Does the upturned lip matter?

[911Maverick]

Good afternoon all,

I have been doing a lot of reading and a lot of post searching with not much success to answer my question.

On the factory "lip" or "chin spoiler" for my 86 Carrera there is an upturn in front of each front wheel. I am not an aerodynamics guy and am curious how much affect this upturned area has on the effectiveness of the spoiler. I have read numerous posts about having no spoiler at all leads to a substantial amount of lift at higher speeds especially if you have a rear spoiler or "tail" in place. Nothing front and rear seems to be okay for everyday driving.

Looking at up-level or aftermarket offerings for the fronts of 930 Porsche's it does seem like having something wrap all the way to the fenders wells is desirable but is that only for aesthetic reasons?

The reason I ask is that I have been tossing an idea around in my head for a different front spoiler (custom but not gaudy) and the only downfall I can see is that it would not have these upturned areas.

Thoughts?

[Discseven]

Mav... would like to see what you're referring to. Pic?

[winders]

The 930 had this chin spoiler stock:



As you can see, without it, the front fender would not be complete.

The Carrera chin spoiler is pictured here:



Rest assured that both "upturns" provide aerodynamic benefit along with the aesthetics.

[clinerg]

https://m.youtube.com/watch?v=NO3usApt-x4

3:00

[RSBob]

The code word is "Dive Plane"

[Steve W]

They act as front wheel Gurney flaps deflecting air away from pocketing under the front fenders, which the tires would otherwise funnel in there and create lift. 2006+ GT3 Cup cars have an adjustable flap that runs through the forward edge of the front fender archs, not only to reduce lift, but create more vacuum in the wheel wells to help extract heat from the front radiators and pull out heat from the brakes. The 2010+ RS also have a form of this deflector on their forward edge, with the 4.0 adding dive planes to swirl a current around the sides of the car to help further with extraction from the wheel wells, creating additional downforce on the front.

[winders]

Well, the idea behind the "dive planes" is to generate vortexes down the sides of the car. These vortexes, if the dive planes are done properly, will prevent the high-pressure air around the car entering the underside (low pressure) of the car. You want the area under the car a lower pressure than the surrounding air.

[Discseven]

Originally Posted by winders

The 930 had this chin spoiler stock:



As you can see, without it, the front fender would not be complete.

The Carrera chin spoiler is pictured here:



Rest assured that both "upturns" provide aerodynamic benefit along with the aesthetics.

Wind... agreed that it does create a nice aesthetic and aero services at front end. For lowered rides, difficult if not impossible to keep spoilers in tact. Chin would never survive on this car...




How-bout flexible dam look and functionality...

[RSBob]

The silver car would never make it over a good sized speed bump or down a steep curb cut even without a spoiler. The stance is great the functionality not so much.

[Vereeken]

Doesn't Singer incorporate a front air dam without the upturned flaps on their Uber-Porsche?

I guess if they claim so much development work aero -tests should have been performed, no...?

Just my 2 cents...

[Bill Verburg]

Her's some aero data, H series used the p/u chin spoiler the op asked about



This looks like my car

when new I ran it that low on 205/50 and 225/50 x15 tires w/ f/r spoilers, you just learn to be a little carefull at transitions like driveways, my 993 is much worse the 911 chin doesn't project as far forward as the latter cars, this gives you more clearance

[Discseven]

Great data chart!

[911pcars]

Notice the common reference point on each of the rows of data. The numbers were measured at 143 mph. Thus, for most owners, some aero devices (e.g. dive planes), have minimal effect at "typical" road speeds and greater visual effect when parked. However, for those occasional spirited trips to the grocery store.........

Sherwood

[VFR750]

Bill,

That's a great table. Where did you get it?

It explains a lot. Add in some rake angle to drop the front and who knows, we might be getting a little bit of downforce out of the ol' SC.

So yes, the clever lip helps. And you do have to be a little more careful at driveways

[Bill Verburg]

Originally Posted by VFR750

Bill,

That's a great table. Where did you get it?

It explains a lot. Add in some rake angle to drop the front and who knows, we might be getting a little bit of downforce out of the ol' SC.

So yes, the clever lip helps. And you do have to be a little more careful at driveways

Hey Mike, The raw data comes from Porsche, I just normalized to use the same Q and speed

The base #s are for street cars @ std height and w/ std wheels and tires, lowering and adding a little rake improves the C's, using wider wheels and tires lowers them.

[911Maverick]

Thanks for the feedback everyone. I guess it answers my questions as to whether or not I will swap it out with something different!