Fall and Winter musing about fuel efficiency...warming up the engine and thermal efficiency of the Prius Grill Blocking early this Fall/September (after the outside morning temperatures started to drop below 65F) appears to be helping my fuel efficiency by about 10% over last year at about this same time. It looks like the Prius will be getting about 67mpg for this October vs. 61 mpg it got last year. I've started grill blocking earlier than last years because I've noticed that when the outside temperaturs drop below 65F that the Prius' fuel efficiency is not as good until the ICE coolant temperature goes over 170F. I've also notice that if I use the battery/electric motor too frequently in the first 30 minutes of my 16 mile commute (60minutes) it will take a much longer time for the Prius ICE (coolant) temperature to reach its more optimum temperature range and so when I use the ICE FE in the beginning of the trip/commute it is a tad less efficient than when I use it at the end of the trip/commute. One tactic I am currently testing is when a trip last longer than 45 minutes during the winter, to raise fuel efficiency a driver will focus on using mainly the ICE during the first five minutes just to accelerate/move the Prius to accelerate the warming up of the ICE to its most fuel efficient operating temperature as soon as possible(*). As long as the Prius doesn't loose this heat too rapidly - I'm guessing this might help boost the average mpg. (*) this is a hypermiling technique called a "Warm-up Pulse & Glide," see Cleanmpg.com FAQ for more
Thanks for the info, and the yearly comparison. It's around 55-60 currently where I am. I've had the insulation for the grill block for a couple of months... just need to do it. The low MPG I'm getting now is depressing!!
I just noticed another temperature drop this week over here, next door to Walter. My mpg is struggling to stay around 49 right now, so I'm thinking of at least blocking half of the lower grille this weekend. We still can hit 70s with a warm front, so I'm hesitant to block all of it right now.
Our temps are currently in range 5C to 15C, and I've put in a single tube of pipe insulation, in the lower grill, blocking 50% of it. This is the first year I've had a ScanGuage, and temps look good so far, nothing over 190~191F. We also use a blockheater for around 2 hours before first start of the day, which we do year 'round: makes a big difference with short trips I think.
I am only really blocking to keep the road grime out of the radiator. The Prius cooling system is pretty advanced with the heat recovery. With that said, I left the blocking in all summer long. Only had to take out one strip when I was on a road trip with lots of mountain climbs. Could smell things overheating a bit.
That engine block heater sounds really really nice. BTW -- What kind of voltage does a Prius blockheater take? Is it a 120VAC or is it a 220VAC (Washer/Dryer plug) type?
It seems to make a difference on shorter trips, like mine. Considering my daily commute is just under 5 miles and there's 8 or 9 traffic lights, I need as little air flow in as possible. I've also noticed a slight uptick in the MPG after blocking in the past. I agree with the road grime, too. Sometimes that black pipe insulation almost looks a light gray if we've had snow. At work, we have a running joke that you park "on the beach" in winter, because there's been times that the thickness of the sand was more than the snow in the parking garage. Then they'll throw down enough salt that you can easily slip on it as you walk.
I didn't fully remove last winter's grill blocking until a mid September mountain climb. Because of the cool Pacific Northwest summer this year, it didn't experience any 90F temperatures until then. Prior to that, the ScanGauge temperature display showed no reason to remove it. 3/4s of that block was put back in two weeks later.
Just 110 volt alternating, regular North American household. It draws 400 watts in use. We got it put in at purchase. The part is under $100 but installed was around $400. I'd get a few quotes if you want it installed, and it might still be the simpler way to go. It's a bit of a handful to do yourself. It doesn't immerse in coolant, it's slipped into a cylinder adjacent to coolant, and requires a heat transfer gel. It's pretty hard to reach, and the gel can be troubleprone. Works though. Be sure the power cord's carefully zip-tied in the front grill, maybe double zip tie, a few inches apart. And try to set up your extension cord so it can pull out if you forget it, and doesn't leave the block heater side of the connection dangling to the ground. Also, get into habit of walking around the front of car, looking for the connection.
We are currently seeing daily hi temps of 45F here. So I guess it would help for me to block my grill now.
I started blocking upper (100%) and lower (only one insert in so far) about 3 weeks ago when temperatures started dipping down--Akron, Ohio area. In a few weeks, will add one more insert on lower and probably won't fully block lower until late December/early January on my Gen II Prius.
You have to be careful which zones you block, with different generations. I think it's established with 3rd gen the radiator for the inverter is in the top opening, and you need to leave at least 50% of that open. Here's a good guideline: http://priuschat.com/forums/gen-iii...62556-2010-prius-grill-blocking-strategy.html
A simple habit I do with my motorhome when I plug it in to the garage is to loop the plug cord a couple of times around the driver's side mirror. Sure is easy to remember to unplug when that is hanging there!
