Blocking the grill

Crap appearance is relative. If I saw human crap I would be repulsed; however, if I saw the crap of a Tasmanian Wolf (Thylacinus cynocephalus) I would be overjoyed and find it beautiful! :lol:

The best looking method would be to take apart the plastic facia over the radiator area and put some kind of flat plastic-like panel to block air coming through the openings from hitting the radiator. There are numerous threads in here that show a pic of someone using a yellow panel for such a purpose.

In on the of the newer threads someone used thinner pipe insulation and tucked it in nice and neat. I thought it looked good myself. I would recommend doing a search and finding the latest thread on the subject. It was only posted about a month ago.

This is the thread:

Looks good IMO.

 

<div class='quotetop'>QUOTE(New2Prius2008 @ Nov 18 2007, 03:16 PM) [snapback]541272[/snapback]</div>

Misunderstood advice, but still very good.

Realistically, unless the temperature is well below freezing, you aren't really gaining warmth from blocking. I certainly haven't from my first month's of data... and I've got 4 years to compare back to. When it gets a lot colder, observations from lower-grill blocking may be revealing. But we're talking 20 F at the very warmest.

At above freezing temperatures, the blocking benefit mostly comes in the form of improved aerodynamics. The sealing of the upper-grill section definitely contributes to higher MPG, especially at highway speeds.

So regardless of the whys, it is indeed a good thing to do.

 

We use the simple pipe insulation that one can purchase at any home improvement type store. it comes in about 4 ft. lengths. cut is one lengthwise opposite that existing cut so you end up with two long pieces. then you just tuck it in and trim it to fit.

Its one of the cheapest and effective and safe additions for wintertime. Good Luck!! B)

 

<div class='quotetop'>QUOTE(efusco @ Nov 18 2007, 04:41 PM) [snapback]541301[/snapback]</div>

This has taken a weird turn.

How could improving airflow not make a difference?

I live 3 blocks from a 70 MPH highway with an uphill ramp. Only the upper-grill is blocked and the 2 lights are usually green. The first 5-minute segment shows a definite MPG increase.

 

<div class='quotetop'>QUOTE(efusco @ Nov 18 2007, 08:48 PM) [snapback]541390[/snapback]</div>

You seem to be forgetting that my driving style, situation, and fuel is the quite different from yours... I haul nice person onto the highway. I never, ever pulse & glide. I don't have an EV button. Maximizing engine-off means little to me. My efficency aim is simply keeping the current MPG over 50...

So our basis of measure have little in common. You are that guiding-light for aspiring enthusiasts. I am the representative of joe-consumer-never-participate-online. That's a huge difference.

I blocked the upper-grill. I didn't witness any temperature difference on the ScanGauge, just very stable as usual. Yet, MPG climbed. Preventing the pass-through/entry of sure makes a heck of a lot of sense as the major influence at temperatures above freezing, since the warmth isn't needed yet. With the upper sealed, the pressure pocket reduces input from the bottom.

If it was warmth, how does that factor in at 70 MPH? My engine stays at a happy 186^F quite consistently, like before upper blocking. What's different if it isn't aerodynamics?

 

I notice a difference with my blocked grill. The car warms up faster and stays warm longer without the engine running. At an ambient temp close to freezing, so far (hasn't gotten cold here yet), in city driving at 50-70 km/hr (30-45 MPH) the car will not warm up. With the blocking the coolant will reach 70-80C. It gets to 50C in just a few minutes, and will blow nice warm air inside.

Here's what mine looks like, with 3/4" pipe insulation in the top grill and 1 1/2" to 2" in the lower grill. Bonus, it also protects the grills from winter crud and makes it easier to clean the front.
[attachmentid=12522]

 

No worries about over heating?

 

After watching the coolant temp with the Scangauge for awhile, I'm confident it will not overheat as long as the outside temp is below 20C (70F). If the temp goes above 20C it might overheat on the highway, but probably not in the city. At any rate, it's easy to remove the foam. Just cut the two zip ties and pull it out (lower). The upper can be left in until it's 30C (80F) ambient.

You'll note I left the sides of the foam open. So if necessary the fans can draw air in from there. So far, I haven't see/heard the fans run, even when the ambient was at 21C. So the fans give me an extra "safety factor".

 

John and Evan:

Let me throw in one fact here regarding aerodynamics. Whenever air is forced to change direction, you have drag.

So John may be seeing an aerodynamic improvement by reducing incoming air which strikes the engine, gets deflected, and causes drag. This technique has been used to great effect by light-aircraft manufacturers. By redesigning air intakes, cowling shape, and directing airflow, they greatly reduced the drag of air cooling the engine.

This effect, which may be small at automotive speeds, could still be noticeable on some cars in some conditions. For John, it appears to be noticeable. For others, it may not. Factors such as driving style, tire pressure, vehicle load and vehicle drag contribute. (Some cars may actually have lower drag coefficients than others, based on production variations.)

So I think you're both right, though the main intent of grille-blocking is to increase temps, improving warm-up times.

 

Evan and John: Good thread. Thanks to both of you for your expertise and willingness to share your experiences. And, David, thanks for the photo of your grill blocking. I blocked mine after hearing from you guys with the ScanGauges that the temps would not get too high.

 

how do you get such great mileage? i'm "only" getting 46mpg.

alex :blink:

 

<div class='quotetop'>QUOTE(efusco @ Nov 20 2007, 09:11 AM) [snapback]542012[/snapback]</div>

I tend to agree. It's a small improvement in aerodynamics at best.

Maybe John's MPG improvement is because they've changed the timing on the green lights!

 

I'm a new convert to blocking. I'm in Seattle and the temperatures have been heading down the past few days. I only do a 3 mile commute, so my mileage runs anywhere from 41 - 46MPG, depending on how late I slept in. Tires are 42/40PSI. Over the past week, my mileage has been down to 38.8MPG. In the morning, I usually get 25MPG for the 1st 5 minutes, followed by 50 - 70 MPG - again, depending on how cozy my bed felt. Lately, it's been 20MPG for the 1st 5 minutes, followed by 25-35MPG as the temp's have fallen.

So I bought 6' of 3/4" insulation for $1.19, cut it in half and put 1 strip in the top grill and 2 strips in the bottom grill. I still have about 3'-4' left over. The resulting MPG has dramatically improved. My 1st 5 min. was 25MPG, followed by 50MPG! So there's another endorsement for blocking.