Building the Beast - 2005 Acura RSX Type S

[JoeThaMan]

Building the Beast - 2005 Acura RSX Type S
In January of 2005, Honda of North America began a new vehicle campaign-looking to showcase the newly remodelled 2005 Acura RSX Type-S to the general public while keeping close tabs on the youth of the import tuner market. Scouring the top automotive publications within the industry, Honda approached Import Tuner Magazine with car keys and the expectation that 2NR had the skills and backing to build an RSX that would kick some serious ass. Faced with unlimited access to an orgy of companies who were willing to join forces with the magazine, the 2NR staff took into consideration that the build should appeal to our readership, and took the steps necessary to turn this mild-mannered sport compact into a streetable racecar. After months of deliberation, the final decision was made and it became apparent that the "King of the K-motors," Skunk2, was the logical choice.
Skunk2 Racing of Norco, California, has etched themselves deep into the import industry as the premiere import performance manufacturer of the last decade. Skunk2 has set numerous track records for the "Fastest All-Motor Vehicle," the first taking place in March of 1998 when their silver DC2, known as "Project Beta," clicked off a 12.8-second pass in the quarter mile at Sacramento raceway. Today, Skunk2 currently holds world records in NDRA, IDRA and NHRA with sub 9-second passes at 141 mph in their K-powered all-motor RSX dubbed "Project Delta." It doesn't take a genius to recognize these guys have done their homework over the years and have what it takes to accompany us in building one serious street machine.
Seven-hundred "streetable" horsepower. That's the magic number we're attempting to accomplish as you, the readers, will follow our journey from beginning to end. Over the next few months, look forward to our grand finale when the RSX-T will pound the Buttonwillow Raceway tarmac as we attempt to break the official front-wheel drive track record. Did your eyes deceive you? No... let me repeat that for you again...700 hp! An incredulous power number for any four-banger import engine and a challenge both Skunk2 Racing and Import Tuner will push to create as we team up and venture into the world of forced induction. You heard it first! Skunk2 has officially sold their souls to the devil and will fabricate their very first custom turbocharged project car.
Planning the first steps of the build took both teams to the brink of insanity. Numerous scenarios were laid out on the table while each option was carefully weighed and the RSX's fate lay firmly in our hands. "We wanted to do something different. Everybody was expecting us to build an NA car, so we said 'Hey, let's get these people to wet their pants and build a turbocharged car,'" says Skunk2 Owner and perfectionist Dave Hsu. With the plan complete, the K20Z1 powerplant was plucked from the engine bay and disassembled. The first item thrown into the scrap heap was the factory crank. Hsu and his head engineer/mechanic, Jeff Giovino, envisioned a custom K20 engine setup that would handle the rigors of road racing while delivering a mind-blowing 700 hp.
Replacing the crank with a K24 crankshaft, taken from a Honda Accord's K24A3, the tedious journey had officially begun as the larger displacement crank was shipped out for processing. Joe Castillo of Castillo's Crankshaft Service, located in La Mirada, California, received the K24 crankshaft to perform the necessary modifications. Castillo's Crankshaft Service center has been the driving force behind Skunk2 and their record setting 9-second drag cars for a number of years and is stacked with an impressive clientele that ranges from imports to domestics alike. Before the crankshaft was to receive its altering makeover, the unit was hot tanked then magnafluxed to inspect for hairline or micro-fracture cracks. After checking the unit over for any inperfections, the crankshaft was then inspected for straightness. "A normal crank varies from dead on to off by five thousandths. If it encountered a spun journal, there's a good chance it will be bent anywhere from 10 to 15 thousandths. If a crank comes in bent, we can fix it up to 40 or 50 thousandths max," states Joe Castillo. Luckily for the RSX-T crankshaft, minimal straightening had to be addressed while the crank's rod journals were opened up and machined to accept the 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 lbs in the process. Additional machining to the crank included modifications to the oil galleys, which were teardropped and chamfered. Chamfering is a process often used to relieve the sharp edges on the oil galleys and allow the oil hole to flow at an improved rate. This process is also used in reducing the chance of scoring or damaging the bearings during dry startup or when encountering high rpm. 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. Jeff and Dave 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 vs. long rod debate to new heights, as Giovino pulled a set of off-the-shelf Pauter B-series rods to mate with the K24 crankshaft. Imagine that, B-series components in a K-motor! 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. Calico, world renowned for their specialized coating process has been catering to the high-performance automotive world by providing products and services ranging from ceramic-coated cylinder heads to their popular CT-3 dry lubricant applied on piston side skirts. In recent years, Calico has become a trusted name to Skunk2 and their quest to dominate drag racing's all-motor class, as one key component to their success has been the Calico treatment. Calico CT-5 is known as a non-stick, non-wetting oil-shedding coating that significantly reduces drag and windage, resulting in increased RPM acceleration and horsepower.
Since this engine was destined to crank out serious horsepower, the original factory main bearings were replaced with a set of ACL (Automotive Components Limited) race series bearings treated with Calicos special CT-1 treatment. Providing a range of .0002-.0004-inch layer of CT-1 dry film lubricant to the bearings adds protection that many factory bearings fail to provide when flirting with high RPM's for an extended period of time. The K20 block was sent to Golden Eagle Manufacturing, located in San Dimas, California. The bottom end was outfitted with a set of Golden Eagle race sleeves, addressed with a standard race hone job and machined to a 90mm bore (40 thousandths over factory). It was then stuffed with the K24 crank and 96.5mm B-series rods.
A methodically planned and meticulously assembled bottom end is just one step towards achieving a longer-lasting long block, but the main focus on unleashing those elusive ponies fall into the category of possessing a well-built cylinder head. Skunk2 had no second guesses when selecting what ports to use for the force-fed RSX-T. Since the debut of the K-series power plant, Skunk2 has endured years of trial and error in producing custom headwork that has propelled their drag race division to new heights. Using the same port design as Skunk2's 9-second beasts, Dave Hsu himself hand ported the cylinder head. Each port and combustion chamber goes through the Skunk2 special porting process, opening up the runners to gain more cc's and is outfitted with CNC-machined titanium retainers and Pro Series valve springs. The stock-sized valves, utilizing a custom valve job, are orchestrated by the factory camshaft for the time being. Skunk2 has acquisitioned the RSX-T as a test mule for six unique camshaft profiles that are currently in the testing phase with a public release date to be determined. 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.
Dr.Charles Madrid, mechanic and fabricator at Skunk2, kept true to his mad scientist persona as he was credited as the mastermind behind the design and fabrication of the RSX-T's custom intake manifold. "We were basically looking to build an intake that had the shortest, most direct route to the turbo. We just looked at where the intercooler was positioned, where the outlet of the turbo was and where the inlet of throttle body sat, and just placed them as short and straight as possible," stated Madrid. Using his trusty grinder and chopsaw, Dr. Charles performed his open-heart surgery, slicing open the intake manifold to redesign the plenum. The factory Type-S manifold was TIG welded and constructed using multiple sections of aluminum sheet metal. The prototype manifold consisted of a tapered design leading into the 70mm Skunk2 Pro Series throttle body. The final results produced a more direct manifold that flowed better than other manifolds on the market today. Interestingly enough, the intake manifold was dynoed on a naturally aspirated motor and netted 10 more horsepower over the standard Skunk2 manifold. You can bet it's only a matter of time before copycat manufacturers take this newly introduced manifold into production and credit it as their own.
With so many aspects of the engine build to cover, it's a shame that we have to leave our readers hanging high and dry 'till part two of our buildup for project RSX-T. But all good things must come to an end sooner or later, right? Look forward to our next issue as we cover all aspects of the forced induction system, complete with a custom turbo and a mind-boggling exhaust manifold as we inch closer to completing the ultimate street RSX.

Photo Gallery: 2005 Acura RSX Type S - K20 Build - Import Tuner Magazine



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