Until about a week ago, I hated Lotus machines. With their kit-car interiors and doors no bigger than a tank commander's access hatch, they represented the epitome of English engineering almost as well as Lucas electrics and Jaguar's V12 (found in old E-types). They were great in theory, or for a few laps, but hardly the thing for I'd want to live with every day.
This wasn't snobbery. I've spent time in the new-generation Elise and Exige: an occasional loop on the skidpad or the stuffy commute. While the inherent lightness and purpose was clear from the stratospheric red line, unassisted steering and over-boosted race-package brakes, the pieces didn't add up. The shifter was rickety, switches were only a step better than a TVR, there was constant understeer, and, without a supercharger, the car didn't make enough power to get out of its own way. It was so uninspiring that flogging it never crossed my mind. Each time I tried to wriggle in and out I swore it would be my last.
The problem was, I knew the Lotus to be a phenomenal car by reputation and design. It's made of all the right stuff: no-frills weight, proper suspension and a linear powerband with a great power-to-weight ratio. These are all things we strive for in our project car creations. I just couldn't put my finger on why I didn't like it.
My mind changed when I tried the new Elise SC, a supercharged version of the car we already know, with added aero tidbits. It was then that my pride forced me into slamming the machine over the mountain roads of San Diego in chase of Lotus' head engineer. A light turned on and the Elise's brilliance flowed into my veins more than any junkie's syringe ever could.
I was eager to pick the guy's brain for any little secret I could extract and transplant into my own Project NSX. If anyone knew how to set up a mid-engine supercar, this man would. I threw every question I could muster out of my meager arsenal of suspension knowledge and got some vague but surprising answers. While not everything would translate directly to Project NSX, the fundamental principles still held.
The key to a great-handling car is Lotus' approach to keeping the chassis neutral, while remaining driveable by less talented drivers. The car had to be predictable and linear in every respect.
Regarding tire size, Lotus decided to throw away front grip. With up to 60 percent of the mass in the back, the rear wheels do most of the work. So the rear tires are as large as possible to maintain grip while not being too large and/or sticky to overpower the appropriate spring rates. There are roughly three degrees of static camber in the rear so it stays planted in cornering, while the smaller front tires maintain little camber to prevent oversteer into corners. This is why the car might feel sluggish at turn-in.
The front tires are small enough to maintain neutral balance throughout the corner. With too much tire in front, not only would the car oversteer, but the rears would approach their limits faster and operate in a non-linear grip threshold well before the fronts, which hurts predictability a lot. So stuffing as much tire as possible under each fender isn't necessarily the best solution.
A little understeer is a good thing. While the Elise doesn't have terminal front-end washout like a Scion tC, Lotus designed the car to push mildly after the chassis takes a set in a turn, so it remains controllable in mid-bend and as it powers out. This is the same approach drifters use to keep a car catch-able once a drift is initiated.
Bump steer is also good as long as it's done properly. Most OEMs dial in a given amount of bump steer in the front suspension for the car to remain stable in a straight line as the front wheels encounter different bumps at different times. It's only in race applications, with stiff spring rates and an experienced driver, where bump steer is minimized so there's a mild amount of instability and a precise connection with the steering. Whereas modern jet aircraft are designed to be unstable to increase maneuverability, bump steer elimination isn't necessarily good for a street car-not even a Lotus.
Even with everything else set up perfectly, damping and damping control is everything. While this magazine has gone to great lengths to compare dampers through shock dynos and damping force curves, we're still only scratching the surface. Aspects such as damping repeatability, actual damping force versus spring values, piston design and a damper's digressive nature are much harder to evaluate through a shock dyno. And just because it works on paper doesn't mean it'll work on pavement. Lotus' Bilstein dampers are so dialed-in from the factory that the minute but noticeable change in turn-in feel between sport and regular modes are strictly a result of valving changes, not spring or alignment.
In the end, I realized I already knew the answer. There was nothing I could do to make Project NSX (or any other project car, for that matter) turn the tricks the little Elise was capable of. What ultimately makes a Lotus a Lotus is the well-focused and uncompromising direction of a small, passionate company composed almost entirely of staff members involved with professional racing, who are willing to spend endless hours of development time on making a street car exactly as they want it. Brilliance is designed in from the ground up and isn't something a tuning magazine editor could come close to replicating. It's discouraging, but at the same time inspiring. Until we can afford cars like the Elise, all we can do is to continue learning and trying.