Aerodynamic aids - are they actually tested?

[VladTheDad]

There are a lot of 3rd parties selling rear diffusers and front splitters and they claim they improve downforce, which all sounds very reasonable. But the question is have they actually been tested?

When two or more of these add-ons are put together this should have some effect on high speed handling but again has this been tested or would you be meddling with the unknown by attaching these things?

[slatess1]

Simon who runs Reverie tests his carbon fibre splitrers / spoilers etc in a wind tunnel... Ive seen pics of them there...

Edited by slatess1 on Thursday 8th November 14:37

[VladTheDad]

I wonder if they'll give comparative numbers if I contact them?

The reason I was thinking about it in the first place is that Lotus are saying the new Elise SC won't be as fast on track as an Exige S because of aerodynamics (downforce I would guess). But this could probably be fixed with a few bolt-ons while retaining the Elise light weight and rear visibility. It might not be cost-effective but it got me thinking.

Thanks for the reply.

Edited by VladTheDad on Friday 9th November 09:10

[slatess1]

VladTheDad said:

I wonder if they'll give comparative numbers if I contact them?

The reason I was thinking about it in the first place is that Lotus are saying the new Elise SC won't be as fast on track as an Exige S because of aerodynamics (downforce I would guess). But this could probably be fixed with a few bolt-ons while retaining the Elise light weight and rear visibility. It might not be cost-effective but it got me thinking.

Thanks for the reply.

Edited by VladTheDad on Friday 9th November 09:10

Im sure Simon at reverie would be more than happy to advise if you give him a buzz.

His website is on my profile page. Think he may be away at the moment for a sailing competition but he'll be back soon...

[SimonK]

I would guess almost all of the lap time difference between an elise and exige fresh from the factory is down to the sticky tyres on the exige which are wider at the front too, and the stiffer suspension. Despite what lotus say, concensus seems to be the aero is not very effective.

If you were to modify both cars to be identical spec, then i think you would find the difference in lap times and weight to be next to nothing.

Basically there would be better ways to make the elise faster:
http://wiki.seloc.org/a/S2_Track_Modifications

[Sam_68]

SimonK said:

asically there would be better ways to make the elise faster

Remember, also, that for higher speed ranges, what you gain in downforce, you lose (to some extent) in aerodynamic drag.

And, yes, you are meddling with the unknown. Wind tunnel testing only tells half the story. Remember that even Lotus fcuked up big style with the 80 (which suffered uncontrollable porpoising due to aero effects, despite extensive wind tunnel testing) and Ford fcuked up with the Sierra (inadequate consideration of lateral Centre of Pressure movement in varying conditions) and, most recently and most famously, Audi fcucked up with the TT. So no disrespect to Reverie, but how much would you trust a couple of hours of wind tunnel testing from a manufacturer of specialist aftermarket body bling?

[VladTheDad]

I wonder if the standard (or any other) diffuser actually generates any downforce at all (or is the car just too high off the ground). If it does create downforce would a splitter at the front improve that effect significantly?

It may be a relatively easy and effective mod - or it could be a waste of money and an exercise in kidding yourself - or even worse it could create more drag and upset the car in high speed corners?

And it'll get smashed on speed bumps / car park ramps.

[Phil-CH]

SimonK said:

I would guess almost all of the lap time difference between an elise and exige fresh from the factory is down to the sticky tyres on the exige which are wider at the front too, and the stiffer suspension. Despite what lotus say, concensus seems to be the aero is not very effective.

The aero is different, regardless what many may think of the S2 wing. A german magazine tested the downforce and while it's nothing as much as you'll get on an S1 Exige, the S2 Exige still has more downforce than a standard Elise, even if not much.

Edited by Phil-CH on Friday 9th November 13:36

[Christian43]

It is always iffy playing around with the aero on a car as the manufacturers spend a lot of time and money on it and still get it wrong (as said above). I would imagine the rear diffuser is too high off the ground to do much in terms of CL, however it looks good and the C of G is low so no halm there, and it probably is good for Cd. A front splitter would probably help front end grip but wont help the diffuser work and will probably make it worse due to lower flow rates. I guess the best is to get aero mods from companies who race said parts and hence have a good idea of what they do at high speeds. Although what you can live with in terms of aero balance if you are a race driver on the track and what you can live with on the road are two different things. Fortunately there are no mods available for a Europa so one less thing for me to worry about.

[VladTheDad]

I thought that the point of a front splitter was not so much to generate downforce itself, but to deflect air from above the splitter level around the car so it doesn't interfere with the flow under the car.

[hbaumhardt]

On A048 or R888 rubber until you get to higher bhp you have more mechanical grip than power and aerodynamic aids (splitters, wings, diffusers) will actually slow the car down with induced drag. I relase that experience is valued less than opinion by some, but for example Gav Kirby's 190bhp S2 Exige was faster through Eu Rouge at Spa but could not match the other 160bhp Class A Elises top speed on the following straight until he actually REMOVED the rear wing in the second race.

[Gooby]

Efficient rear spoiler


Plus the power of the 240R and a good driver.

[peter450]

Rear diffusers are the modern day version of the 80s spoiler, a road car sit's to high off the road for them to function correctly, but it makes it look fast an mean and has no ill effect so i've no issue with them