Time-Trial Car Classifications
XC2A In line 5 cylinder; rotary; four or more valve per cylinder 4 cylinder or less than 185hp
XC2B In line 5 cylinder; rotary; four or more valve per cylinder 4 cylinder with high output engine lightened or greater than 185hp
XC3A 6 cylinder & 4 valve per cyl 6 cyl less than 245hp
XC3B 4 cylinder turbo or supercharged; V6 with high output or lightened or greater than 245hp
XC4A 8 cylinder; turbo or supercharged 6 cylinder less than 300hp
XC4B 8 cylinder; turbo or supercharged 6 cylinder with high output or lightened or greater than 300hp
XC5 Greater than 8 cylinders; turbo or supercharged 8 cylinder; turbo rotary; any 2 stroke
equipped vehicle; or 400hp or greater
XO Non-winged open-wheeled cars
XOW Winged open-wheeled cars
Progression to Higher Classes
Engine - Engine modifications other than intake or exhaust after catalytic converter will add one point.
Tires - DOT approved competition tires are allowed in each class. Racing slicks will add one point.
Weight Reduction - Any weight reduction (including removal of passenger seat) will add one point.
Cars with one point are moved to the next class up (e.g. from XC-2A to XC-2B or XC-2B to XC-3B)
Cars with two or more points are moved up two classes (e.g. from XC-2A to XC-3A or XC-2B to XC-3B)
Examples A Miata (4 cylinder < 145HP) stock will run XC-2A. A Miata that has been lightened will be awarded one point and run XC-2B. A lightened Miata running racing slicks will be awarded 2 points and run XC-3A.
A stock turbocharged Miata runs XC-3A. A turbocharged Miata with an upgraded (larger) turbo will be awarded one point and run XC-3B. The Miata with the upgraded turbo that has been lightened and running slicks will be awarded 3 points and run XC-4A.
Notes XC-1 has been eliminated.
