titanle

I was under my car the other day and noticed a number of small holes in the bottom of the front bumper, is this where a front spoiler or air dam could be bolted up to? I've seen some cars on here that have that big black front spoiler which I think looks pretty cool.

Easy Mike

Post a pic. All C3s have a plastic or rubber spoiler mounting on the lower valance fiberglass, not the bumper. The spoilers aid cooling by directing air through the radiator.

titanle

MelWff

filling out your profile with the year or stating the year in your thread would help so I am guessing it is an early C3 and you are missing the stock front spoiler/air dam listed in the link below.

https://willcoxcorvette.com/corvette...am-stock-68-72

0Willcox Corvette

The 68-72 spoiler mounted in this fashion.

Willcox

titanle

jb78L-82

titanle

Jstan2014

MBrianB

Metalhead140

They do both actually. Create a high pressure zone in from of the air dam, pushing air up through the holes in the bottom of the nose and through the radiator, while simultaneously creating a low pressure zone behind the dam/radiator to pull air through the radiator.

MBrianB

Metalhead140

I'd be happy to learn if you want to share? With the c3 being a bottom breather I thought that it works similarly to described/pictured on this page: https://www.carthrottle.com/post/wb4b4y3/ - air moves from high to low pressure areas, and a high pressure area will build in front of a "wall" moving through the air, with a low pressure area behind?

MBrianB

Thanks for the diagrams and pictures. If you will note he first wants to increase cooling for long highway drives. He also wants to increase downforce while minimizing drag.

In the airflow diagram 1 you will see that in the stock configuration there is applied force, the large arrows on the left, which are not shown to be applied in the area in front of the radiator. At that point the force is equal. The arrows pointing up from the air dam would have to over compensate the arrows coming from the front. The radiator in the diagram is also an air dam for all practical purposes and a point of resistance. The purpose of the fan on the front of the engine is to create a negative pressure zone within the shroud which pulls the cooling air over the radiator.
Furthermore and more importantly, the smaller arrows flowing over the hood are creating a low pressure area identical to the air foil of a wing on an airplane. This is where he is getting the lift in his original complaint.

A low pressure area must be created behind the splitter to cause a low pressure area behind the radiator and the undercarriage. Look at NASCAR and especially F1 race cars.

As the diagrams describe the "difference in air pressure across the radiator is what causes air to move through it" He is wrong where he says this results in a force pushing up on the nose of the car creating lift. The air dam cannot with a negative pressure cause an increase in pressure that would cause the nose to lift which is what he says.

While adding a splitter can cause additional air flow to be available it must have a way to have the pressure released and actually pulled out which is effected by the splitter and the negative pressure zone behind it..

In the diagram "force directions around the splitter" he says he is creating a high pressure zone in front of the air dam to push down on thus increasing the down force..

While the effect is true it is not caused by any pressure applied by a high pressure zone in front of the air dam but only by the negative pressure zone behind the splitter.
Again look at the F1 race cars if they could find a place to do it, they could, at speed drive upside down due to the negative pressure caused by the airfoil.

So the physics question arises again, is the speed of the air over the top of an airplane wing cause a reduced pressure zone thereby lifting the wing, or is the wing lifted by the compressive pressure caused by the wing moving through the air.

Metalhead140

I agree with basically everything you say. I was of the belief that on our cars, which have quite small frontal intake area, that a large proportion of the cooling air did come from the front lower vents (hence the bottom breathing comment), and certainly a number of people have shown that the forward facing grills can be blocked completely if a good air dam is used. If the high pressure zone in front of the air dam does not force air upward through the radiator, then why the large openings in front of the radiator under the nose? I'm not sure whether you're telling me that you can't create a high pressure area and that all work is done by low pressure areas? Certainly low pressure areas are often the easiest to make use of. But my understanding is that higher pressure areas are used as effective locations for intakes etc (e.g. cowl hood). I thought the C3 airdam causes a high pressure area in front of it which helps to feed the vents for the radiator, while at the same time also causing a low pressure area behind the radiator to further increase the pressure differential. I certainly don't claim to be an aerodynamicist though! Thanks for the discussion.

Metalhead140

What would be your thoughts on his article describing a high pressure caused by the air dam working on the splitter? https://www.langracing.com/bmw-race-...ir-dam-design/

jb78L-82

Let's make this easy and wait for an aeronautical engineer to weigh and say adding a front spoiler/air dam causes more air to be forced into the nose either from underneath (bottom feeder), through the front grilles, or less air to flow underneath the car at speed, causing increased cooling since more air flows through the radiator...............One observation that cannot be denied by me and many others is that adding a spoiler extension like mine in post #7 undoubtingly increased the cooling ability of the radiator at speed..no debate.

titanle

So will the 2nd picture from post #8 fit on my car or do I have to put on the stock piece first and then add the bigger one??

jb78L-82

The OEM stock chin spoiler must be in place first before adding the spoiler extension to it in post #8. All of the 79 C3's had the chin spoiler. The spoiler extension was added to the L-82 cars with heavy duty cooling and was riveted on to the chin spoiler. My car is a 78 L-82 4 speed and I bought the chin spoiler from a GM dealer in the late 1980's after seeing the spoiler extension on a 79 C3 at a car show back then. I attached the spoiler extension to the chin spoiler with aluminum bolts and nuts back then and the bolts/nuts look brand new even today since they are aluminum.....

Easy Mike

You may not need the stock plastic spoiler, but you're missing fiberglass under the nose of your car, so it's a toss up on what it would take to mount the aftermarket piece. Contact the vendor and ask how the aftermarket piece is fitted.