Rear Diffuser / UNder Tray Diffuser

r34nismo · Post by **r34nismo** » Thu Jul 31, 2008 8:15 am

Can everyone post up some picture of content they have as I am looking at how to develop something for the back/under tray for my car.

Cheers

duncan · Post by **duncan** » Thu Jul 31, 2008 8:51 am

here is what mine is going to be based upon:

when I get round to making it

IWANT1 · Post by **IWANT1** » Thu Jul 31, 2008 9:06 am

Um where you looking to purchase that fron dunk as i may be slapping one on the evo at some point? They make them for the 7-9 but not the 5-6.

duncan · Post by **duncan** » Thu Jul 31, 2008 9:29 am

I will be making it Lee. Not out of carbon though - plain old ally sheet for me.

r34nismo · Post by **r34nismo** » Thu Jul 31, 2008 5:38 pm

I am looking at Ally at the moment much easier to make and mould to what I want.

Will be looking at a complete under tray the full length of the car, the idea is to have some bonnet scoops upside down in the tray to bring air flow into areas that need it ie.

Diff / Geabox and also for rear brake routing....

duncan · Post by **duncan** » Thu Jul 31, 2008 6:47 pm

be careful about a full length undertray as it can really upset the engine temperatures.

The best stuff I have seen for the undertray is a aluminium honeycomb - mega strong and mega light.

r34nismo · Post by **r34nismo** » Sat Aug 02, 2008 8:33 am

now thats a good idea for select areas.

r34nismo · Post by **r34nismo** » Tue Dec 09, 2008 6:03 pm

going to be putting through to paper over christmas.

Lets face it not much else going on apart from Drinking

)

RX7 · Post by **RX7** » Tue Dec 09, 2008 7:15 pm

Here's a link to the rear diffusers on RX7s mate:
http://www.fd3s.net/diffuser/index.html

RPS13 · Post by **RPS13** » Tue Dec 09, 2008 9:41 pm

duncan wrote:here is what mine is going to be based upon:

when I get round to making it

It has been a little while since i did any real aerodynamics, but the angle change on that diffuser looks very aggresive. Air may stall/ break up and make the diffuser less effective, so just be careful it is a real diffuser you copy and not just a piece for show. Most race cars based on production bodies run very shallow angles unles there is a huge rear wing very close to the diffuser interacting with it. Most diffusers on sports and supercars are exagurated for looks over real performance. The rule of thumb i was taught is 7 degress constant slope angle is safe, 13 degress is the maximum you may get away with without interacting flows.

F430 road car:

and race car:

Covette endurance car:

Very easy to make, but dont forget the loading they create (having seen a few diffusers and splitters colapsing or ripping off the brackets!). 100kg at 100mph should be easy enough to create from a subtle diffuser if you are making a flat floor too.