Sunday, October 25, 2009

USAC Sprint Car test - Oval racing?!

Through my good friend Bruce Ashmore, a world-class racecar designer/engineer currently working out of Indianapolis, I had the good fortune of getting introduced to Ken Pierson.

Ken has been racing on ovals as a team owner for over 30 years and has - wait for it - 139 main event victories and 5 championships. One of the cars he races is a USAC Sprint Car. This car boasts an enormous V8 engine generating 750hp and weighs in at only 550kg (1300lbs). The end-result? Acceleration that is FASTER than Formula One! The rear tires are just ridiculously wide in an attempt to maximize traction. More on that attempt later....

Here's how they look when they fly by -

Pierson Racing Bos Sheet Metal USAC Sprint Car

I have never before driven on an oval, with the closest thing being the Motegi exhibition race in an N1 endurance Nissan 350Z set-up for road-racing. This fun event took place on the Motegi oval, with chicanes built in at the end of each straight, and in the RAIN...

So I prepared as well as I could, talking to drivers and engineers with experience with this kind of car.

All in all, I got about 50-60 laps on the 1/4 mile oval - where one lap is 12~13 seconds. Driving this monster is something else. I have never experienced the rush of acceleration that this car can deliver.

The sound is a little off in the video unfortunately.

Let me first describe the machine.
No clutch or flywheel, one-speed transmission, solid-rear-axle (no differential), staggered left and right tires, seating position is very upright with the driver almost on top of the steering wheel that is closer to being parallel to the ground than at the usual 90-degrees in road course cars.

The end result? Absolutely the biggest rush I have ever felt! Each straight was probably just a little over 100 yards, since the entire oval was only 1/4 mile. But, the due to the power delivery of this engine, there is no point on the track where you could actually put all of that torque down without lighting up the tires - including at the end of the straight going around 100mph.
Think about it - coming out of the corner, concrete everywhere, adding in the throttle and the car just bolts forward, jerking you back, but you can only continue to add throttle at a pace to where even after going around 100mph, the car is still traction limited. I've definitely spun those rear tires plenty of times in an attempt to inch toward that 100% throttle. NOT POSSIBLE on a track this short!

My thanks go to Scott Pierovich and Kevin Urton for helping me understand the car and how to drive it. Scott raced in the Sprint Car that weekend and finished in 3rd place on the podium. Kevin, now retired, boasts an incredible career of having won over 100 races both of asphalt and dirt.

Here's a video of the Saturday night rolling start for the USAC Sprint Car race:

I continued to get faster every session I went out as I got more comfortable with the car, and now I cannot wait to get in it again! I've had a chance to think over all of the dynamics of the car.
One of the biggest things that did not click initially - the left-right stagger. The fact that the circumference of the tires is smaller on the left side of course means that the neutral state of the car is turning left, not going straight. This makes the cornering easier, but the disconnect I had was how that affects the available traction - both for braking and acceleration. Normally, in a car that is symmetrical, maximum brake/acceleration traction is available when the car is pointing straight with no steering input. In a staggered car however, the car's neutral state with maximum longitudinal traction is actually when the car is turning at that exact angle when the steering wheel is straight - which occurs twice during the corner - as the steering wheel is released from essentially turning right during the straight, and then when it is getting unwound but the car is still turning at the exit.
I was just throwing the car into the corner to where I was not losing any time at the entry and the middle, but I was still down by several hundred engine revs compared to Scott at the end of each straight - because of my conservative initial throttle application while the car is still turning, coming out of the corner. THAT is when the car has maximum traction for acceleration! Well.. that and I did not want to stick Ken's car into the wall on my first-ever drive on an oval. Probably would have left a sour taste for everyone.

Ken Pierson and Pierson Racing Bos Sheet Metal USAC Sprint Car

I am hoping that next up is another test in the Sprint Car, with Ken's blessings, at Irwindale 1/2 mile track in November.

Where is all of this going? Ken Pierson and Bruce Ashmore are involved with the Silver Crown series and the next-generation Gold Crown - a new series slated to debut in 2011. The Silver Crown car is very similar to the Sprint Car, but with an extended wheelbase to accommodate a larger fuel tank for longer races, and another 100hp, just for kicks.

I have had the most fun pressing on the throttle in this monster and just waiting for it launch off into space at every straight. Thank you Ken!
Ovals - here I come.

Visit Bos Sheet Metal for any A/C and heating needs in the Sacramento area!

Visit Ashmore Design for information on Bruce Ashmore and the Gold Crown Series.

The Gold Crown Concept