par401

SPASM?

J.Ho

I thought it was magic ?? !!!

seattle_sun

Yes

par401

im sure you know its raised higher with SPASM, I agree it almost looks weird. I have Spasm and I think the wing looks better with the level it raises with regular pasm.

squid42

On a 911 that spoiler's (which is not a wing with distance between wing and car) main aerodynamic purpose is to prevent air from flowing down the 911's back into the area where you want to create downforce from the rear underbody. That's also why 911 cars with wings still have a ducktail. They need to get the air away from the car's back before it reaches the bumper. Non-911 cars, including Boxsters, almost all have hard edges at the rear so that doesn't need to be done.

I could easily imagine that the car electronics decide to deploy the spoiler earlier than high speed depending on air pressure, air temperature or something else random they notice about the air and how the car moves through it. Remember that once you lift the rear tires it's too late, so be conservative.

Valvefloat991

I think the spoiler's purpose is to break up the smooth airflow down the 91's rear window and rear bodywork, which strongly resembles a wing profile. By breaking up this flow, it reduces the lift generated in that portion of the body. What goes on underneath is something unrelated.

Also, remember that aerodynamic forces vary with the square of velocity, so there's not much in the way of lift or downforce going on below 75 mph, let alone lifting the rear tires. But the spoiler deploying does create an air dam, which forces more air into the intercoolers. That is the most likely reason for the deployment at lower speeds.

seattle_sun

Explained- love this guy's videos

JCtx

Yeah, it opens flat on Boxsters. But you can clearly see it deployed on Caymans. But on that 911 it looks like an air-brake. Ha ha. At any rate, I keep it open. Don't want it to crap out with closest dealer 400 miles away.

cug

That's actually not a bad idea. Spoilers that deploy significantly above the legal limit on most roads (in the US) and don't retract until you drop way safe speed on the same roads are just an invitation for law enforcement. But if the spoiler always deploys below legal freeway limits in most areas, this indicator is gone.

It might not have anything to do with this, but I like it anyways ...

MKW

.:

MKW

that's why Porsche has included a button to manually raise the spoiler at anytime , whether moving or not , since it's intro with the 964 in late 1989 , since its 75mph auto-rise speed was well above US highway spd limits back then ..covering its drivers in case of being pulled over by a Porschephile cop !

cug

The button is one thing, but you need that one for way more, like cleaning or getting to fasteners underneath or even just function checking. Might as well allow operation not just at standstill.

But I still think the logic of a spoiler to raise before a typical speed limit is hit, is in general a much better idea. I imagine being a cop, driving on a freeway and somewhere in my view a spoiler goes up – it would take me a bit to remember the typical deployment speeds for each vehicle, after that it would be like a red flag. Much better if the cops subconsciousness sees a deployed spoiler at legal speeds as typical. The button doesn't help at all with that.