Rear Diffuser? How much does it help?
 

Hi guys, I've tried to search for the benefits of a rear underbody diffuser at a track event, but didn't really find anything in the racing/comp threads. Does anyone have any info on this? Thanks!

-stephen

I guess no one really uses them hehe :(

Well there's no doubt that aerodynamics help. However, without a wind tunnel, it's hard to quantify how much they help and on what tracks at what speeds. There was a thread in which underbody panels/aero was discussed not too long ago, too.

Yeah, a wing is much simpler to analyze. You can just change the angle of attack and check your lap times and mid-corner and braking zone speeds.

Yeah both of your replies make perfect sense, I'll look up the thread thanks!

-stephen

:iagree:

A diffuser on its own probably gets you nothing measurable but I'm sure it would work very well as part of a complete aero package designed by an expert and tested in a tunnel. That said there is more time and speed to be gained in driver mods vs. vehicle mods.

A properly designed diffuser conceivably can get you MORE than a wing, the problem being, are there any properly designed ones being built for our cars.

I know that if the angle of the diffuser is between 8-12 degrees then it is possible to get downforce without the drag that you get from a wing, but the angle is just one of the pieces to the puzzle. Our rear ends do appear to allow for a diffuser of that angle.

I too would like to know if anyone is running a diffuser to any benefit. I wouldn't like one of the gargantuan Nascar type diffusers.

isn't the diffuser effectiveness as much dependent on the ride height..and cleaning up the airflow with a flat bottom..

it's a shame honda didn't do anything with the rear aero.. apart from making it a parachute.. even the most mundane cars have been running rear bumpers that help rather than hinder the areo..

for example, one of the new saabs.. with a shaped rear bumper.

http://cache.jalopnik.com/cars/images/saab_95_pr_1.jpg

want to see a functional diffuser, look at the arse of the f430.

here's a functional diffuser on my friend's elise....

http://www.s2lstudio.com/car/du/images/_DSC1278.jpg

i am in the process of making one for the S but yeah its really hard to engineer a functional one without wind tunnel.....