village idiot

There has been a lot of debate about this and why it isn't on Z51 (and z06?) but is on the base model:

I've heard it increases downforce, which seems strange because the performance model(s) don't have it, but have more downforce in the rear.

Can you give us an explanation for why it isn't on the performance models and any data on what it does for aero (effects on lift/drag/etc).

Thanks!

Hubertus Kohnen

The centre air dam on base Stingray is fitted for fuel economy purposes, it helps reducing aerodynamic drag. It is not fitted to Z51, Z06 and GS in order to allow more air under the car to help cooling the drivetrain and Brakes,too. It could be fitted to Z51 if maximum fuel economy is desired instead of performance driving.
C4 and C5 generations definitely needed the centre air dam to guide air towards the Engine Radiators, this is not the case with the C7.
Regards Hubertus

village idiot

Makes sense. Does it do anything for aero?

LOW11GS

I have a GS and it has one .......

n8dogg

Your C7 should ONLY have the center spoiler IF your car does NOT HAVE DRY SUMP. If your car has dry sump and you have the center spoiler, then the dealer that prepped your Corvette installed the center air dam in ERROR. Every Corvette gets shipped with the center spoiler in the loose parts bag. However only non-dry sump cars get the center spoiler installed. Why GM does this? I don't know, but clearly the penny pinchers missed this one and clearly the dealership personal do not read the important information on the PDI sheets.

The dry-sump cars need the air flow under the car for cooling (brakes, fluids, components). Why the base/non-dry sump cars do have the center spoiler is a good question, probably because it's the best combination of fuel economy, drag, lift, etc... Might have something to do with the softer ride and keeping the car stable at higher speeds.

village idiot

I assume you forgot to negate the second statement?

n8dogg

Oops! Thanks for catching that!

Bruce Jarrett

My 2017 GS is the way it came from the dealer. Are you saying that the portion marked in yellow should not have been installed ? Thanks

n8dogg

Correct. Your GS should not have the center spoiler. See the attachment. FYI Z52= Dry Sump

village idiot

Sooo this seems like a fairly legit question. What does the center air dam do, who isn't it on performance models and what impact does it have on aero?

n8dogg

I think it's pretty self explanatory. There is an aerodynamic benefit of having the center spoiler, be it high speed stability, reduced lift or fuel economy. GM found that the Z52/more performance equipped cars have a greater benefit of not having the center spoiler by allowing air to flow under the car for a cooling affect and the aerodynamic goals are reached through other methods such as spoilers and ground effects.

village idiot

seems odd though. I cant imagine underbody air doing much cooling. I don't recall seeing the oil pan being finned or anything. Maybe the fast moving air underneath the car helps draw out air faster?

As far as aero, they didn't do anything to the Z51 as far as front aero. Does the Z06/GS come standard with a front splitter? If nothing else, that seems off because it's dependent on getting a performance model/dry sump, not on getting an aero package.
It seems silly to think it had an aero advantage (as in lift/downforce) but they decided to just take it off to do it another way.

n8dogg

They didn't do anything to Z51 with front aero but Z51 also has a rear spoiler, stiffer suspension and a rear stabilizer bar. The Grand Sports have a front splitter and side skirts as standard (stage 1). There is an oil cooler on Z52 near the engine block IIRC. Air is also needed under the car to cool the brakes, hence the scoops attached to the lower control arms.

rb185afm

Thanks! My GS came with the middle deflector installed as well. I will be removing today.

Bruce Jarrett

Went to my dealer today about my center air dam being installed on my GS by them. I looked at 6 GS and Z06 cars on the lot and 3 had the center dam installed. The dealer said they install whatever comes with the car from the factory and some come with it in the trunk and some don't. I showed them the bulletin that n8dogg posted and after doing some research they said the forum is correct. No matter what comes in the car from the factory dry sump cars should not have the center dam installed. Whether it is for cooling or performance is no matter for me, I will follow the advice of the engineers at GM. Thanks to the Forum members for bringing this subject up and informing me of a problem with my GS.

n8dogg

We see this every once in awhile. This is the difference of dealers that actually care and are knowledgeable in Corvettes and those that are not. From time to time we will have a customer come in for service who bought their Corvette from another dealer and we will bring them down into the shop so they can meet our Corvette technicians and show them the center air dam that is not supposed to be on their car.

My guess is that GM made a last minute decision to not have the center air dam installed and a contract was already signed with the supplier who makes the part. So all Corvettes come shipped with the spoiler in the loose parts bag, even tho GM found a greater benefit to not have them installed on the performance/dry sump models.