2010 Prius Grill Blocking strategy

Once the daily highs fall below 55*F, there's no concern with the lower blocked entirely... no gauge necessary.

 

Hey guys! I live in Mpls, and got our 1st prius a couple weeks ago. I was surprised at how much the mpg dropped the last couple days with temps well before freezing. I think I will give the lower block a try, sounds like its a safe temporary mod.

 

Give it a try, has worked excellent for me!

 

I made a trip from Sacramento to LA today and forgot to remove my grille block. Driving at sustained speeds of 80-85mph probably didn't cause too much harm but once I started up the grapevine I noticed my coolant temp was at 208F. The fans would bring the temp down to 202F but it would climb right back up. Before I could slow down and get to a safe exit I saw the temp hit 211F. Needless to say I yanked the grille block out. After that the coolant temp rose no higher than 198F even while doing 80mph up the rest of the mountain.

Interestingly, the outdoor temp sensor had been reading mid to high 50s for most of the trip. At one point prior to taking out the grille block the outdoor temp read 72F. After removing the grille block the outdoor temp went back to the mid 50s. It must have been getting pretty hot in there.

 

F8L there is a big difference between grill blocking while driving 65 mph on rolling foothill and grill blocking while driving 80 mph up a mountain.

I don't ever remove my half grill block but then again I never do 80 mph in my Prius.

It's also interesting that grill and grille are both proper for an automotive grill.

Some use grill to mean a cooking device and grille to mean the automotive feature.

Myself I think of grill as the automotive or cooking device and grille as a german artillery peice. See Grille (artillery) - Wikipedia, the free encyclopedia

 

All of my grille manufacturers spelled it grille so it stuck with me. Too many years selling parts.

I know I should have removed the block. I forgot about it. I just wanted to share my experience so others would be more wary. The grapevine is a pretty serious hill. At 80+mph you are over 4,000rpm for quite some time.

 

Is it true that the slogan for the Roadkill Cafe is, "From your grill[e] to ours"?

Ken-san, yoroshiku onegaishimasu. Are there any particular driving conditions in mind when considering your grille blocking guide? Would your guide be valid for sustained high speeds?

Since temperatures are in the range 18-30 during that day in Canberra I block 2/3 of the lower and leave the upper open.
I regularly drive from Canberra to Sydney, a distance of about 280km (174 miles). Most of the journey is at 110km/h (68 mph) and there are a lot of steep climbs.
I just drove back from Sydney after Xmas lunch. It was raining quite heavily. My coolant was peaking at 93°c (199F) even though it was below 18°c (64F) the whole journey and was only 12°c (54F) outside during the heaviest rain. A/C on 22.5°c to clear the windscreen. Speed was 110km/h (68 mph) and I generally stayed in the ECO zone even on steep climbs, maxing at 2450 rpm. Short periods of Super Highway Mode.

My peak coolant temperature was also 93°c yesterday (Xmas Eve) in temperatures approaching 30°c (86F).

1. Is 93°c (199F) too high, indicating that I should remove part of the grille block?
2. Why was my coolant so hot even when it was cool and wet outside?
3. Is there a way to know if the cooling fan is working too hard?

Here's a very old blog post that shows the elevation profiles of Canberra to Sydney and Sydney to Canberra. (It also shows me using cruise control and PWR mode!)

 

If it was wet on the road then you were using more horsepower to maintain a specific speed than if the roads were dry.

 

What was the temp of the MG1&2? How about engine oil temp?

Here is interesting info that could be relevant to transaxle failures due to grill blocking:

from: http://www.motordiagnostics.com/papers/TTFE1.pdf

If one wants to save on fuel in cold, one should install engine block heater. That would also decrease engine wear.

 

I fully agree that anyone blocking their grill should monitor important temperatures, unfortunately the Prius doesn't have an oil temperatures sensor. Fortunately oil temperature is largely a function of engine load, coolant temperature, ambient temperature and air speed so as long as coolant temperature is within reason and load is about normal oil temperature will likely be a little lower than normal warm weather driving.

There is no indication that people who live in moderate climates have problems with premature motor winding insulation failure. So, as long as you keep your MGx temperatures at or below whet they would run on a nice comfy 80F day, there is no real world meaningful harm done to to motor windings by blocking your grill.

 

I didn't monitor anything but water temp. My upper grille, where the inverter radiator is located, was unblocked completely.

 

Unfortunately, temp in engine compartment and air speed in engine compartment will be affected by grill blocking. Looks like people HOPE the oil temp is unaffected by blocking.

Luscious Garage | Blog | Gen 2 Prius (2004-2009) Transmission Failure, P0AA6, P0A92, P0A7A

writes this:

 

Thanks for sharing.. I do that trip every week thru the grapevine and most of the time at 80+.. I was thinking about grille blocking but probably wont now.

 

I wouldn't. I think the gains in mpg (small) are not worth the stress on the car.

 

100% lower grill(e) block this am. Lows in the 20's F highs in the 30's F. When do I take the block out?

 

Spring time! I originally blocked my lower grill at the end of Sept. and won't take it off until temps at least in the 60s.

With those temps, you should also block the upper grill.

 

There's a small radiator behind the upper grill that doesn't like full blocking. It's the separate coolant circuit, the one for the electric inverter or something.

If you want to be cautious I'd say just leave the upper grill completely open, stick to blocking the lower.

 

Is the temp gauge function on the scangauge FIA?

 

I wanted to post my initial findings in this sticky thread so others may feel a little more at ease regarding Inverter and MG1/MG2 temps when grille blocking.

The following are the results of 2 days worth of morning commutes with and without grille blocking. The weather was nearly identical on both days as was my driving style and speed. The second day was very slightly warmer but evens out with the fact I didn't follow any diesel trucks like I did on the first day (trying not to draft of course).

Using Torque app, I measured Inverter temp (MG Cool), MG1 Inverter Temp, MG2 Inverter Temp, MG1 Temp, MG2 temp, ICE Coolant Temp and Intake Air Temp. I took the screen shot after about 1/2 mile of city street driving 1/4 of which was EV and the other 1/4 was uphill on a steep slope. The car was parked but the shot was taken immediately after stopping so as to avoid heat soak being displayed.

Day #1:
I removed my grille block and kept a close eye on the relevant systems during his morning's commute. Ambient temp was 37F+-. No wind and dry roads. No heater use. 60mph with CC on.

This shot is at the end of my commute. MG temps were pretty maxed at this point but ICE coolant temp had dropped from a high of 194.8F because of the EV driving for the last leg of the commute.


Temps overall do not appear drastically different from the full lower grille block numbers. Also interesting is that my mpg for the trip was within a few 10ths of what i got yesterday with the full grille block.

My commute profile for reference. <20ft. ASL to 1,200ft. ASL over 48 miles.


Day #2
Today's result with 100% lower grille block.
Ambient temp was 41F-43F+-. No wind and dry roads. No heater use. 60mph with CC on. Ended the trip at 49.6mpg. Yesterday's trip was 47.2(?)mpg. No change in driving style.

 

As long as you are not going up a very steep hill for a long period of time at a high rate of speed.