13 replies to this topic

[not so mini dan]

Did a search and didn't find anything of use so i thought i'd ask.

Saw the mention of undertrays a while back and i can't remember the thread and the search didn't turn it up and i was wondering where i might purchase one as i have neither the time nor the inclination to make one myself.

Cheers in advance!

[Ethel]

Midas Gold kitcar - there was a thread same guy that has 2 golds with 8port & 16valve heads.

Don't know of any for Minis.

[Jammy]

There was a guy called carbon weazel that was doing one, I think Smudger might be able to do them as well.

Personally there is no point unless its for a race mini.

[Turbo Nick]

made a fair deal of difference on my mates estate, was a lot more stable at 70+ mph with 180 odd horse pushing him along.

[Retro_10s]

It's interesting,.. My thoughts were (and i admit to having very little aerodynamics knoweledge if any) ,... Would it have to be shaped in a certain way to give the downforce,... and would there be a chance of creating the type of bad airflow that turns a road hugging mini, into one that becomes less stable, possibly leaving the ground?

(ok you'd have to be going very fast for this to happen)

Edited by Retro_10s, 13 September 2007 - 10:51 AM.

[mini93]

it does help to curve upwars towards the end of the car, but getting a flat edge on the bottom is important, its harder thing with the mini i believe because the bottom of the car curves up at the sides of the car not using and kind of body kit which is lower than the floor. one of the most important bits is the rear subframe, air comes of the floor and then circulates around the recess made for fittment also the rear valance is again just trapping it there, even just by plating that should help.
same for the front end but theres more to think about being mainly cooling fins on the engine sump, if you manage to shape the front tray so that is sits with the fins stick under tray then should be good, may also need to employ an oil cooler, its somthing i will be looking into for the track car when i build it.
i hope to be using 1mm or less is possible aluminium sheet cut into 3 sections, front section around engine etc main body from very front of the body (probably where subframe mounts) right to the back just about where the subframe mounts, obviously the 3rd piese will be for rear subframe area, not yet thought about end shaping but i might do away with rear valace and shape up the end, the curve will have sides so stop the air travling out the sides to where the rear wheels sit

[mini93]

and this would be the thread project thread the 1st pic on that page shows the front section of the under tray for the kit car

[steveobennet]

they are used to suck the car to the road really, as mini93 says air can easily escape out by the sills area. don't know if anyone remembers but in f1 a fair few years ago the were using side skirts the moved with the road surface, giving superb suction to the track, which meant they could corner much faster. got banned though, due to an unfair advantage.

anyway back to the diffuser, basically on a road going car it is abit of a gimmic if you will, yes it will help with motorway speeds but speed humps will always cause a problem. more suited to a track mini, but saying that i wouldn't mind one on the front and back of mine.

[Sprocket]

Mr Fastcarl titanium Austin, Force Racing


http://www.foxwebsit...gn.co.uk/4.html

[mini93]

thats also mentioned in the topic i linked, no specific information tho

[Turbo Nick]

the one my mates running is on an estate and is just on the rear at the moment (well not at the minute because we've stripped it for a respray) made out of 2 pieces of 1mm ally sheet. closes off the rear subby and sweeps up the rear valance, the only thing exposed still is the exhaust. might see if we can get round to making one for the front but it's definately a lot more civilised now, and even nicer with the lsd.

[biggav]

just a p-shop, but something like what i want!!!!!!!

i have emailed fast carl for a price.

[Jammy]

I dunno Biggav, it almost looks like your minis arse is melting! I think one that has boards 1/3 and 2/3rds the way along that come vertically down, and then horizontal boards sweeping up towards the boot would suit your mini more?

[JetBLICK]

Theres a huge difference in aerodynamics between creating downforce and making things more aerodynamically stable. Its quite complicated, but there would be a lot to gain from putting undertrays on a high powered mini. I wouldn't think so much on a-series power as its not so often you're seeing well over 100. But for others who are capeable of reaching well over those speeds you'd make the car much less twitchy just by sheeting under the engine and rear subby. Creating usefull downforce after that tho becomes quiet complicated. You can just take off the rear valance and have a big diffuser with a big rake angle and it'll work, but there are better ways of doing it. Theres a brilliant article in this months race car engineering mag, they where doing some very useful tests with undertrays and diffusers at mira with an elise, came up with some good results and conclusions