09/03/2010 I had to look at the blog to figure out when was the last time we ran at PIR and it was exactly a year ago, at the Lotus event just like today. A few things have changed since then and this time we brought out the dp4 and the dp1/e in the Mothership. Some friends came out as well so our space had an interesting mix of cars around it. These included an Exige S240 (yes that's Kermit), a classic Mini and a Cosworth RS.

The main goal for today was to test a wing on the dp4. I've had a few conversations with Wayne at Stohr and he was saying that without a wing their cars are nearly undrivable and that I'm going to need one too. Of course if we do go with a wing Wayne will end up making them for us so he has a motive - but the first one is free :) He graciously let us borrow an old wing off of one of his DSR cars. Couple days ago Tristan fabricated an adjustable mount that would let us try several angles and elevations. With the hardware ready we came up with a plan and now we just need to do it..

In the first session I went out wingless just to set a baseline. It took a couple laps to warm up the tires (car moves around a lot when they're cold!) but when it felt like some heat was in the rubber I started progressively upping the pace. And promptly spun it coming out of the chicane - an obvious driver error trying to carry accleration and lateral g over a set of bumps. No damage done though and I simply pulled back onto the track and continued on. The car is still a bit edgy under brakes so I'm having to brake early and gently, relatively speaking. Lateral grip is good though I do have to pay attention all the way through a corner. Then the session is over and Tristan installs the wing for the next one, in the low/flat position first.

I go out in the next session and the difference is immediately noticeable - and huge! The car is now rock-solid under brakes and I can apply them a lot harder, being able to go in just past the 300 ft marker into the chicane before braking. It is unflappable in the corners too an the g forces start reminding me of my days flying aerobatics - over 2g sustained. The car is way better than me now and I'm not using all that it can deliver. I'm certain that it can do turn 10 flat out but I'm still lifting for it, although even with that I'm taking the turn at 100 mph flat which is considerably faster than anything I've logged there before (80-85 was more typical in other cars).

Mid-session I pull in to have Tristan change wing angle to our 'high' setting and go out again. A bit more stability along with a bit more drag as evidenced by shift lights coming on a couple hundred feet later on the straights. It is a hot day and my induction system for the engine at the moment consists of a foam filter sucking very hot air from under the bodywork. Far from optimal and we're only getting about 117 mph top speed so power is way down. The original dp1 prototype with this very same engine went 18 mph faster at this track - it had a scoop directing outside air near the filter. Of course what I need is to develop a proper airbox which is definitely going to be standard on the production cars. And we need to check the engine, just in case.

Next we tried a higher setting at both angles:

Up higher the wing operates in cleaner air and should be more effective but it didn't feel too different. There was no significant difference in top speed, less than 2 mph from fastest configuration to slowest. Here's a video of a lap. For the final session we went back to low/flat setting that was actually lower than the initial one but moved the wing back about an inch. M got to drive the car in the last outing. She had driven Kermit earlier in the day and now I jumped into the Lotus for a comparison. What a contrast. Kermit is a very fun car on its own and is the ultimate streetable Elise but after the dp4 it just feels sloppy, soft and slow. I'd be braking into the chicane at what feels like a conservative rate and the ABS is trying to kick in. Then through the turns the car moves around, slides and squirms. And this is after putting aftermarket shocks on along with doubling the stock spring rates. I suspect the tires are at least in part to blame and we'll try a different set on the car later.

The comparison really brings the dp4 value proposition into focus. For half the price and much lower maintenance cost you can go faster and have way more fun. We just priced replacement front rotors for the Lotus and they're $798 EACH, along with $275 for front pads. Rotors for the dp4 are $75 each and pads are $50 per set. Plus it needs them less often. The entire one-piece dp4 body can be replaced for 1/2 of what just the front clam shell on the Exige costs. So you could get a $65K Exige which is compromised both on the street and on the track, with high maintenance cost and no way of getting home if something went wrong at the track. Or you could get a dp4 with trailer AND a nice $30K sedan of your choice to tow it with, have more fun on the track and be more comfortable on the street without risking getting stranded at the track with a broken car. Same money. I know which I'd rather have.

All that said, I have to admit that Kermit does look great :) It also makes every street drive a special occasion which is both good and bad. The good is obvious. The bad is the fact that parking it is a very stressful endeavor, both getting it done with no rear visibility and leaving the car there knowing there are no bumpers and that SUV drivers can't see it. Lane changes are a pain as well.

Now of course I'm faced with designing a custom wing for the dp4 that both works well and integrates better into the aesthetics of the car. I already figured out the mounts so the wing can tilt up with the bodywork and I have a general idea of how it'll work and what it'll look like. Just need to make it happen. That and the airbox.

A very good day overall. At Laguna, when I asked Jonathan Frost what would let him go faster he replied 'stability'. With the shock changes and the wing we now have that in spades. Should still sort out the power issue, but I'm now eager to find out what a better driver than myself can do with the car. I would also feel confident having just about anyone drive it now - you only need to be a pro to be very fast. Just to have fun, be safe and still go rather quickly is within any trackday driver's capability. Which is what the car is about.