986 aero & cooling mods

[The Radium King]

I've thought about the 'parachute' effect when the oem muffler was replaced with a smaller aftermarket muffler, and how you could vent the rear bumper cover to avoid it. also thought about adding something like this that would run from the transmission pan to the rear bumper cover (trim the cover so that the diffuser came just under the licence plate) - one on each side of the exhaust outlet:

Universal Rear Diffuser Kit Under Body Spoiler Increased Down Force Reduce Drag | eBay

[j.fro]

The universal diffuser is interesting. I've thought about adding something like that and exiting the exhaust behind the rear wheels.
Anybody got a DIY for making a wind tunnel?😃

[woodsman]

Originally Posted by The Radium King

I've thought about the 'parachute' effect when the oem muffler was replaced with a smaller aftermarket muffler, and how you could vent the rear bumper cover to avoid it. also thought about adding something like this that would run from the transmission pan to the rear bumper cover (trim the cover so that the diffuser came just under the licence plate) - one on each side of the exhaust outlet:

Universal Rear Diffuser Kit Under Body Spoiler Increased Down Force Reduce Drag | eBay

That looks like a good price for what it is but I doubt it will have enough positive effect to offset it's weight (if you care). Seems perfect for a civic or BRZ. I've thought about splitting the exhaust as well and building a deep diffuser up to the height of the bumper but really don't understand how they work- it's got to earn it's keep on my car. I've wondered if I could trade a diffuser for a wing on a track car to decrease overall drag while sucking the rear down...Porsche did real aero and anytime we let airflow in somewhere
we risk adding drag and/or increasing lift.

[The Radium King]

Originally Posted by woodsman

Seems perfect for a civic or BRZ.

or a boxster spyder:



or a 918:

[woodsman]

With respect to the rear diffuser, Porsche forgot the 'form follows function' rule on the Spyder- but not the 918.

[JAAY]

I will say that I noticed something a couple years ago at brbs. I was parked next to a new spyder and my aerokit 1 rear spoiler was pretty much exactly the same slope and shape as a new spyder. Quite interesting when I noticed it. Not a great comparison but it was cool to see in person.

[tonichristi]

Originally Posted by woodsman

Porsche forgot the 'form follows function' rule on the Spyder- but not the 918.

Are you some kind of expert in aerodynamics, rear diffusing and aesthetic design? More so than Porsche? I'm sure Porsche would love to hear from you. Just shut up, already.

[j.fro]

Alright, moving to the front of the car I've replaced the destroyed front wheel air dams with ones similar to those in the rear. As well, I've added a small air dam to the middle of the underside. Both sets direct air towards the GT3 brake ducts.


Another bit, while we are under the nose, is that I've closed off the factory air exits for the center radiator. Air is now forced to exit through the vents cut in front of the hood. Theoretically, this should produce some downforce. The less air there is moving under the car, the better off it is, right?

[jaykay]

You might consider front fender liner vents:

Flow Through Front Fender Liners

[JayG]

Originally Posted by j.fro

Another bit, while we are under the nose, is that I've closed off the factory air exits for the center radiator. Air is now forced to exit through the vents cut in front of the hood. Theoretically, this should produce some downforce. The less air there is moving under the car, the better off it is, right?

are you an Aeronautical Engineer?

I guess theoretically, you could produce some down-force, but without putting it in a wind tunnel there is no way to actually know what is happening. you are likely to cause other things like drag.

Yes, the GT3 has them. Porsche did aerodynamic design and testing to calculate and design exactly what was needed.

Without that design and testing, who knows what is happening. You could actually cause more lift on the from end by disrupting the aerodynamics.

its kind of like using a butt dyno to calculate HP increase

I'm not trying to pick on you. IIRC, you were asking about making modifications to the spoiler as well to increase MPG. Its just without advanced computer modeling and actual wind tunnel testing ANY modification to the aerodynamics of the car as designed could cause unwanted properties and have a negative effect on handling and efficiency