No vehicle within my four and half year tenure of working for Import Tuner magazine has required as much time and devotion as the masterpiece you see in front of you today. The daily grinds of hardship were magnified tenfold as Import Tuner and Skunk2 Racing joined forces as we shed and shared the same blood, sweat, and tears-transforming an average, run of the mill Acura RSX Type-S into our latest and greatest creation.
The RSX Type-S's K20Z two-liter powerplant has slowly taken over the reigns of the once dominant B-series engines. Owning up to a well-engineered engine is one thing, but the team of Import Tuner and Skunk2 wanted to build an engine with enough gusto to send all challengers foolish enough to challenge our machine with their tails between their legs. After numerous closed-door meetings and hush-hush conversations, our collaborated team had finally decided on a battle plan with high expectations of building the ultimate street machine Acura-dubbing the vehicle the RSX-T.
As the first stage of the engine build was to begin, Skunk2 replaced the factory crank with a larger stroked K24 crankshaft, taken from a Honda Accord's K24A3. The K24 crankshaft was shipped out for processing and custom machining under the watchful eyes of Joe Castillo of Castillo's Crankshaft Service, located in La Mirada, Calif. The unit was hot tanked, then magnafluxed to inspect for hairline or micro-fracture cracks. After checking the unit over for any imperfections, the crankshafts rod journals were opened up and machined to accept a set of Honda B-series rod journals, while maintaining the standard-sized mains. To improve engine rev ability and reduce windage, the crank was lightened and knife edged, saving 3.5 pounds in the process. Additional machining to the crank included modifications to the oil galleys, which were tear dropped and chamfered. After a quick nitrating process to harden the surface metal of the crankshaft, the unit was shipped back to Skunk2, ready for installation.
Interlining the K24 crankshaft within the K20Z block required a custom set of rods and pistons. The Skunk2 staff took turns manning the phones in search of a manufacturer willing to machine a custom set of pistons, only to realize they were asking a wait time of 6 to 12 weeks-a timeframe that Skunk2 could not expense. Never scared to try something out of the ordinary, the Skunk2 team decided upon taking the short rod versus long rod debate to new heights, as Jeff Giovino, Skunk2 head engineer/mechanic, pulled a set of off-the-shelf Pauter B-series rods to mate with the K24 crankshaft. Wiseco Pistons took the B-series rod ratio and K-series crank formula to their CNC machine and machined a set of custom 9.5:1 dished pistons with a full-round design 17cc dish. The piston skirts were specifically designed to accommodate the new engine specifications. XR piston rings were coaxed onto the custom-made slugs using the standard ring size. Before the reassembly process began, the Pauter rods were shipped off to Calico Coatings of North Carolina where they received their special CT-5 coating. The CT-5 process worked wonders on many of the previous Skunk2 project vehicles as this non-stick, non-wetting oil-shedding coating significantly reduces drag and windage, resulting in increased RPM acceleration and horsepower.
Stock engines might serve as the perfect candidate for daily commutes but the RSX-T powerplant was destined to crank out some serious horsepower. The factory main bearings were replaced with a set of ACL (Automotive Components Limited) race series bearings and treated with Calico's special CT-1 treatment. The K20 block was sent to Golden Eagle Manufacturing, located in San Dimas, Calif., and outfitted with a set of Golden Eagle race sleeves, using a standard race hone job and machined to a 90 mm bore (40 thousandths over factory). Like pieces to a jigsaw puzzle, things finally seemed to come together with the bottom end as the fortified block was reassembled with the K24 crank and B-series rods altering the displacement to a larger 96.5mm stroke from its original 86mm setup.
Skunk2 has maintained a strong reputation of building some of the fastest import cars to grace God's green earth, but none have even come close to the ability of replicating their infamous custom headwork designs. A design that has managed to set numerous track records within their drag race division. Using the same port process that propelled their quarter-mile drag machines well into the 9-second, the combustion chambers were CNC ported and outfitted with Skunk2 titanium retainers, Pro Series stainless steel valves, and Pro Series valve springs. The factory-sized valves, utilizing a custom valve job, are orchestrated by Skunk2 Stage 2 Turbo camshafts bolted to a pair of Pro Series cam gears. The freshly ported head was sandwiched between a Cometic .036mm head gasket and bolted down using Skunk2's ultra high tensile strength Pro series head and main studs, a crucial component for K-series engines that possess notoriously weak OEM head and main bolts.
A custom designed exhaust manifold consisting of 1.75-inch diameter primaries with an equal-length runner measuring at 15 inches long methodically wraps around the engine bay like a winding snake. Combining a custom TiAL GT-35R ball-bearing turbo and freshly built exhaust manifold didn't disappoint expectations as boost was initiated at 2800 rpm while max boost was recorded at an impressive 3800 rpm. "The combination of the turbo setup and the engine's larger 96.5 mm stroke over the factory 86 mm setup really enables the turbo to spool up pretty fast," says Giovino. Skunk2 called upon the experts from down under (Australia) in acquiring a 20-inch PWR Performance Product intercooler core. A set of custom fabricated end tanks were specifically made as a means to eliminate turbo lag, ensuring boost is flowed in a straight and narrow path from the turbo and into the throttle body. Skunk2 mechanic Charles Madrid, otherwise known as Dr. Charles, took the factory Type-S intake manifold and began hacking away at its runners and stock plenum, building a prototype manifold consisting of a tapered design leading into the 70mm Skunk2 Pro Series throttle body. The custom 2.5-inch turbo pipes were attached using Hose Techniques silicone turbo hoses and coupled by a set of turbo t-bolt clamps. TiAL's ever- popular blowoff valve was on call to relieve boost pressure while a TiAL wastegate helps to safeguard the engine from unwanted boost creeps and pressure spikes. A custom 3.5-inch stainless downpipe huffs spent fumes out a one-off Skunk2 MegaPowerR exhaust.
Before the transmission was bolted into place, an ACT clutch combination was installed, consisting of their Xtreme pressure plate, six-puck race disk and race-recommended Prolite chromoly flywheel, weighing in at a feathery 8.8 pounds. The true art of form and function was exemplified though a set of 18x8.5 Volk CE28N wrapped around a set of BFGoodrich R-compound tires and mounted on a set of Skunk2 extended wheel studs. The RSX was outfitted with Moton fully adjustable coilovers sitting on all four corners. A Quaife limited slip differential was shoehorned into the custom six-speed transmission as it spins through a set of The Driveshaft Shop's stage 5.9 chromoly axels rated to withstand up to 1000 hp. Stillen, of Costa Mesa, Calif., came to the rescue, supplying the project RSX-T machine with a set of AP Racing four-piston calipers. Paired with an AP Racing 330mm cross-drilled up front and A-Spec slotted rotors in the rear, the four-piston binders clamp down with the aid of Ferodo DS2500 high-performance street compound pads. The end result is a sick brake setup that can easily tame this 700hp beast.