Best Engine RPM for minimal FE loss.

[ScubaDadMiami]

LOL. No, I suppose not. For some reason I thought you would chime back in. :D

Well, you certainly started a great thread, on a new method. 

[ScubaDadMiami]

80 mph is a MPG killer! LOL :)

 

Paul

On my 2,000 mile trip to NC and back, I came up with a rule of thumb of: 80MPH=35MPG, 75MPH=40MPG, 70MPH=43-45MPG, 65MPH=45-47MPG.

Edited January 7, 2014 by ScubaDadMiami

[RaPieR]

On my 2,000 mile trip to NC and back, I came up with a rule of thumb of: 80MPH=35MPG, 75MPH=40MPG, 70MPH=43-45MPG, 65MPH=45-47MPG.

I wish my C-Max was that conservative when it comes to consumption vs speed.  Mine is more like 80MPH = 29MPG, 75MPH = 35MPG, 70MPH = 38MPH, 65MPH = 42MPG

[Jus-A-CMax]

Guys, are we talking about the same fish here - loaded, unloaded...makes a big diff, the weight and also the elevation of the drive as well. Trust me... ;)

[MacGyver]

Are you saying the ICE is more efficient at that range by having slightly higher instant MPG at 73-75MPH speed?  Not the overall mileage of the C-Max?

 

I just completed a 3000+ mile trip from Michigan to Texas.  In one 400 mile leg I set eco-cruise to 80MPH and only managed 29MPG.  Granted this was with a heavy head wind.  I also didn't average higher than 38MPG for a single tank in mixed driving with sections of 65MPH and 80MPH.

 

I tested speeds all the way up to 90mph, and 75 seems to be the upper limit before mpg starts dropping.

 

The surprising part is that 55 used to be considered the most efficient speed before you generated such wind drag that your mpg started dropping.

 

I'm as surprised as anyone that the most efficient speed can be that fast, but I've seen it over and over again on the instant mileage readout on Torque.

 

Not 100% sure/clear on what you're saying/asking here; "Are you saying the ICE is more efficient at that range by having slightly higher instant MPG at 73-75MPH speed?  Not the overall mileage of the C-Max?

 

But

 

basically I'm saying that 75mph is the peak as far as GEARING RATIO/engine load/mpg combo, delivering 40-60mpg. Both ICE and EV are more efficient there, as this is the sweet spot combo re; gearing/wind resistance/(lift? the cmax is kind of wing shaped...)

 

And 

 

of course a headwind is going to bring that down, even a slight up or downhill will affect the instant mpg dramatically, as at 75mph, you're right at the very EDGE of its performance envelope, the instant numbers jump around like crazy at 75mph (in a good way, like 45-60+mpg)

Edited January 7, 2014 by MacGyver

[MacGyver]

I wish my C-Max was that conservative when it comes to consumption vs speed.  Mine is more like 80MPH = 29MPG, 75MPH = 35MPG, 70MPH = 38MPH, 65MPH = 42MPG

 

According to your signature, you should have between 8000-9000 on the odometer unless that's outdated info, I have 18,400, maybe my engine's just more broken in?

 

I think I might see what you're getting at re; Not 100% sure/clear on what you're saying/asking here; "Are you saying the ICE is more efficient at that range by having slightly higher instant MPG at 73-75MPH speed?  Not the overall mileage of the C-Max?

 

If "Overall"= average mpg? If so, I could do a reset of the lifetime average, but my routes always vary, so it's difficult to use that as a reference... I do get high trip mpgs on a regular basis... in the 40's and 50's when I'm really hypermiling, but during the day, I'm doing so much even while I'm driving, calls, navigating, etc., and a LOT of paperwork/administration sitting in my car (sometimes with the motor on to run ac or heat or just to listen to my podcasts over the car system) that really impacts my average.

 

Guys, are we talking about the same fish here - loaded, unloaded...makes a big diff, the weight and also the elevation of the drive as well. Trust me... ;)

 

I travel with about 100lbs of tools and what not, I'm 230lbs. Ok, 235 but I'm dieting. I'm mostly at sea level. Tujunga is the highest elevation I get to on a regular basis, which ranges about 1300-1800 feet.

[Jus-A-CMax]

I travel with about 100lbs of tools and what not, I'm 230lbs. Ok, 235 but I'm dieting. I'm mostly at sea level. Tujunga is the highest elevation I get to on a regular basis, which ranges about 1300-1800 feet.

 

...then you probably passed me or I passed you. That 210 is my :airquote: home freeway, travel that all the time to get to Glendale from the SF valley, to avoid the 5. B*tch to climb from Sunland...

 

As a side issue, I've not seen my Maxine do the ICE High MPG dance post 13b07 - except coming down from the top of Sunland heading east but thats down slope and I practically have a full battery. Otherwise, at 66mph, it only sits about 40MPG and just chills out there. Does not dance in the mid 40s or 50s, even with blipping. Pfffh, I want the old ICE High MPG back :cry:

Edited January 8, 2014 by Jus-A-CMax

[RaPieR]

According to your signature, you should have between 8000-9000 on the odometer unless that's outdated info, I have 18,400, maybe my engine's just more broken in?

 

I think I might see what you're getting at re; Not 100% sure/clear on what you're saying/asking here; "Are you saying the ICE is more efficient at that range by having slightly higher instant MPG at 73-75MPH speed?  Not the overall mileage of the C-Max?

 

If "Overall"= average mpg? If so, I could do a reset of the lifetime average, but my routes always vary, so it's difficult to use that as a reference... I do get high trip mpgs on a regular basis... in the 40's and 50's when I'm really hypermiling, but during the day, I'm doing so much even while I'm driving, calls, navigating, etc., and a LOT of paperwork/administration sitting in my car (sometimes with the motor on to run ac or heat or just to listen to my podcasts over the car system) that really impacts my average.

 

 

I travel with about 100lbs of tools and what not, I'm 230lbs. Ok, 235 but I'm dieting. I'm mostly at sea level. Tujunga is the highest elevation I get to on a regular basis, which ranges about 1300-1800 feet.

Actually I have around 42,000 miles on the C-Max so I doubt there is difference regarding to break-in period for the engine.  When I mentioned overall, I was referring to the average mpg for a specific trip etc.  I was confused by what you wrote and though that you were only referring to instant mpg when the engine came on.

 

Maybe my C-Max was one of the first production models with first revision transmission or maybe something isn't working properly an aero-feature like grill shutters maybe but on the highway mileage drops off pretty quickly from 60MPH as I increase speed.  I've driven the C-Max at a whole range of elavations and temperatures, I don't think I've driven at an extreme enough elevation so I've only seen the big hit caused by temperature.

 

I also usually drive the C-Max that is probably loaded with max 250lbs total so I don't think overloading is causing the mileage I'm seeing.  Of course, this is for no hypermiling techniques.  Just driving on the highway with eco-cruise set to a target speed and no drafting/following other cars or semi-trucks.

 

When I did follow semi-trucks then I could easily hit 45-47mpg at 65-70MPH depending on the elevation changes.

[MacGyver]

MacGyver,

 

I have followed this thread with interest, but I need you to explain to me slower and more carefully how you came to decide that 75mph is the C-Max's most efficient speed. As a physics guy, I just can't make sense of it. I have an open mind about these things, so lay it on me.

 

Simple, same reason my Grandma's 1997 Lincoln towncar (what a car!) gets 25-30mpg on the highway once it gets up to speed, that is; low engine load (low engine load=small demand for power from ICE engine to maintain speed) and high gearing.

 

Just as when you're on a bicycle and work your way up to higher gears where you're pedaling the same speed or possibly less to maintain a higher speed than you could say, run, the car, once it reaches 75mph (or so, I suspect my speedo to be reading as much as 2-3mph fast, that is, my 75mph may ACTUALLY be 72-73mph going by OBD and GPS speed readouts on Torque) it has reached the sweet spot where the ICE engine is not working hard to maintain that speed, and the point at which it maxes out its aerodynamic slipperyness. Any faster (I've tested up to 90mph, which progressively worse instant mpg) and wind resistance fights down your efficiency.

 

I know, it was counter-intuitive to me too, tested it MANY MANY times before I believed it and became convinced it wasn't just wishful thinking (instant mpg readout jumps around between 40-60mpg at that speed, given that you're at the top end of the efficiency performance envelope and any little headwind, up or downhill will affect instant mpg).

 

Try it , you'll like it.

Edited January 11, 2014 by MacGyver

[MacGyver]

Just driving on the highway with eco-cruise set to a target speed and no drafting/following other cars or semi-trucks.

 

When I did follow semi-trucks then I could easily hit 45-47mpg at 65-70MPH depending on the elevation changes.

 

I see improvements when drafting semi-trucks too, but short term ones, both because it usually results in EV only power being slowly but surely exhausted, then switching back to ICE until battery reaches a sufficient state of charge to re-engage, by which time, unless we're in traffic, the truck driver will typically start varying his speed to make it not worth my while/annoying to draft him. 

 

Also, that means my mpg is 60+ while drafting, so I may have gotten lucky with my break-in or whatever separates the high from the low mpg cars...

 

I'd really recommend getting Torque, the smartphone app that, coupled with a $9 bluetooth OBD, gives you instant feedback of when you're driving well and what doesn't work... my lifetime average is around 40-42mpg, depending on how careful I'm being, but seeing highs like 72mpg or even 83mpg (personal best trip mpg) keep my spirits up despite that rather mediocre lifetime average. (I sometimes speed, gun it, am too busy to value 10 cents worth of gas over getting there ASAP, do hours of paperwork / administration in my car which can drag down my average mpg 2-3mpg...

 

Also, there's a solid 5-6mpg discrepancy in Torque's analysis of my efficiency that I've yet to find a way to overcome/verify as in/correct/account for. Which is in large measure what I base the actual numbers I report on.

 

Which is not to say that I'm recanting that 73-75mph is the most efficient speed, far from it, I'm just saying that instead of 40-60mpg, it might only be 40-45-50 or something. Most efficient gearing and load is going to be the same whether you're burning this much fuel or a little more or less.

Edited January 11, 2014 by MacGyver

[Ryan McEachern]

Simple, same reason my Grandma's 1997 Lincoln towncar (what a car!) gets 25-30mpg on the highway once it gets up to speed, that is; low engine load (low engine load=small demand for power from ICE engine to maintain speed) and high gearing.

 

Just as when you're on a bicycle and work your way up to higher gears where you're pedaling the same speed or possibly less to maintain a higher speed than you could say, run, the car, once it reaches 75mph (or so, I suspect my speedo to be reading as much as 2-3mph fast, that is, my 75mph may ACTUALLY be 72-73mph going by OBD and GPS speed readouts on Torque) it has reached the sweet spot where the ICE engine is not working hard to maintain that speed, and the point at which it maxes out its aerodynamic slipperyness. Any faster (I've tested up to 90mph, which progressively worse instant mpg) and wind resistance fights down your efficiency.

 

I know, it was counter-intuitive to me too, tested it MANY MANY times before I believed it and became convinced it wasn't just wishful thinking (instant mpg readout jumps around between 40-60mpg at that speed, given that you're at the top end of the efficiency performance envelope and any little headwind, up or downhill will affect instant mpg).

 

Try it , you'll like it.

Okay, I understand what you are saying now. My personal experience is quite different. I have 20,000 km on the car now, under a lot of different conditions, and I achieve the best MPG at the slowest speeds. The slower I can drive, the less gas I burn getting to the destination - I haven't figured out how slow is too slow, but there is a stiff penalty in going fast in my situation.

 

We do a cross-province trip that is about 800 km round trip, and it is obvious, that in my situation, the slower I drive, the more efficient the car is. When we are in a rush, we cruise at 10-20 above the speed limit, so figure about 120-140 km/h, mixed terrain. When we are not in a rush, we drive the speed limit, or 5 over, and burn much less fuel on the trip.

 

The very best efficiency I have seen on the highway trips was when there was a pretty good blizzard going on, and I was slowed to 50-60 km/h for a lot of the trip. The city driving follows the same pattern. Picking a route that keeps my speed to 50-60 km/h burns far less fuel that routes that have 80 or 90 km/h sections in them.

 

Each to their own I guess.

[ArizonaEnergi]

I found this 2,000 RPM idea intriguing, so I tried it this week on my recurring 300 mile trip I take mostly on the Interstate to visit the mother-in-law.  After switching from EV Auto, to EV Later to start the ICE about a mile from the Interstate I selected the view with the tachometer and made an attempt to keep the RPMs at 2,000 for the majority of the trip.

 

What I observed on the 75MPH Interstate is that the speed varied from about 62 to 72 as a result in the gentle change in slope and elevation, but speed hovered at about 67-68 for a majority of the time, but for a short time until going up or down again.  This speed was when it appear the road was the most level.  Luckily traffic on the mostly 3-lane Interstate was moderate so my varying speed wasn't an issue.  Driving through Phoenix was another matter all together and there I had to maintain a 68-70 speed during that 20 mile segment.

 

So, what was the result?  Well, it did return the best MPG of my five monitored trips, but not by much.  And this trip was largely without the A/C on, while the previous ones used it constantly.  Considering the amount of effort required to keep it at 2,000 and the result, I would not do it again but just set the cruise control at 68 if I wanted to maximize MPG for some reason.

 

Each segment starts with a full EV battery so I also calculate a "hybrid-mode"(HM) MPG by subtracting an estimate of 40 miles driven in pure EV mode.  Two bikes on the back also contribute to mileage in some fashion.

65-70mph: 37.9 MPG - 35.4 HM  Ending miles: 635
     75mph: 38.8 MPG - 33.8 HM  Ending miles: 1,540
     67mph: 41.8 MPG - 36.3 HM  Ending miles: 5,817
     71mph: 41.0 MPG - 35.7 HM  Ending miles: 6,800
62-72mph: 42.2 MPG - 36.9 HM  Ending miles: 7,458 (2,000 RPM test)

 

It would be interesting and maybe useful to have a cruise control that allowed you to set the RPMs rather than the speed!

Edited January 11, 2014 by ArizonaEnergi

[ScubaDadMiami]

Maybe the 2,000 RPM makes a bigger difference for getting up to speed, not just at constant speed?  Anybody know about that?

[MacGyver]

Maybe the 2,000 RPM makes a bigger difference for getting up to speed, not just at constant speed?  Anybody know about that?

 

That's my contention, and I'm frustrated that I can't prove it by getting Torque to actually do the line graph that (technically is one of its features, but it crashes) would show fuel used via slow 2000rpm burn reaching speed then cruising vs. moderate acceleration (2000-3000rpm) then cruising vs. fast climb to speed then cruising (pretty sure this isn't the way to go, but scientists shouldn't not test something they THINK won't work, plus, initially, this worked better than my overlong sloooow climb to speed using EV only by 0.1%, so significant).

 

 I'll get it eventually, or just plot it out by hand, just too busy right now.

Edited January 11, 2014 by MacGyver

[John Sparks]

Maybe the 2,000 RPM makes a bigger difference for getting up to speed, not just at constant speed?  Anybody know about that?

My whole intent is when you drop out of EV and need to accelerate or just need to accelerate in general, is not to go over 2000 RPM. I learned this technique with my Civic Hybrid, which doesn't even have a true EV mode. It's basically a power assist hybrid, ICE would shut off when I let off the gas but I could not accelerate in EV, just glide. Anyway it was a well know technique among HCH drivers and it made a major difference in reducing FE loss.

 

When you guys are trying this out there, where are you letting the engine come on? My rule of thumb is to run the Empower threshold down to 1 bar. I feel like this gives a good combo of long EV mode while not allowing the battery to drop too much. I'll be honest. I haven't done any testing with a different threshold so am curious what others do.

[ptjones]

Over a year ago when I got my CMAX I noticed as well as everyone else on this forum that you don't drive CMAX/FFH like any other hybrid on the market. I personally had 08 and 10 Escape hybrids and I have driven my daughters 2012 Prius. There are several difference including larger Lithium Ion battery, computer charges the HVB very aggressively, higher EV speed , etc.  It seems to me that the computer is programed for the two bar approach and it almost naturally does it. With P&G , 2,000 rpms just is impracticable, maximum EV and minimum ICE gets the best MPG's. :) 

 

Paul

[ScubaDadMiami]

Over a year ago when I got my CMAX I noticed as well as everyone else on this forum that you don't drive CMAX/FFH like any other hybrid on the market. I personally had 08 and 10 Escape hybrids and I have driven my daughters 2012 Prius. There are several difference including larger Lithium Ion battery, computer charges the HVB very aggressively, higher EV speed , etc.  It seems to me that the computer is programed for the two bar approach and it almost naturally does it. With P&G , 2,000 rpms just is impracticable, maximum EV and minimum ICE gets the best MPG's. :)

 

Paul

I haven't really tested the 2,000 RPM thing, but this makes sense to me.  Sure, you may have a momentary improved fuel economy during a lower RPM, but then you have to run ICE for longer to get up to speed.  The important thing is total fuel used during the ICE burn, not how much fuel is being consumed at the moment that ICE is running at a specific RPM.

 

Again, I haven't really tested this, but the best balance seems to be how long ICE runs (not floored, but with reasonable burns) rather than the instant FE of the lower RPM.

[Jus-A-CMax]

1 3/4 to 2. Also I cannot tell you how IMPORTANT the other factors not discussed here: road condition/slopeage, traffic and weather. Sticking to RPM only and disregarding the other 3 factors is jus a waste of time. As I post in my review, know your roads to max your MPG.

 

Also, I think we're talking pennies here guys. As long as you keep to under or at around the EMPOWER 2 bar burn as I, Matt, Paul and the old hypermilers here, you're doing fine and better than 99% of the other non-forum Maxers who do not have a clue/know.

 

You're killing it!  :)

Edited January 13, 2014 by Jus-A-CMax

[MacGyver]

I did manage to get Torque to create a line graph of fuel used, but it's pretty limited, i.e., x=time y=fuel used, but I can't get it to display more than one factor at a time, i.e., fuel used/load/rpms/degree of uphill-downhill, etc.,etc.,etc. so I could easily test and retest the same street using different acceleration curves to determine the most efficient one...

 

There is a "track recording plug in" that WILL display all that info and let you play it back, but then you'd have to create a line graph by hand... maybe I'll get around to that when I'm not in the middle of my busy season, say after march or so.

[MacGyver]

1 3/4 to 2. Also I cannot tell you how IMPORTANT the other factors not discussed here: road condition/slopeage, traffic and weather. Sticking to RPM only and disregarding the other 3 factors is jus a waste of time. As I post in my review, know your roads to max your MPG.

 

Also, I think we're talking pennies here guys. As long as you keep to under or at around the EMPOWER 2 bar burn as I, Matt, Paul and the old hypermilers here, you're doing fine and better than 99% of the other non-forum Maxers who do not have a clue/know.

 

You're killing it!  :)

 

Agreed that we're chasing that last 5% of efficiency, which is ok as long as it's not affecting your life in a negative way- 

 

Also, I find it hard to believe someone hasn't figured out this already, but at the same time, to be the one doing this cutting-edge research is catnip for me, just wish I were independently wealthy so I could just drive around all day testing this stuff.

[ScubaDadMiami]

Doing mostly two bar burns is working pretty well for me.

 

 

From today's drive.

[John Sparks]

So I've been experimenting with incorporating a 2 bar burn into my daily driving.  I find it good for acceleration / pulse & glide but, I live in East Tennessee and we've got a lot of hills around here. (putting it mildly)

 

What I've found is while I get up a hill faster :shift: , my battery has no where close to the charge that it does with a 2000 RPM burn, and it definitely uses more fuel.  That being said, On "more" :airquote:  level ground my findings so far are that if I'm at a good speed, a 2000 RPM burn will generally keep my momentum, okay maybe 2100 RPM, while a 2 bar burn helps with accelerating.

 

All in all I agree with JUS, knowing your roads is a large factor in increasing fuel economy.  For the terrain I have around here I think that 2000 RPM with occasional 2 bar burn mixes up to the best fuel economy but, of course I've just reached 5600 miles on my Cmax so that may have something to do with it too and I'm still relatively new to driving it.  

 

This forum ROCKS :rockon: BTW.

 

(This is just my observation.  I have no app, or scan gauge for hard data)

[ptjones]

So I've been experimenting with incorporating a 2 bar burn into my daily driving.  I find it good for acceleration / pulse & glide but, I live in East Tennessee and we've got a lot of hills around here. (putting it mildly)

 

What I've found is while I get up a hill faster :shift: , my battery has no where close to the charge that it does with a 2000 RPM burn, and it definitely uses more fuel.  That being said, On "more" :airquote:  level ground my findings so far are that if I'm at a good speed, a 2000 RPM burn will generally keep my momentum, okay maybe 2100 RPM, while a 2 bar burn helps with accelerating.

 

All in all I agree with JUS, knowing your roads is a large factor in increasing fuel economy.  For the terrain I have around here I think that 2000 RPM with occasional 2 bar burn mixes up to the best fuel economy but, of course I've just reached 5600 miles on my Cmax so that may have something to do with it too and I'm still relatively new to driving it.  

 

This forum ROCKS :rockon: BTW.

 

(This is just my observation.  I have no app, or scan gauge for hard data)

You need to get on Fuelly and post your average like we do on here. When you get some extra money get a ScanGauge, it will give you more info and improve your MPG's. :)

 

Paul

[fbov]

Scan Gauge ordered over the weekend, and Torque for my new smart phone... about $20 total.

 

Of course, this is from someone who hasn't remembered to involk Test Mode yet... not even once.

 

HAve fun,

Frank

[ptjones]

Scan Gauge ordered over the weekend, and Torque for my new smart phone... about $20 total.

 

Of course, this is from someone who hasn't remembered to involk Test Mode yet... not even once.

 

HAve fun,

Frank

I used test mode once, missed empower and love ScanGauge. :)

 

Paul