Can someone explain grill blocks to me?

[Christ]

It shouldn't get soggy at all... you can put shellac coating on it to waterproof it. (Shellac is environmentally friendly and edible when dry.. it's made from bug poop, though.)

I wouldn't do the lower ones, though... it might defeat the purpose, since your bottom grilles are presumably lower than the stagnation point. (Usually, you let the dirtiest areas stay dirty, and clean up the other areas.)

It might be in your best interest to start at the upper grille, then, once you're comfortable with it, block one part of the lower grille, etc.. until you start noticing the fan coming on more often, or noticing that your heater is hotter, blah blah blah..

You really should get an aftermarket temp gauge, at least. The OEM gauge isn't accurate at all, and will read normal in a range of ~160dF to 205dF before it changes position again.

[cfg83]

Christ -

Originally Posted by Christ

...

A grille block merely allows less direct airflow over the radiator, which affords less cooling capacity (not necessarily a bad thing) to the coolant, so that when it is able to re-enter the engine, it's warmer than it normally would be, takes less time to cycle back to 195dF, which means the engine warms up quicker than normal, with less heating/cooling cycles of the coolant before stabilizing.

...

I thought that another purpose of the grille block was to keep the engine running hotter in general (maybe this is what you wrote). The idea is, we are "narrowing" the operating range temperature of the engine on purpose because hotter means more efficient (to a point). We can get away with this because we are running under reduced load and we are monitoring the engine at a higher degree of attention than regular drivers. Does this make sense?

CarloSW2

[RandomFact314]

Originally Posted by Christ

It shouldn't get soggy at all... you can put shellac coating on it to waterproof it. (Shellac is environmentally friendly and edible when dry.. it's made from bug poop, though.)

I wouldn't do the lower ones, though... it might defeat the purpose, since your bottom grilles are presumably lower than the stagnation point. (Usually, you let the dirtiest areas stay dirty, and clean up the other areas.)

It might be in your best interest to start at the upper grille, then, once you're comfortable with it, block one part of the lower grille, etc.. until you start noticing the fan coming on more often, or noticing that your heater is hotter, blah blah blah..

You really should get an aftermarket temp gauge, at least. The OEM gauge isn't accurate at all, and will read normal in a range of ~160dF to 205dF before it changes position again.

Oh ok.. I figured it would be better to block off the 2 lower ones since the top ones is so small anyways but I guess Ill do the top one first..

btw... If my results come out like metro-mpg and I get a 3.1% gain then I would be getting an extra 1 MPG which is pretty good... But that obviously is "IF"

[Christ]

Originally Posted by cfg83

Christ -



I thought that another purpose of the grille block was to keep the engine running hotter in general (maybe this is what you wrote). The idea is, we are "narrowing" the operating range temperature of the engine on purpose because hotter means more efficient (to a point). We can get away with this because we are running under reduced load and we are monitoring the engine at a higher degree of attention than regular drivers. Does this make sense?

CarloSW2

Carlos -Sure, this is an added bonus, in some cases. The coup here is that many engines already run hotter now than they did in the past (generation-wise, not "my car used to run cooler than this") and are much closer to their optimal range.

Obviously, they're still not perfect, and a grille block can have a mixed effect to this. In most cases, though, you're right on the money here.

I didn't mean that it was the only purpose of the grille block, I meant that the other effects are a matter of circumstance, and the primary effect is reduced airflow over the cooling surface.

[cfg83]

Christ -

Thanks for the clarification.

CarloSW2

[orange4boy]

I always thought the main reason for a grille block was aerodynamic. The faster heating a side benefit becoming greater in winter. I found these numbers recently. Someone posted them and I'm trying to find the original source.

sources of aero drag: from Toyota Nation Forums

Cooling package (including radiator, intercooler, oil cooler, etc) - 33.4%
Exterior - 31.7%
Front wheels - 13.1%
Rear wheels - 6.9%
Floor - 6.9%
Rear Axle - 3.1%
Engine - 3.1%
Front Suspension - 1.4%
Exhaust - 0.7%

[micondie]

Interesting numbers from Toyota.
I would suggest that anyone contemplating a grille block should also look at how you can make the air that you do let in do a better job of cooling, maybe some form of ducting to get the air to the radiator. This would potentially allow even more grille block. My 93 Trans Am has NO grille. All cooling air is ducted from below ahead of the air dam.

[Christ]

First things first, would be to make sure that any air that DOES get through the grille, will inevitably flow through the radiator, as well.

Some sheet metal roof flashing does the job very well of closing in gaps around the radiator, and can be done very tastefully.

[wagonman76]

Grille block can be for both aero gains and to get your engine up to temp faster.

Mine on either car makes little to no difference in engine temps, but that's in Michigan. Yours may help some.

[Christ]

Oh, another thing that's been brought to my attention a few times:

Adding a grille block can actually INCREASE the ability of your radiator to cool your engine.

It's a rare occasion, from what I can tell, but on some cars, the grilles are placed in such a way that the pressure at the upper grille circumvents the lower grille because of the stagnation point being where it is on those models. I have yet to actually see one in the wild that I could openly point this effect out with, but I'm sure it can happen, and might be something to look into. If you happen to have one of those cars, adding a grille block would force the air through the radiator, rather than it swirling around in front of it from one grille to the other, or out underneath the radiator.

Another aeromod that is often overlooked that doesn't affect cooling in any negative way is to shroud the radiator completely, so that all the air that does hit the radiator has to go through it, rather than around it, into the engine bay.

This creates sort of a parachute effect, but the excess air has nowhere to go, so instead of going around the radiator, like it normally would, it creates a (insert proper term here) that blocks further airflow until the air that's already being pressurized in the grille/radiator area is through the fins of the radiator.

In other words, it builds pressure there, so excess air is forced around the grille, rather than allowed through it.