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A'PEX V-MAX Pro Skyline
What has 1,000 hp and runs the 1320 in 8.47 seconds?
By Josh Joquot
Photography by Josh Joquot & Les Bidrawn
| Think back,
for a few minutes, to the first time you felt the surge of acceleration
provided by a turbocharged car. For most of us, that was a defining moment
in life: The first time the small of your back was pushed into the seat,
fighting against the expanding g-forces as the boost built and sent you
rocketing down the road in an unforgettable rush of acceleration.
That's right, 1,000 hp--a number more often heard in the NHRA ranks of drag racing than in the import scene. All that power, believe it or not, is generated from the R33 Skyline's stock displacement of 2.6 liters and is attained at 28 lbs of boost. The barely oversquare RB26DETT powerplant uses readily available off-the-shelf A'PEX and Nissan parts with the exception of its prototype A'PEX crank. |
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A'PEX cams, valve springs and connecting rods round out internal mods to the mill. Twin 90-mm Infiniti airflow meters feed two IHI turbochargers. A huge A'PEX Drag Series intercooler replaces the Skyline's already oversized stock unit routing air through a single 83-mm Infiniti throttle body instead of the GT-R's stock setup of six individual throttle bodies. One hundred and four octane racing fuel reaches the combustion chambers via 1,000 cc/minute fuel injectors.
A relatively low compression ratio of 9.3:1 sustains engine life at a maximum boost level of more than 40 psi. Although capable of running such inordinately high boost, the team has kept boost to a more conservative 28 psi thus far. "There's no need to run higher boost," crew chief Hiroto Kaneso said after the car's American debut in February's Battle of the Imports. With more than enough power on hand, higher boost would likely only result in more tire spin and slower ETs. After the car's initial setup was determined, all subsequent tuning was done at 28 pounds of boost for consistency.
A sequential six-speed Hollinger transmission was used for all the runs the car has made in United States as of this writing. Shift points of 10,000 rpm in combination with the efficiency of the sequential box cut at least .2 seconds from the car's quarter-mile time, according to Toshi Hayama, A'PEX's U.S. operations manager. A digital display built into the car's composite-covered steering column housing shows gear selection.
The job of piloting this 1,000 hp GT-R is in the hands of Eiji Yamada--one of Japan's most renowned drivers. Yamada, or "Tarzan" as he's known by the A'PEX crew, uses a driving style similar to that we've witnessed by other Japanese drivers, including Jun Auto Mechanic's Sosumu Koyama, the driver of the 700-hp Silvia on our December cover. The strategy is simple--these drivers jam their right foot to the floor and don't lift no matter what happens until the traps fly by at the end of the track. Yamada's driving is truly impressive with shifts banged off regardless of the car's attitude. Going sideways toward the wall? Keep right foot planted, shift and aim for the end of the track. Big cajones. Very big.
Yamada is better known in Japan for his experience as a circuit, top speed and drifting competitor than he is as a drag racer. Now 36, Yamada has been driving professionally since he was 18, including contracts with Japan's Option magazine and considerable time in formula-style open wheel cars. His personality and enthusiasm brought tremendous excitement to the V-MAX's debut in the States as he rode back on the car's roof to cheers from the crowd after making the fastest pass.
To make Yamada's job easier, the Skyline's electronically controlled torque split is replaced by a manually-adjusted lever just inboard of the shift handle. Although A'PEX engineers wouldn't reveal the car's torque split on the track, they did admit it uses a heavy rear bias that is adjusted to suit track conditions as determined by the car's data logging equipment--more on that in a minute. According to Kaneso, a 50/50 torque split gives the car incredible stability at the cost of reduced trap speed while a rear bias is usually the fastest and safest setup to get power to the ground. Judging by Yamada's outrageous foot-to-the-floor driving style, the car was pretty well dialed in when we saw it run.
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In its current
configuration, the Power FC monitors oil pressure, air/fuel ratio and two
water temperature sensors in addition to all the factory positions.
Digital information is also downloaded in real time to the ECU from all of
the A'PEX gauges built into the car's dash. A handheld controller can be
used to monitor several parameters directly from the Power FC while the
car is running.
Second to the car's aftermarket ECU is a massive accelerometer bolted where the back seat used to be. Built into the car's floorboard is an electronic fifth wheel measuring acceleration and distance over time. |
Data from all of the car's acquisition systems are gathered through two interface systems to be relayed back to the team's various computers for analysis. Engine parameters logged by the Power FC as well as information from the accelerometer are gathered by two removable data card systems. Drivetrain sensors relay information via a direct PC interface.
Once data has been gathered, the team analyzes it based on two parameters: How the car reacts to the track surface and how the engine reacts to the available air. Factors such as temperature, altitude, humidity and barometric pressure are taken into consideration. Tuning adjustments are made based on the thousands of track and air quality variables and information gathered from the data acquisition systems. The results are dramatic, as we witnessed during the car's shakedown runs at LACR the week before Battle of the Imports in February.
Less than 24 hours after being unloaded off the boat from Japan, the V-MAX made its first pass down the quarter-mile. The initial run, designed to make sure all systems were operational, was made at 23 lbs of boost and was essentially nothing more than an analysis run. The V-MAX shot off the line and through the traps in 9.52 seconds at 138 mph--damn impressive for a shakedown pass that was cut short before the traps. The best was yet to come as we witnessed the effectiveness of tuning and higher boost.
The team went to work and brought the car back to the staging area an hour or so later. Yamada went through the requisite staging procedure and then laid down a 9.02-second pass at 155.43 mph--now things were getting serious as it became obvious what the V-MAX was capable of. The second pass was made at a slightly higher boost (26 psi), but the throttle was held open for the entire length of the track.
Before making any more runs, the team consulted and decided that more data was needed on what was happening when the car launched. After several nose-to-the-sky launches, the team regrouped and made the appropriate changes. A different setup was needed to optimize off-the-line acceleration. Following these changes, the V-MAX made two back-to-back 8.8 second passes at 156 and 157 mph respectively--quite convincing, and this was nothing more than a test session. The final two runs brought the day to a close as the team had achieved its goal by going faster in the United States than the car was able to run in Japan at a lower elevation--a real testament to the effectiveness of electronic tuning aids.
With professionalism and equipment rivaling the best racing teams in the world, including those competing in CART and F1, the A'PEX team demonstrated what is possible with the incredible preparation made before it came to the United States. With three Japanese crewmen, a driver and host of help from the American A'PEX headquarters, the team made quite an impression in the world of import drag racing--bringing with it welcome professionalism and preparedness. Speaking of preparedness, shipped with the V-MAX from Japan were an extra RB26DETT engine as well as a conventional H-pattern transmission should the team run into substantial mechanical problems--which it hasn't as of this writing.
Built in record time at A'PEX's headquarters in Sagamihara-City, Japan, the Skyline represents a monumental feat of engineering from one of Japan's best tuner companies. The Skyline was designed to showcase A'PEX's engineering and design talents as its construction took place in a record-setting two months. Kaneso decided to build the V-MAX for drag racing after attending the 1998 SEMA show. Since the show was held in November of last year, and the car needed to be on the boat bound for the United States a full month before it was scheduled to make its first appearance, a rushed buildup was scheduled. The team worked in a four-person rotation for 24 hours a day to finish the car in time.
There are still several areas left to develop before the V-MAX is finished, according to Kaneso. Faster times will likely be possible with further refinement of the car's aerodynamics. At the time of its first appearance it utilized a front undertray and splitter made of wood that extended from the leading edge of the car to its front axle line. The rear of the car also utilizes a wooden undertray and diffuser. All wooden pieces are prototype units that will be replaced with composite when development is complete. Kaneso says that there is also much lightening of the car left to do as it weighs 2,888 lbs with its driver in race trim. Experimentation with different sizes and compounds of tires will also help lower ETs.
All in all, the A'PEX team is quite pleased with the car's performance thus far in the States. "The engine and suspension are both quite good but are not yet functioning in perfect harmony," Kaneso said at our photo shoot the week after the car's debut. These are obviously the words of a crew chief with high expectations. In fact, as the V-MAX charged across our middle-of-nowhere dry lake photo location, the crew video taped the swirling dust coming off the back to the car to learn more about the its aerodynamic traits--just another example of the ever-present competitive thinking of a team of this caliber. Impressive to say the least.
Courtesy of :-
