Hi folks,

I've shared these charts, projected and measured MPG vs speed with HP and ICE specific fuel consumption and HP, with PriusChat.com but hadn't posted and discussed them here. The data was captured using a Graham miniscanner recording all of the energy related data:

• traction battery voltage
• traction battery current
• MG1 torque (28% of ICE torque)
• ICE rpm
• injector timing
• MG2 rpm (speed)

The horsepower is common to both charts, which allows us to map relative specific fuel consumption versus the power needed at different speeds:


The following chart uses a drag formula publish by Toyota in Japan for the drag as a function of speed. This allows us to calculate the power required as a function of speed and plot the HP as a function of speed. Using a previously measured engine efficiency, 31%, and energy content of gasoline, 121 MJ/gal, we can calculate the MPG based upon drag alone:



The key point is what happens at 25 hp and 30 hp. You'll notice 25 hp, in the efficient engine range, corresponds to about 70 mph while 30 hp, the limit of efficient engine operation, is needed at 75 mph. This means going 5 mph faster at 70 mph goes from getting ~50 MPG to less than ~40 MPG at 75 mph. This assumes a standard 70F/21C day, no wind, well maintained vehicle, and no grade.

Bob Wilson

 

Hi bwilson4web..

Your graphice display info.. are excellent.. This really me to understand more.. Thank a lot..

Please help me explain why automatic resetting on display occurs.. if possible.. read my post please..

 

Hi,
You're welcome. The engineering data we've needed for true MPG understanding is not available from either Toyota or the EPA. I've been assembling it over time and finally got enough information to make the type of MPG/efficiency charts I've wanted. Naturally, I wanted to share it with folks who helped me get the data.

I have but your 2006 is a model NHW20 and my 2003 is a model NHW11. My display does not work like yours and I've not seen in any of the forums I frequent a description of "why" the display has an automatic reset. Everyone with your model seems to share the same unhappiness with the "automatic reset."

My own display appears to have some problems that I'm slowly figuring out but "automatic resetting" is not one of them. I have found how to trick it into reporting all bars at 100 MPG. I've also noticed that when I run test loops at greater than 100 MPG, the bars do not follow the calculated number but are driven by some undocumented algorthm.

But let me ask what problems does the "automatic reset" cause? There may be workarounds and technical solutions that might resolve the problem(s).

Bob Wilson

 

Hi,

Just foolin' around this evening. It took about 40 minute at a constant speed of 15 mph:


Although this test was speed driven, it looks like a better strategy is to run by battery discharge rate. Running the car EV at 4 amps looks to give a speed closer to 12 mph and appears to be a better strategy. When the ICE runs, it puts in about 16 amps so a 4 amp EV mode will result in a 25% ICE duty cycle.

Bob Wilson

 

Where did you get this OBD scanner? Is there a website?

Thanks

 

Yes, but it is specific to the NHW11 Prius. It won't work with an NHW20.

http://www.ecrostech.com/

Bob Wilson

 

Hi.. bwilson4web..

Hey !!.. not too bad for what you've done. I was thinking when I made 63.3 MPG, yes, battery discharge rate combined with gasoline. The grahpic display was similar to yours. Pulse n release / touch n glide techique is quite important. It depends on how you use your right foot.

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I have question for you.. the temperature dropped during last week and this coming will be approx 28 to 30 again. I heard about block heater.. How can I find/buy it. Is that hard to install? How to ? If you could explain.

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Would an old time dipstick heater work?

 

Hi,

The block heater is a pain to install because the receiver hole is located at the rear, between the ICE and firewall. Also, it has to be ordered from 'a friend' in Canada. Worse, you have to take a lot of stuff off just to reach the awkward to reach the receiver hole BUT it can be done:

http://techno-fandom.org/~hobbit/car...s/pagetwo.html

Much easier is to install a radiator shield:


I understand that for your NHW20 model, hot water pipe insulators work great. Just cut them to fit with a large knife or small saw and stuff in the grill openings. Then when the warm weather comes back, take them out. BTW, I've switched from duct tape to a short bungie cord with hooks to the grill.

As for dip-stick heaters, they are rigid tubes and can't make that first bend in the dip-stick guide:


However, another option would be a heater pad that JC Whitney sells. I'll be testing something like this with my transaxle oil pan but I don't have any results, yet.

Bob Wilson

 

Zippie Kandie and Bob Wilson,

The block heater is not that difficult to install, look here http://priuschat.com/index.php?showt...l=block+heater. I have done 12 installs and the under the car method is far easier if your arms are skinny enough. '04-'05 Prius 30 minutes, '06-'07 Prius 45 minutes (extra spoiler lip and undertray). '01-'03 Prius I have heard about 30 minutes also.

Jesse Wright from http://www.metrotpn.com/ProductDetai...1&SortIndex=22 sells them. Also PriusChat is putting together a discount buy http://priuschat.com/index.php?showt...l=block+heater.

Bob, I look forward to your transaxle pan heater experiment.

Wayne