The NASA Pro Racing Honda Challenge series started in 2003. According to the official rules, "The Honda Challenge was created to meet the needs of Honda owners looking for a series specifically tailored to accommodate vehicles that are modified to a degree which would be found illegal in other import series, yet provide a set of rules that would still accommodate existing Honda racecars and provide a showcase to unify the field."
The Honda Challenge rulebook is extensive, giving competitors the opportunity to run either a pretty stock Civic with minimal bolt-ons or even all-out big-budget rigs. But let's face it, to be really competitive in your class, you have to build a car that just touches the outer limits of the rulebook.
Tsuyoshi Higashi, of Los Angeles, has been racing for about 10 years and has been nicknamed "The Master of Disaster" in racing circles. He chose the Honda Challenge because of the combination of easily modifiable cars, available parts and the spiritual similarity to Tsuyoshi's dream racing series, the British Touring Car Championship. His goal was to build a car that was extreme but could be driven on the street if he so desired. Also, he wanted flexibility; Hondas keep it simple and changes of intakes, springs, exhaust and other components make it a snap to adapt the car to any track environment. Perfect for all kinds of destruction.
To accomplish his goals, Tsuyoshi's weapon of choice is a 1993 Honda Civic hatchback. Why? First, he loved the EG Civics that ran rampant in Japanese Touring cars back in the early '90s. Second, Integra Type R bits bolt right up. And third, parts are plentiful and cheap. Tsuyoshi's sights were set on the Honda Challenge H1 Class, created for "hybrid Hondas"-cars that are enhanced with improved Honda hearts. Competition is stiff in H1, as the class includes not just hybrids, but also S2000s and NSXs.
Although the car was in good shape and already modified with a bolt-in rollcage and Acura disc brakes, the first thing Tsuyoshi did was strip the car to its bare chassis. Honda Challenge rules encourage a full strip of the interior and removal of almost all glass, which Tsuyoshi did. This includes the entire HVAC system, the airbags; you name it, Tsyoshi took it out. Another look at the official rules says a roll cage is required, which Tsuyoshi took to heart as he had Hy Tech Exhaust in Irvine, Calif., bend him up an 18-point roll cage. For additional safety and to satisfy the rules' side impact requirements, Tsuyoshi left in the door beams.
The rules also require a basically stock body, but certain mods are allowed. GTP International provided the carbon-fiber hood, rear wing, front spoiler and side skirts. Headlights can be removed, but as the car occasionally sees street duty, all the lights are functional. The whole shebang was then covered in primary sponsor Endless USA's proprietary blue paint. After that, all the obligatory sponsor decals and graphics were applied-Endless USA, 5Zigen USA, ZEAL and GTP International. The Honda Challenge rules mention vehicle identification, mandating NASA stickers and number height and color.
Once the car looked pretty, it was time to attack the mechanicals. The rules don't allow forced induction or nitrous, so Tsuyoshi stole a page from the factory and borrowed some VTEC. A bolt-in 1996 JDM B18C carefully built to Challenge rules by Sy Nakashima in Los Angeles was built to take serious abuse while running between 6500 and 9500 rpm for hours on end. Internally, the engines must remain pretty stock with limitations on bore size, valve size, compression ratio and timing, but blueprinting, balancing and port matching are permitted. A Mugen oil pan was slapped on for better baffling and oil control. Overall, Sy built a pretty stout engine, proven as they didn't have one engine problem in 2003. They never even took off the cylinder head.
Concerning the externals, the engine rules loosen, but not much. Air travels through a J's Racing carbon air intake duct and custom RS Akimoto Spiral intake, and spent fumes exit via a JDM 4-into-1 Honda header, a 5Zigen straight pipe and a 5Zigen Border 304 Max muffler. According to the rules, an OEM Honda ECU must be used, but can be reprogrammed. Tsuyoshi employs an Erick's Racing ECU to serve that end, as well as a permitted A'PEXi VTEC controller. Keeping everything cool within the rules is a C&R racing radiator, Earl's oil cooler and Mugen thermostat and fan switch, which is needed because the car can run hot.
Of course, the rules impact gear changes as well, mandating a stock diameter flywheel and clutch and a stock ratio transmission. But improvements can be made. Tsuyoshi runs an Xact ProLite flywheel and an ACT Xtreme clutch, which connects to a stock geared Integra Type R five-speed and limited slip. The final drive ratio can be changed, and Tsuyoshi decided a 1998 Integra Type R's ratio was better for the big tracks he competes on. Raxles CV axles complete the package.
Next step? Suspension. Tsuyoshi needed a combination of control, neutral handling characteristics and the ability to stay flat out in fast sweepers. The rules regulate ride height to 4 inches and shocks to single-bodied versions. To design this suspension system, Tsuyoshi relied on proven Japanese Touring car technology. Neuspeed front upper strut bar, front and rear lower tie bars and 19mm rear lower tie bars keep it all stiff.
Damping is provided by Zeal Function B6 shocks all around and Zeal/Swift 1,150-pound springs keep the front settled. The rear spring setting is track dependent, with rates varying from 784 pounds to 1,118 pounds. Alignments are also track dependent, but those are proprietary to Tsuyoshi-he has to keep something secret, doesn't he?
Braking systems are not regulated in the Challenge, so this is where Tsuyoshi's sponsorship from Endless USA really kicked in. Surprisingly, Tsuyoshi started out with the set of Acura discs, which were on the car when he bought it, only adding a set of Endless pads. That combo worked on the track for a while, but soon the fronts were upgraded to a full Endless big brake kit for better slowing ability. A stock Integra master cylinder handles the discs just fine and Endless brake lines feed the fluid as needed. Notably absent on this car, but allowed by the rules are front brake ducts. Tsuyoshi says he doesn't need them, as the Endless pads work best when they're hot, with no overheating or fading problems.