact turn the key back to the run position within seconds of turning the key off. however even though the dash display comes back on the scanguage display remains off until the engine is running. The Odometer keeps counting distance but the scanguage does not. one of the nice things about the 2007 Yaris is the electric power steering and brakes, which keep working even though the engine is turned off.

[PaleMelanesian]

Ah I see! Change the SG fuel type to Hybrid and that problem is gone.

[redyaris]

For now I actualy like the way it is working, because it gives me a rough Idea of the time/distance the car is coasting with the engine off. I may change it latter when the pattern is well established and stable.

[McTimson]

I hadn't really done P&G too much, as I figured it wasn't worth it at higher speeds. But I tried this today, and WOW! My typical morning commute, I'll get 42MPG, and afternoon I'll get 39-41, depending on the traffic.

But I tried the LOG technique today, and got 47MPG in the morning, and 48 on the way home. With a little more planning of the pulses to the terrain, 50 should be no problem. I used pulses up to 60MPH (No SG, so I can't determine 'Load'), and would coast down to 45, 50 if there were too many cars behind me. Definitely very effective. I've been blaming my relatively poor mileage of late on my new area, but now there's no reason to not be pulling 50+ tanks.

[California98Civic]

Originally Posted by McTimson

I tried the LOG technique today, and got 47MPG in the morning, and 48 on the way home. With a little more planning of the pulses to the terrain, 50 should be no problem. I used pulses up to 60MPH (No SG, so I can't determine 'Load'), and would coast down to 45, 50 if there were too many cars behind me. Definitely very effective.

Congratulations! And without gauges. Pretty nice. You might try 55-65 or 55-70mph. There is more wind resistance, but safer re: people behind you and no chance of police attention. You're on the Jersey Pike? A lot of fast movers across multiple lanes, and I-80 and I-95 are as big as any CA freeway near the City where you live.

Cheers, man. james