[Flyntgr]

I race a 2005 Elise NA with no aero. My lap times are in the 1:58-2:00 bracket on 2.75 mile newish asphalt track with 16 turns. It is fast in the corners, but not too swift on the straights. Questions:
1. If I keep my car without forced induction, and assuming everything remains the same otherwise, how much help would front splitter, canards and rear wing help on straights? ...in corners?

2. Depending on weather, traffic, etc,
how much do you think a combined splitter/wing could reasonably shave off those LAP times?

I'm not trying to look cool, but trying to get more grip and go faster around the track. The car is fun to drive and fast for 160 rwhp, but I have a need for more speed. Please give me your best thoughts on this question. Thanks.

 

[Guest]

I have been doing Track events ( about 20 days a year) with my 05 Elise since 2005. I just put on the Carbon Fiber APR wing and the Difflow diffuser and the Front splitter. the improvements are noticable. I had very little overall speed reduction but in the late braking at the end of a long straight the rear stays planted which improves overall braking and is confidence inspiring. In the long fast sweeping turns the car is much more planted and therefore you can push it to slighly higher speeds thru those turns. So all in all its not revolutionary but evolutionary for sure. You might make sure you have worked the suspension and the brakes and pads to their greatest result before you spend money on Aero (with all due respect) Jon in Delaware

 

[Flyntgr]

Aero questions

Thank you for your reply. I realize that the Elise is not as aero as it appears to be, so I am trying to go faster without upgrading the engine or spending millions of $$$$. Have you noticed your lap times improving with these aero mods? I have really good brakes and Nitrons, so I believe aero should be considered. I have raced for the past 5+ years, but that was with SMs and a Porsche 951. I could always use more grip, though the Hoosiers do pretty well. The only upgrade on rubber would be slicks, and in NASA they would bump me up to ST class. So, I have to either consider aero or adding sixty more h.p. Thanks again.

 

[pwildfire]

At stock horsepower, aero bits will almost certainly slow you down.

The car already has lots of mechanical grip, and is low enough on power that cornering is its strong point. Adding aero will slow you down on straights (because more downforce=more drag). It will also require you to run stiffer springs (to keep from bottoming out at high speed), which will reduce your mechanical grip. It potentially will allow you to take high speed corners a bit faster and brake a bit later, but I do not think you will make up enough time from that to cancel the lower straight speeds and lower slow speed corner speeds, although it does depend on the track and your driving style.

While most aero mods add downforce at the expense of drag, it is possible that there are some aero mods that reduce drag on the car, and if so it would be worthwhile to look into those. However, within the rules of your class it is likely that there are some horsepower or handling upgrades that will give you a lot more improvement for the same money.

 

[Flyntgr]

aero questions

Pat, you are hitting the issue squarely, though neither you nor I have reached the answer as to which aero parts will both REDUCE drag, speeding up the car, AND enhance grip in the turns. I suppose you have put the question in more certain terms than I had the understanding to pose.
Thus, I ask: which, if any, aero pieces help
1. Reduce drag and make the car FASTER on straights, while also
2. increasing grip in the turns, high speed turns included?

As an alternative: what speed equipment can be used to make the car faster on the track in lieu of aero pieces? I don't care what makes the car faster and grip better as long as it isn't too expensive for the return on the money.

I just want more grip and speed without forced induction and the incumbent maintenance, heat and break-downs, together with being pushed up to a higher class of ST. I'm hoping to do something and stay in PTB, or no higher than ST3. Whatever "improvements" I make, I want to lower the car's lap times, or at least the potential to do so. If nothing can be done, I'm stuck where it is.

 

[sleepe]

Last time I was at NJMP the fastest car on the track that day (at least the guys using transponders) was a track-prepped Elise with no aero mods and normally aspirated. It smoked all the turbo and supercharged Elise/Exiges by a wide margin.
All the mods were suspension/wheels/tires (slicks) /brakes/etc.

 

[4380r]

Last time I was at NJMP the fastest car on the track that day (at least the guys using transponders) was a track-prepped Elise with no aero mods and normally aspirated. It smoked all the turbo and supercharged Elise/Exiges by a wide margin.
All the mods were suspension/wheels/tires (slicks) /brakes/etc.

That's driver and setup.

Have the same guy who set up the N/A elise set up a turbo/supercharged Elige, and then put the same driver in that car, and the story would be different.

 

[Flyntgr]

I wonder if those were all racers or D.E. drivers at NJMP? I am sure that my supercharged Elise was much faster (10-15 mph minimum) on the front straight. But it had the track pack (60th anniv. 2008) and was a street car without mods.

 

[qu1Z]

Get a diffuser. Channel the air properly, reduce air swirl and drag behind the car. Our aeroplates will also reduce drag by sealin the holes in your undertray/diffuser.

Difflow Diffusers - Lotus Elise and Exige Diffusers!

 

[XHILR8N!]

This is a great topic. I've wondered about it alot.

I do not see forced induction as having any drawback with maintenance or really anything. I have only 225 WHP dynoed and love every minute.

I have the obligatory rear wing and diffuser ans a splitter and canards and have seen maybe slight mph reduction on end of a long straight (in the area of 127 from 131). I have no other data for speed in turns. Our laptimes dropped but i really believe it was because I'd had many more laps, and improved gradually as a driver.

 

[3X163]

I'm no expert, but...

The wing, splitter, and canards will definitely add drag, so I guess those are out for what you want. I think the diffuser and the aeroplates will help downforce without creating drag (and might even lessen drag). You could also add a smooth undertray under the nose of the car to further smooth out the underbody. Maybe side skirts too.

If you haven't already moved your exhaust from the stock diffuser exit to a high exit, that will also help.

The lower your car, the better these aero things can work in your favor. Go too low with the Elise though and you will be out of its designed suspension parameters.

For reference, see this Exige aero article as some can apply to the Elise: https://docs.google.com/file/d/0B5kL...jU1/edit?pli=1

Otherwise, just start doing everything you can to lose weight from the car.

 

[XHILR8N!]

Ronin used to run twin canards a big diffuser and a "Gurney strip". I've always wondered if that wan not the real performance way to go.

 

[Flyntgr]

Quote: "The wing, splitter, and canards will definitely add drag, so I guess those are out for what you want. I think the diffuser and the aeroplates will help downforce without creating drag (and might even lessen drag). You could also add a smooth undertray under the nose of the car to further smooth out the underbody. Maybe side skirts too.

If you haven't already moved your exhaust from the stock diffuser exit to a high exit, that will also help."

Undertray under nose seems to be necessary on the list, along with Diffuser in rear. This is good information. As to the exhaust, I have a Larini (bought it that way) exhaust with dual pipes pointed down. I wonder if these parts plus the BWR s/c would not work well with canards and front splitter? The s/c would make it faster for sure; it would more than overcome any drag from aero parts, but s/c would put me even higher in class in ST. I'll have to check on diffuser to see what penalties go with that.

 

[3X163]

Quote: "As to the exhaust, I have a Larini (bought it that way) exhaust with dual pipes pointed down.

Take a quick read of the article I linked above. They come to the conclusion through wind tunnel testing that simply moving your exhaust exit from thru the diffuser (stock location) to over the diffuser makes a large difference.

EDIT: Crap - it looks like that article has been deleted or something. I will have to find it again...

 

[holmz]

Get a diffuser. Channel the air properly, reduce air swirl and drag behind the car. Our aeroplates will also reduce drag by sealin the holes in your undertray/diffuser.

Difflow Diffusers - Lotus Elise and Exige Diffusers!

Do you have proof of that?
All the measured data I have seen says that the plates have no benefit.

----
The queastion can only be answered frsecific cases.
Case-1: The car is speed limited and not tractin limited.
Answer=no aero modes.

Case-2: The car is traction limited.
Answer=Add aero.

All real world cases are a combination. While it helps on the turns, it hurts on the straights.

The only thing better llooking that a car with Aero, is one without it that is passing the first car.

 

[shay2nak]

Racecar Engineering magazine did a large 3 part story about Exige aero using Reverie parts. They had their own version of the plates, however these plates had a vertical extension at the end blocking off the inside of the rear tire. That showed improvement in downforce and IIRC a big reduction in drag. Basically the outside vanes(?) of the diffuser were extended towards the front of the car, beginning at the front of the rear tires.

Those articles were PDF-ed and posted here.

 

[forkmeupscotty]

Get a diffuser. Channel the air properly, reduce air swirl and drag behind the car. Our aeroplates will also reduce drag by sealin the holes in your undertray/diffuser.

Difflow Diffusers - Lotus Elise and Exige Diffusers!

Do you have proof of that?
All the measured data I have seen says that the plates have no benefit.

Racecar-Engineering article on Reverie Lotus Exige wind tunnel testing at MIRA
http://www.abendanio.com/Manuals/Au...car Engineering- Lotus Exige Aerodynamics.pdf
Under 'Underbody Improvements' - page 20- , the car lost downforce by 1.8% when the panel gaps were closed. :facepalm



Back on topic, it's generally accepted that underbody aero has better Lift-to-drag ratio than traditional 'wings'

 

[qu1Z]

Because the air went above the diffuser on to the top side, acting like a rear spoiler would, which would increase downforce and increase drag. The aeroplates keep the air from going above the diffuser and getting trapped (parachute effect) and causing drag.

That's why S111, FTP performance and others recommend our aeroplates for drag reduction. RLS also has a similar aeroplate just like ours. BOE seals the suspension cutout too. Our coverplates are also the #1 aero mod, sealing the exhaust cutout.

Racecar-Engineering article on Reverie Lotus Exige wind tunnel testing at MIRA
http://www.abendanio.com/Manuals/Au...car Engineering- Lotus Exige Aerodynamics.pdf
Under 'Underbody Improvements' - page 20- , the car lost downforce by 1.8% when the panel gaps were closed. :facepalm



Back on topic, it's generally accepted that underbody aero has better Lift-to-drag ratio than traditional 'wings'

 

[Gunpilot]

I have the wing, canards, spoiler, diffuser, aeroplates, and relocated exhaust. I drive like **** so think there is an improvement even though there most likely isnt.............

I look cool though and chicks did it!

 

[XHILR8N!]

In deciding what to do we have various sources for decision parameters:

Scientific data such as the Racecar-Engineering article,

"What makes sense to me?" or

"What's everyone else doing?" or

"What looks cool, what do chicks dig?"

I think most of us look at the real race cars where people with experience and funding that are driven by desire to win are doing. A car without a big wing looks like a poor person unconcerned about sex appeal.

But there is also the element of "what works on my particular car?"

I've heard and experienced that with an Elige, rear downforce is easy to come by but front is not. We are considering double canards. I would love to see some real data for a double canard, splitter, diffuser and Gurney flap versus a splitter, diffuser and wing set up.

I think we can all agree about getting the exhaust above the diffuser and closing up anything not smooth underneath.