720 WHP Acura RSX - Power Production

Rear
The rear of a top-speed car has one job to do: stay on the ground. Weighing considerably less than the front, and prone to turbulent airflow where areas of high pressure exiting the underside of a car merge with areas of low pressure coming off the roof, the rear is often the first part of a car to lift when something goes wrong.

"Generally speaking," explains Doug, "the longer the vehicle, relative to its other dimensions, the more aerodynamic it is." Adding this aluminum rear wing extends the RSX's effective surface area parallel to the direction of travel, creating a more streamlined, or "laminar" path for air to travel, decreasing speed-robbing turbulence and drag. And by engineering it with four adjustable tensioners, it can also be fine-tuned to provide some downforce.
"Generally speaking," explains Doug, "the longer the vehicle, relative to its other dimens
Even more vital to decreasing turbulence is a rear diffuser, or "valence". Fast-moving air underneath a vehicle has a tendency to curve upward sharply upon exiting the rear, creating turbulence with air coming off the top of the vehicle, which can generate lift and impede forward motion. The gradual upward curvature of the RSX's valence helps airflow merge at a more gradual angle, while the five vertical vanes help streamline it. "Looking back," begins Doug, "we should've extended the diffuser farther toward the front of the car, and led it upward at less of an angle, for even better results."
Even more vital to decreasing turbulence is a rear diffuser, or "valence". Fast-moving air
Even the RSX's custom exhaust was designed with aerodynamics in mind, curving upward at nearly the same angle as air exiting the rear diffuser. "With forced induction, we're producing 720-plus whp at above 8,000 rpm for almost the entire run," explains Doug, "That's a lot of additional airflow to the rear of the vehicle."
Even the RSX's custom exhaust was designed with aerodynamics in mind, curving upward at ne

Power
After aerodynamics, a top-speed car needs power. Wind resistance increases exponentially with speed, meaning 80 lb-ft of torque might be enough to propel a car to 100 mph, but 320 would be needed to get it that same car to its 200, at standard temperature and pressure. Almost equally as important as power production in a top-speed car is gearing. If an engine can't produce the minimum amount of torque needed to overcome wind resistance as it's shifted into the next gear, it's not going to move the car any faster. Doug managed to figure out this magical combination of peak power/torque production/gearing to make his RSX's K20A competitive in multiple classes.

G/GCC- and G/FCC-class regulations forbid forced induction, and Doug knew that the easiest way for the hungry K20A to breathe on its own would be through a set of individual throttle bodies. "Kinsler and I tested dozens of combinations of varying width, length and shape runners and inlet set-ups before deciding on what you see here, and a lot of the data went into the revision and development of off-the-shelf kits." To make the most of them, Doug's RSX spins IPS S2 cams for naturally aspirated duty, and fuel is provided via four 1,200cc RC injectors, managed with a Hondata K-Pro to produce 284.9 whp and 182.2 lb-ft of torque.
G/GCC- and G/FCC-class regulations forbid forced induction, and Doug knew that the easiest
In the "fuel" classes, where the use of an oxidizer is permitted, Doug uses a custom Edelbrock direct-port dry system that delivers two 70hp shots that produce a total of 415.7 whp and 274.4 lb-ft of torque. "We found that we could effectively increase power by a factor of about 50 percent before reliability becomes a concern," he explains.
In the "fuel" classes, where the use of an oxidizer is permitted, Doug uses a custom Edelb
Not much changes with the engine for blown-class prep. Two Kraftwerks Rotrex superchargers--a C30 and a C38--are fitted to the engine, and plumbed into a liquid-to-air intercooler. Injectors are swapped out for 1,600cc RCs, the IPS cams are yanked in favor of a stock '06 TSX intake cam and an '04 RSX-S exhaust cam, and the engine is re-tuned to make 684.7 whp and 390 lb-ft of torque. "The linear power production and instant throttle response of supercharging is very advantageous to top speed racing," explains Doug, "And we found that two smaller chargers offer the ability to spin faster than one large one,"--an important point to mind when your engine spends about a minute and a half of each run producing between 600 and 680 whp at a constant 8,500 and 9,500 rpm. Adding a small shot of nitrous to this set-up produced just over 765 whp once, "But that was just for fun," Doug advises.
Not much changes with the engine for blown-class prep. Two Kraftwerks Rotrex superchargers

Control
Weight reduction isn't a major concern in top-speed racing, where acceleration takes a back seat to speed. Still, Doug's RSX was stripped of anything not necessary to make for the required six-point rollcage, and to reduce the amount of material that could dislodge, catch fire, or just get in the way during unforeseen events. Reducing weight also allows greater flexibility for adding weight in crucial locations--something the RSX hasn't undergone, yet.

In front of the RSX's cabin-mounted battery is something not too familiar to import builders: the Kenne Belle Boost-A-Pump, which increases voltage to a fuel pump from the typical 11-12 volts to 18 volts, spinning it faster to flow a greater volume of fuel. It's how a single Walbro 255lph drop-in pump has the capacity to power the RSX's 765whp K20A. It also lowers current during operation, which could extend pump life.
In front of the RSX's cabin-mounted battery is something not too familiar to import builde
One of the first pieces of equipment that should be added to any car that's driven spiritedly is a quality bucket seat. Doug's Sparco unit meets FIA requirements for competition use, accepts a required five-point harness, provides whiplash support, and, in Doug's words, "is very comfortable."
One of the first pieces of equipment that should be added to any car that's driven spirite
The larger of these two bottles is reserved for nitrous; the smaller feeds a constant 1,000 psi of additional pressure into the nitrous bottle for consistent delivery during spray times in excess of one minute. "After 20 seconds or so," explains Doug, "depleted nitrous and cooling bottle temperatures decrease pressure. Without supplementary pressure, we'd lose power."
The larger of these two bottles is reserved for nitrous; the smaller feeds a constant 1,00

Despite one world and six class records set with the RSX, and the title as "World's Fastest", Doug still sees room for improvement, though he's cautions to speak at length about it. While he does plan to campaign it throughout the '09 season, he's also building a new machine: a turbocharged, K20-powered CRX. "It's an old platform," he explains, "but more aerodynamic than the RSX. By applying what we learned racing the RSX to the CRX, we're expecting better results." As for the long-term future of the RSX--a full cage, weight reduction, aerodynamics, 770 whp . . . could we be seeing the first images of a Hondata drag car?

HOTBOX
Hondata 2341 W. 205th St. Torrance CA 90501 3-10/-782-8278 www.hondata.com	IPS
Kraftwerks	Hytech
Kinsler	Church Automotive Testing
Tein N/A www.tein.com	Port Flow Design
Edelbrock Dept. 5.0 2700 California St. Torrance CA 90503 310-781-2222 www.edelbrock.com	Prototype Racing
Southern California Timing Association (SCTA)