Pueblo Motorsports Park. Exactly the opposite of the last week end. Dang, it was HOT. Like Africa hot. Air temps in the high 90’s, track temps up to 140*. Lots of direct sunshine, a little bit of wind.
The advantage to the hot surface temps was that the tires worked really well. With a light weight car, it’s tough to get enough heat in the tires to make them really sticky. Tire temps finally got above 150*.
The car was smokin’ hot this week end. It really performed well. I mean absolutely superb lap after lap. Every time I went out, it just kept getting faster. Because of the heat, other cars were getting slower. This car kept getting faster.
I posted a number of laps in a number of sessions in the 1:40’s. That’s pretty darned fast. The only cars faster were highly modified Corvettes. These are 6 figure cars. I’m driving a $25K car made from used parts that I built in my garage. I feel pretty good about that.
Heat management is important. In a 20 minute session, many other cars were dropping out, or slowing down for cool off laps. Their water temps were 250*, and oil temps were above 300*. My LS engine uses a stock 190* thermostat. The oil cooler does not use a thermostat, and the cooler is mounted behind the radiator. Water temp got above 200* once, and oil temps generally ran about 205*. Alcohol is a good thing.
The one problem we had was keeping the fenders on the car. 2 of the fender brackets broke off. And we removed the third because it kept coming loose. I’ll work on that before the next race. Otherwise, the car ran flawlessly.
High Plains Raceway. Horrible Weather! We didn’t even pull the car off the trailer on Saturday. Snow, sleet, and hail most of the day. Temps never got above freezing.
Some cars did run on Saturday, but we didn’t. In an open car, it’s not fun. And we only have Hoosier R7’s, no rain tires. Yes, this is the last week end in April. Gotta love Colorado.
Sunday was better weather. Still cold and a bit windy, but dry. So we did manage to get a couple of runs in. Times were slow, because we couldn’t get any heat into the tires. But we had fun anyway. We had a tough time getting the engine to fire in the cold, because we run alcohol. I had to jump start it from the truck.
But something really cool happened on Sunday. There was a film crew there from Blend Line TV, an Australian company. They took one look at our car, and said, “We need to film that!”. They took some video of the car in the pit and on the track. And then they interviewed me! The video came out on Facebook in July. Look for it on the NASA Rocky Mountain Facebook page. 🙂 We’re infamous (which is more than famous).
Pueblo Motorsports Park. The weather was great on Saturday. The track wasn’t bad either. It’s was pretty green from recent bad weather. And the wind the day before deposited a lot of fine dust everywhere. You could see some cars kicking up a rooster tail of dust in the morning.
I made some small suspension changes over the winter. I raised the ride height just a little, 2 turns on each spring. That, of course, required a new alignment. Pueblo and High Plains have a lot of high speed right turns. An asymmetrical alignment works best there. I used 1.8* of camber on the left, and 1.5* on the right. Based on tire temps, that’s just about perfect. The right side could use a little less camber. But turn 7 is a difficult left hander, very tight and banked. Making good time through there really helps your lap times. Not enough negative camber through there could cost you.
The Exocet did really well. I made some errors in the AM, and that cost me a little. But they were quickly corrected and we were back at it full steam.
Saturday were were running about 1:44, with some dips in to 1:43 lap times. Not bad at all, really. The fastest the Cobra has ever run was mid 1:44’s.
Sunday we woke up to cooler and wet weather. We didn’t run the first event because it was raining. I don’t race in the rain – everything to lose and nothing to gain. But by the second event the track was dry and the sun was coming out. It stayed cool all day, though.
The car seemed to be bouncing around a little bit on rougher sections, so I softened the rear compression and rebound a couple of clicks. Made a huge improvement! Car was much better planted, and didn’t spin the tires as easy on corner exit. Later I softened the front by a couple of clicks, and it got a lot worse. Cornered well, but couldn’t find traction anywhere. I’ll go a couple of clicks the other way and see what happens next month
Despite the cold track, we managed to run a 1:42! Not a track record, but certainly a personal record. My MXL data logger said 1:41.99. The official NASA time was 1:42.001.
We took second place in our class. We were beat out by a Porsche GT3 by less than 1/2 a second. I’d say that’s not too bad at all for a Sub $20K home built car with a used LS1. 🙂 If the Exocet had a better/bolder driver, I’m sure the lap times would be a lot better.
The bump stops in the rear are jammed into the top of the retainer. I think the suspension is running out of travel in the rear. That might be why I’m getting wheel hop coming out of some corners. It got better this time out with the subtle changes I made.
The front shocks are out of extension, I really can’t extend them any further without adding spacers – which are readily available from Exomotive. But I could add more height in the rear, which might imbalance the car. Or I could add a stiffer spring in the rear. The stock bump stops are about 2″ tall, so I could just cut them in half.
So, what about next time? I’ll raise the car just two more turns on each corner, keep camber the same on the left but decrease it a little on the right. It needs just a little more tire pressure.
And, it needs a better driver. I’ll work on that. 😉
Also, I fabricated/modified new front fender mounts. There’s a new rule in NASA this year, no fenderless cars.
Took a bit of work to make them heavy duty enough for the track. And I had to buy some new ones, since I burned one up last year. But it seemed to work pretty well. One fender came loose at the end of the day on Sunday.
I’m not really happy with the fit, though. Because of the shape of the fender, it sits up higher over the tire than I would like. It would fit fine on a standard sized Miata tire. But on a 275 Hoosier, it just doesn’t fit well. On a full turn the rear of the fender contacts the frame a little bit.
I think I’ll fabricate some flat fenders out of aluminum and see how that goes.