Using Grill Blockers to Improve Winter Fuel Economy

If you live in an area where temperatures plunge well below freezing, you might already know that grill blockers improve winter fuel economy a bit by keeping ultra-cold air out of the engine compartment. While cold weather presents challenges, we can fight back against Old Man Winter by taking simple measures to stabilize temperatures under the hood. Take a look at the trucks in any random parking lot; it’s no secret that engines are most efficient when run at an optimum temperature. Jury rigged apparatus abound at this time of year – from slabs of zip-tied quick-and-dirty cardboard on up to the most aerodynamic and weather-resistant designs. But you won’t find an off-the-shelf bolt-on product at AutoZone, PepBoys, or Costco. It’s all about the D-I-Y …

I found a nifty grill blocker scheme in a YouTube video that was just posted a few days ago. This ingenious technique uses foam pipe insulation. It’s super quick, but it’s not dirty, whatsoever. You’d be hard pressed to find something that’s as easy to install and modify … not to mention inexpensive. All you’ve got to do is spend a few bucks at your local hardware store, Amazon (or Home Depot) and five minutes fitting, cutting and installing.

Foam pipe insulation is sold in a number of widths. Manufacturers include Duck Brand (shown below), M-D Building Products, ITP, and Thermwell Frost King. Look for insulation sticks that are pre-slit to save time.

foam pipe insulation for grill blocking

Unfortunately, the foam pipe insulation method won’t work with everything. If you have a grille with horizontal slats (like the Honda Civic shown in the first video), you might be in luck. For other grill designs, the Coroplast and Zip-Tie method will get the nod. This next video shows that method being used on a Scion Xa, with a super stealthy installation.

Cardboard should never be used as anything other than a temporary solution. It’s only a matter of time until it begins to disintegrate once it gets wet. That’s why Coroplast is so cool … it’s similar to cardboard, but is made of plastic. Coroplast is most commonly used in the sign industry, so while you might have a hard time finding it at retail stores, you should be able to buy a sheet from a friendly local sign shop. If you can’t turn up any Coroplast locally, you can always order it online from Uline or a sign shop supply house.

A number of dedicated EcoModders have gone through the effort of sculpting grill blocks from insulation foam. This approach can be extremely time-consuming if your goal is a smooth factory-like appearance. Get it right and the results are rewarding. Get it wrong and you’ll end up with a lumpy nose. Beauty takes time.

Well designed grill blockers can improve aerodynamics. While this may help to increase gas mileage year round, you run the risk of reducing cooling during the summer months, and that’s not a good thing. You should monitor your engine temperatures carefully, when using a grill blocker. If your vehicle lacks a factory engine temperature gauge, use an OBDII device. A ScanGauge will get the job done or you can use an Android or iOS device running TorquePro or DashCommand.

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2 thoughts on “Using Grill Blockers to Improve Winter Fuel Economy”

  1. That last part about monitoring temps is very important. Back when I was playing with grill blocks on my Fit, I found it was a fine line between not doing much and starting to overheat.

  2. I live in an area with cold winters but I’ve never heard of grill blockers. It’s interesting to know that a grill blocker could improve the fuel economy of my truck by keeping cold air out of the engine compartment, like you said. I think I’ll have to look into having this installed on my Mitsubishi before this coming winter. Thanks for the helpful post.

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