Wayne,

I am a bit embarrased to be reading threads here at greenhybrid.com for the first time. I had no idea all this chatter was going on.

It seems I should add some air to my tires to stay competitive.

Since my 1150 mile tank, I have been trying P&G without turning the engine off in glide, and am getting only 70 +/- mpg displayed on this tank at 125 miles. I guess I need to go back to turning the engine off in glide mode.

How do I know when my HCH is in lean burn mode? How do you maintain lean burn mode?

Bob

 

Let me know when, I will try to be there! I would love to get some tips on how to drive the HCH! I am also willing to give up anything I have learned, but it can be difficult to describe. Maybe it would be best for the various hypermilers to demonstrate their techniques and let on person describe them all, or make a video of them.

 

I have been pulsing in 5th, keeping the rpms low, but taking more time to get back up to speed. I guess I should try pulsing in 4th and see what happens.

BTW, where can I see one of your videos?

 

Lakedude,

Do you really think the bad mpg in winter is caused by cold air intake? I always heard that colder air intake allowed the engine to produce power more efficiently.

Have you ever noticed that in the cold or wet weather, the HCH simply will not glide as far on the same terrain and at the same speeds? My sense is that in extreme cold weather, the car tightens up (wheel bearings, u joints, gears, oil thicker at startup) providing more mechanical resistance for the engine to overcome. I think the reason mpg goes down in the rain is simply increased road resistance from water on the road and the energy wasted when our tires trow that water into the air.

Bob

 

The whole P&G thing is still highly expermental in the HCH. Dan seems to have it nailed down pretty good with his Prius Silk Shorts.

Rain lowers mileage because you gotta push the water out of the way of the tires just like the car body must push the air out of the way. Think about driving and hitting a deep puddle, the car slow down like you hit the brakes does it not?

The car is "stiffer" in the cold, plus the engine is not as efficient.

 

BTW, I plan to retire from hypermiling in November. No, I am not afraid of the cold. My fiance' will return after being in Europe all year and I know she will not put up with my current driving habits.

 

That will take some of the heat off. Perhaps I'll get married if I ever find a girl with higher mileage than mine. November will mark the end of the first full year with IMC.

It will be a shame to see you go down the tubes. Dan is too far ahead to provide motovation. I'll miss you!

 

Lakedude,
Don't give up so easily. After this tank and the next marathon tank, you can also expect to see my FE go down. it is just too much effort to maintain 80's. I will probably drop to the high seventies for the rest of the summer & Fall and low 60's for the winter.

Hang in there!

Dan

 

Hi Hot_Georgia_2004:

___I really wanted you on board with this from the get go. Forced Autostops are very similar to the P&G except that we use our FAS’s wherever they seem natural to do so, not over an exacting speed range and repeating basis. The Prius II has an advantage here in that you do not want to pulse above 41 + mph area because of the ICE spinning up to protect one of the MGSets. In other words, the Prius II, HH, and RXh have a max top speed of 41 mph before you begin the glide when using the technique to its maximums. There is no reason not to use the technique from higher speeds either but you will not maximize the effect is all. More on this in another thread …

___For the HCH, I believe 45 mph would be a better top speed. I am guessing but will try and have Tom lighten up his CVT based HCH for some test runs out on my own FE test road near work with him as the driver sometime later on this year. Seeing that 60 + mpg while accelerating in his has me thinking that if we dropped that to maybe 45 - 50 mpg up to a top speed of 42 - 45 mph during the pulse, force autostop, reboot, and coast down to maybe 32 - mph on the low side, re-start, re-engage, and pulse on the way up, repeat, we might see similar spectacular results that the Prius II has shown any number of us to date. Maybe even 100 mpg! The key is that the HCH’s w/ a CVT should be locked into top gear at 32 + mph with a slow re-application of the accelerator. The Prius’ are locked into a top gear solution all the time but I believe the sun and planetary gears are outputting their top ratio above 31 mph. Someone will have to provide better guidance as I know most say it is always in top gear but in reality, it isn’t. The ratios are ever changing with ICE RPM and with the two gears interacting with one another. Another digression … In the MT based HCH, I am guessing here but since you really want to be near top gear during the pulse, a 33 - 35 mph Pulse initiation might be more optimal. An IMA start at 34 mph, re-engagement in 4th gear, slow acceleration with at least 45 mpg on the instantaneous, extremely quick shift into 5th at maybe 37 - 38 mph while still accelerating up to a top speed of 42 - 45 mph, and then a very fast FAS, repeat. Lakedude and RJBarlow will have to find the best speed ranges and acceleration rates to find the HCH w/ a sticks max FE using the technique.

___Having P&G’ed the non-hybrid Accord (EPA rated 24/34 --> 77.x mpg using P&G with a 33 on the low side and a 45 - 50 mph on the high side speed range), Acura MDX (EPA rated 17/23 --> 39.x mpg using P&G w/ an ~ 42 - 52 mph speed range), and last night in a 4WD Explorer (EPA rated 14/20 --> 27.4 mpg using P&G using the low 30’s to the low 40’s on the low side and 53 mph as a max on the high side), I have come to the conclusion that smooth re-engagement transitions are a large portion of the FE received. The Accord and MDX in particular have very smooth restarts and transmission re-engagements whereas the Explorer could not get out of its own way when restarted (2,000 + RPM surges) and transmission re-engagements (the Tranny was hunting all over the place to figure out what gear to be in) as a slow re-application of the pedal was applied. The Explorer was a mess to say the least. Anyway, The MDX and Explorer are very heavy automobiles and with an hour or two, I could probably figure out what is best but it doesn’t matter, you aren’t going to P&G a non-hybrid for long because of the damage you will cause when using the gear reduction based starter once every 1.5 - 3 minutes or so let alone the non-Honda auto tranny re-engagements at speed … Honda’s auto tranny internals are built very similar to the manuals so long term damage is far less likely. I want to add here that the AH’s auto tranny is not a good candidate for P&G either. When restarted after a FAS and reboot, the Auto tranny has a smooth re-engagement but OD is usually locked out from any speed above 20 mph as an example. You have to drop almost all the way to 0 mph, restart, and re-engage like you would when first starting out from your driveway or garage before the Auto tranny’s logic is clear for an OD lock up above 42 mph.

___RJBarlow, it is about time you started posting here This is where the extreme hypermiler’s discuss the business of pushing segments and tanks to their respective maximums!

___I believe Lean burn in the HCH’s per its indications is hidden to the end user because the Instantaneous is buffered. In an Insight, you would transition between Lean-Burn and NOx purge like clockwork. The Instantaneous would actually “jump”(up and down) by 15 - 20 mpg’s between the two modes although you could control the NOx purge drop to a smaller loss with a small let off of the accelerator, reapplication, let off through the initial ½ second of the event. You could also feel the transition as it would be like a small kick when NOx purge was just activated and a slight sinking feeling when Lean-Burn re-initiated. That slight sinking feeling felt very similar to the feeling you get when a plane is just starting a slow descent from 30,000 + feet only forward and back, not up and down. When driving Tbaleno’s HCH, I never saw any jump but immediately noticed the buffered FC meters. They didn’t jump around at all and I know when you let off the accelerator at speed, that meter should peg almost instantly. In Tom’s HCH, it simply did not. This is not a bad thing because the meters are much easier to comprehend and thus control but because of this buffered action, you will probably never see a lean-burn/NOx purge event. I don’t remember feeling a transition either because I was accelerating very gently and I bet was in lean-burn from 20 - 25 mph on up anyway!

___For a better idea of what P&G actually does, it isn’t just about a speed range, it isn’t about an acceleration rate, it is about a given amount of fuel and distance traveled in the “Pulse” or acceleration phase vs. the distance traveled in the “Glide” or coast phase. If you “pulse” for 45 seconds at 35 mpg, you need to “glide” for ~ 90 seconds (actually at least twice the distance of the steady 35 mpg acceleration traversed) to receive a 105 mpg average. You might even be able to use a “G” meter and a stop watch to better optimize the results. Let us imagine you “Pulse” at a rock steady .15 G’s for 45 seconds. I am guessing that a 35 mpg acceleration rate in a Prius II correlates to ~ .15 G’ on average? On the “Glide” phase, you will need to average < .1 G’s for the entire coast down (you need to cover at least twice the distance of the “Pulse”) to the previous low speed limit. I cannot imagine correlating a “G” rating with distance because they are not linear to one another but imagine it like that. You can correlate a distance traveled at a given average instantaneous FE with a coast at twice that distance with no fuel being consumed. When “P&G” is broken down to its component parts, you simply have to figure out the best acceleration rate and speed range to minimize the Fuel consumed to a given max speed and maximize the coast distance back down to a pre-determined minimum speed. Someone with the education and training could mathematically model this for a good condition - flat road and no wind using a Prius II, HCH, or Insight (all 3 setup with max pressure in the tires and 0W-20 low kinematic viscosity oils) with some basic data inputs including their deceleration rates or curves from various speeds, Fuel consumption rates (curves) during acceleration at various rates, as well as from and too various speeds. Plot the multiple curves on top of one another and where the Acceleration and Deceleration curves intersect, you have a good idea what might be best. I am not a mathematician by any stretch of the imagination but there are those at Toyota, Honda, Ford, GM, DCC, any number of universities or national labs that could model this in a day or two and tell us where the ~ best acceleration rates and speed ranges would be to maximize the result, I am sure.

___Finally, I know Krousdb and now Lakedude love small hills but there are hysteris losses that cannot be recovered from a “FAS”, “Glide”, and/or “Coast” down the back side after the acceleration up an elevation. I was quite surprised at the Prius II’s efficiency when climbing the hills of Dan’s test route but give me a flat road with minimal stops and I think I can beat an ascent/descent based RT course any day of the week. My prejudice to low delta elevation changes to maximize ones FE is my Achilles’ heel but just like Charlton Heston, the NRA president quite a few years back said, you will have to pry that “thought” out of my cold dead finger’s … So I changed his famous statement a little? Just shoot me

___Good Luck

___Wayne R. Gerdes
___Waynegerdes@earthlink.net

 

Wayne,

Thanks for the info re: lean burn in the HCH.

I will also start using P&G a little more religiously to get a better handle on what is possible. Frankly, while I can be fanatical about hypermiling, I have not been serious about it. Does that make sense?

I absoluetely agree with you about the advantages of flat ground versus small hills. I think there is no way you can recappture as much energy on the back side of a hill as you expend getting up the front side of it. I think it would defy the laws of physics since we are not driving machines that provide for the perfect transformation of energy. Of course, I drive lots of hills and use the same techniques that lakedude and hot georgia do, but I drive them because they are between my house and my office, not because I want to.

In fact, I never drive for gas mileage or even to test mpg segments, I drive to get to where I need to go and try to make the most of it in mpg.

See you in Pittsburgh next weekend?

Bob