In order to fine-tune my pulse and glide (P&G) technique, I wanted to know how strong to make the pulse for best fuel efficiency overall, so I decided to do a simple experiment.

This was to test low speed P&G, mostly between 30 and 45 MPH, except where I hit a red light where it was 0-45. All tests were done on the same stretch of mostly flat road, and the segments were 4.1 miles. There were about 5 stop lights and a hill (freeway overpass) at one end. On average I got hit by 2 of the lights each time through.

I found it much easier to use the tachometer as a control instrument (meaning I was targeting a certain RPM on that gauge during the pulse) rather than the number of bars of assist because it was a more precise indicator. Temp was 46 degrees F. Here's what I saw.

1700 RPM, 3 bars of assist: 55 MPG
2000 RPM, 3 bars of assist: 58 MPG
2500 RPM, 5 bars of assist: 47 MPG

In the 1700 RPM test, the assist dropped off to zero at about 32 MPH. In the other two tests, assist remained constant as shown.

So, 2000 RPM seems to be the sweet spot, even though I had to use a bit of assist, I think because it got me up to speed faster and therefore shortened the fuel-hungry pulse. At 1700 RPM I used less assist, but it took almost twice as long to pulse so I used more gas overall.

Battery level stayed constant at 7 bars for the 1700 and 2000 tests; the little bit of assist that was used on the pulse was made up in regen when lights stopped me. I think that's representative of real world conditions. Battery level steadily dropped to 6 on the 2500 test, so the 47 MPG number above would probably have been even lower over a longer segment because regen would have eventually caught up with me.

i was doing some tests on this too today. haha but you stole my thread!

2000 rpm in D is my sweet spot as well. higher or lower yields less mpg for me too.

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I posted this in slajeune's thread but i'll put it here too:

I was able to do some tests over 10 miles today regarding how many bars of assist to use in ev-mode p&g while gliding on the 06 hch

it depends on the amount of battery charge you have:

7-8 bars of battery charge: during glide mode, use anywhere between 0-5 bars of assist. Don't worry about the battery drain: you have plenty of battery charge to use.

5-6 bars of charge: during glide mode, use between 1-3 bars of assist. You don't want to keep draining the battery too much anymore. 5 bars of charge is the optimum level you settle at - reaching a balance between assist and regen during pulse and glide intervals so that your battery remains steady at 5 bars. This is a good equilibrium point, I found, where forced regen is at most 1 bar that hardly affects your FE.

0-4 bars of charge: don't enter glide mode until you get at least 5 bars of charge back again. During this state, there will be 3 or more bars of forced regen that impacts your FE significantly. You're better off holding your speed or doing some slight driving with the load. (let speed decrease 5-10 mph uphill, let speed increase 5-10 mph downhill by holding your throttle steady)

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I also found that the HCH is excellent in the city - maintained 60.0 mpg using pulse from stoplights and ev-mode gliding/braking in heavy traffic.

The more data points, the better, especially when they agree

I forgot to mention that I didn't use any EV assist during the glides in my tests since I just wanted to find the best RPM for the pulse (minimize the variables). But in regular driving, I agree with your assesement for 7-8 bars: use it when you've got it. When it's 5-6 though, it's borderline. I wouldn't use any assist in that situation unless I knew I had a regen opportunity coming up (hill, red light) because forced regen starts kicking in at around 5.

hahaha more like ANY HONDA 2000 rpm is the sweet fuel mileage spot. MMMMMMMM them 2000's rpms'

i got around 20 km a liter when i drove a civic 5 spd using advanced hypermiler techniques
and now I drive a salvage nwh20 prius that gets almost to 25 km/l with 195,000 km to date.

Hi all,

NASA, thank you for you experiment! This is GREAT stuff. This ties in very well with the data from the motor. The IMA is at its maximum efficiency at 2000RPM, which got confirmed by your experiment. So, if you are using assist, make sure your getting the maximum out of it.

Thank you very much,
Stephane.

Great post. I find the challenge of "getting" the glide intriguing and enjoyable... and an extra bonus being the remarkable FE.

Neat stuff.

Hey guys if you all keep this stuff up, the ones of us that are going to get our new rides come the 1st of Jan. are going now to have an idea of what to do with them with all the guess work taken out.

This is beginning to sink in finally now that it is getting to be put into (Simple-English).

Way-To-Go

Terry

BTW; Things are looking up for the Newbies:

Actually, you could apply this to almost any Otto-cycle engine, regardless of manufacturer. The range tends to be listed as between 1700-2200 rpm. Stay there, and you've got a good shot at optimum FE. This is assuming decent valve timing and gear ratios.


This is for accelleration, of course. If you can cruise at a lower speed, by all means do so.