Casey and his team developed and built the second Tornado Intercept Vehicle, dubbed "TIV 2", to be featured in their next IMAX movie and the Storm Chasers series.[3] Work began in September 2007 by 40 welding students at the Great Plains Technology Center in Lawton, Oklahoma and was completed in time for the 2008 tornado chase season. TIV 2 was designed to address some of the problems experienced with the original TIV, namely its low ground clearance, lack of four-wheel drive, and low top speed. It is based on a Dodge four-wheel drive one-ton truck frame that was strengthened and converted to six-wheel drive by adding a third axle. After season two the six-wheel drive system was modified to four-wheel drive.[citation needed] It is powered by a 6.7-liter Cummins turbodiesel engine, modified with propane and water injection to produce 625 horsepower (466 kW). This gives TIV 2 an estimated top speed of over 100 mph (160 km/h). Its fuel capacity is 92 U.S. gallons, giving TIV 2 an approximate range of 750 miles (1,210 km). The body of TIV 2 is constructed of a 1/8-inch steel skin welded over a 2-inch (51 mm) square tubing steel frame. The windows in TIV 2 are all bullet-resistant 1 5/8-inch interlayered polycarbonate sheets and tempered glass. TIV 2 also features an IMAX filming turret similar to the one on the original TIV. The original TIV's somewhat cumbersome hydraulic claws were not used on TIV 2 in favor of six hydraulic skirts that drop down to deflect wind over the TIV to stabilize it and protect the underside from debris, and four hydraulically operated anchoring spikes.
TIV 2 debuted on the second season of Storm Chasers, which began airing on the Discovery Channel in October 2008. Its initial performance did not go well, as it was plagued by mechanical failures, including several broken axles, which forced Casey to abandon TIV 2 and return to chasing in the original TIV until TIV 2's issues could be resolved.[4][5] Although Casey hoped he would be back in TIV 2 before the end of the season, repairs and modifications on TIV 2 took longer than expected and Casey was shown on Storm Chasers ending the season in the original TIV.
In the fall of 2008, TIV 2 received several modifications, mostly focused on reducing the vehicle's 19,800-pound weight. To achieve this, certain less crucial areas of TIV 2's armor were converted from steel to aluminum while more vital areas were reinforced with supplemental composite armor consisting of thin layers of steel, Kevlar, polycarbonate and rubber. In all, the weight reduction measures brought TIV 2's weight down to 14,500 pounds. The safety systems were also improved, with the three front wind skirts being consolidated into one and new hydraulic stabilizing spikes to further increase stability in high winds. Other modifications included additional doors that provided every seat position with an exit (wind skirts up or down), and a redesigned IMAX turret with 50% more windows. The third axle was disconnected from the drive train, thus changing TIV2 to 6×4 from its 6×6 design. The third axle now acts as a brace for the vehicle's weight.[6]
The TIV 2 appeared again in the fourth season of Storm Chasers, and also in an episode of another Discovery Channel series, Mythbusters, wherein both the TIV 2 and the "Dominator" vehicle operated by Reed Timmer of TornadoVideos.Net were tested to determine their endurance to storm-force winds by being parked behind a Boeing 747 with the engines at full throttle. When tested at a wind speed of 160 MPH, the TIV 2 had the driver's door pulled open, though this was due to human error as Casey had forgotten to lock the door prior to the test. When tested again at 250 MPH (equivalent to an EF5 tornado), the TIV 2 suffered no ill effects whereas the Dominator ended up getting blown approximately 50 feet.
