Pulse and Glide

[trikkonceptz]

Originally Posted by Daox

I normally use a 10 mph delta when P&Ging. 15 is nice when traffic allows. I rarely do 20 unless its a totally abandoned road and I'm really in no hurry at all.

Thank you for that, but it begs this question ... What speed range?

I have been toying with 55 - 65mph, which keeps me going at a pace I can tolerate. I am guessing if I use 55-70 I will get worse mileage due to wind resistance and perhaps better if I do 50 - 60, for the same reason?

Any thoughts?

[Daox]

In a 55 mph zone I normally do 60-50. In a 65 mph zone I go 65-55. Any extension of my delta is always slower.

Average speed is what we need to look at mainly. If you increase it your mileage will go down.

[Twerp]

I'm still in the experimental / practice phase, but I've noticed that over my 30 mile commute that I get my best FE between 30 and 40 mph. At those speeds, sometimes my pulse consists of little more than a nudge from 5th gear. Usually it doesn't take long to push my truck up to 25mpg average, but if I hang in and combine it with a little EOC on some of the downhills, I can usually push that up to 27-30mpg by the end of the trip. Fortunately, the route that I take has a top speed limit of 55 and is mostly 30 to 50mph. There usually isn't much traffic, but I still get more people up my butt than the average gay porn star. When practical, I pull over and let them by, still nudging myself between 30 and 40.

Of course, my situation is a bit different. I don't exactly have the lightest or most aerodynamic vehicle. The engine is small for a larger truck, but it's still got some very decent power at low rpm. My route is slow but it's the most direct.

If you don't mind spending the time, and you can find an alternate direct route that tops out at 45-55, try doing some P&G there.

[wagonman76]

At least on my cars, it would be extremely easy to remove the steering column locking feature. It is just a little notched plate behind the steering wheel. I think the only reason automakers install it anyway is a supposed theft deterrent.

[ebacherville]

Originally Posted by EP3

Yeah just that WTF second is what I am talking about...True the brakes will still work but if you push like heck it can stop. I just relized how spoiled we are now in these day with all the assist things. My first car was a 76 Datsun 280z. No A/C, no power steering, no power windows, no power locks. Just a sweet car with a inline 6 and a 4 speed man.

Hell the power breaks were out on my 1 ton ford diesel van.. i could stop that with no power assist .. sure it takes effort but its no less safe i can licok the tires up if i want to .. If you know to expect the power breaks and power stearing will be harder its not a safety issue.

[EP3]

Yea very true. They don't make many cars if any with out power brakes anymore. I think my first car did not have them ethier. I guess no biggie if you expected it.

[skyl4rk]

I have a 94 Toyota pickup and have been doing some P&G lately. I don't have a gauge so I don't get the instant feedback and I'm wondering about some P&G strategies. I'm wondering if anyone else has any advice.

Most of my driving is on country roads, some hills, some flats with not a lot of traffic. I do a motor shutdown at speed and coast with the ignition on, and shift it into gear when I want power again. If I pick the right roads I can do this for many miles and anticipate the few stop signs.

When doing P&G, where does the benefit come from? My theory: the engine is not idling while coasting, air resistance is lower at slower speeds, acceleration is relatively efficient when done for a short time.

Questions:

1. My 4rth gear will work pretty well from 30mph to 40mph at relatively low rpms without bucking, so on flats, I usually coast down to 30mph, start up the motor, accelerate up in 4rth from 30mph to 40mph then shift to 5th. I am wondering how to decide on the motor shutdown speed. Usually I go up to 55mph to shut down (which is the speed limit) then coast down to 30mph, trying to see how far I get.

2. I generally will try to coast down hills and power up hills. Sometimes this just happens because the truck slows down quickly on uphills. Is there any strategy for hills? We just have rolling hills here, not mountains. I do try to eek it over some hills, reaching the top at very slow speeds so I can coast down. I am learning the streets, there are some stop signs just over the hills that surprise you, just when you think you can coast for a mile, oops a stop sign.

3. Is P&G better than driving slow? Would I be better off driving in 5th gear at 40mph at low rpms than doing P&G from 30mph to 55mph?

4. When accelerating, I give it a little bit of throttle but not a lot. I try to run the motor at low rpms and give it just enough gas that it is speeding up. What is better, a long drawn out acceleration, moderate or a quick acceleration to the motor shutdown speed?

This truck is pretty much like driving a tractor, no power brakes, no power steering, no ac. It is a lot of fun to P&G, although it definitely takes longer to get where you are going.

[jonr]

The gain from P&G is that you operate the engine at the points where it is most efficient. Typically around 75% of max load at 2000-3000 rpm (#4 above) and when turned off . So definitely no drawn out accelerations.

On my car, hitting resume on the cruise control accelerates at a moderate rate that I think is in the range of best acceleration FE. So I can "pulse" just by hitting resume.

I also find that there is a point right around 45 mph where my car shifts into top gear (auto trans) and seems to lock up the transmission. If I can run at this high FE point, I don't bother with P&G. If I have to average 35mph, I use P&G.

[adrive7]

Originally Posted by jonr

I also find that there is a point right around 45 mph where my car shifts into top gear (auto trans) and seems to lock up the transmission. If I can run at this high FE point, I don't bother with P&G. If I have to average 35mph, I use P&G.

In my Cobalt, the Auto trans shifts into top gear (4th ) around 42 mph, so if I am in a 35 zone I usually try to hover around 42. Same for a 40 or 45 zone. At this point I get mileage in the mid 40s range according to the built in gauge.

[whatthe]

I haven't been hypermiling long enough to get into P&G but I plan to start trying a few different ways on the next fill ups.

Most practical for me on a daily commute would be less than 10mph pulse glide around 50-60mph. Low speeds will have less rolling and aero drag and your car should hold the glide longer and require less effort in the pulse, but low speeds are probably better for closed track testing than the real world.

Another thing to consider is the point where your ECU goes into a rich power tune mode. My car goes really rich around 1/2 throttle so I'm thinking that I may have more gains by going to the max throttle opening before the ECU goes into a power tuning mode for my pulse. This throttle point is very vehicle specific. Generally most econoboxes like the base Civic tend to be very difficult to get out of stoich so you should be able to apply more throttle... and the more performance oriented versions of a car - like Civic SI, BMW, etc.. tend to go rich at much lower throttle openings.