Are Carbon Fiber Trunk Lips only for show?

[adobeee]

Hello all.

As you may already know, I am a car noob..

Do carbon fiber trunk lips actually help with performance/aerodynamics or they are only for looks?

Thanks all!

[Greenkirby21]

i would say mostly for show, but I am sure they provide some downforce on the rear.

[adobeee]

Originally Posted by Greenkirby21

i would say mostly for show, but I am sure they provide some downforce on the rear.

Is the difference in downforce big?

[ItsHectic]

Do they stay on at top speed? lol
I am serious its a lot of wind pressure at that speed and I dont know what they are stuck on with but I think its something sticky and not screws so I cant imagine them staying secure at 220km 135mph+

[Greenkirby21]

Originally Posted by JustMe

Do they stay on at top speed? lol
I am serious its a lot of wind pressure at that speed and I dont know what they are stuck on with but I think its something sticky and not screws so I cant imagine them staying secure at 220km 135mph+

They are usually put on using double sided tape, or betalink adhesive, which is impossible to remove. I would assume it stays on at top speed, or BMW probably wouldn't sell it if it would fly off and hit other cars xD.

[ItsHectic]

Yea I know the stock one wouldnt but looking at some of the aftermarket ones they come out a lot. The stock one is just a lip, this I would classify as a spoiler:



^ Would have lots more leverage to stress the adhesive.

This is a different design, wonder why they went with it, looks like more drag but less downforce although more secure

[adobeee]

thanks for the comments guys..but i still need someone to answer my question hehe

[ItsHectic]

They help but only at high speed, I remember reading aerodynamics comes in at 70km/h, doesnt seem like a reasonably accurate statement though cause there should be factors.

The way it works is its a trade off of fuel efficiency and top speed(if your car isnt electronically limited) At the benefit of more stable heavy braking at high speed followed by more rear wheel traction all together.

I dont think its worth putting on unless you track.

[FDM68]

Not sure how much they help with down force but they'll stay on, at least the adhesive attached ones, will at top speed i.e. 135+.

[ErvGotti]

Mostly show I'm sure they'll help at higher speeds, but if your driving 100 plus you might have other problems. (unless your on the autobahn or a track)

[fusion01]

there is no way that rear boot lid spoiler will be removed easily. and it will not fly off no matter what speed. and yes, a little downforce. and it looks pimpin' hot. why I have one.

[SV Concepts II]

The carbon fiber lips are mainly for aesthetic purposes. They look awesome

[VividRacingSale]

You'd have a hard time trying to quantify any sort of performance increase, but your car will look good!

A properly installed trunk lip will definitely stay on at speed. "properly installed" being the operative words

[KingOfJericho]

To directly answer your question: Generally speaking it will make virtually no difference in performance. I had a Lotus with a large wing that was noticeably effective at speeds above 70 mph but our cars are heavy and powerful enough to push through aerodynamic walls and the spoilers add little to no benefit.

[bogart]

I'm sure the iCarbon CSL style trunk creates some downforce.

[blue2fire]

Originally Posted by JustMe

Do they stay on at top speed? lol
I am serious its a lot of wind pressure at that speed and I dont know what they are stuck on with but I think its something sticky and not screws so I cant imagine them staying secure at 220km 135mph+

I had one on my E90 for 40,000 miles with the factory BMW betalink and it didnt move an inch through 100 deg heat, rain and snow. Not falling off in a hurry.

[dtwyim]

Originally Posted by JustMe

They help but only at high speed, I remember reading aerodynamics comes in at 70km/h, doesnt seem like a reasonably accurate statement though cause there should be factors.

The way it works is its a trade off of fuel efficiency and top speed(if your car isnt electronically limited) At the benefit of more stable heavy braking at high speed followed by more rear wheel traction all together.

I dont think its worth putting on unless you track.

Depending on the car, the rear spoiler/lip does make a difference.

IIRC, when the Audi TT first came out, some of them do not have the rear spoiler. There were some high speed crashes potentially related to rear end lift at high speed. There was a recall in 1999/2000 where the rear spoiler was added amongst other things.

[ItsHectic]

Originally Posted by dtwyim

Depending on the car, the rear spoiler/lip does make a difference.

IIRC, when the Audi TT first came out, some of them do not have the rear spoiler. There were some high speed crashes potentially related to rear end lift at high speed. There was a recall in 1999/2000 where the rear spoiler was added amongst other things.

Yep it was also the suspension though, http://www.fleetnews.co.uk/news/1999...y-recall/6138/

Here is what no downforce does, same thing but incorrect dampers is pretty embarrassing for the engineers, missing a spoiler not so bad:
youtube.com/watch?v=lY-BC0bH6j4&t=0m11s