Can the mph that raises the rear spoiler be changed?

[KRAM36]

Originally Posted by linderpat

why does it matter at what speed it raises? You can't see it when it's up from inside the cabin.

Because it creates unnecessary drag on the car, plus I don't really care for the looks of it in the up position. It doesn't go back down until you slow to 50 mph. It's easy to hit 75 and then travel a long distance at a lower speed and the spoiler stays up for no reason. Yes I know about the manual raise and lower button at the fuse panel door, but that's PITA.

I'd rather it not deploy until I hit 100 mph or even 85 mph. Was hoping maybe the Durametric could set this function.

Guess I could buy one of these. http://www.ebay.com/itm/261698591779



.

[j.fro]

Even with the switch, once the spoiler has been automatically deployed I don't think You can override the function.

[JayG]

Originally Posted by KRAM36

Because it creates unnecessary drag on the car, plus I don't really care for the looks of it in the up position.

It keep the car from lifting at higher speeds. Probably does add some negligible drag, but that is what it is supposed to do.
Porsche put it there for a reason!

Why are you concerned with drag anyway? Are you trying for a high speed record?

In any case, if you don't want the spoiler to deploy, you probably could get inside it and disconnect the gears and while the motor would still work and therefore no CEL, it would not move.

There probably are alternate methods as some have added fixed wings and disconnected the spoiler and have no codes.
Do some searching here, on boxa.net, boxster register and rennlist boxster forum

[KRAM36]

Originally Posted by JayG

It keep the car from lifting at higher speeds. Probably does add some negligible drag, but that is what it is supposed to do.
Porsche put it there for a reason!

Why are you concerned with drag anyway? Are you trying for a high speed record?

In any case, if you don't want the spoiler to deploy, you probably could get inside it and disconnect the gears and while the motor would still work and therefore no CEL, it would not move.

There probably are alternate methods as some have added fixed wings and disconnected the spoiler and have no codes.
Do some searching here, on boxa.net, boxster register and rennlist boxster forum

I want the spoiler to come up, but I don't think it's needed at 75 mph.

Why am I concerned with drag? Because this is my DD and that causes fuel economy to go down and drag isn't the only thing, I think it looks tacky when deployed for no reason.

I rarely hit 85 mph, but 75 mph is easy when the highway speed is 70 mph and you need to get around another car. So here is this spoiler up for no reason and doesn't come back down until 50 mph.

[Porsche9]

For safety reasons raising the speed at which it goes up is risky. My thought is that instead the speed at which it drops back down be changed. Instead of 50 let's say 65 or maybe even 70. I always thought the 25 gap was a bit much.

[KRAM36]

Originally Posted by Porsche9

For safety reasons raising the speed at which it goes up is risky. My thought is that instead the speed at which it drops back down be changed. Instead of 50 let's say 65 or maybe even 70. I always thought the 25 gap was a bit much.

That is probably a better idea. To change the speed at which it drops. Installing that button would probably be the easiest way to drop it back down.

I was really hoping a tool like the Durametric could change the spoiler operation speeds. I have not had enough time to explore what all the Durametric can do.

[j.fro]

Fwiw, I picked up 1-2 mpg by going to an underdrive pulley.

[KRAM36]

Originally Posted by j.fro

Fwiw, I picked up 1-2 mpg by going to an underdrive pulley.

That's already on my to do list, didn't know it helped mpg though, thanks.

I need to change out the metal impeller water pump I installed when in a pinch last summer. So I'm going to do the UDP and Low Temp Stat at the same time.

[JayG]

Originally Posted by j.fro

Fwiw, I picked up 1-2 mpg by going to an underdrive pulley.

Was that using your butt dyno?

[JayG]

Originally Posted by KRAM36

I want the spoiler to come up, but I don't think it's needed at 75 mph.

Why am I concerned with drag? Because this is my DD and that causes fuel economy to go down and drag isn't the only thing, I think it looks tacky when deployed for no reason.

I rarely hit 85 mph, but 75 mph is easy when the highway speed is 70 mph and you need to get around another car. So here is this spoiler up for no reason and doesn't come back down until 50 mph.

Fuel economy, really? slow down a bit, that will improve your fuel economy.

I get around 27 mpg on the hwy doing 75-80, so I don't know what you expect. A Boxster is not an economy car and was not meant to be one
Besides the spoiler at worst has a negligible effect on fuel economy

The spoiler comes up at 75 for a reason. I am fairly certain that Porsche did a lot of wind tunnel testing and determined that 75 is where it is needed.
The spoiler is up FOR A REASON!!!

Basic aerodynamics are in play here. the shape of the car acts like an airfoil (wing). when air flows over the top of a wing, it moves faster than the air below the wing and creates a partial vacuum. this causes the wing to move towards the partial vacuum, in this case up. by disrupting that airflow over the top, it prevents the partial vacuum and therefor prevents the car from lifting. It is exactly how the wing on an airplane works and why they deploy spoilers on landing.

A proper wing on the back of a car is in fact inverted and the airflow is faster on the bottom, causing down-force. In a car you need to counteract that down-force with springs (adjustable coil-overs)to push up a bit

They probability have the down set at 50 so once it is up, its not constantly moving up and down

[Topless]

A little bit of science and aerodynamics:

https://www.youtube.com/watch?v=TKH1DyV9vNU
Pickup Truck Tailgates | Fuel Economy - Consumer Reports News

[KRAM36]

Originally Posted by Topless

A little bit of science and aerodynamics:

https://www.youtube.com/watch?v=TKH1DyV9vNU
Pickup Truck Tailgates | Fuel Economy - Consumer Reports News

In the youtube video it says the spoiler on the Porsche creates more drag at the rear of the car.

" the redirected air leads to a lower pressure zone behind the car, which can increase drag"

Having the spoiler up will not improve the mpg.

[j.fro]

I've used an app to track mpg for a few years now. When the UDP went in, average mpg went up by 1-2.

[JayG]

Originally Posted by j.fro

I've used an app to track mpg for a few years now. When the UDP went in, average mpg went up by 1-2.

cool
That is a fair calculation. Does it track your speed or shift points?

in that time have you changed tires or tire pressure?

[Topless]

Originally Posted by KRAM36

In the youtube video it says the spoiler on the Porsche creates more drag at the rear of the car.

" the redirected air leads to a lower pressure zone behind the car, which can increase drag"

Having the spoiler up will not improve the mpg.

I guess we will just have to agree to disagree then. Tailgate up always improves highway gas mileage on a pickup. The Boxster spoiler operates under the same principles. Separated bubble.

[KRAM36]

Originally Posted by Topless

I guess we will just have to agree to disagree then. Tailgate up always improves highway gas mileage on a pickup. The Boxster spoiler operates under the same principles. Separated bubble.

The air flow over a truck bed is completely different then the air flow over the rear of a Boxster. You're video proved it would lead to more drag on the car.

[JayG]

Originally Posted by KRAM36

I want the spoiler to come up, but I don't think it's needed at 75 mph.

Why am I concerned with drag? Because this is my DD and that causes fuel economy to go down and drag isn't the only thing, I think it looks tacky when deployed for no reason.

I rarely hit 85 mph, but 75 mph is easy when the highway speed is 70 mph and you need to get around another car. So here is this spoiler up for no reason and doesn't come back down until 50 mph.

I realize you have now seen the light and understand that the spoiler goes up and down at a specific speed for a reason and does not lower mpg as that was your concern. So if getting better mpg is your concearn, why are you looking at increasing HP with a bunch of engine mods in another thread? That will surely decrease MPG. The easiest way to increase MPG is to slow down a bit, especially if you are going 70+

[KRAM36]

Originally Posted by JayG

I realize you have now seen the light and understand that the spoiler goes up and down at a specific speed for a reason and does not lower mpg as that was your concern. So if getting better mpg is your concearn, why are you looking at increasing HP with a bunch of engine mods in another thread? That will surely decrease MPG. The easiest way to increase MPG is to slow down a bit, especially if you are going 70+

My answer is in the quote, but it's no longer an issue in mind.

[jb92563]

If you did not see your spoiler come up at 75mph, then did it actually happen?

Your mileage will vary depending on what you think happened as indicated by the little spoiler light on the dash.

Now to the aerodynamics

Spoilers are in fact designed to spoil lift, hence the word used to describe then, and in our case since it is also behind the the aerodynamic center of lift it may also generate a bit of down force due to the force vectors generated, all designed to enhance stability and so the rear rubber stays firmly planted on the road so you don't loose the tail and end up pointed in some direction other than intended.

I would not mess with that if you drive over 75 often as the chances of loosing control/stability will increase and the Porsche designers will just shake their heads wondering why someone would defeat their measures to keep you in control.

Embrace the perceived ugliness and know that many are appreciating the looks even when you are not.