Technically, the Pro 4s are based off of production trucks; however, the modified and highly developed chassis are about as far away from stock truck as skiers who were expecting peace on the mountain during race week. Starting as a blank canvas, they use either 4130 chromoly or ASTM 1018/1026 CDS/DOM round tubing, building from the ground up and following rules set by sanctioning bodies.
Every truck uses a V8 engine block based on an OEM design, which must be made from steel or aluminum, though most run aluminum blocks and heads to save weight, with Holley 4-barrel carburetors pushing 650 CFM on top. Running carburetors present unique challenges in trying to find the correct carburetor tuning, because similar to the trucks, the mechanics are out of their element in these conditions as well.
It’s a constant battle between temperature and tuning.
Since metals contract at different rates, and tolerances could become impossibly tight, it’s paramount for the trucks to maintain a certain temperature range. “Heaters keep everything at 100 degrees. Once they dip below 40 [degrees], they have issues, because the aluminum shrinks and the engines won’t turn over,” 21-year-old rookie R.J. Anderson admits.
At minus-20 degrees, oil has the consistency of peanut butter, so keeping an eye on internal temperatures is key to providing the engines with the proper care. Rotating a high-performance motor, such as the V8s in Frozen Rush, without the proper lubrication could end in catastrophic results. Industrial heaters are brought in to feed hot air onto not only engine blocks but brakes and suspensions as well. It’s like watching someone on life support being meticulously cared for.