Have any here installed hood vents, vents along the windshield wiper tray or looked into what other engine compartment venting solutions might work for our trucks. I do some grill blocking and by keeping the engine bay cooler could block more of the front end openings for some additional fuel economy.
Around the city grill blocking doesn't do much but at freeway speeds there can be marked improvements for most, as much as 5 mpg on some vehicles depending on speeds traveled. One of the things that I've noticed from doing a complete block of the center V section of the rad grill is that my windshield stays a lot cleaner during the summer bug season.
I guess I'd have to take off the grill blocking if I was to do some trailer or boat towing.
YMMV
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