First Morning with a Blocked Grill

If I can ask a question, do all of you who block your grill drive really short trips or something? And so this helps your engine warm up by the time you get there? Or are you trying to improve your gas milage? I really don't get it.

The way I look at it is this:

Toyota designed the engine compartment to provide sufficient heating and cooling to each component. A huge amount of calculations and testing was done before the final design was arrived upon.

Electronics must remain cool to work correctly and last. Excessive heat is the enemy of electronics. Also other parts of the engine too.

By blocking your grill and placing insulation on the engine, you are liable to do more damage to your engine in the long run than save money on gas or whatever else you're trying to do.

This is my opinion anyway.

I can see if you live in a climate that never gets warmer than 32 degrees F, it might be a good idea to block the grill.

But I saw someone posting that they were blocking their grill, this was about two weeks ago, and I checked their temp and it said

79 degrees F!!!

I think it is *very important* that the moderators of this board clarify carefully for all users the dangers of blocking your grill in warm and hot weather.

If someone suffers damage to their car by taking bad advice from a moderator on this board, or even following their example, I would really feel bad for them!!

In Seattle we have mild winters. My Prius will always breath freely and never have any blocked grills. I monitor the coolant temp with my scan gauge. It's always up to 150 degrees F within a couple three minutes of driving, and maintains 182-184 degrees F during normal operation. This is how it was designed and this is how I will operate it.

Just my two cents. It's important to express that blocking your grill can possibly do damage to your car.

-Dave in Seattle

 

I've been blocking it for 3 years now and watch the ICE temps and the MG's along with the inverter temps and up here, same climate as Seattle it never get's hot. I've never seen 100C (212F) ever and have driven it at 60 mph on the freeway for over a hundred miles and it has only ever once got to the point ,98C, were I stopped and pulled one panel out of the grill. That took it to 87C thermostat opening temp. That was a day when the OAT got to 70F. I don't worry about it increasing the gas mileage to any extent, it's just nice to have the heater work like a priustoric automobile. If you look at the belly pan in front of the rad you'll see two oblong holes in the pan, the reason they're there is to keep the ICE cool in case the grill gets blocked by a plastic sheet or bag while your on the hiway in hot temps. What ever you do don't block them off, if for some reason the inverter gets hot enough to turn on the fan or the ICE gets too hot, it'll pull air from there to cool the rad. This is also important if like Dave you live in a humid cool climate and use the A/C to de-humidify the interior, the fan runs all the time that the A/C is on. The only down side to blocking the grill is the Temp indicator on the MFD no longer indicates the correct temp.

 

ya frank, you noticed, OAT on MFD does read a bit high when the grill is blocked? my main reason for blocking grill is also to have a bit of heat MUCH quicker. my commute is 35 mph. on colder days, i was just hitting 175F by the time i got to work... with the grill blocked, i get good heat after just a mile.

 

ya frank, you noticed, OAT on MFD does read a bit high when the grill is blocked? my main reason for blocking grill is also to have a bit of heat MUCH quicker. my commute is 35 mph. on colder days, i was just hitting 175F by the time i got to work... with the grill blocked, i get good heat after just a mile.

 

<div class='quotetop'>QUOTE(DaveinOlyWA @ Nov 6 2007, 08:03 PM) [snapback]535853[/snapback]</div>

As for getting heat quicker, set your temp control to MAX and you'll get heat instantly. At least I do. Even then I still drive for a couple minutes before turning on the heat just to let things warm up.

I would think a block heater would be a much better solution over blocking the heater vents.

And Frank, it does get colder up in Vancouver, BC than it does down here in Seattle. I've been up there numerous times, I absolutely love Vancouver and want to go there right now! Amtrak Cascades leaves every morning from Seattle at 7:45a.

-Dave in Seattle

 

<div class='quotetop'>QUOTE(DaveLeePrius @ Nov 6 2007, 05:24 PM) [snapback]535862[/snapback]</div>

I don't know, I think you guy's got more snow than we did last winter. the climate for the two are virtually the same. Your commute must be a lot longer than mine so that you don't see a increase in mileage with the grills blocked in the winter. Mine is about 17 miles each way. That should be "was" as I retired this spring.

 

On a similar theme, the temp has dropped to about 5C in the morning and I'm struggling to get my summer mpg. 62mpg has gone down to 54mpg. I'm not unhappy with this but I'm interested in what causes the drop.

On a good cool morning, EBH for 3 hrs most of the grill blocked, dry roads, no heater, tires still at 42. Drive in exactly the same way. The question is what is causing the drop.

What I find is that I get less perfect drives, seems to be more traffic, but is that just the cause.

So can any body advise, in cool weather with all the precautions to cancel out that effect should I get the same, or is there another factor. I am not talking about very cold weather.

Thanks
gary

 

<div class='quotetop'>QUOTE(gazz @ Nov 7 2007, 08:20 AM) [snapback]536068[/snapback]</div>

That's probably about right, with cooler temperature as the cause. You don't say what your temperature has dropped from, but a quick analysis with the Prius MPG Simulator shows an approximate 14% decrease in FE when temperature drops from 25C (77F) to 5C (41F).

 

<div class='quotetop'>QUOTE(JimboK @ Nov 7 2007, 07:35 AM) [snapback]536071[/snapback]</div>

I suppose its why the drop if you offset the temp drop by all the measure I mentioned. Is it the just the cool intake air or density of the cooler air. With the block heater even the intake stays aroung 10-12C for the first 3-4 miles during the warm up. How does the car know its cold?

Yes summer temp was around 20C.

 

<div class='quotetop'>QUOTE(gazz @ Nov 7 2007, 05:02 AM) [snapback]536081[/snapback]</div>

there is a temp sensor in the intake air flow sensor. It's interesting to watch the temp swings on it's output.

 

Side question here-- How do you keep your blocks in place? I've lost two already this year.

PA P

 

<div class='quotetop'>QUOTE(gazz @ Nov 7 2007, 09:02 AM) [snapback]536081[/snapback]</div>

From the Simulator site I linked previously:

"Cold air is more dense than warm air and it simply takes more energy to cut through. In this case it takes about 11% more energy to cut through the cold wind. The mechanical energy increase (70%) is due mostly to thicker lubricants (both oils & greases), stiffer seals & the ICE needing to operate longer & more often to keep the emissions equipment & the passengers warmed up."

So it's largely just the cold air requiring more work. The block heater and grill block just help the ICE get and stay warm, reducing the need for it to run only to keep itself warm.

<div class='quotetop'>QUOTE(PA Prius @ Nov 7 2007, 10:43 AM) [snapback]536114[/snapback]</div>

Cable ties, available in the electrical section of home improvement stores.

 

<div class='quotetop'>QUOTE(DaveLeePrius @ Nov 6 2007, 03:17 PM) [snapback]535665[/snapback]</div>

You are right that the grill shouldn't be blocked in warm temperatures, although some people say it can be done up to 70'F if you have after-market equipment to monitor engine temperature. Still, I didn't start blocking the grill partially until it was consistently in the 50's or cooler, now that it's being consistently in the 40's, I'll block almost all of the front grills. I'm being cautious as I don't want to block it one day and forget about it being there a couple days later while the outside air temperature (OAT) rises 20 degreees.

There's a big difference between the engine and electronics. Electronics do run better at cooler temperatures, although you can get heat-resistant parts. Obviously it is designed to work in warm temperatures like Arizona summers, so I don't think blocking the grill during winter in northern climates will cause a problem for the electronics. There is a reason why the electronics are not attached to the engine or manifold, which is where the air thru the grill goes other than the radiator, so grill blocking has little effect on electronics, IMO.

The engine however is more efficient at warmer temperatures, and in the conditions described in this thread, the engine won't be heat-damaged, and quite likely will improve the life of the engine. Blocking the grill actually makes more sense in highway conditions since then you have a strong constant airflow thru the engine compartment. Constantly blowing cold air over the engine in these conditions makes it work harder to stay at the temperature that Toyota designed. Toyota had to make a large enough grill to handle all conditions such as the Arizona summers, but it isn't optimum for northern winters. This is true on all highway vehicles and why long-haul trucks use the cloth grill cover during winters. You know they take care of their engines (a couple 100K miles on an engine is just getting started for them). We've done this for decades in Minnesota and other cold climates, I haven't heard of negatives on it, as long as you make sure you unblock the grill in warm weather.

 

<div class='quotetop'>QUOTE(PA Prius @ Nov 7 2007, 10:43 AM) [snapback]536114[/snapback]</div>

The individual pieces in my upper grill are compression fit. I use black twist ties for the lower grill.

 

setting to max heat turns on the electric heat and i am too cheap with my mileage to want or need instant gratification. i garage my Prius so its not all that cold initially in the morning... besides its fogged up windows i have to deal with mostly

 

alright... i gave in to this grill blocking phenomenon today.

filled up last weekend, drove to work on monday in low 50s temps (my commute is prius hell, this is the first time it's been under ~70 degrees outside when i drove it) and got 35 mpg. ouch. i had it up to 39 after the rest of the week but i've never had mpg that crappy without a tank of bad gasoline to cause it.

went to home depot on the errands route this morning, two guys strike up a conversation with me about the stuff i'm carrying... part of me thinks "yeah i still got it" and part of me thinks "how am i gonna explain this in the south without looking like a total idiot?" :lol: in the north at least people know what you're talking about.

i blocked most but not all of the lower grille this afternoon. i think i'll just go ahead and do the rest of it tomorrow. hopefully that will help a little bit. DH says i'm nuts, this is the south. but i know he secretly loves that i tinker with the car on my own :lol:

 

<div class='quotetop'>QUOTE(galaxee @ Nov 10 2007, 08:46 PM) [snapback]537884[/snapback]</div>

ok about time you got to doin this. Block it off and watch CAN-view and see what the ICE temp goes to. If in the Hi 90C range pull a couple of pieces. I don't like it much over about 95-97C. Did about a 80 mile run at hiway speeds today and the OAT was 12C about 55 F and it ran at 94 -97 the whole trip. I bumped the heater up to about 75F and that pulled it down to 87C which is thermostat opening temp. Trip out and back and the mfd say's 4.4L per hundred or 53.4mpg US not too shabby for a Classic.

 

with my short drives i probably won't hit near that temp. but i'll keep an eye on it, yeah. we're in the mid-teens C around here lately, currently all the way down to 3 :lol: wow so cold!

 

<div class='quotetop'>QUOTE(galaxee @ Nov 10 2007, 10:59 PM) [snapback]537917[/snapback]</div>

3C BBBrrrrrrrrrrrrrrr that's mid winter temp for us here.

 

I blocked the top grill with 7/8" pipe insulation yesterday before leaving for work. My first 5 minute bar was higher than it usually is. It's supposed to be close to 60 degrees here for the next two days and I have to have my oil changed in a couple of weeks so I will wait to do the lower grill until after that.
It looks a lot better than I thought it would, you don't really notice it unless your looking. So now I'm on the lookout for other grill blockers in my area.