After-Market spoiler for 1999 boxster

[The Radium King]

Originally Posted by Luv2Box

I didn't say "every one has failed." Racing cars are a different breed than our every day use Boxsters and the air dam that is designed specifically for our Boxsters works as it was designed to work. Unless the manufacturer of the after market spoiler has some form of testing documentation (which I have yet to see as I was once interested in this spoiler) one stands at risk to lose control at higher speeds. I wouldn't want to risk losing control of my Boxster on a highway, would you?

i wouldn't put too much faith in Porsche aero. look at the airflow through the front bumper cover - it takes the air hitting the three rads and directs it downwards. it actually creates front end lift that increases with speed. uncertain if it was lazy engineering or purposely designed understeer. they fixed it in the 9x7 series (and the 996 gt2/gt3).

it also introduces air under the car. once you have air under the car then you get bernoilli effect (the air traveling over the car and under the car have to get to the back at the same time - the air traveling over the car has to travel a curve vs the straight line under the car so has a longer distance to go - as a result it has to accelerate - this creates a pressure differential between the top and bottom of the car that lifts the car). this lift gets reduced by putting an air dam on the back that disrupts the airflow over the car. caymans have a more aggressive front spoiler and no third radiator so less air under the car, they don't need an air dam and get a wing to create down force instead.

so, really, aero should be done as a package, but given how jacked-up the front airflow is on our cars, I don't think a rear air dam vs wing is going to be a deciding factor in losing control at hwy speeds.

[JayG]

at least you got it right that an air dam does not create downforce, but reduces lift

I would bet that Porsche did a fair bit of wind tunnel testing, so they probably do know what they were doing and have at very least a fair bit of aero design knowledge

Throwing some piece of fiberglass on the back of the car without any actual aero testing is at best dumb and at worst dangerous

does the caymen "wing" look better, IMHO, yes. The problem is the aero of the car is different and as you stated, aero needs to be a full car integration, not just adding a piece here or there.

I guess it depends on what you are trying to gain, looks or performance

[Luv2Box]

Originally Posted by The Radium King

i wouldn't put too much faith in Porsche aero. look at the airflow through the front bumper cover - it takes the air hitting the three rads and directs it downwards. it actually creates front end lift that increases with speed. uncertain if it was lazy engineering or purposely designed understeer. they fixed it in the 9x7 series (and the 996 gt2/gt3).

it also introduces air under the car. once you have air under the car then you get bernoilli effect (the air traveling over the car and under the car have to get to the back at the same time - the air traveling over the car has to travel a curve vs the straight line under the car so has a longer distance to go - as a result it has to accelerate - this creates a pressure differential between the top and bottom of the car that lifts the car). this lift gets reduced by putting an air dam on the back that disrupts the airflow over the car. caymans have a more aggressive front spoiler and no third radiator so less air under the car, they don't need an air dam and get a wing to create down force instead.

so, really, aero should be done as a package, but given how jacked-up the front airflow is on our cars, I don't think a rear air dam vs wing is going to be a deciding factor in losing control at hwy speeds.

I put enough faith in it to not worry at high speeds. I don't know about your Boxster but the faster mine goes the more it squats down and hugs the road. I don't experience anything like what you are describing and I'll risk life and limb on the Porsche design before I fall for looks over performance in a product that has yet to disclose any performance tests whatsoever. When they do and it is shown that it works just as well as the dam then I'll buy one as I think the Porsche one, even though it works, looks terribly unfitting on the car.