True value of grille blocking?

I could be wrong, but I personally don't think you could stay below 200 degrees at 70 mph up a big hill around 45 degrees.

 

I don't think a climb long enough with a 70 mph limit exists in Minnesota.

I wouldn't attempt it anyway. 45°F is considered balmy, light jacket, spring activity, winter over weather here.

 

I actually travel I35 quite a bit between Des Moines and The Cities. There aren't a ton of them, but there are some good hills on that stretch. If I didn't own crappy OBD bluetooth adapters I could give you some better numbers.

Don't ask, but I had to travel around 82 mph for a while the other day at about 55 degrees. Needless to say I made sure to take out some of the grill blocking.

 

I am curious what coolant temps have been noted via Scan gauge or Torque With lower grille blocked that have made you concerned enough to remove all or part of your lower grill blocking.

Please note what outside/ambient temp and driving conditions that gave you greater than 200F (and if lower grille not 100% blocked, mention your ≈%. I'm in Northern Calif and have ≈66% of lower grill blocked. We have had days of mid 7o'sF and I don't think it has caused temp issues on ≈2 min. small hills of Vasco Rd. But My wife drives it mostly and I have only used Torque a few times. (Torque is on her Android. Not available for my iOS 5.1.5 4S.)

 

Since the purpose of blocking is heat-retention and 50°F is dramatically warmer than anything we consider cold here in Minnesota, it seems pointless to even bother. The benefit comes from outside temperatures well below freezing.

 

I understand the ICE run time (energy) required to heat the ICE from say 32F to 190F is significantly more than from say 50F to 190F. But I wonder if there is marginal energy savings even in our CA warmer climate. Or if the blocking marginally reduces drag as some have posited. Just wondering if the marginal savings amounts to (maybe low single digit) dollars per month vs. (low single digit) dollars per year. Just trying to get a sense of how far I am into the "why bother, it's not even going to pay for the $2.7o worth of foam used." This may well be one of my 'over do it' things, But for $3.00, I just couldn't help myself.

The one 6' piece of foam I used covers ≈ 66% of the lower grill.

 

I agree that for that price you might as well and try to get some benefit out of it. Just be careful and monitor temps when the outside temp gets very high. And there is also no point in using blocking if you are ever running the AC, in fact you don't want to block then.

 

Good point on the AC running. I will be sure to remove my partial blocking before AC is called for.

 

I recently took a vacation trip, Kentucky to Florida and back. I started the trip with an OAT of 20f and 100% lower + 50% upper grill block with "Torque" running on my Galaxy Tab. On the second day in the mountains of South Carolina the OAT had climbed to 65f and coolant temp started hitting 204 then falling quickly to 195 as I climbed hills at 65MPH (I assume that was the effect of the radiator fan(s)). At the next rest stop I removed the top block and reduced the lower block to 75% (which is how I ran the rest of the trip). After that I never saw coolant temp hit 200F even when the OAT hit 75 but by then it was basically flat land. On the return portion of the trip the OAT was about 50 F, in the hilly portion, and coolant temps stayed below 200f.

 

Thanks for the info Jerry. We had 78F temps this weekend in Nor. Cal. so I removed the 66% lower grill blocking before it was driven in these warmer temps. Wife commutes and usually works late, so it has only seen early morning and late evening drives over the Vasco Rd (small) hills. Decided to forego the small advantage this may have provided for my wife's piece of mind (and therefore mine too ).

 

running 100% blocked lower grille.
One observation I had recently was how fast the coolant temps drop when I switched back to EV mode at highway speeds preparing to exit the highway.
It was mid 20's outside and coolant temps were around 190 when I switched.
Speeds were mid 50's mph.
The coolant temps dropped about 2 degrees every couple seconds!
Wonder how fast it'd be without the blocking?

Galaxy Note 10.1 ? Pro

 

Assumptions:
12,000 miles per year
50 mpg
$3.50/gal gas
3% improvement in fuel economy

240 gallons of gas burned per year for a total cost of $840. Saving 3% of that would be $25 (7 gallons), or roughly $2/month.

I don't know what % savings the Prius can gain from a grill block, but some people report up to 5% improvement.

It's possible to calculate the improvement in aerodynamics by doing a coast-down test. This thread explains the testing procedure.

It looks like the answer to your question is that it saves low single digits of dollars per month.

I disagree. Most cars run 1 cooling fan whenever the AC is turned on. There is a gap between the grill opening and the front of the radiator. Even with 100% grill blocking, air is still drawn through the radiator by pulling in air between the gap. A small opening in the grill block can further provide cool air to the AC.

While I don't yet have hard data, my best guess is that a partial grill block would still be more efficient than no block, even while running the AC. My reasoning is that the AC itself might represent a 5% reduction in fuel economy compared to a 3% increase in fuel economy by running a grill block. You would have to reduce the efficiency of the AC by approximately 60% to completely negate the positive effects of the grill block.

My advice, regardless of AC use, is to run as much grill block as possible while avoiding significant engine coolant temperature rises, and especially avoiding temperature rises that result in the electric cooling fan kicking on.

 

My black duct tape grille block. 100% lower grille blockage. Redid it once this winter. And cheap too!

Galaxy S4 ?