TheAirman

Before I had to put my HS up in late December for insurance concerns, I was playing around with partial grill blocking which is a heat retention technique I was studying and learned from hypermilers.

One of the biggest problems with trying to increase fuel mileage in hybrids, especially in the cooler weather, is maintaining adequate engine temperature. Hence the elaborate heat recovery system in our HS’s. Most of the time in cooler weather, when the ICE runs, and burns extra fuel, it is for nothing more than to keep the cabin warm for our comfort.

Grill blocking helps to keep the engine temperature up higher for a long period of time, so we can run our cabin heaters, and helps to keep the HS in specific stage of operation determined by the computer, so we can run on battery power alone and not rely on the engine running and burning fuel just for cabin warmth.

I’ve often wondered why hybrids being such a high tech advance design, never had electrically operated shutters in the grill to control engine and cabin heat as determined by the computer. Grill blocking in cooler weather is just a “manual” way of doing that. Keep in mind you do this on your own, and don’t beat down my door when you overheat your car or your service manager or Lexus finds out you been playing around with “their” car !!!

As the pictures show, I just used some ½” copper pipe insulation which I got in 6 foot sections at Lowes. The black tie wraps were there too. Total cost, about 5 bucks, which I recovered in the first tank of gas. At the time of my tests, the outdoor temp. was in the 50’s and 40’s in the day and going down to the 30’s at night. And I kept my heater on “auto” set at 73 F.

In the next picture I experimented with just blocking the lower grill, and with the 1/2” pipe insulation, it’s not a total block of the grill and there is enough gap to allow plenty of cooling air across the radiator. I could of possibly stuck 3 pieces in there but decided not too. The results from this experiment were moderate, so I tried to block a little more of the grill.

The next picture show the blocking of the upper and lower grill in the next part of my test.. Keep in mind there still is a gap in the bottom of the grill that allows some cooling air in, so it is not a total grill block as some extreme hypermilers try.

The last picture shows my results. Not bad mileage for the hills of Western Pennsylvania in the fall and winter time, huh? My Ultragauge shows the engine warms about a minute or more faster on initial startup, to the point where I can run on battery alone that much sooner. The Ultragauge also show the ICE staying warm longer which allowed me to run the battery pack down to one bar “purple” on one section of my daily drive where as I couldn’t before because the engine ran just to keep itself warm, and me in the cabin warm.

I’ll try to get more specific time and temperature numbers from my Ultragauge when I put the car back on the road in March. But you people from Canada and in colder climate might benefit from the mileage boost from giving this technique a try. At your own risk, of course!!

JayGoldste

I used your grill-blocking method on my '06 Prius but hadn't thought about doing the same with the HS.

Based on your observation that your car warmed up about 1 minute sooner with the grill blocked I don't think that using pipe insulation will help when it's -17C (0F) or lower. A thermostatically controlled radiator shutter would be much more effective.

I have found that an engine block heater (standard equipment here) makes a noticeable difference in how quickly the heater starts churning out the BTUs, even when it's well below freezing.

TheAirman

In your area, or any further north than where I'm at, a engine block heater is the way to go! But in my area it is not cost effective for me to have one. By that I mean the electricity used for the warm up time saved. But for people with hybrids in cooler climates, the block heater makes perfect sense.

But what happens after you leave the driveway? That's when the grill blocking helps to retain that engine heat that your block heater (and electricity) made for you.

And you're right, the shutters would make the most sense. Maybe the hybrids of the future will have this option because I have seen a Prius or two in this area using grill blocking also. So people understand the theory. I just wonder why the manufacturer's don't?

RJQMAN

Airman and others - a question. I cannot seem to get my 'past record' function to perform correctly. It only shows one bar (the one that is not displayed in your photo), and it seems locked on 37 mpg no matter how I have really been driving. The instantaneous bar graph works fine. Is there some master setting that I need to change to get that bar graph to show past history? Appreciate your advice.

TheAirman

Sounds like you don't press straight in, and hold for a second or two, the "reset" button on your steering wheel.

Do this right after your fill-up, and it adds a new blue bar and puts the date down at the bottom so you can monitor your fuel use, fill-up to fill-up. It also updates the past record "best" if you did better than the last time you pressed and held "reset".

In my owners manual, it's page 37, if that helps you.

RJQMAN

I feel like an idiot with this response, Airman, but I don't have a 'reset' button on my steering wheel. I have read the owner's manual, and the instructions are not clear to me. But perhaps it is associated with the toggle button on the right side of the steering wheel and the display button next to it (I have never used that button - after six months I feel like I am still learning things about this car every day). There is a 'clear' button on the navi screen that seems to erase the minute-by-minute graph, but the first graph with the large bars on the second screen just always sits at 37 mpg. I will experiment, and perhaps I will eventually get it. Duh.

TheAirman

Yes, that's the button. The toggle button on the right side of your wheel. You use it to page thru the multi function display screens in the center of your hybrid meter.

Just push it straight in at your next fill-up and hold it in for a second or two without toggling it up or down. That will add a new blue bar and date on your navi screen. Try it without the power on and you'll see what I mean.

The clear button on the navi just resets those screens.

RJQMAN

Got it, Airman. Thanks. I will give it a try in a few days when the gas level gets low. I had no idea that you could push that toggle button in for another function. I appreciate your help.

noku

+1 Thanks Airman

RJQMAN

Well, I got gas today, and pushed and pulled that thing on the steering wheel, and it finally worked and setup the next column of data! Not sure exactly what finally caused it to work, but I will figure it out eventually now that I know where the control is that causes it to move to the next data column. Airman, your help is greatly appreciated. Thanks again.