Grill Blocking Caution

**efusco** · 12-03-2007, 11:02 AM

I posted this in the KB article as well, but thought more folks might see it here:

Hey guys...I have some key info I think is important for those blocking their grill.

I recently converted from my old style of block (one piece of insulation for the top grill and one for the bottom) to blocking each individual slat for a nicer appearance. I drove today from my home to St. Louis. Temps were around 42F and the terrain is hilly..steep in areas but nothing dramatic by Ozarks standards. This is all interstate with a70mph speed limit...and that's what I had the CC set at.

Previously I've driven this in similar conditions with grill blocking and temps for MG2 and the ICE were fine. Today, however, I got a little concerned. I actually witnessed MG2 temps climb slowly during the drive up to 114F sustained and ICE temps up to 204F spikes, but sustained closer to 197F.

I think the individual slat blocking gives a much more complete obstruction to air flow...great thing for short, low ICE used (aka city) trips, not so great with high speed hill climbing continuous ICE trips. If temps had been closer to 50F without ability to monitor I'm seriously concerned I could have been in the danger zone for the temps.

I stopped for gas with the intention of removing a block from one lower slat but actually forgot. When pulling out of the parking lot I remembered and stopped, backed up a few feet (25' max)...saw MG2 spike to 152F briefly!!! That's,by far, the highest I've ever seen it. I pulled the middle insulation strip for the lower slats and took off. MG2 temp quickly dropped and was down to 120 by the time I was off the exit and within a mile was below 110.

From that point on ICE temps ranged b/w 182F and188F(trending lower), MG2 was in the 70s and 80s the rest of the trip. Actually those are cooler than I would have liked, but I didn't want to stop again. And I didn't want to risk higher temps.

So, if you have your grill completely blocked with the individual slat technique and do NOT have a way to monitor temps be very very careful on highway/high speed/high demand driving conditions esp. if OAT is over40F...I used to say 50F was safe, but I would not reconsider under slightly more extreme conditions.

**Tideland Prius** · 12-03-2007, 02:22 PM

Good to know Doc! Yeah I have mine in several pieces actually.

For the upper grille, I have two pieces for the bit above the grille bar and two pieces below.

Hmm.. 10°C for city driving?

I had them on until 15°C

Bob64 · 12-03-2007, 05:51 PM

I have mine arranged in a 90% blocked 10% gap on the right side of the lower grill.

a priori · 12-03-2007, 06:57 PM

Very important warning! Thanks, Efusco, for keeping track of this.

We aren't getting above freezing for a few days, so I'm not much concerned, but this is a critical warning to remember when Spring rolls around.

Would you be able to add this to the Grill Blocking Summary article? I thing we should include a link there to this posting so people can keep track of the ongoing discussion.

Proco · 12-03-2007, 07:32 PM

Thanks for the heads-up, Evan! I use the individual slat technique & have a daily commute of ~50 miles. I'll make darn sure I keep at least one lower one clear.

**efusco** · 12-03-2007, 08:11 PM

Quote:

Originally Posted by SJL

Very important warning! Thanks, Efusco, for keeping track of this.

We aren't getting above freezing for a few days, so I'm not much concerned, but this is a critical warning to remember when Spring rolls around.

Would you be able to add this to the Grill Blocking Summary article? I thing we should include a link there to this posting so people can keep track of the ongoing discussion.

I posted it there first.

craigk · 12-03-2007, 10:45 PM

Thanks for the details and warning, I just blocked one upper and one lower a couple of hours ago! The temp here is 15f, but maybe I'll unblock one anyway on my highway road trip coming up soon. I don't think it helps as much for a 400 mile highway drive anyway, does it?

**efusco** · 12-03-2007, 10:52 PM

Quote:

Originally Posted by craigk

Thanks for the details and warning, I just blocked one upper and one lower a couple of hours ago! The temp here is 15f, but maybe I'll unblock one anyway on my highway road trip coming up soon. I don't think it helps as much for a 400 mile highway drive anyway, does it?

With even just one lower slat unblocked at 43F I showed ICE temps below normal operating temps...I don't know how much, if any, that affected efficiency, but it certainly wasn't in the 'normal' range.

At 15F I'd have the whole thing blocked up tight as a drum.

craigk · 12-03-2007, 10:54 PM

Quote:

Originally Posted by efusco

At 15F I'd have the whole thing blocked up tight as a drum.

I'm afraid to block the grill 100% when on the highway without the scanguage.

ad78 · 12-03-2007, 11:38 PM

i just blocked the whole grill this evening, went to home d**** and got it for $2. getting worst weather here in CT. so i think i can say its safe to blocked all the grill till february i guess.

will get SGII the next payday

12-03-2007, 11:02 AM	#1
efusco Troll Slayer Join Date: Nov 2003 Location: Nixa, MO Posts: 17,242 My Car: 2004 Prius Model: Package: #9 Thanks: 49 Thanked 255 Times in 153 Posts Friends: 37	Grill Blocking Caution I posted this in the KB article as well, but thought more folks might see it here: Hey guys...I have some key info I think is important for those blocking their grill. I recently converted from my old style of block (one piece of insulation for the top grill and one for the bottom) to blocking each individual slat for a nicer appearance. I drove today from my home to St. Louis. Temps were around 42F and the terrain is hilly..steep in areas but nothing dramatic by Ozarks standards. This is all interstate with a70mph speed limit...and that's what I had the CC set at. Previously I've driven this in similar conditions with grill blocking and temps for MG2 and the ICE were fine. Today, however, I got a little concerned. I actually witnessed MG2 temps climb slowly during the drive up to 114F sustained and ICE temps up to 204F spikes, but sustained closer to 197F. I think the individual slat blocking gives a much more complete obstruction to air flow...great thing for short, low ICE used (aka city) trips, not so great with high speed hill climbing continuous ICE trips. If temps had been closer to 50F without ability to monitor I'm seriously concerned I could have been in the danger zone for the temps. I stopped for gas with the intention of removing a block from one lower slat but actually forgot. When pulling out of the parking lot I remembered and stopped, backed up a few feet (25' max)...saw MG2 spike to 152F briefly!!! That's,by far, the highest I've ever seen it. I pulled the middle insulation strip for the lower slats and took off. MG2 temp quickly dropped and was down to 120 by the time I was off the exit and within a mile was below 110. From that point on ICE temps ranged b/w 182F and188F(trending lower), MG2 was in the 70s and 80s the rest of the trip. Actually those are cooler than I would have liked, but I didn't want to stop again. And I didn't want to risk higher temps. So, if you have your grill completely blocked with the individual slat technique and do NOT have a way to monitor temps be very very careful on highway/high speed/high demand driving conditions esp. if OAT is over40F...I used to say 50F was safe, but I would not reconsider under slightly more extreme conditions. __________________ Evan E. Fusco, MD "It's a damn poor mind that can only think of one way to spell a word." -Andrew Jackson

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12-03-2007, 02:22 PM	#2
Tideland Prius Moderator of the North Join Date: Oct 2004 Location: Canada Posts: 19,633 My Car: 2010 Prius Model: N/A Package: Technology Package (Canada) Thanks: 229 Thanked 345 Times in 244 Posts Friends: 23	Good to know Doc! Yeah I have mine in several pieces actually. For the upper grille, I have two pieces for the bit above the grille bar and two pieces below. Hmm.. 10°C for city driving? I had them on until 15°C

12-03-2007, 05:51 PM	#3
Bob64 Sapphire of the Blue Sky Join Date: Apr 2007 Location: Virginia Posts: 1,135 My Car: 2007 Prius Model: N/A Package: #2 Thanks: 3 Thanked 9 Times in 9 Posts Friends: 0	I have mine arranged in a 90% blocked 10% gap on the right side of the lower grill.

12-03-2007, 06:57 PM	#4
a priori Canonus Curiosus Join Date: Aug 2007 Location: Chicagoland (West) Posts: 2,663 My Car: 2010 Prius Model: V Package: Adv. Technology Thanks: 150 Thanked 297 Times in 181 Posts Friends: 18	Very important warning! Thanks, Efusco, for keeping track of this. We aren't getting above freezing for a few days, so I'm not much concerned, but this is a critical warning to remember when Spring rolls around. Would you be able to add this to the Grill Blocking Summary article? I thing we should include a link there to this posting so people can keep track of the ongoing discussion.

12-03-2007, 07:32 PM	#5
Proco Senior Member Join Date: Jun 2006 Location: The Beautiful NJ Shore Posts: 2,414 My Car: 2006 Prius Model: Package: #5 Thanks: 62 Thanked 93 Times in 53 Posts Friends: 9	Thanks for the heads-up, Evan! I use the individual slat technique & have a daily commute of ~50 miles. I'll make darn sure I keep at least one lower one clear.

12-03-2007, 10:45 PM	#7
craigk Senior Member Join Date: Dec 2006 Location: Golden Valley, MN Posts: 113 My Car: 2007 Prius Model: Package: #2 Thanks: 0 Thanked 0 Times in 0 Posts Friends: 0	Thanks for the details and warning, I just blocked one upper and one lower a couple of hours ago! The temp here is 15f, but maybe I'll unblock one anyway on my highway road trip coming up soon. I don't think it helps as much for a 400 mile highway drive anyway, does it?

12-03-2007, 11:38 PM	#10
ad78 Senior Member Join Date: Nov 2007 Location: Rocky Hill, CT Posts: 119 My Car: 2008 Prius Model: Package: #6 Thanks: 0 Thanked 0 Times in 0 Posts Friends: 0	i just blocked the whole grill this evening, went to home d**** and got it for $2. getting worst weather here in CT. so i think i can say its safe to blocked all the grill till february i guess. will get SGII the next payday