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Discussion Starter #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.
 

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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!
 

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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.
 

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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.
 

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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
 

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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.
 

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GM removed my airdam.
384484
 

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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.
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.
 

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Discussion Starter #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.
 

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Discussion Starter #10
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.
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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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.
Yep, live in South Florida. I am not worried about it either and I am not saying it would directly lead to overheating. Since it is a simple gauge I don't know if it runs a little hotter. From what I have read in technical journals it is mostly about operation under loads that they advertise it will handle. Not arguing just reacting to Fastlanefreddies "string theory".
 

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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.
 

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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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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.
YES!!!!!!!!!
 

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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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If the ZR2 had an airdam ... I wonder if I'd get better gas mileage?

384538
 

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