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Upper grill block

25K views 52 replies 19 participants last post by  Sunline Fan 
#1 ·
Ok well the middle grill...

(more pics below)
So the Cruze Eco (which I don't have) has a lower grill block that's automatic; thermostatically controlled shutters, blah blah blah wish I had it. :)
In reading lots on Ecomodder.com I have come to believe upper grill blocks are better; pushing air up over the smoother top of the car rather than the rough underside. Our cruze had the awful recall done on it; the dealer took a sawzall to the bellypan and removed a 2x3 foot section of it.
Anywho, the photo above shows where I started. The regular Cruze has a lower grill (not shown) and a middle grill which is partially blocked off on the sides, and a tiny upper grill that is totally fake. Behind the fake upper is the air intake (end of the silencer) that feeds around to the airbox, then the turbo, intercooler/ducting, and intake manifold.
I initially wanted to block the middle grill from the outside with lexan but the wife wants all the ecomods to be invisible, so...
I cut a cardboard template based on the outside shape of the hole, then removed the front belly pan. It took eight T-20 Torx screws and four plastic retainers that were removed with a flathead and needle nose pliers. I tried the cardboard template and modified it to fit better and used the template to cut a sheet of coroplast (corrugated plastic campaign sign) to the shape. I painted it with Krylon fusion plastic paint and slid / wedged it in. I used a flathead screwdriver to poke some holes in the coroplast (CAREFUL to not push another couple inches past and into the AC condenser). I was planning on using zip ties (photo) to hold it in, but my zip ties were brittle and useless. I grabbed some black 14 gauge wire I had sitting around (solid copper core like the stuff in home wiring) and pushed "U" shaped pieces through from the front and twisted in the back. You can see one in the last picture, about four holes to the left of the Chevy Bowtie. I have a total of four in there and it seems to be holding great. Not too experimental, we've only had the car for 3 weeks and I also fixed the bad spark plug gap today. I know theoretically and due to some other folks' wonderful research that it will work. :)


 
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#2 ·
I'm interested to see what kinds of results you see from this, particularly with engine/coolant temps. Make sure to watch them close, especially initially, to make sure you don't overheat it.
 
#5 ·
Thanks. I drove it today and it was fine but COLD! outside. When it warms up to non crazy cold temps I will have to ask the wife (her car) about time to warm up and to see if the temp needle ever crosses the halfway mark. Thermostat appears to open one mark below that spot.
I figure this won't present ANY problem in the winter or anytime the AC isn't being used for that matter. I have blocked off much more in other vehicles that didn't have cooling fans. :)
Relative to the lower grill, the upper is only about 1/4 to 1/3 the size after you consider the fact that it's already partially blocked.
I will keep this thread posted!
 
#7 ·
Uh-Oh, gonna let the wife test ?

J/K, I have wanted to do the same.

Wish there's a way to motorize the grill block.

The motor itself And intake air are my intent to heat. Like Smokey Yunick's succes.
 
#8 ·
Careful with this. Air flow through the engine compartment is a serious design consideration these days that the engineers design for. You may have unintended consequences. For instance, my '90 Olds Ciera was notorious for having alternators fail because they didn't get adequately cooled due to their location. Lack of air flow.

And I'm not so sure this sort of mod will make a difference in fuel economy. Air flow is a tricky thing.
 
#9 ·
On the Eco's that shutter on the lower grill is not thermostatically controlled, it is speed sensitive above 35 mph. Personally I wouldn't be blocking off the main grill, during the winter with the cold temperatures it'll help the engine warm up quicker but if there's not enough air flow over the radiator you'll have it running warmer than it needs to be. And definitely a bad idea for warmer temperatures. I drive 30 miles one way and even with the cold temperatures my car warms up in 15 minutes of driving. The designers plainly thought on mpg when designing the body of the Cruze to get the best Co-efficient of drag.
 
#19 ·
There has to be a temperature basis to the Eco's shutter control as well. I spend most of the winter with my shutters closed, even at low speeds. It may be that they won't close below a certain speed but that once closed they won't reopen if the engine doesn't require the additional cooling.
 
#10 ·
In winter weather I don't see a big danger with this. I've learned that the 1.4 engine runs a 225F temp in the winter and about 206F in the summer when driven normally. There's some extra cooling capacity there, but I wouldn't count on it.
 
#11 ·
Most cars upper grill does less than the lower one. looking at the cruze upper grill it allows some air flow but is still part of the aerodynamic shape. One could probably block most of it without issue.

Since the eco has an automatic lower block I would suspect that even though his feature is speed sensitive that if temps got to high it would fully open at speeds above 35mph anyway, if not it should.
 
#12 ·
I looked at making a grill block(upper or lower) but decided that it would require me to monitor temps closer than I would like.

My plan? I am going to pack the lower or upper grill with wet snow so once outside temps are high enough the grill block will automatically melt away!
 
#13 ·
My plan? I am going to pack the lower or upper grill with wet snow so once outside temps are high enough the grill block will automatically melt away!
I love it!
1000 miles in there is a little difference in warmup and obviously MPG increase will be very small.
Absolutely no threat to cooling in the winter; or anytime when the A/C is not on for that matter.
If I kept this on in the summer, it would surely cause the fan to run more... but it will come off this spring before A/C season.
I want to make an exterior block for next fall but it will require a bit more precision work to look nice.
 
#14 ·
#16 · (Edited)
Shutters

Shelf Shelving Wall Display case Furniture


I have my bumper cover from my fender bender.
This allows easier pre-fitting of internal dampers.


I think a HVAV motorized damper would work using a eng temp sensor set above 226F but lower than the DTC alarm point.


Make sure that it's Not Spring Close or Spring Open.
Make sure the motor is "sealed" or weatherproof.
HVAC controls are usually 24vac
A $20 inverter & used 120-24 transformer starts the rig.
Controllers are about $20.new.

Check with a local HVAC supplier or ebay.

It's possible to use a power door lock actuator instead of using a factory motorized unit.
 

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#18 ·
View attachment 11498

I have my bumper cover from my fender bender.
This allows easier pre-fitting of internal dampers.
I think a HVAV motorized damper would work using a eng temp sensor set above 226F but lower than the DTC alarm point.
Make sure that it's Not Spring Close or Spring Open.
Make sure the motor is "sealed" or weatherproof.
HVAC controls are usually 24vac
A $20 inverter & used 120-24 transformer starts the rig.
Controllers are about $20.new.
Sounds like a neat project.
 
#20 · (Edited)
FYI.... I don't think I would be too worries about covering up the grill:

GM said cooling systems for all of its vehicles are designed for the worst-case scenario, which is pulling a trailer up a grade in Death Valley. The shutter allows vehicles to improve fuel economy and still provide the cooling needed in that extreme case.

Just don't do any of that ^

Also - don't look to spend too much money on grill blocking as you may spend more then its worth:

According to Greg Fadler, Chevrolet aerodynamics engineering group manager, the air shutter system contributes nearly half a mile per gallon in combined city and highway driving.
Source: Air shutter system aids fuel saving in Chevrolet Cruze Eco : John Day's Automotive Electronic News
 
#21 ·
I had my Eco's upper grille 100% blocked since January when we had that BRUTAL cold spell... lows were below -30C here in Ottawa and my easy low speed drive meant the car wasn't warming up properly with ANY use of the heater. I left the grille completely blocked until this weekend when I took a long highway trip to Toronto. Temperatures were over 10C this weekend in TO and I didn't want to take a chance at overheating with the grille completely blocked.

The Eco's shutters WILL open if engine temps require extra cooling. I've read this in several articles as well as proved it in my own un-intentional testing: Two weeks ago I went to Mont Tremblant skiing, about a two hour drive, and it was snowing REALLY heavily... the heavy wet snow you get when temps are just below freezing. The roads were snow covered and we were driving directly into a strong east wind. My SES light turned on about halfway into the trip, but the car was running fine.

After getting home I checked the codes with my OBDII scanner. Two codes were set (can't remember exactly what they were now), but they were both specific (not generic) codes and related to the grille shutters not operating properly - they were frozen shut. With the strong head wind, thick heavy snow on the roads, and me driving at 50+MPH the load on the engine was high (confirmed with extremely poor mileage) and the engine tried to open the grille shutters for cooling. Since thawing the car out and clearing the codes they have not returned.

So the grille shutters WILL open if you need them to for cooling purposes. NOTE, even though the shutters were trying to open I never saw the temp gauge go above it's normal resting place (just below 1/2). This "gauge" is a glorified idiot light and won't move unless things get to the point of an overheating situation.

I trimmed about 2" from the top of my grille block before heading to Toronto this weekend as I don't want my grille shutters constantly opening and closing all the time to keep engine temps under control. Until I hook up a shutter "monitor" I won't know for sure exactly when I'm blocking too much of the grille.
 
#22 ·
I've had my grill blocked all winter. Even on a 60 degree day I haven't had overheating problems. I have monitored the digital coolant temp. display. On long highway trips it will get up to about 235 degrees. I assume the lower air shutter opens and it drops to about 217. It keeps doing this no matter what the outside temp. is. I'm going to leave it on through spring to see what happens.
 
#23 ·
I am not really a fan of this idea......here's why.

We all know the thermostat won't open unless the coolant temp in the engine has reached a certain point.
Many have discovered that the heater core is capable of making the coolant temperature drop when the fan is on at speeds above 1/2.
That means that the thermostat is likely not even opening or only opening a bit to maintain a pre-determined coolant temp....same for the shutters on the eco version.
All that aside, I think everyone is forgetting about underhood temperature.......meaning the air temperature that all the underhood components are being subjected to.
Part of airflow engineering includes air movement underhood......it enters through the grille (obviously) moves hot air off the turbo/manifold/vacuum lines/hoses/battery/other underhood fluids......yada yada, and hot brake fluid comes to mind.
And then, that hot air exits out the bottom to the rear of the engine (this is a low pressure area so air tends to be drawn out)

I sometimes suspect if high underhood temps were not the real reason for the undershield modification.

I've not yet put a remote air temp sensor down there but I may just for the 'need to know' part of me.

But, I think those who are contemplating this should give it a great deal more thought......

Rob
 
#24 · (Edited)
...I think those who are contemplating this should give it a great deal more thought......
You bring up some good points, especially for those who are reading this and may not have any technical knowledge of what's being impacted by this modification.

I think some common sense is needed whenever messing with stuff like this... obviously, it would be a bad idea to block the grilles and then go towing a camping trailer through Arizona in July.

In my case, I live where it gets really cold and my daily driving is very easy on the car. So much so that if I use the heater at all the car will not warm up after driving all the way to work. True, radiant heat from the exhaust system and coolant temperature are two different things, but in my case I'm confident that little damage is happening under hood due to the easy nature of my driving.

I recently removed about 1/3 of my upper grille block as I was heading out on a highway trip and the weather had warmed up to above freezing. I didn't want my shutters opening and closing all the time keeping the engine cool, so I opened a little airflow to keep some cool air flowing over the rad. Still, my highest speeds were around 65-66 MPH (106 km/h) and temps were only about 10C at their highest. Far from hot.

Once I get into logging actual temp data I will try to experiment a little more with how much grille block I can get away with using while keeping the shutters closed. As usual, I will post my findings.

One little tidbit for Eco owners: Those with a front license plate already have a slight upper grille block. The plate holder actually blocks part of the grille opening, and after watching a few videos of the Eco in GM's wind tunnel it's quite obvious that the airflow into the grille happens quite vertically. The car in the video doesn't have a front plate holder, but it doesn't take much imagination to see how it would restrict flow. Pause the video at 17s, then 18s, then 19s to see what I mean:

â–º 30th anniversary of the world's largest wind tunnel - part 2 - YouTube

For those who may be interested, I compiled a bunch of videos in a thread on the ecomodder forum:

http://ecomodder.com/forum/showthread.php/gm-wind-tunnel-cruze-eco-25087.html
 
#25 ·
Well, the potental for elevated underhood temperature is the thrust of my comment, but the other half of my thoughts revolve around the perception of better or quicker heat for the cabin.
I'll restate that, If the thermostat is operating as desiged, restricting or preventing coolant flow through the radiator to maintain block coolant temperature, why then is it being considered useful in any way to block airflow?
If the thermostat is operating as designed there really is no (or very little) circulation through the radiator.

The blocking of the radiator is a old timey way to overcome the need to make heat when the thermostat is stuck open.

And you are correct in the common sense thought process, but a lot of readers would not think of potental downsides to this experiment.
My hopes are no one is tempted to just haphazardly try to out engineer a engineer.

Rob
 
#26 ·
The blocking of the radiator is a old timey way to overcome the need to make heat when the thermostat is stuck open.
It is still a very common practice for trucks of all sizes to use a grille block in cold weather. I'm talking everything from pickups to tractor-trailers. Yes they are diesel engines, but that doesn't matter as the common trait here is improving warm up times and helping keep temperatures up in extreme cold. We're still talking internal combustion engines with a liquid cooling system, radiator and thermostat. By keeping the stream of cold air from pulling heat directly from the surface of the engine (and to a lesser extent, the transmission) warm up times are shortened and it becomes easier for the engine to maintain temperature with use of the heater.

And you are correct in the common sense thought process, but a lot of readers would not think of potental downsides to this experiment.
My hopes are no one is tempted to just haphazardly try to out engineer a engineer.
I couldn't agree with you more here... all too often I see people thinking they can do something better than the way it came from the factory. In some cases they're right, but in the vast majority of cases they aren't and what they're doing is actually sacrificing a system's "overhead".

This is EXACTLY what's going on here. The cooling system is designed to work in the worst case scenario, which is some sort of uphill climb at some target speed loaded to some target weight at some target atmosphere/temperature. ANYTHING we do to reduce airflow through the radiator will reduce the cooling system's ability to shed heat and will therefore reduce the car's ability to cool itself under those extreme conditions. These are the laws of physics.

Having said that, when temperatures are less extreme and the car is travelling on level ground the cooling system has FAR more capacity than needed. In this scenario, reducing airflow through the grille makes sense. There's also an aerodynamic benefit to doing this, and this is exactly why the Eco has shutters in the lower grille: variable cooling system capacity, trading cooling capacity for aerodynamics. The KEY here is that the shutters can open if cooling demand requires it. It's a very smart thing to do and will likely become a standard feature on most cars/trucks in the next 10 years.

Now taking this one step further, my Eco lives in a Northern climate where, in winter, air temps are FAR below what the Eco is designed to operate in even with it's shutters closed. Knowing this, and the fact that the lower grille shutters can open if needed, I block my upper grille opening in extreme cold. To be clear, if I drove another model of Cruze without the automatic shutters I would never block both grille openings, even in cold weather. I would block either the top or bottom, but not both.

I am not trying to out-Engineer the Engineers, I'm just trying to optimize the cooling/aerodynamics balance for my particular driving scenario. I understand the cooling system fairly well and also understand the risks.

Regarding actual underhood temps, I'm willing to bet that with the engine at full load climbing a hill in extreme heat, the combination of heated air coming through the rad and high levels of radiated heat from the exhaust system would pose much higher thermal loads to components underhood than what my car will experience loafing along.

It is everyone's duty to understand what they are doing and to monitor any changes they make to measure the impact. As interested as I am in fuel economy, I would never modify my GF's car because I know she doesn't have the ability to monitor any changes done, and if something were to start acting up while on the road she wouldn't know what to do to correct it. Cars are Engineered for people like her who don't understand the mechanics of how a car works, they just put the key in and drive carefree.
 
#27 ·
I recognize the temp extremes you deal with.....I'm just North of Chicago and our extremes are limited to maybe once every ten years and that is maybe one or two 25 below (f).
And, run a winterfront of my (gas) Jeep all winter......the upper grille is fully covered but there is a 3foot by 6inch opening to the radiator below the bumper cover centerline.
My purpose though, is to retain heat after shutoff and slow down the heat loss due to the winds blowing through it.
There is no change in warmup time or heat production (two heaters....it'll run ya out of the truck).

I think, and you picked up on my thoughts, in the last paragraph regarding being aware of changes in operation during and after a 'experiment' is extremely important and I applaud you for that.
I hope the readers take a moment to think twice before any re-engineering experiment.

Stay warm up there,
Rob
 
#28 ·
I hope the readers take a moment to think twice before any re-engineering experiment.
Yes, excelent point and I hope it sinks in that you can't just go plugging up the front of the car without monitoring what you're doing!

Stay warm up there,
In the grand scheme of things, I'm not much farther North than you are... -25F (-32C) is bloody cold! We had about five days in a row back in January where the overnight lows were between -30C and -35C, but that's pretty rare. It was during that cold spell I decided to block my upper grille.

We only usually get temps that low for a day or two once every couple of years. But -25C (-13F) is pretty close, and we see that quite often. :)
 
#30 ·
I agree with Robby's points but probably not an issue unless you are blocking off the upper grile AND have an eco.
I took off the grill block about a month ago when it started getting warm so the wife wouldn't try to use the A/C or anything with it on.

I also agree that it's not going to do anything huge for FE; I think next winter I'm going to do a plexiglas block over the front (outside) rather than from behind. Will take come careful cutting to make it look decent while putting it behind was easy to disguise, but I know it will be slightly better for aero if it's flush. (avoiding the Pelton wheel or "parachute" effect)
 
#31 ·
Whoa buddy, sorry to gravedig but just found this through Google.

I'm curious what the outcome of this were.

And, more-so, I'm curious what the effects of the opposite would be - actually removing the stock blocker things on the sides.

Personally, I find it looks really odd in the winter when show builds up on just those spots and it bugs me. Plus, I assume it may provide better cooling during the summer.
 
#32 ·
Dave, Kobalt removed his large upper grill blocks from his Eco MT, because they are now on my car! The only thing is, the duct work for the stock intake is behind there, so it'll be visible when you remove those unless you pulled the bumper and got rid of that.

I've been running with my lower grill block still in, and the larger upper grill blocks in since Lordstown. I do it because I'm tuned and it's programmed for lower engine temps. Today in nearly 90 degrees and full sun, the car got up to 207 coolant and 188 trans fluid after my slow commute home. I watch it daily and this is quite typical- it never gets higher than this.

Totally agree with Rob and Lance that these mods are not for the average joe. You really have to be willing to monitor the car to prevent damage. I know that if need be, I could remove my lower grill block on the side of the road in just minutes.


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#34 · (Edited)
No, the tube is more visible and uglier looking with the blockers removed. If you bypassed the resonator already, it's just there doing nothing.


*Adding picture to the thread so it kinda makes sense.

Red is the intake tubing that he is talking about that goes to the resonator that we bypass in the http://www.cruzetalk.com/forum/129-engine-transmission/5479-how-bypass-intake-resonator.html thread.

Yellow is how much air Eco gas and Eco Diesel sees in winter time or at least temps 46* and below. When I wash the salt and snow off the car in the heated garage, the shutters still stay closed. I don't see them open up again till almost April.

Green is about the difference between eco and rest of the Cruze lineups grille.

Blue is what the eco controls for open or closed and what some members have manually blocked off



Pic w/o all the colors and stuff.

 
#35 ·
Nice job with the pix, Merc!

Merc6 said:
Yellow is how much air Eco gas and Eco Diesel sees in winter time or at least temps 46* and below. When I wash the salt and snow off the car in the heated garage, the shutters still stay closed. I don't see them open up again till almost April.
Just to clarify for those not aware, the Eco automatic uses the same wider upper grille opening as the regular Cruze, and while the lower shutters do seem to stay closed in colder temperatures, they do open any time extra cooling is needed. In the warmer months they will open at lower speeds and close at speeds above 40MPH where their effect is greatest.

I still haven't gotten any closer to an upper grille block that I can open and close from inside the car. That would be the best option, along with a way to tell when the lower shutters are opening for added cooling.
 
#37 ·
Nice job with the pix, Merc!



Just to clarify for those not aware, the Eco automatic uses the same wider upper grille opening as the regular Cruze, and while the lower shutters do seem to stay closed in colder temperatures, they do open any time extra cooling is needed. In the warmer months they will open at lower speeds and close at speeds above 40MPH where their effect is greatest.

I still haven't gotten any closer to an upper grille block that I can open and close from inside the car. That would be the best option, along with a way to tell when the lower shutters are opening for added cooling.
What timeframe was this and was it a Canada trim thing? The few Eco autos I seen(I never see a manual ECO ever) had the smaller openings but they were 13 and up. I would assume if it were larger, it was for the tranny cooler. Tried searching my dealership and no luck on any ECO trims.

I would guess tie it in with the lower shutters circuit using a 2nd set of shutter motors. There are a few Ecos who went fmic so they maybe could help you with the shutters but they may have the sensors still in place to prevent a cel.



Sent from my iFail 5s
 
#44 ·
Commute today in 94 degrees according to dash

- Fan system off and A/C off
- All windows down and sunroof vented for most of trip
- Stop and go traffic most of the way, but driving for mileage.
- @ end of commute: trans fluid 181, coolant 204. Coolant crept up to 204 that I saw, trans up to 183 that I saw.


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