build diary

April 24, 2006: My poor tires.
Larry Webster from Car and Driver was finished with the straight-line data acquisition (0-60, 1/4 mile, braking) and went off to do a quick skidpad test on an open area we'd found. Jeff Dworin (the Car and Driver art director) and I followed in the minivan and Larry wasn't hanging around on the way. He seemed to have bonded with the car. Once he hit the skidpad, he discovered just how easy it is to hang the tail out on the Seven. He proceeded to do a couple of complete circuits sideways. When he came in, he was laughing and claimed "I could do that all day!" He encouraged me to give it a shot so I could feel a difference in behaviour between left and right turns. I came in laughing like an idiot. It didn't take much encouragement to get Larry back out there as I ran the video camera. A few laps in one direction, then he tried going the other way and it worked just as well. "This car is a drift machine! Man, that was fun." was the verdict. He had definitely been enjoying himself. I was worried yesterday that he hadn't had enough seat time to really appreciate the car, but I'm not worried about that anymore. He even started to think out loud about building one of his own. Ahh, so he did understand.

The day started off early. Chris was unfortunately absent, but Jon and Mark were there with their creations. Jon's BMW 318i-based car was run first, then the turbo car. Larry was impressed with the speed of Mark's buggy. It was twitchy on the transition from the sticky dragstrip to the asphalt run-out area and we could hear a surprising amount of tire noise as the car hit the high-traction surface. After the runs, there was visible toe-out. The lower control arms had bent under braking, allowing the wheels to move backwards. It must have been quite a ride but Larry kept it all tidy and out of the big retaining walls lining the drag strip. Mark was pretty happy with the results - the car's a bit heavier than he had originally expected and the performance was about what he expected when the extra weight was taken into consideration. Jon sounded a bit disappointed as the times weren't quite as good as he saw in Florida at the GRM Challenge.

Time for the little orange car. From the sidelines, it sounded absolutely glorious. A full-throated induction beat combined with the exhaust howl to make a classic patented Sports Car Sound. The turbocharged cars I deal with at work just can't do that. Jeff had a big grin on his face as we watched the car tear up and down and I was having a hard time maintaining a professional demeanor and not dancing around. Larry was very impressed with the brakes ("Porsche 911 braking distances!") and was definitely enjoying himself. He reported that it felt much more settled and stable than the other cars and wasn't bothered by the transition of surfaces at all. Fair enough, the car's had more track-biased development than Jon's car and of course Mark hasn't had time yet. My car was in its element.

So how did it perform?
0-60 in 4.7 seconds
0-90 in 10.8 seconds
0-100 in 14.8 seconds
1/4 mile time of 13.8 seconds with a trap speed of 97.4
70-0 braking in 141.4 ft and 1.156G
0.98G on the skidpad

For comparison, a Porsche 911 Carrera S takes 154 feet to stop. A 2005 Corvette Z-06 corners at the same 0.98G. The baddest Aston Martin on sale right now - the V12 Vanquish S - takes 4.8 seconds for 0-60.
It was obvious from the side of the track that aero became a real problem in 4th gear as the acceleration tailed off. You can see this in the difference between the 0-90 and 0-100 times. I had asked if I could remove the windshield but that apparently is cheating. We were going to try it later but got distracted by the hooligan potential on the skidpad. Regardless, I'm tickled pink with the performance and even happier with confirmation that the car does indeed seem to work as well as I'd hoped. I've been aiming for a world-class sports car and not just an oddity that was notable for being, well, odd. It looks as if I might have pulled it off. Larry's sheer joy when he got out of the car was a big reward. I'm very interested to see how he writes the article.

The asymmetrical handling? I think it might have been a low-pressure rear tire. There was a flat on the car by the end of the day. I'd checked pressures before testing to be sure, so it could also be a setup issue. The extreme caster means the steering is quite heavy when sliding the car (I've always had trouble with catching really big slides in the car) so I'll experiment with that as well. The rear tires are looking well scrubbed in by now though! I'll have some video up soon that shows just what happened to all that rubber.

A long drive home, but I'm very happy with how the trip turned out. Despite the earlier problems, the Seven delivered when it was asked to give a full effort and I was able to sort out the driveability problems with some tweaking of the computer.

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