Grill block worth about 1mpg
 

I put an experimental partial grill block on my manual shift 06 mazda 5 ( http://www.google.com/imgres?imgurl=...iw=862&bih=571 )that covered about 2/3rds of the large lower grill opening, and took a trip up north to visit relatives that I've made many times before, so I had a fairly reliable baseline of about 30 to 31 mpg on this trip. Keep in mind that the epa hwy mpg is only 27 on this car. I do run the tires at max sidewall pressure of 50 psi.


When I returned I squeezed in 15.44 gallons on 497 miles for 32.18 mpg. Thats 3% more mpg or about 16 extra miles from the tank for $1.00 worth of coroplast. The mod has already paid for itself. :)

I watched pretty carefully to see if the motor ran any hotter at all, and except for a bit faster warm up, I really couldn't see any difference at all. The car did seem to coast better, needing a bit less throttle, but I have no way of quantifying this result.

There may be more to gains to come by going further, covering even more grill, but I'm going to wait for really hot weather to ensure I haven't already gone too far. I don't want to have a car thats borderline overheating in hot weather.

Yup. That mod works every time. And it'll keep dropping $$ in your pocket, one at a time, week after week. Buy a cup of coffee... a donut. :)

that's about the same result i got, except mine starts to run hot, so im gonna put a gap in the middle to let more air flow to the radiator.

Thanks for sharing the news. I'm thinking about this on my '05 Accord V6 5AT but these 98-100 degree temps this week are making me think otherwise...lol, at least until after summer. I do plan on looking into a bellypan type piece from the front bumper lip back to the front axle.

I would suggest covering the upper grill opening completely, and see how that helps. The lower opening is generally much better at getting air through the radiator, since it is near the stagnant point, and close to the ground.

Also, once you limit the air flow into the cooling system, you can improve cooling by blocking off any openings in the lower "chin" area, that were needed before -- now with less air, all of it should go through the radiator. This way, just the right amount of air can do the job, and the lowest amount of drag can improve you FE by 10%+.

You might try ducting too. Yesterday night, just before sundown, I took 45mins and installed ducting behind my 80% lower grille block in order to deliver as much available air as possible to the radiator. The engine SEEMS to be a few degrees cooler. The real test will be if the coolant temp stays under 206, which seems to be the moment the fan cuts on. A second benefit is that my WAI gets warmer air sooner. I'll have to watch that too, as the air intake temp hit 45-50 degrees above ambient temps quickly.

MD - I wanted to experiment with a grille block also, but was a little worried about the same thing going into summer. I just spent a couple of bucks for some of that blue painter's tape and laid strips of it vertically across the front of my upper grille. If I started to run too hot, I figured I could just pull over and easily take it off. As it turns out, even with temps in the 88* to 92* here over the last week or so my engine temp only gained a few degrees (from a normal 184* to 192* at worst).

Go for it and see what happens. The worst you can be out is the cost of the tape.

Hint: I attached my tape in vertical strips from each outermost side and worked my way to the middle with a slight overlap on each strip. That way if your engine temp gets a little too high for you, you can just pull off a couple of strips from the middle to get a little more cooling. (I can't take credit for this, I read it elsewhere here on the forum. It was just easier to relate the info than try to search for who was the original poster.)

My bet is that you'll be just fine with the front grille completely taped. When you are satisfied that there's no danger, you can go ahead and make a more permanent block. That's my strategy going forward.

Good luck!
John

John, thanks for the info buddy! Do you have a pic of your more permanent setup? And did you only block the upper grille in your Camry or also block some of the lower opening?

MD -

I only taped it (the upper grille) up last week. Still rolling with that for now and probably for another week or so. I'm taking a longer highway round trip to the airport in about an hour and will be monitoring my temps during that. I'll be surprised if the engine warms up more than that 192* that I mentioned earlier.

When I do go with something more permanent, I'm pretty sure it will be a coroplast shield like most on here use.

I was looking at the lower openings just yesterday and there is really a lot of open area down there for air to get sucked in. I have to believe that I can block off at least the upper of the two lower openings...and then probably the outer sides of the remaining one.

I'm still relatively new here myself, so I'm attacking this stuff slowly but surely. :)

John

I have to say other than airing up the tires, this has to be one of the easiest mpg mods you can make. It took me all of 1/2 hour to do, and would have been easier if the grill opening wasn't vaguely trapazoidal. I used cardboard to play with the shape till it fit well and then transferred to the coroplast.

When I finally get the final size decided, I am going to make a new one from black coroplast and use black zip ties. The mod will be all but invisable then.

Dean