I’ve watched them on TV when I was a kid and on YouTube where I could, but I’ve had a fascination with the Sprint Car. I was finally able to catch them live at Perris Auto Speedway with USAC CRA and now I know what I’ve been missing all this time.
That’s probably a surprise revelation to people who know me – that I’ve never been to a Sprint Car race live in my entire life. You’d think that while I was living on the East Coast, I would have been to at least one. Nope. Been to plenty of short track stock car races, attended dirt oval kart races, NASCAR races, but never an open wheel dirt oval race. This night, I was given an opportunity to be introduced to the Amsoil USAC CRA Sprint Car Series at Perris Auto Speedway with the “So-Cal Showdown.”
- CRA Sprint Cars?
- Sprint Car Tech
- Full Lock and Three-Wheelin’
- Open Wheel Dangers
- Brody Roa Take the Win
- Open Wheel Dreams
- Amsoil USAC CRA Sprint Car Sample Gallery
CRA Sprint Cars?
The Amsoil USAC CRA Series made its official debut back in 2004, however the CRA part is a historic acronym. Back in 1945, a group of guys gathered around in Babe Ouse’s garage and created the California Roadster Association because he was frankly getting tired of dry lake racing. He, Bill Dehler and Emmett Malloy built a racetrack that would eventually be known as Ascot Park. Yes, the same Ascot Part that J.C. Agajanian made famous for decades and a name that’s also still around-ish. He and Judge Carrell were also the driving forces behind the CRA in those early days.
In 1957, the named changed to the California Racing Association was created when Sprint Cars began to make their way over to the West Coast back in 1953. They wanted their own series and began racing under that banner instead. In 1978, the 410-cubic-inch limit was introduced along with tire rules and safety measures like padded roll cages thanks to Gary Sokola. He would leave and join USAC while Frank Lewis would take over as president of the CRA until the series suspended in 1994, just four years after the closing of Ascot Park. While there was racing, there was no champion crowned for that four-race season.
The USAC Connection Comes Around
Just about 10 years later, on January 15, 2004, USAC announced a meeting at the Elks Club in Downey, California and to the joy of old fans and hot rodders, USAC recreated the CRA series. While it was a California heavy series – and still is today – but the 2004 CRA visited tracks like Perris Auto Speedway in Perris, CA; Kings Speedway (now known as Keller Auto Speedway) in Handford, CA; Manzanita Speedway in Phoenix, Arizona (closed in April 11, 2009); Ventura Raceway in Ventura, CA; Skagit Speedway in Alger, Washington; and Bakersfield Speedway in Bakersfield, CA.
The CRA in 2019
15 years later, the series still sees a few of those tracks (Perris, Ventura, and Bakersfield), but now visit Canyon Speedway Park in Peoria, AZ; Santa Maria Raceway in Santa Maria, CA; Arizona Speedway in Sun Tan Valley, AZ; Merced Speedway in Merced, CA; Ocean Speedway in Watsonville, CA; Calistoga Speedway in Calistoga, CA; and Petaluma Speedway in Petaluma, CA as part of their 24 race schedule. Many of those races are double header weekends, however the night I went was a single weekend race with the WoO.
Sprint Car Tech
Unlike what you’re familiar with in NOS Energy World of Outlaws, the CRA cars run wingless with a mandated 410-cubic-inch (about 6.7-liters) displacement V8. However, there are many similarities between the CRA and WoO cars in their designs.
Now, not every car is the same. Within the rules, yes, these cars look the same to an untrained eye but there are plenty of differences between each car that goes beyond setup. Some drivers had their headers in the classic position while a couple of others ran the right-side upside down. Some drivers ran with torsion bars in the front while a few were running coilovers or even both and using a torsion bar to control chassis roll for both coilover and torsion bar suspensions.
Yes, some cars will run three torsion bars on the front of the car. There were even a few running tire bleeders with digital readouts that could be quickly looked at by their crews. These are all parts that can change as the driver and their crew chief decide what’s best for each track.
Basic Sprint Car Design
What makes these cars interesting is how they are designed. You take the bodies off these cars and you’re essentially looking at an old hot rod chassis from the 1950s or earlier. It’s a straight front axle with a track (panhard) bar to locate the axle side-to-side and three radius rods to control the axle in travel– two on the right had side and one on the left.
The steering box is straight out of traditional hot rodding with the box directly connected to the steering wheel and the steering rod running the length of the front chassis to the left spindle. The spindles are then connected between them with a tie-rod.
The rear is almost always using a pair of radius rods with torsion bar springs. Some cars will use a panhard bar, but the majority will use a Watt’s Link design. However, most sprint car builders will call it by another pair of names: the Jacob’s Ladder or the “Z-link.” No matter what you call the Watt’s Link, it has the same job and that is to locate the rear end from side-to-side.
Jacob’s Ladder in Simplistic
How it accomplishes that job is different, though. Instead of transferring its roll center down as a panhard bar does as the sprint car rolls towards the outside of the turn (right), the Jacob’s Ladder will move its roll center up. This is good for a sprint car as moving its roll center up during its turn will cause the car to be loser in the turn. This is because a higher roll center resists roll in the rear and increases weight transfer. As you need to tighten a car up, you adjust the Jacob’s Ladder so that it sets the roll center lower as the car rolls right.
The adjustment is made at the “Bird Cage” of the axle’s rear end on these cars. Move it down will raise its instant center (the intersection of the two ‘straps” that hold the ladder to the chassis). Doing so will also raise its roll center and loosen up the car. Moving it up will cause the roll center to lower and tighten up the car.
Brakes are for Sissys
There are only two brake calipers on a sprint car. One on the left front wheel and one on the left side of the rear axle. The single brake on the rear axle makes sense when you read on about the drivetrain design of a sprint car. The front will leave you puzzled as to why they only have one. Don’t you need one on each front wheel to stop? If you’re trying to stop on asphalt, yes, you’re going to want equal speed at the front wheels.
On the dirt, you can get a way with a brake on just the left front wheel. This is because its only there to help the car turn into the corner. By slowing down the left front, it forces the right side to drive the car into that left turn when you use the brakes. After that, its all about using throttle control and the steering wheel to keep the car in a slide and out to the straight.
Well, that is if the front wheels are on the ground. Even without rear down force, these cars pull enough traction to lift the front tires coming out of the turn and the left front will even hang in the air as they drive though the turn.
Wheels and Tires
The wheels must be made of steel or aluminum with a diameter of 15-inches. The front wheels can only be ten-inches wide each. The left rear can only be 15-inches wide while the right rear can only be 18-inches wide. The right rear is also the only wheel and tire that has mandatory use of a tire beadlocker approved by USAC. They are usually multi-piece wheels with a single nut retaining each wheel to its axle. The rear wheels also have drive splines cut into its wheel center to match the splines on the axles. The front wheels are connected directly to the hub that’s attached to the brake rotor or the spindle.
The USAC CRA mandates the use of Hoosier tires, but only the right rear tire has a mandated size and compound type. They may use a 105/16-15 Medium or 105/18-15 Hard tire on the right rear. That means it’s either a tire with a 105-inch outer diameter with a 16-inch wide tread or a 105-inch outside diameter with 18-inch wide tread. No tires can be “sauced” or have a chemical applied to change the durometer and construction.
The Drivetrain, Rear Axle, and Starting a Sprint Car
As mentioned, these cars have a hollow tube for the axle. So, what you’re seeing isn’t a housing – that’s the axle. So, it’s almost exactly like a go-kart axle and it is a solid piece straight across and through the carrier, which is a “banjo” style quick change. There is no differential action and why you only see a single rear brake. Since it’s one tube bolted to the ring gear directly, a single brake caliper and rotor is all that’s needed to stop the rear axle. You have a set ring and pinion, but you can change the ratio by pulling the rear cover off an changing the two gears located inside.
There is also no transmission, it’s a direct drive going from the engine’s crankshaft to the input shaft of the quick-change unit. Between the input shaft of the quick-change and the lower gear in the housing, there is a gear box. It’s only used to allow the sprint car to be pushed. Once up to speed, the gear is engaged, and the push truck is now fighting the engine’s compression. In the case of a traditional 410 sprint car engine, the driver will keep the magneto off and wait for the oil pressure to build up. Once they see the right oil pressure, the magneto is turned on and the engine should fire up. Using a USAC allowed “Alternative 410,” it’s a LS2/LS7 ignition coil-near-plug system with an MSD 58X 6LS-2 ignition controller.
So, since I mentioned the two different engine types there, I guess I should talk about why there are two versions in the USAC CRA. The first is more of a traditional 410 setup that’s been around since the 50s and 60s. They are small block, cast aluminum V8 engines with a maximum displacement of 410-ci. The aluminum cylinder heads are two-valve with a “traditional valve pattern.” That’s pretty much a Chevrolet head so, one exhaust port on each end of the head with two right in the center and intake ports between them.
These engines are allowed a mechanical fuel injection system with 16 nozzles max. That means only one in each cylinder head and one in the injector manifold. That manifold can only have a single throttle shaft per bank with a single, round throttle plate per cylinder. They can only use pure methanol. Ignition wise, as mentioned they can only use a magneto type, but they can run a crank-trigger system as a back-up ignition system only. There are no other electronics allowed and the tachometer is the only thing allowed to record any data. Even then, it’s only allowed to record RPM only.
The A4MP – Alternative 410 Motor Program for Sprint Cars
For the CRA series, there is another 410 option that’s a bit more economical as it has street car roots. The Alternative 410 Motor Program (A4MP) is based off readily available GM LS engines. This makes entry costs due to engine procurement lower since these are all off-the-shelf parts from GM, Manley, Comp Cams, MSD, ARP, and many other aftermarket suppliers.
The block itself is an all-aluminum GM 19213580 LS7 block and rotating assembly with LSA heads from GM. It uses a GM carburetor intake manifold for the LS3 with a throttle body that has 2.25-inch bores. It still uses a mechanical fuel injection system, but there is no recommended supplier for that so it’s up to the builder as to which one they will run.
Not anyone can just build the A4MP engine. They must apply annually to the A4MP administration and each engine must be registered. They pay a $350 fee for each engine they build. If there is a protest and technical inspection, the builder will then have to post a bond for the engine. If found illegal per the A4MP rules, the builder is liable for $10,000 to be paid to A4MP from the bonding company of the engine builder. However, the max bond per engine builder is $25,000 with an approximate bond of $250 per engine.
In order to protest that engine, the protester must pay $5000 to A4MP to have it confiscated by USAC and shipped to A4MP’s headquarters in Indianapolis, Indiana. The engine builder can be present, if they chose to be. If its legal, $2500 is awarded to the team that was protested for inconvenience. It then goes back with to the team or the engine builder. If it’s illegal, $10,000 goes to A4MP for expenses occurred while checking the engine.
Full Lock and Three-Wheelin’
While driving a sprint car is still a balance of traction and throttle, it was amazing to see just how sideways these guys were willing to go. Some would get a slight amount of opposite-lock while others. Well…
They would give Formula Drift cars a run for their money. It wasn’t unusual to see a few of these cars with the face of the wheel nearly parallel with the bumper of the car.
The other amazing thing to watch was how often these cars would retain bite going into the corner. Fully locked or not, the inside front wheel was off the ground for many of these cars.
Open Wheel Dangers
Unfortunately, as the night progressed, it wasn’t free of wrecks. Some were simple spin outs but there were a few tumbles at this night’s feature race. Right at the start, Cody Williams went over despite starting in fourth place. He would end up in 20th of 22 drivers for the feature.
On lap 16, AJ Bender would hit the wall outside of turn four and bring out an Open Red, allowing teams to check their cars and refuel, if necessary.
At the restart, R.J. Johnson was dominating and leading up to this point but would slide up the wall while chasing the track for grip. He would end up rolling over and out of the race for the rest of the night but be counted in 16th place.
Brody Roa Take the Win
The guy who was right beside R.J. Johnson most of the night was Brody Roa in the 91R Maxxim Chassis. After Johnson rolled, Roa took the lead and never looked back. Of the 30-laps, he lead 14 but the last one was the most important. Without it, he would take that checkered flag that night in the BR Performance HD Industries/Burris Racing car.
Watching this race remined me of why USAC drivers used to move on to the IndyCar series or the Championship Auto Racing Teams (CART) Series when it was still around. Now, you’ll probably end up watching these guys and gals end up in a NASCAR Monster Energy Car instead. It’s kind of a shame, when you think about it. This used to be where the next American open-wheel champion came from – open wheel, dirt oval racing. It taught you to anticipate and drive protectively while still being aggressive in an open wheel car.
Open Wheel Dreams
It was a dream for drivers from the 50s and as late as the 90s to end up at Indy or CART until drivers like Tony Stewart, Jeff Gordon, Kasey Kahne, Ryan Newman and others ditched open wheels for fenders in stock car racing. Ok, technically Stewart went to Indy after USAC, but he eventually found his way into NASCAR. Regardless, most USAC drivers now get development careers that takes them towards stock cars and trucks instead of the Indy 500.
That’s not to say we don’t see American talent in those IndyCars. They just come from go-karts and club-level formula cars now instead of the dirt ovals that made open wheel racing what it was for the United States. Though, that could also reflect what IndyCar has become and with the demise of CART, there aren’t as many open wheel oval races as there were during their heyday.
Amsoil USAC CRA Sprint Car Sample Gallery
Below is just a very small sample of the full gallery that you can find here.