another yaris noob

[SVOboy]

This picture:

Tells a different story about engine temperatures and fuel trim correction values.

[MetroMPG]

You start blocking the grill in the summer time ... and you will end up overheating the engine.

Maybe a little hyperbole, JanGeo? I haven't heard any reports of overheating from anyone here running blocks.

Obviously, it goes without saying: caveat experimentor. Any change to the cooling system needs to be monitored.

Cooling & A/C systems are designed to operate in worst-case conditions - e.g. idling, in Death Valley in July - and they contribute to inefficiency as a result when not operating in those conditions.

The appearance of active grilles on production cars is proof of that.

If you block agressively, then YOU have to be the active element in the system (ie. open things up if it gets hot).

[ketel0ne]

Here is the best front end shot I got so far. Ignore the second set of 30 day plates The pic is huge.

http://i66.typepad.com/mpg_digest/yaris/IMG_3114.jpg

[schmeep]

yeah, that shows it really well. thanks ketel0ne

[SVOboy]

I still say block it!

[ketel0ne]

Can it be blocked in a similar fashion to how the cutouts where the fog lights would go are? Or does it need to make the front end flat?

[MetroMPG]

Yup. As a VERY conservative start, I'd at least block the area that's not directly in front a radiator. But the block, if not done in front of the grille, would have to go directly up against its "back" on the inside. But that'll just trap bugs 'n' stuff, won't it?

Any air you can keep from going through the grille and ultimately exiting under the car is better off going over/around the outside.

[MetroMPG]

Just as a reality / perspective check: I measured just under a 3% increase in FE by agressively blocking my grille openings (which has a MUCH larger stock open area and smaller radiator= more room for improvement, than the Yaris).

[schmeep]

i wonder if maybe completely blocking the bottom one, but keeping the top one open might be an improvement

i would rather be conservative with a block, rather than worry about overheating the engine.

[schmeep]

when i say "blocking the bottom one", i mean the bottom grill