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I used both upper and lower grill blocks this winter...in the past I'd used a bad upper block only. I also was religious about the EBH use this winter.

And the reward was dramaticly better winter mileage than I've ever before seen. My worst month was Nov. with a 1338 mile average of 56.4mpg (note my lifetime mpg is only 53.7 for an idea of my prev. winter mileage). My best month was March where I finished with 64.9mpg over 930 miles of driving. Dec.-Feb. all hovered right at 58mpg.:woot:

I don't have my previous winter data in front of me here at work but if someone really wants the info I can get it tomorrow. At 57,000 miles it's tough to get the lifetime average up into the range of you hypermiler folks, but after this year I fully expect to be over 54mpg for my lifetime and could easily finish the year with an average of 60mpg or more.:Banane27:

Of course the freeway trip up to Madison will give a hit to my average, but I guess I'll go anyway!

im surprised toyota doesn't have a built in grille block that is electronically controlled, when coasting with the engine off in cold climates, the coolant temp drops like a fly unless covered with a piece of whatever in front of it.

It should automatically be blocked during a cold start, when its warmed up the computer should let some air flow in and blend in a mix of efficency and areodynamics in one since air going through a radiator influences drag.

I said that a while ago and everyone seemed to think that that was unfeasible. I don't know how though. It'd cost like what, $50 to install everything and program it, and it'd only add like 1 inch of extra space, if that. All for what, a FE improvement of at least 10% during the first 5 minutes where the FE is the worst. I think that's a pretty amazing trade off if you ask me.

Hi Evan:

___I would like to see the data. Have your techniques and/or route changed along with the due diligence with the EBH and radiator block for higher FE?

___Lastly, drop her down to 55 mph on the upcoming road trip and you would be surprised what your Prius is really worth even out on the highway ;)

___Good Luck

___Wayne

It should automatically be blocked during a cold start, when its warmed up the computer should let some air flow in and blend in a mix of efficency and areodynamics in one since air going through a radiator influences drag.

Actually, with a proper design, air flowing through a radiator can give you net thrust. This was done on the P-51 Mustang in WWII and is one of the reasons why the aircraft had amazing range. A scoop under the fuselage harvested air which was slowed down in a plenum behind the pilot, passed through the rads, and exhausted through a slot under the tail, giving net gain in thrust from the heat energy gained by the air. The Spitfire and Hurricane used a Merlin engine, like the Mustang, but their underwing radiators were draggy, which limited their range and speed.

I suppose this effect would be much smaller at automotive speeds.

I read somewhere that the air intake opening for a car radiator needs to be only 1/6 to 1/7 of the area of the radiator. I believe this is because you actually want to slow the air down as it passes thru the rad for better heat exchange. Faster airflow doesn't give you much more heat shedding, so the extra opening is wasted.

Hi Evan:

___I would like to see the data. Have your techniques and/or route changed along with the due diligence with the EBH and radiator block for higher FE?

___Lastly, drop her down to 55 mph on the upcoming road trip and you would be surprised what your Prius is really worth even out on the highway ;)

___Good Luck

___Wayne

Ok, I'll post up month by month data sometime tomorrow.
No route changes at all. The main thing is that over the past 6-8 months I've really focused on keeping ICE RPM in the 1700-2300 range with a target of 1850rpm whenever there is fuel flow (monitored via CAN-View). It is now vanishingly rare that I drive above 2300rpm and infrequent that I drive below 1700rpm. I'm sure that's had an impact as well, but being able to get into stealth within 1/4 mile after a "cold" start using the EBH and grill blocking is also, clearly, a factor. In the past or when I have a true cold start it can take up to 1-2 miles to get the ICE warm enough.

Note, also, that I leave the heat off (max cold, fan lowest setting, No AC, No "auto", no defrost) until the ICE is fully warm. I don't think this delays cabin temp from coming up and it clearly allows the ICE to get warm much more quickly. In moderately cold weather I'll leave the heat/AC off the entire trip.

RE:Driving 55mph on 70mph interstates just isn't something I'm going to do. I don't intend to be critical of those who do, but I try to drive at the speed limit and feel this makes me and others safer as they're more able to predict my behavior in relation to others on the road.

Hi Evan:
RE: Driving 55mph on 70mph interstates just isn't something I'm going to do. I don't intend to be critical of those who do, but I try to drive at the speed limit and feel this makes me and others safer as they're more able to predict my behavior in relation to others on the road.___I live in an area where 55 mph Interstates are a reality. You can travel any number of roads other then 65 and 70 mph Interstates where 55 is more then likely a higher speed then what most would travel. Think of what Dan and I did during the 2006 TDS for the last 200 or so miles … It was worth it.

___Whenever traversing the country, 62 in the far right lane no matter the speed limits is always a great idea other then taking a bit longer :(

___Good Luck

___Wayne

Hi Evan:
___I live in an area where 55 mph Interstates are a reality. You can travel any number of roads other then 65 and 70 mph Interstates where 55 is more then likely a higher speed then what most would travel. Think of what Dan and I did during the 2006 TDS for the last 200 or so miles … It was worth it.
Sure, I understand that, but the time factor for a trip of the distance I'm traveling and the amount of time I have to get there really dictate taking the 'main drag'. As I said, I drive the speed limit, I look for the best route, but high mpg doesn't rule my travel, esp. for long distances.

___Whenever traversing the country, 62 in the far right lane no matter the speed limits is always a great idea other then taking a bit longer :(

___Good Luck

___Wayne
Different strokes...I'll stick to the speed limit or even a little above on the interstate, accept the mpg hit, and enjoy a coupla beers while I wait for you to get there!!:Banane35:

... Different strokes...I'll stick to the speed limit or even a little above on the interstate, accept the mpg hit, and enjoy a coupla beers while I wait for you to get there!!

I also find that sometimes I feel more comfortable not hypermiling to the max. On Rt. 9 (four-lane, limited access, major hills) in CT I usually can P&G between about 50-70. However on I-95 the traffic pattern is usually more intense; I sometimes find I need to stay away from the more "extreme" speeds.

As requested....let's hope this is readable.

Month|2003|2004|2005(EBH/part. grill blk)|2006(EBH/full grill blk)*
OCT|45.2|53.7|53.1|59.2

NOV|45.2|53.1|55.5|56.4

DEC|43.1|50.6|50.6|58.2

JAN|44.1|49.3|54.6|58.4

FEB|48.2|50.8|49.4|57.9

MAR|49.5|53.5|55.8|64.6
*First year with careful use of acceleration b/w 1700-2300rpm also.

As requested....let's hope this is readable.

Month|2003|2004|2005(EBH/part. grill blk)|2006(EBH/full grill blk)*
OCT|45.2|53.7|53.1|59.2

NOV|45.2|53.1|55.5|56.4

DEC|43.1|50.6|50.6|58.2

JAN|44.1|49.3|54.6|58.4

FEB|48.2|50.8|49.4|57.9

MAR|49.5|53.5|55.8|64.6
*First year with careful use of acceleration b/w 1700-2300rpm also.


Hello from Cuchulain

Congratulations on improving your winter FE. :woot:
I have a question about EBH usage. 2003 and 2004 were without EBH?
I have seen on Prius chat that EBH typically uses 400W(measured using kill-a-watt) for 3 hours. At 1200Watt hrs, Prius would travel 6miles at 200Wh/m (50mph) or 4.5mile at 260Wh/miles (70mph) in EV mode only. (if it was a PHEV). I see from your mileage logs that your trip length is about 10m?, so I understand that you worry about warmup.

I understand trying to reduce gasoline usage as much as possible, but this seems an inefficient use of electricity. The grill block data is impressive though.

Thanks Andrew

Thanks Wayne for the much prettier table....looks official that way!

Andrew...
Yes, the EBH uses about 400W. Someone calculated that the cost of electicity vs the amount of fuel saved had a net positive cost and energy savings when the EBH was used for 3 hours prior to ICE start....That calculation is somewhere in the long EBH thread at Priuschat if you want to see how it was arrived at. So, used that way, I do believe there is a net energy and gas savings.

That said, when at work my Prius EBH is NOT on a timer...I use the outlet the hospital pays for and leave it plugged in for my entire 8-10 hour shift. So there may be some net increase in energy use and cost...though not to me. Still, my primary goal with my prius has always been to 1)Save GAS (not money on gas, but gas itself) and 2)Reduce emissions. I still think I'm being successful at that the way I'm currently using the EBH.

Finally, even if there were some minor net energy loss and cost. It's worth it to have the instant heat when needed rather than waiting several miles for the ICE to get warm.

I wish I could completely isolate the EBH, Grill block, and limited RPM data to see the relative impacts of each individually. But I don't think that will happen and without controlled environmental conditions would be tough to show convincing data anyway.

Correct, all of 2003 and (I'm pretty sure) 2004 were without the EBH. I may have had a small upper grill block over the radiator only in '04...same as in '05. Only in '06 did I start using the foam pipe insulation on the outer grill to actually prevent any air flow into the engine compartment. I should also add that I used some insulation on the ICE itself for about 2/3rds of the winter period this year. I'm not convinced it mattered much as so little of the ICE was covered and the large area under and behind the ICE was wide open.
http://farm1.static.flickr.com/131/328227089_5374f3c175.jpg

Thanks Evan:)

Given your primary goals of reducing gasoline usage and emissions, you are suceeding.
The ability to EBH at both ends of your commute means if a PHEV-10? was available you could probably do the commute in all electric. If and when, PHEV are available those with short commutes <AER range are going to make those of us with long commutes, look really gas guzzling.:D

Andrew

Sorry, I didn't address the commute length ? I have 2 distinct "commutes". The main one to my work is about 14 miles each way...so a PHEV 15-20 would be perfect there. My other commute is about 10 miles round trip to my kids' school and I usually make that at least once, if not twice, daily.

I work 12-14 shifts/days per month so my average commute numbers are thrown off.

Actually, with a proper design, air flowing through a radiator can give you net thrust. This was done on the P-51 Mustang in WWII and is one of the reasons why the aircraft had amazing range. A scoop under the fuselage harvested air which was slowed down in a plenum behind the pilot, passed through the rads, and exhausted through a slot under the tail, giving net gain in thrust from the heat energy gained by the air. The Spitfire and Hurricane used a Merlin engine, like the Mustang, but their underwing radiators were draggy, which limited their range and speed.

I suppose this effect would be much smaller at automotive speeds.

I read somewhere that the air intake opening for a car radiator needs to be only 1/6 to 1/7 of the area of the radiator. I believe this is because you actually want to slow the air down as it passes thru the rad for better heat exchange. Faster airflow doesn't give you much more heat shedding, so the extra opening is wasted.

very interesting, i'd have to wiki that some more, thanks for the share.

In case someone didn't notice, the block heater for the prius is one guzzly application! 1200 watts! so around 7 cents an hour for me to keep it running. Usually 3 hours do the trick in outside 3-5 degree C temps. By that time it has creeped up towards 40 degrees c avoiding the rich fuel mixture of lean! and of course S1 of hybrid warmup

you don't save much, but im sure the CAT and the engine oil will thank you later in the long run.