Tuning a 600-HP, Time Attack S13

Lighting up the rears with 600-odd horsepower. Photo credit: Andy Perry

You can take the 240 out of the drift event, but you can’t take the drift out of the 240. Photo credit: Andy Perry

Will Wattanawongkiri has been racing competitively for nearly thirteen years. After racing NASA club events in his 350Z, he turned his attention to the world of time attack, which then was just getting a foothold in the United States. By the late oughts, Will had taken a hiatus from racing, and decided that his 240SX fastback could make an interesting time attack machine if massaged the right way.

Some might avoid the Nissan for a time attack platform, due to its reported propensity to light up the rears with the slightest sniff of the throttle, but much of that turns out to be overblown. With the right suspension tuning, the shortcomings of the suspension layout can be circumvented and the natural nimbleness of the FR sports car can be better exploited.

The Silvia front end with a fastback tail makes this hybrid a real head-turner wherever it goes.

The Silvia front end with a fastback tail makes this hybrid a real head-turner wherever it goes. Photo credit: Andy Perry

His fastback was originally a semi-dedicated canyon car; boasting Tein Flex suspension, a stockish SR20DET, and most of its interior left in place. When 2011 rolled around, the bug sank its fangs in a bit deeper and the build really commenced. Will spent much of the year testing and refining the modest car, which now sported a Silvia-style front end with fixed headlights. It was a case of less is more, with the 2,700-pound Nissan keeping up with ostensibly quicker machinery thanks to its weight and a decent amount of torque from the SR20, which, fitted with a GT-RS turbo, delivered a healthy 300 ponies to the rear wheels.


A massive Blitz intercooler decorates the open maw of the underdog champion.

With plenty of seat time and a well-sorted car underneath him, Will won the street class in both the Redline and Global Time Attack events, despite operating on one of the lower budgets in the field. High on his success and eager to continue climbing the ranks, Will took his car to Auto Club Speedway for a bit of track time. The motor blew, and to make the matter worse, the FR Shootout held by Import Tuner was only four days away!

A spartan interior; carbon doors are to come.

A spartan interior; carbon doors are to come.

With a mildly-built SR20DET that was collecting dust in his garage, Will swapped the engine in a hurry, threw in a new wiring harness, and shipped the car off to have it tuned the night before the event. As the fog cleared the next morning, Will’s tuned 240SX was dropped off and with little sleep, and a Double Shot in either hand, he rocketed off to compete. Though late, he managed to squeeze in a few trying runs towards the end of the timed sessions, running on the frustratingly greasy summer tires mandated by the rules. To have even competed was impressive, given the circumstances, but as luck would have it, he won. Beating guys like Jeff Westphal and Craig Stanton takes a combination of luck and talent, but it seemed the Motorsport Gods were smiling on Will that day.

For 2014, Will stepped up into the Modified category, which, while not totally unrestricted, allows for a lot more tweaking. Now running on R-compounds, Will focused on having a sorted, dependable chassis to capitalize on the grip available. Will ditched the pedestrian Teins and went for something more aggressive and widely-adjustable. With KW 3-way competition coilovers at each corner, spherical bushings, a custom front splitter, and a monstrous, draggy Voltex wing, he had the stability and grip to claw into the pavement and find more speed.


However, the quest was far from over. For 2015, he picked up a GT250 wing from new sponsor APR. The new item reduced drag without losing downforce; a more aerodynamically-efficient piece. To help put the power to the ground, he moved on from his 300ZX gearbox to a 350Z’s six-speed, to which he strapped on an OS Giken twin-disc clutch.

The Japanese company, his then-newest sponsor, also provided a 1.5-way limited-slip differential to give the ideal compromise between turn-in and lockup on the corner exit. He would need decent lockup and corner-exit traction, since the minimally-fettled SR20 was on its way to a serious overhaul.

Engine tuning underway.

Engine tuning underway.

Will would eventually double the horsepower his SR produced, thanks largely to a choice of new engine management. Part of that added grunt came from an SR20VE head, which helps build power from low revs, as well as a reasonably-small, twin-scroll Garrett GTX3076 turbocharger, but it was the AEM Infinity system running the show. Worried about blowing another motor and intrigued by the multiple forms of safeguarding the system offered such as lean-out protection, fuel pressure protection and rev limiting, Will would have peace of mind on a flying lap, as well as control over every parameter of the motor. Boost-by-gear and boost-by-RPM settings could also be utilized. He’d even have the ability to log every channel coming into the Infinity, at a staggering rate of 1,000 samples a second, if he desired.

Garrett, proud of Will's performance, decided to supply him with a twin-scroll GTX3037.

Garrett, proud of Will’s performance, decided to supply him with a twin-scroll GTX3037.

With the VE head in place, the AEM Infinity allowed Will to capitalize on the system and not have to lock out the camshafts. His affiliation with the company happened to coincide with AEM’s release of the their plug-and-play setup, and the two parties benefited by getting the VE-hybrid system to work.

The initial tuning gremlins reared their heads in fueling. With the injectors maxed and the stock fuel system not strong enough to complement the added ancillaries, they went with a fuel system from Ignite Racing providing E85 to the thirsty mill. After going with 11:1 compression and bigger ports, the motor was ready for tuning. Depending on the boost pressure, the 2.0-liter SR can produce a staggering 570-620 horsepower at the rear wheels. Perhaps more incredible is how the combination of a modestly-sized turbo, high compression, an appropriate head for the circumstances and proper tuning, make the SR as responsive as it is powerful.

Contemplating the future of the four-cylinder.

Contemplating the future of the four-cylinder.

AEM’s Beau Brown was instrumental in tuning the demanding powerplant, and used his roadcourse wisdom to make that peaky SR a little more progressive and predictable. The first step to complete control over the motor came through a boost-by-throttle position setup. Since a modern, responsive turbocharger like the GTX3036 can build boost too quickly to create a linear power delivery, the boost-by-throttle setup opens and closes the wastegate to dole out the power smoothly.

Additionally, to flatten the curve at peak torque, as well as try to lengthen the lifespan of the drivetrain components, Brown set the motor to go with boost-by-RPM. Additionally, that flatter torque curve makes the power more predictable in on-off throttle situations. With all these systems in place, the engine’s delivery is manageable, and doesn’t constantly turn the Hankook Ventus TDs at the rear into a plume of blue-gray smoke, despite what some might think.

Setting the motor to make power sweetly and predictably.

Setting the motor to make power sweetly and predictably.

However, it’s not just the way the power is delivered that counts. Will ensured the suspension was working properly; raising the subframe, adding custom knuckles and rear uprights to fix the roll center, and adjusting the rebound to counter some of the car’s inherent anti-squat. He’s even removed anti-roll bars at both ends to make the car more progressive on the limit and make better use of the 285-section tires he runs at all four corners.

The constant search for speed led to Will winning the Modified class at the 2016 Redline Time Attack, but like most obsessive-compulsives who can turn a steering wheel, his appetite is never sated. For this year, he’s planning to run the 240SX at Pike’s Peak, but will first need a new rollcage, a larger Garrett turbo, and more engine tuning.

A trim pot allows Will to change the boost settings on the fly.

A trim pot allows Will to change the boost as well as corresponding engine map and traction control settings on the fly.

To suit the specific demands of the “Race to the Clouds,” Beau will tune the AEM to change parameters as the air pressure diminishes on the way to the 14,114-foot summit. For instance, they’ll add duty cycles to the boost control solenoid to keep the wastegate closed. This is because the turbo has to ingest a larger quantity of air, which is thinner up high, to push the same mass.
Obviously, the ECU is constantly changing the mixture to suit the altitude, but they’re also considering throwing on a turbo impeller speed sensor to keep it from overspinning at those heights.

Not many vehicles have made it from understated canyon carver to contender in the hillclimb of hillclimbs, but the Will Wattanawongkiri Racing 240SX doesn’t easily fall into the “vehicles” category, since it isn’t so much a car as it is a manifestation of its owner’s superhuman drive to succeed.


About the author

Tommy Parry

Tommy Parry has been racing and writing about racing cars for the past seven years. As an automotive enthusiast from a young age, he worked jobs revolving around cars throughout high school, and tried his hand on the race track on his 20th birthday. After winning his first outdoor kart race, Tommy began working as an apprentice mechanic to amateur racers in the Bay Area to sharpen his mechanical understanding. He has worked as a track day instructor and automotive writer since 2012, and continues to race karts, formula cars, sedans, and rally cars in the San Francisco region.
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