Originally Posted by Simon S
Have to ask, What the hell do you want traction control and an LSD for? ..... if you are spinning one rear wheel, then sort out the suspension
Simon...in the US, the most common form of entry level racing is called Autocross. Most of the Elises that autocross do so in the stock class. No...stock is not actual stock out of the showroom, but many of your suggestions cannot be performed for stock class competition. They'd be illegal. But they could be added to cars running in other classifications.
In stock class, we have to run at stock achievable ride height, use stock or stock size wheels within +/- 1/4 inch on offset. Any DOT-R tire that will fit on those wheels and the car. Any (or no) front sway bar. Shocks close to the stock overall length, but with the spring perches set to match the stock dimensions on either end. So the popular (outside the US) Nitrons would not be legal as-is: since Nitron moved the spring to allow for the rebound adjuster. Yes, moving the spring coaxially does nothing for performance. And stock springs would have to be used, not sure if they fit a Nitron modified for stock class or not. You can use a larger front sway bar to help the back of the car gain acceleration traction. But at some point the inside front lifts off the ground hence 100% of the front weight is carried by the outside front and no more help for the back of the car is possible from the sway bar. Engine mods such as another panel air filter and a cat-back exhaust are okay. Interior items stay mostly stock. You can't change the seats....add stiffer suspension bushings...bump steer the suspension...add a faster steering rack...machine bits to gain more negative camber up front (we even have to leave in the last camber shim since it holds the ABS wire ~.7 degrees of negative camber is often the max achievable with these limitations)....bore and stroke the engine, add cams or port work...change to an aftermarket clutch...add a supercharger...add an accusump...baffle the oil pan...add better brake calipers...convert to a sequential gearbox, etc, etc.
Compared to the open track note that Autocross is primarily a 2nd gear sport with few if any shifts once you hit 2nd gear. So at times the car is vulnerable if caught off the cam in certain parts of a course. Can't change the gearing to deal with that. But on the open track you'd not spend much time in 2nd gear...so the torque to the ground is often lower on the open track - being in the higher gears reduces the likelihood of wheelspin. As opposed to Autocross where you are generally in 2nd, but sometimes in 1st or 3rd (very rarely).
An LSD can be added since that was a 2005 option. So then by definition it is a stock part. If we could do some of the mods you suggest, the need for a LSD would plummet or maybe even go away. We have to use the options open to us in this setting though. It is this setting with which you might be less familiar.
Take a look at some of the autocross videos hosted on this site or Randy's Chase Cam site. A great deal happens during a one minute autocross run. Giant, rapid transients. No long, steady cornering forces like a long sweeper on the track. Generally way, way more than in one minute on the track. It is very intense and you can routinely push harder than you can on the open track because: there are only cones and your pride to knock down...there are no other cars running with you so you won't have to deal with them. Think of it as a more intense, lower speed version of the old F1 qualifying sessions. In F1 you see the same tracks each season, model them on the computer, practice and test there on non race periods. In autocross the venue (huge, flat, unobstructed parking lots or airfields) is the same..but the course never is the same. Most of the time you show up at an event, see the course for the first time, walk it a few times and then get as few as 3 chances to compete on it to the thousandth of a second. No practices. No dial in time to get the car perfect for that course. No videos to watch before you get there. After that event, the course is gone forever. Many excellent open track racers just cannot handle autocross. They can't do well in it.
Check out the tires used in Autocross. They are so sticky and gummy that they can overheat in a few one minute runs with generous cool down between them! Often the competitors rush to spray water on their tires to cool them back to ambient just before an upcoming run. They use pump up portable water tanks intended for garden insecticide spraying. That's not an open track thing either. You'd have to come in every lap for a cooling down and watering session!! BTW the autocross tires allow just amazing amounts of lateral and longitudinal grip...a few clicks higher than typical track day tires...this also tends to increase the inside rear wheelspin issues. Since even more weight can transfer away from the inside tires. The tires are way stickier than A048s or A039s.