Grill Block

[Kururu]

I have a Ridgeline and i wanted to see if the mpg will improve if I put a grill block. I do not know what to use or what I should cover. Here are some pics to show the front.

[SVOboy]

Which holes covers the radiator? I'd use corrugated plastic and cover everything not in front of the radiator + a little more.

[Tango Charlie]

First of all, a caution; make sure you can accurately monitor coolant temperature before blocking up large areas of your grille. A Scangauge is perfect for this.
That being said, coroplast works well for a block. See my Vibe thread for a blow-by-blow with pictures. Its the first link in my signature below.

[Johnny Mullet]

If it were my truck, I would internally block the entire grille where the Honda logo is and then externally blocking the entire bottom section leaving the center opening and test the results from there.

Most guys here like using coroplast, but I prefer using plastic truck mudflaps available in 24X30 or 24X36 inches and found at truckstops.

[Xringer]

Cover the top, bottom and side air-intakes with duct tape.
Use a SG2 to keep an eye on the radiator temp.

Here's my 1999 CRV.



Also did the wheels.


The ICE doesn't over-heat and it's about 75% covered over.

If you put the grill block inside, I don't think the aero is going to be as good.

If it doesn't work out for you, the cost was only some tape..

[lunarhighway]

on most cars the top grill is more for looks than aero and generally in a less high pressure area. on a large truck is is probably less so. open the hood and see where the actual radiator is... also see where the engine breaths air. sometimes you can get away with blocking the whole grill be FE and performance falls as the engine breaths hot air trapt in the engine bay. initially make something you can quickly take off and take the tools along to do so... if temps go up to high you can correct the situation.
carboard is great for initial testing if it's not to rainy... it's more available than coroplast and if your first attempt is not successfull just throw it out

[Cobb]

Hows the ridgeline doing? 17.6 mpg is that right? Your lex is getting almost 3 times that. My tacoma with the v6 and supercharger was getting 18 mpg.

[tyronasauras]

Blu painters tape works great for testing and will hold up for months even in rain and easy to fix and remove. They also make it in an extreme version now for exterior use. Duct tape not so much.
I think you can start by blocking the top half of most upper grills without any problem..
Wish we could get the "blu tape in a gray or silver color.

[aerohead]

The distance from the grille opening,to the face of the radiator is an important consideration.High performance cooling systems have an inlet duct which is at least as deep as the height of the radiator,and are airtight.
Without the proper depth,momentum of the incoming air stream may prevent enough divergence,necessary for the air to impact the entire face of the heat exchange media.

[ME_Andy]

I highly recommend this peelable caulk. If you screw up the first time, you can rub it off with your fingers. Much better than the epoxy I used which is pretty much permanent.

Amazon.com: Dap 18354 Seal 'N Peel Removable Caulk, 10.1-Ounce: Home Improvement