Make Your Boxster Noise Free

[Marc Gelefsky]

Originally Posted by Brucelee

Actually, I would try one of these. Lets face it, the OEM is totally cheesy and is noisy to boot!

Seems like adding the plastic inside of it could cause it to blow out, best to velcro it.
I'm sure it would be easy to make the part yourself.

[RandallNeighbour]

$78??? Wow. You are indeed proud of this little enhancement.

I think I'll make myself a template and go down to the local Lexan reseller and make myself a pair of them for $12.

[YellowJacket]

This is hilarious -- did you guys see his "guarantee" which is, in his own words, legally binding? It reads:

Mr. ______________________has on this day paid for a set of Jay Senoff's Porsche Boxster windscreens.

It is agreed that the purchaser may return to me, within thirty days from date of receiving the windscreen.

With this certificate properly signed , I will return the all monies paid as cheerfully as I took it. ______________

The second paragraph merely states that you're allowed to see him again (it says you can return to him, not that you can return a product to him)...

...and the third paragraph says that if the certificate is "properly" signed (I guess properly must mean that you use your hand instead of your foot to hold the pen?), he will return ALL MONIES PAID. Wow, that's great -- all monies paid by whom to whom? By me to my mortgage company? Awesome! By the entire US population to the IRS? Even better!

This is awesome... I needed a good Monday morning laugh. Thanks, Jay!

[prOk]

I know people like 'modding' cars, but this kind of silliness is killing me

Unfortunately, in the past, i've had one of my windscreens blow out WITHOUT a piece of lexan in there to turn it into a parachute! Either way, some really wild claims about silence.. A sucker born every minute I guess.

[Marc Gelefsky]

Originally Posted by prOk

I know people like 'modding' cars, but this kind of silliness is killing me

Unfortunately, in the past, i've had one of my windscreens blow out WITHOUT a piece of lexan in there to turn it into a parachute! Either way, some really wild claims about silence.. A sucker born every minute I guess.

If I wanted a quiet car with no wind noise I would not have bought a ragtop.

[SD987]

My understanding of aerodynamics is that the air comes over the windshield, above the cabin and then around, hitting the deflector from behind as it were. So I'm not sure if hole-less deflectors would be more inclined to blow off, as some comments below imply.

That being said, I've never seen a windscreen element on any car, that crossed the width of the vehicle, not have "holes", including BMW (the six series using a small solid windbreak), Merc, Audi, Porsche. This leads me to believe there is a reason not to have unperforated wind deflection. I'd be curious if any of the engineer types on the board would know why that is.

[Brucelee]

Not sure if this seller offers money back returns.

If so, easy way to check it out.

[blue2000s]

Originally Posted by SD987

My understanding of aerodynamics is that the air comes over the windshield, above the cabin and then around, hitting the deflector from behind as it were. So I'm not sure if hole-less deflectors would be more inclined to blow off, as some comments below imply.

That being said, I've never seen a windscreen element on any car, that crossed the width of the vehicle, not have "holes", including BMW (the six series using a small solid windbreak), Merc, Audi, Porsche. This leads me to believe there is a reason not to have unperforated wind deflection. I'd be curious if any of the engineer types on the board would know why that is.

You're right, in general, as to what's happening with the airstream. The blockers keep the air that's made it's way over your head and separated from the body of the car from coming back and hitting you from behind. The passenger's are basically in a "dead air pocket". (FYI: This happens to be the same behavior that makes it more aerodynamic to keep the liftgate on a pickup truck up. Dropping it down or adding an "Airgate" hurts drag coefficient or at least doesn't help, but that's another story).

The airstream constantly changes with speed as you might imagine. The faster you go, the lower the "pocket" gets. Back behind the windscreen, the air is making big circles as it's spinning between the tonneau, the windscreen, and the free moving air above the screen.

The key here is that faster moving air has a lower pressure than slower moving air and non-moving air will be at the highest pressure. (Bernoulli's Principle) So there will be a pressure difference between the non-moving air in the cabin and the swirling/moving air behind the screen. If the screen is big enough, this pressure can turn into a fairly large force pushing the screen out of the cabin. The holes in the windscreens help to reduce the presure difference by letting some air from the cabin "bleed" into the air behind the screen and also reduce the overall area of the screen, both reducing the force on the screen.

Because the holes are small, the overall screen is still doing a good job of blocking the backflowing air. Without the holes, not only would the roll bar screens have more of a tendancy to pop out at speed, but the overall pressure in the cabin would be higher and would tend to push the middle screen off as well.

As to the ones without holes. They are either held in place better or the airflow is such that this phenomena is less pronounced.