As part of our conversion to an X275-legal combination, Project Evil was going to need some gearing adjustments. We’ll be utilizing a 440 cubic-inch KBX billet block engine equipped with Edelbrock SC1 heads and a Vortech XB105 or Xi-Billet, plus an ATI Turbo 400 transmission. We punched up our calculators and figured out what kind of gear ratios we wanted to run. We ended up going with a 1.48 first gear in our new ATI Turbo 400s, along with a 4.10 rear gear to go with the Mickey Thompson 275 Pro Tires. The only issue was, previously with the 26 x 8.5-inch tires, we had been running a 3.70 rearend gear.
A radial car with 1,800 horsepower and sub 1.10 60-foots means there’s no skimping with cheap parts in the driveline. A key piece in the equation is the center section, which is responsible for taking all the power and torque from the transmission and driveshaft and applying it to the axles to set things in motion. It’s got to be beefy, and it’s got to be strong. And so we turned to US Gear to fix us up with a 4.10 set of gears in our Strange center section to get the job done.
The question of starting line ratio with an X275 car is an interesting one — but it really applies to any radial tire car. You need enough starting line ratio to be able to manage bad air (where there is less power being applied because of the air), but you also have to be careful not to have too much ratio where you have a problem controlling the power multiplication. It’s a balancing act that’s probably tougher on a blower car than on a turbo setup.
Then you have your finish line RPM, which drives your final gear ratio. This is partially driven by converter slip, which is also a factor. It all adds up to an equation where the top tuners in the business know what kind of ratios make the most sense.
We selected the US Gear Pro gear setup, 9.5-inch diameter. Made from 9310 material, this is the same gear material that is used in Top Fuel dragsters and Funny Cars. It also features a 35-spline pinion shaft. We’ve had good luck with US Gear’s durability and fit.
While US Gear provided the gears, what we have been using for Evil is a Strange Ultra Case. The case has a 3.812-inch bore for up to 10-inch ring gears, outfitted with a Strange Pro Series HD lightweight spool, a chromoly 1350 yoke and U-bolt kit for the yoke, and a magnetic pick-up collar for a data acquisition sensor.
We are excited for our debut in 2019, going to be racing in NMCA Street Outlaw and X275. With this brand new combination, it’s going to take us a little while to get a handle on it.