About Pulse and Glide deltas

[Piotrsko]

freebeard is correct,

However, noise needs some sort of filter, no matter the definition of that noise, or its measurement, otherwise it simply degrades overall average of measurement. If you want to work with much smaller less accurate increments, then you don't have to remove the noise in your data, unless the result is so far off you need to change your original definition.

[Appletank]

Originally Posted by Piotrsko

freebeard is correct,

However, noise needs some sort of filter, no matter the definition of that noise, or its measurement, otherwise it simply degrades overall average of measurement. If you want to work with much smaller less accurate increments, then you don't have to remove the noise in your data, unless the result is so far off you need to change your original definition.

As mentioned earlier, my question is not about data collection, but about wanting to know why longer PnG cycles are recommended to maximize fuel economy. If they're the exact same but the car's readouts are inaccurate, that's another thing, but would also imply conventional wisdom wrong.

[freebeard]

I see a lot of advice... I'm a bit confused...

Assuming the same average speed and roughly similar pulse mpg, shouldn't a 35 mph average 37-32 range produce similar results to 40-30?

As I said, perhaps it does. You cite sources without providing them so we can evaluate (for instance) context, etc.

But keep asking until you get the answer you want.

[redpoint5]

Shorter but more frequent pulse and glide durations would tend to be more efficient since a more consistent speed is maintained, but then it puts more wear on the transmission components.

This is why automatic transmissions with many gears and CVTs have become so popular, to keep the engine at a higher BSFC for any given speed and power demand.

It's also part of the reason a hybrid is more efficient; a smaller engine is under higher load for any given cruise speed.

[Appletank]

Originally Posted by freebeard

As I said, perhaps it does. You cite sources without providing them so we can evaluate (for instance) context, etc.

But keep asking until you get the answer you want.

I'm more asking if anyone else has sources are why PnG deltas are the way they are since I couldn't find consensus. Wayne Gerdes' article on PnG with the Prius II mentions both 10 and 6 mph deltas, though it seems to use lower average speed to get some of the benefits. Might be due to the Prius II's 41mph limit for gliding.

Originally Posted by redpoint5

Shorter but more frequent pulse and glide durations would tend to be more efficient since a more consistent speed is maintained, but then it puts more wear on the transmission components.

This is why automatic transmissions with many gears and CVTs have become so popular, to keep the engine at a higher BSFC for any given speed and power demand.

It's also part of the reason a hybrid is more efficient; a smaller engine is under higher load for any given cruise speed.

Yeah I have a hybrid so transmission wear isn't really a factor in this case, just whether there's statistically significant energy losses from frequently restarting the engine and a very small glide range. Thanks.

I had wondered whether doing only 4 mph deltas would still be beneficial if there are cars behind me that I don't want to hold up too much.

[freebeard]

I'm more asking if anyone else has sources...

I'm going to go with Dead Internet Theory. Were these 'sources' on Reddit?

Bots spreading FUD.

[redpoint5]

Pulse and glide is only appropriate when there's nobody behind. Improving fuel economy by 5% on an already efficient vehicle at the expense of all the knuckleheads following behind who are using their brakes will cause an overall increase in fuel consumption.

[Grant-53]

I am experimenting with PnG using the tachometer rather than the road speed. A delta of 400 rpm seems right but note I have a stick shift and cruise at 1500 rpm when possible and shift around 3000 rpm on the level.

[Appletank]

Originally Posted by freebeard

I'm going to go with Dead Internet Theory. Were these 'sources' on Reddit?

Bots spreading FUD.

More various posts across Cleanmpg, priuschat, and ecomodder.

[Appletank]

sources
https://www.cleanmpg.com/community/i...?threads/1224/
https://ecomodder.com/forum/showthre...ide-24180.html
https://priuschat.com/threads/how-to...-glide.138516/
https://priuschat.com/threads/pulse-...details.57438/
https://www.metrompg.com/posts/pulse-and-glide.htm

The oft given advice is longer glide = better, but also the average speed is lower so I'm not sure how much that counts, and more a hard cap of aero drag on the top end.