2012 Tacoma Grillcraft Aerodynamics

I'm considering the Grillcraft mod for the 2012, but i'd like to hear a little discussion about possible unintended consequences affecting aerodynamics. The grill mod looks sharp compared to the OEM plastic conglomeration, but I feel that function trumps form. It's always nice when form follows function.

I posted this question in the Grillcraft thread, but no takers after 6 days.
I'd like to hear from Grillcraft directly or anyone with some aerodynamic knowledge.


I have a practical question or two and an aesthestic question.

1. Given that the stock OEM grill contains a moderate percentage of solid material which would deflect the air stream, does going with an open grill design negatively affect the aerodynamics? Is it like just having a big open air scoop/ram? All modern car/truck manufacturers do careful wind tunnel testing to minimize aerodynamic drag. Are we creating unintended consequences?

2. In cold climates like here, would the increased airflow affect engine temp?
(the reason you see people with cardboard covers over their radiators.) I'm talking really cold, like -20°F when it takes significantly longer to warm up.

3. If you had a hoop plate bumper, like an ARB, how much of the grill would show? Would it be aesthetically worth it? (I know this is a subjective question, but I'm having a hard time visualizing it.) I'm not crazy about the '12 grill (or any other 2nd gen), and this mod seems to clean it up and simplify the look nicely)

 

1. It's a truck, get the F over it. any changes will be minimal at worst, its a freakin' square block being pushed though air, not a Prius, your ARB bumper you want will do worse for mileage and engine strain than the grill ever will. (don't buy a truck for efficiency)

2. that's what thermostats are for…….paint the cardboard black.

3. As far as I know, ARB hasn't got the 2012 bumper yet so I doubt anyone could answer you question cause it doesn't exist.

 

I doubt you would see any difference in performance or economy even if you removed the grill completely. These trucks are basically bricks on wheels and the grill is a tiny portion of the overall drag created by huge, fat tires, the gigantic gap between the road and the body, all the unsmooth shit in the undercarriage, and the super tall profile. So theoretically i would agree that opening up the grill will cause more drag, but it will be a drop in the bucket.

Now if you're gonna mod this thing up and get it to do 100mph+, then the grill aerodynamics can make the difference between topping out at 122mph vs 124mph.

As far as cold climates, I heard that grills with small openings are more likely to get clogged with snow and ice. I don't have one, nor do I live in snow so I haven't experienced such a thing myself.

 

Hypothetically, yes the mileage will decrease because more air will go through the engine bay and under the truck than over/around. Most people don't understand that the surface of the vehicle that affects aero more than any other is the grill area. It plays a big role in determining how much airflow gets to pass all the garbage under the body. Anything into the engine bay exits under the truck, essentially 'activating' all that drag.

Still, with the Grillcraft vs OEM, I doubt the difference is very severe. The OEM setup lets in a quite a bit of airflow as it is. You could always do the hidden black coroplast block if it's really needed, provided you can figure out where to securely attach it.

This is a peek into the opposite direction: I have my upper grill blocked and it was good for something between 1 and 2 mpg benefit at my commute speeds (55-60mph). Take it for what it is, but I give both it and the tonneau big credit for my trip last weekend driving 71 mph actual (gps) on the 6 speed (spinning that 4.0L at about 2600 rpm) and I still averaged over 21 mpg on regular gas. Last time I did that little stunt I got 17.4 mpg.

As for #2, it's still gonna be as cold blooded as before.

 

I think all 3 questions are ridiculous.

 

I pooped

 

If fuel wasn't $15/hour I'd say #1 is a ridiculous question too.

If the small openings get clogged up with ice in the winter, big deal; even with the clutch in its least-engaged mode the mechanical fan moves way more than enough of that winter air to cool it off. It can always draw it up from the bottom of the bumper.

 

/thread

 

Thanks Guys for the few serious answers.

IROH: The highlighted area of your post is exactly what I was getting at!
I'm not sure what you mean by the "hidden black coroplast block". Is is this how you blocked your grill? I would imagine that blocking too much airflow would risk overheating, far out-weighing any aero benefits.

One of the possible theoretical benefits of undercarriage armor would be decreased drag. But, there are always unintended consequences, and it could block the airflow from exiting the engine bay, thereby increasing drag.

For those others: even increasing the frontal area of a brick increases it's drag.

 

I emailed ARB a few months ago about their front bumper for the 2012 Tacoma. They told me that they had no plans on changing the bumper for the new Tacoma. As far as they knew there was no difference in fit from 11 to 12.

 

This. Way overthinking the situation. If you're worried about this kind of thing OP, don't mod.

JUST THINK OF WHAT MIGHT HAPPEN TO YOUR AERODYNAMICS, NOT TO MENTION SUSPENSION RIDE HEIGHT AND ALIGNMENT, IF YOU PUT A RECLINER OR WASHING MACHINE IN THE BED TO MOVE IT FROM POINT A TO B!

OH THE HUMANITY!

 

thanks sparky. I was wondering the same.

One of the reasons I was considering the ARB was the frontal and side areas seem to provide for more air deflection. Some of the other plate bumpers have minimal coverage in front of the tires. i don't need maximum clearance or approach angle, just a good solid bumper to deflect deer and lame "backer-up drivers"

 

I understand your point already. I knew buying this truck what the mileage expectations were, but it seems a bit worse than I thought.

Every mod is going to have trade-offs. I just wanted to hear an intelligent discussion on the topic and learn something from the vast knowledge you all have.

This may be my daily driver for the next decade or two, so 1-2 MPG is a big deal over the life of the truck.

 

FUCK! Satoshi what have you done!? Now I must rethink my life! Nah just kidding

 

Yes, he blocked off his grille and part of the bumper opening.

Do not do this with an automatic without also having a Scanguage and audible alarms on engine and trans overtemp.
The trans can overheat even if the engine is running at it's proper 200-210 degrees.

And gains are minimal... IMHO, not worth the risk.
http://www.fuelly.com/driver/iroh/tacoma
Iroh was optimistic when the first couple of tanks jumped by close to 2mpg, but seems to have since settled down to a 1/2 to 1mpg improvement.

 

FWIW the recent fall I credit to oil with 5k miles on it (just changed it) and highway driving not normally in my driving cycle (though at the end of that two hours at 71 mph the avg on the UG was 21.8, not too shabby). I used to have to work to beat 20.5 mpg and I've been kind of lazy (lead-footed and late braking) lately because 21 is a given. Freak weather hasn't helped either - four trips home after work in the last 3 weeks I faced a 35+ mph headwind.

Since I took the precaution of the alarm on the UG it's been a good little experiment. I can say the highest temp I've seen is 194F and that was after being in Capitol City traffic for an hour in 90F heat.

As would be proper, to satisfy an A-B-A scenario I'll open it up once temperatures stabilize in early summer to see if there's a corresponding drop in avg mileage.

But like I said I doubt you'd have a big mileage difference with the more open grill. There are so many variables that result in a given mileage that unless you tracked both your driving behavior and results as closely as I you'd likely never notice it.

 

Mine's been all over the place too.
I was averaging 24.5 to 26.5, but about the time I signed up for Fuelly and added the UG, it dropped to 24-25.5.
Weather changing, AC use, inconsistent traffic patterns, etc...

 

Thanks Iroh and Rich.

I tend to approach life with an analytical viewpoint.
I tracked my mileage for every tank over 19 yrs with my last truck and it was helpful to find out which mods (including behavior mods which probably have the biggest cost to benefit ratio) and also an indicator of engine health.

I have an Ultra Gauge on order, but i won't bet the health of my engine or transmission on it. If i do the grill mod and block off part of it I will try to replicate the cross sectional area of the stock opening.

Iroh, how exactly did you fabricate a block? I was considering molding a fiberglass backing to the lateral portions of the grill screen.

 

you base all your mods of mpg? really? even the damn grill

 

LOL @ those who don't feel bad for making fun of those who plan ahead for future cost. Whatever the OP is looking at doing, I guarantee I'm more hardcore, and there are others here even more so than I. It's like there's this established mass opinion that utilitarian vehicles have to be horribly inefficient.

OP, if you consider a partial block, the top-down approach is best for mpg. It's like extending the hood down.