Cold air density vs MPG
#11
01-23-2008, 06:50 PM
Join Date: Oct 2005
Location: Huntsville, AL
Posts: 5,613
Re: Cold air density vs MPG
I guess I wasn't even thinking about anything at highway speeds because EV isn't even possible (at least in my FEH - is it possible to go EV at highway speeds in a Prius?) so it really becomes irrelevant in that case.
I was considering the cases where EV should be possible, but the minimum temperature requirements programmed into the system will not allow it so the engine is forced into ICE-on condition in order to maintain adequate temperatures.
I was considering the cases where EV should be possible, but the minimum temperature requirements programmed into the system will not allow it so the engine is forced into ICE-on condition in order to maintain adequate temperatures.
BTW, this begins to suggest that as the air gets colder, somewhat higher speeds, +5 to +10 mph, may provide better MPG than slower. As you correctly pointed out, the heat loss at lower power settings can result in running just to maintain coolant temperature without adding to the distance covered.
Bob Wilson
#12
01-23-2008, 07:27 PM
Re: Cold air density vs MPG
You are quite right about speeds slow enough to support EV mode. In this experiment I needed to pickup a part in SC so I knew I'd be cruising at highway speeds. It was interesting to see the MPG follow the air density.
BTW, this begins to suggest that as the air gets colder, somewhat higher speeds, +5 to +10 miles per hour, may provide better MPG than slower. As you correctly pointed out, the heat loss at lower power settings can result in running just to maintain coolant temperature without adding to the distance covered.
Bob Wilson
BTW, this begins to suggest that as the air gets colder, somewhat higher speeds, +5 to +10 miles per hour, may provide better MPG than slower. As you correctly pointed out, the heat loss at lower power settings can result in running just to maintain coolant temperature without adding to the distance covered.
Bob Wilson
Along with a Scangauge, I also have a Auterra Dyno-Scan tool/software for my laptop that I can plug into the car (http://www.auterraweb.com/). This has a logging feature which I can record live data coming out of the OBDII CAN bus. Looks like I should be able to log ambient air temp, barometric pressure, air/fuel ratio, and instant economy all at the same time. It'd be interesting to graph this data to see how closely they all follow each other.
I don't use the Dyno-Scan very much anymore since I got the Scangauge and because I mostly just use it for diagnostics on other cars, so I totally forgot about the data recording feature.
Thread
Topic Starter
Forum
Replies
Last Post
phenderson
Toyota Camry Hybrid
19
01-19-2009 10:13 AM
rgx
Honda Civic Hybrid
3
05-08-2006 07:27 PM
