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I REMOVED THE AIRDAM and......

70K views 89 replies 43 participants last post by  spb1122 
#1 ·
What a POC that airdam is! I kept dragging it on low parking curbs and a few times on steep driveway transitions. Who would install that with top down hardware????
However, I immediately noticed a lack of rumble air turbulence, and it seemed so much more quiet. I did 10 runs to work at exactly 65 mph and recorded both trip mpg as well as instantaneous MPG at certain points and there was no difference with the air dam removed. Maybe over a 20 mile trip, it might give you a slight increase in mpg but I could not see it. I also put a string on the lower air ducts under the truck...they appear to draw air from the road and angle it up. I used my front camera to view it at 65 mph and you could clearly see the string take on a characteristic shape. With the airdam off, the string appeared to be showing more air flow...which makes sense. So lets think about this. Taking hot road air and blowing it up into your engine..... Not sure where the air goes. MAybe just to the lower exhaust header, then back out? But it appeared to show more flow...of hot air into the engine. Maybe this is why people are seeing hotter engine temps?????
I have access to a full blown aerospace flow meters with thermocouples and the whole deal.....but there is no freggin way I will put that air dam back on....even if its in the name of science.
 
#2 ·
Yep - I removed my air dam ...........

..... and nothing bad happened.

You’re a lot more anal than I am. You went about to not only prove to yourself but others as well we could live without the damn dam.

Thanks for sharing this with us.

Gusto!
 
#3 ·
My understanding is the airdam concept is to help create a slight vacuum at speed under the engine bay. This should help draw air through the radiator and engine bay. A lot of discussion about mpg but I am not sure it is for that reason. I actually believe it works because they wouldn't bother with it as a cost and in production if it did not have some function. Most contend, and rightly so, they don't care about the small changes. I think the larger grill structure on the 2021 ZR 2 reflects the need to generate more airflow possibly for engine cooling but maybe a better radiator structure to increase tow ratings.
 
#8 ·
I have thousands of miles have been logged on my truck without the air dam in placed. Not once has it ever overheated. Not even in the 100+ degree weather of the south. Others can corroborate.
 
#4 ·
It was added to eek out as much hwy mpg's as possible. It works in conjunction with the grille shutters , to seal off the front end at 55+ mph speeds, to divert air to the sides and reduce underbody drag. It's just an aesthetic detail at lesser speeds.
 
#5 ·
However, I immediately noticed a lack of rumble air turbulence, and it seemed so much more quiet. I did 10 runs to work at exactly 65 mph and recorded both trip mpg as well as instantaneous MPG at certain points and there was no difference with the air dam removed.


Could you elaborate on the "rumble air turbulence". My truck has a definite rumble at starting just under 60 mph. Thought it might be an out of balance drive shaft. Hadn't considered this. Thanks
 
#9 ·
However, I immediately noticed a lack of rumble air turbulence, and it seemed so much more quiet. I did 10 runs to work at exactly 65 mph and recorded both trip mpg as well as instantaneous MPG at certain points and there was no difference with the air dam removed.


Could you elaborate on the "rumble air turbulence". My truck has a definite rumble at starting just under 60 mph. Thought it might be an out of balance drive shaft. Hadn't considered this. Thanks
I never now the rumble until I removed the air dam. It was a lack of rumble I noted.
 
#6 ·
I felt the truck was more stable at speed with the dam. But I still too kit off.
The dam helps create an area of air pressure in front that the majority of air slips around. You're seeing that pressure wave when the beads of water don't blow off the hood at 60mph. The air is going up and over the vehicle. The hood and windshield area is a negative pressure zone. So the dam helps create more neg pressure in and under the vehicle by preventing turbulence on the bottom that disrupts the flow on top.
Spoilers on the rear do the same for the back of the car by creating a cushion of turbulence over the trunk and behind the rear window that the airstream will go around.
It appears counterproductive to use a piece of plastic to create more air resistance, but the rest of the air one or two feet away from the vehicle is going around the vehicle much smoother for it.
 
#10 ·
Your windshield is NOT in a negative pressure area. If it were, your wipers would lift off at speed. The air dam does infact push air around the lower part of the vehicle creating less drag than the air going under the vehicle. Does it create any downforce? Probably not. Too flimsy to do much more than impart the lower air to go around your truck.
 
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#7 ·
GM removed my airdam.
384484
 
#12 ·
The boys at work offered to ATOS my truck and build a SLA scale model for wind tunnel testing. I laughed...they are serious as the 2020 charge numbers are not open for another week. We have wind tunnels for aerospace and often F1 race teams use them for high speed testing as OEM wind tunnels are under 100 mph. We run tunnels to Mach 5, but those are small and probably quiet useless for an automobile. But a 1/4 scale Colorado would fit in the 0-250mph tunnel.
 
#13 ·
Once my IBMprice was agreed, I had the dealer throw in the air dam removal to close the deal, so I have no before/after information to share. I believe any mpg decrease or control issues would be insignificant, but I can't prove that.
In my particular situation traveling up two rut roads in the wilds to access trailheads for hiking would make the air dam an immediate casualty. Besides, I think the front end looks nicer without it!
 

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#16 ·
While removing unnecessary plastic, if one has a diesel, remove the plastic barriers from directly in front of the lower radiator and enjoy lower transmission temps in hot weather.
 
#17 ·
My son had a stop/restart in his PCT hike that gave me a 600 mile back to back test opportunity regarding MPG. I have posted the results elsewhere on this site but the bottom line is that I recorded lower fractional MPG with the air dam.

I have no doubt the air dam actually improves mileage to some minuscule degree and that GM benefits financially from that in some manner. Whatever improvement actually exists is masked by my inability to drive two identical trips.

The air dam likely improves flow through the lower portion of the radiator. I drive a diesel and those are a little different in this regard. I haven't seen any complaints regarding engine overheating on any of the variants. It seems GM knocked that out of the park. I have seen higher transmission temps than I would like on a couple occasions. These were all seen while crawling slow offroad with the TC unlocked. I don't believe the air dam would have made any difference due to the low speeds at the time. I have a fan cooled trans cooler for this but haven't installed yet.

My bottom line is that I would suggest keeping the dam if you only drive on pavement. If you need the extra clearance it doesn't look like you will be loosing much by removing the part. Mine won't be reinstalled.
 
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#23 · (Edited)
highway or interstate? I think a lot of people forget the difference between these two.

The window sticker HWY MPG rating was obtained around an average of 50mph, not 70+mph. It was also done on a dyno. So with regards to fuel economy, the airdam is not there to get you the best MPG on the interstate, it is there to fine tune the truck so it will get max MPG in these EPA tests: Detailed Test Information

An interesting point, the newer EPA tests include an MPG loop with air conditioning load on the engine. Since the air dam is also optimizing cooling/airflow through the engine bay, then it would help to achieve better economy on this test as well.

I routinely get well over 30 MPG avg going to work, because I live in a rural area and travel to work exclusively on highways. However, when I go into town or hop on the interstate for a longer trip I get mid to high 20's. In this respect the EPA highway test closely mirrors my actual daily driving, which I don't believe would be the case for the majority of folks who live in stop-n-go/interstate suburban or urban areas. My airdam will eventually come off, when I upgrade my suspension, but for now it is saving me a couple gallons each month.
 
#18 ·
If the ZR2 had an airdam ... I wonder if I'd get better gas mileage?

384538
 
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#19 ·
Ouch! Is this your normal mpg or just in downtown Manhattan?
 
#25 · (Edited)
If I could somehow managed to drive 50 MPH steady with no traffic, pretty sure my tuned diesel would record mid 60's MPG, as it is barely running under those conditions. Alas, my impatient not lead but definitely "cast aluminum foot" would not permit it.

Have seen low 50s MPG on a couple of 30 miles runs from my house to downtown Denver, with every condition ideal - not cold, no traffic in the way, no wind, cruise set at 60, mile high elevation (thin air). The truck is averaging 27.5 post tune lifetime over 28K miles. It gets driven at 65-70 quite a bit. Best I have ever seen is on a 50 mph road, cop behind me for 7 miles, cruise set at 53 mph, as this is as slow as it will go and smoothly pull 6th gear. Got curious about it, saw 72 MPG in my DIC over that short stretch, all this without the air dam by the way :ROFLMAO:
 
#27 ·
Took my airdam off about 3 months ago during my last oil change. 3.6 V6 2018 W/T extended cab bought new in May 2018. Average MPG before removal: 19 MPG. After removal: 19.1. Mixed city highway. Won't put it back on. No more parking block scrapes, dirt road plowing, grass mowing in the pasture. The airdam was scraped and feathered from the contact with various objects. Just sayin. Personal experience. :unsure:
 
#29 ·
Took mine off a few months ago. I track my mileage with Fuelly, so I don't rely on the display. I've lost about a full mpg. The truck is also less stable at highway speed (70mph and up). It's a fair trade-off, as it looks a ton better and doesn't scrape anymore.
 
#30 ·
I don't mind that they put the air dam on to eek out a tad better mileage or any other reason.

I do fault them for making the dang thing so hard to take off since this would be an obvious mod with so many owners. Could have just had all bolts accessible and removed from the bottom without removing other parts.

I am definitely pulling mine - better that I remove it than a curb.
 
#33 ·
I took mine off, but due to the fact that I thought something looked funny with it off and the fact that I did notice the nose felt less controlled under acceleration or at speed, I trimmed it. I feel like it still keeps the nose tucked better than without, but haven’t noticed a dip in mpgs. Glad I don’t have to worry about it dragging/catching though and I like the trimmed look most (obviously looks are a personal opinion).
Land vehicle Vehicle Car Pickup truck Motor vehicle
 
#49 ·
But you are comparing apples to oranges. Put your truck in 4WD, don't go over 20 miles per hour and come to a complete stop and take off every 1000 feet. Then you'd be comparing apples to apples. My truck has almost 7,000 miles on it and the average mileage over the life of the 7,000 miles is almost 16 miles to the gallon. Gets about 19 on the highway. I consider that pretty good for all I ask of it and all the 4WD parts that are turning. If I was still working and actually had to be somewhere ... I'd of bought another Z71 ... and yes .... I would take the air dam off of it too.
 
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#38 ·
What a POC that airdam is! I kept dragging it on low parking curbs and a few times on steep driveway transitions. Who would install that with top down hardware????
However, I immediately noticed a lack of rumble air turbulence, and it seemed so much more quiet. I did 10 runs to work at exactly 65 mph and recorded both trip mpg as well as instantaneous MPG at certain points and there was no difference with the air dam removed. Maybe over a 20 mile trip, it might give you a slight increase in mpg but I could not see it. I also put a string on the lower air ducts under the truck...they appear to draw air from the road and angle it up. I used my front camera to view it at 65 mph and you could clearly see the string take on a characteristic shape. With the airdam off, the string appeared to be showing more air flow...which makes sense. So lets think about this. Taking hot road air and blowing it up into your engine..... Not sure where the air goes. MAybe just to the lower exhaust header, then back out? But it appeared to show more flow...of hot air into the engine. Maybe this is why people are seeing hotter engine temps?????
I have access to a full blown aerospace flow meters with thermocouples and the whole deal.....but there is no freggin way I will put that air dam back on....even if its in the name of science.
384889
 
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