First Morning with a Blocked Grill

Actually I had both upper and lower grills blocked off last year. If you hadn't been so worried about me tearing your back seat apart to show Parrot Lady you would have noticed.

And listen to the good Doctor. Block off everything and don't worry until May. And get yourself a block heater so the grill block has some real heat to protect in the first five minutes. Besides I need one more install to make it an even dozen block heater install's.

Wayne

 

I am using the same technique with good results. I first put the insulation in all slits in both the top and bottom grills in early November. I took a trip shortly afterward with ambient air temperatures in the 60s (IIRC) on the first leg of the trip. My ScanGauge showed coolant temps frequently creeping up above 200F on the highway, so I temporarily removed the piece in the bottom slit of the bottom grill. Coolant temps have since stayed at or below the mid-190s in all driving conditions. After winter temperatures are here to stay (we had record highs yesterday), I'll put the piece back in the lower grill.

I haven't done a precise before and after MPG comparison, but my per-trip results are similar to Tony's: After the predictably low first 5-minute segment, I routinely see segments above 50. My current tank average is around 52. (It actually was at 57 eight days ago. I've been on a business trip since then that requires 2 or 3 short drives per day of a 1/2 mile or less with cold starts.)

 

Can anyone post some pics of your installation? Just wondering what it looks like and how everything is attached.

 

I've got a Classic Prius which doesn't have the plastic top cover at the front of the hood, so I usually do two levels of blocking.. Instead of shoving pipe insulation in the grill, which I feel really looks bad, I insert a sheet of that foil-lined bubble-wrap insulation right in front of the radiator, but behind the small hybrid radiator. This blocks 90%+ of the air flow through the main radiator, but leaves the hybrid radiator exposed and at full cooling efficiency. This arrangement is good up to about +10C or so and down to about -5C.. For colder weather, I also insert an additional couple of sheets of coroplast (with cutouts to make it around the supports, etc) that further block air flow through the front.

I also have a hood liner made up of the same foil-lined bubble-wrap insulation to reduce engine heat loss through the hood. With this liner, you can drive the car for several hours and hood doesn't even feel warm afterwards.

With the full arrangement (hood liner, radiator insulation and coroplast shields), the car will overheat at any temperature above 0C (I've had the heat turned up full blast and windows open to keep the engine temperature down on warm days when I was too lazy to remove the blockers), but is great down to -30C.. I get full stealth and engine stop, and very good cabin heat. The engine itself runs better as it keeps warm, but additionally, the intake air temperature is now at least 4-10 degrees warmer than ambient, so fuel economy and power are also much better, and there's no obvious signs of blocks of foam, etc from the front of the car..

 

I've been waiting for the real cold, when high's don't exceed freezing for a month. With 3 years of data now, I'm very well prepared to quantify the kind of improvement comes from blocking and I too see it as safe.

A few weeks ago, when the temperature was at 12 F, I played with pipe insulation to see how well it (the 3/4" size) would attach. That worked like a charm. Though the smaller (1/2" size) probably provides a better overall fit.

Since it is now warm again (30's) all is off for more collection of control data. In the meantime, I'm hoping to stumble across a more cosmetically appealing solution... something the masses will easily adopt, so easy installation in the cold is a must.

As for above when this is beneficial, I'm not recommending that another bother unless they routinely deal with sub 25 F tempertures. MPG and the heater have been quite good when it's warmer than that. There doesn't appear to be any real gain unless it's Minnesota cold.

 

Tony, why do assume that the length I chose was random but correct. I spent many a minute in Menards that October day debating which package of pipe insulation was on sale for $.99 before making my choice of the "Prius-centric laser cut winter thermal management devices".

Wayne

 

<div class='quotetop'>QUOTE(theforce @ Dec 19 2006, 03:00 PM) [snapback]364208[/snapback]</div>

I second the request for pics (whether they be cosmetically satisfying or aesthetically appealing)

Thanks!

 

<div class='quotetop'>QUOTE(TonyPSchaefer @ Dec 19 2006, 05:53 PM) [snapback]364338[/snapback]</div>

Thanks - I couldn't figure it out either based on what you said about using the pipe insulation.

 

I'm a bit puzzled. Is the Prius ICE coolant thermostat inadequate to maintain an appropriate operating temperature regardless of the OAT? In Dallas TX, its possible we will have some short periods of 30º and some years down to ~10º, but generally our winter temps are relatively mild.

These solutions make me think of an 18-wheeler cab with a Confederate flag draped over its grill. :lol:

 

<div class='quotetop'>QUOTE(Charles Suitt @ Dec 19 2006, 06:16 PM) [snapback]364347[/snapback]</div>

I used to have a 2000 GMC Sierra, which had the aluminum head 5.3 V8. Driving around Winnipeg in temps of -25 C or colder, it never warmed up either. So I got a winter front from Canadian Tire and cured that problem.

At one time winter fronts were common on cars/trucks here. Heaters work so well now, folks don't use them as much. I also suspect they really don't care if the motor warms up properly.

An all-aluminum motor, and a diesel motor too, really benefits from a winter front. My first winter without the front, at -40 C I just about froze my pointy bits off driving around the city. Got terrible fuel economy too.

With the winter front, even at -36 C I had plenty of heat, and the ICE would - briefly - shut off at red lights.

I would love to post a picture of the front of my Prius, but I only have 1.28 K of Global Space. If a nice moderator could fix that, I will happily post a picture once I return from my business trip this Saturday.

Or maybe first week in January when I get back from vacation.

 

I need a reality check please.

The thermostat in the engine is supposed to close when the coolant is too cold (and open when too warm) such that the radiator cannot deliver "cold" coolant to the engine. What is the purpose of blocking air to the engine/radiator? Is the engine itself efficient enough at losing heat?