DSPORT Issue #247
Text by Arnold Eugenio // Photos by Joe Singleton
Any fan of time Attack should recognize the car you see here – Amir Bentatou’s championship-winning, multiple record-setting Acura. What some may not know is that it took quite a bit of time, trial and error to get the car in a position to be able to reset class records at tracks across the United States. It wasn’t as simple as swap in a motor and start collecting trophies, especially when that swap involved a reduction in cylinders and a loss of 30-percent of the overall displacement volume.
Arguably the star of the show, the K-swapped NSX made waves when NSX purists and much of the Honda community at large learned that the NA1 chassis would soon be home to a powerplant other than the screaming 6-cylinder that many considered the pinnacle of Honda race engineering applied to the street. For a while, it seemed the naysayers were right. The swap itself complete, the car never managed to make progress toward the impressive runs that it was intended to. However, all the changes did provide important data points on what Bentatou and his team could correct and improve, making each destroyed transmission and overheated run an exercise in higher learning. He explained, “With time attack we don’t have very many rules, so I was able to build a car that I felt maximized the rules, rather than follow the typical NSX formula.”
Failing Upward
Starting with the removal of the original C30A engine, Bentatou’s first step in modifying the car of his dreams was to fit the proven K20Z1 into the mid-engine aluminum body, fortify as desired, add boost and then stir until ready. The new 2.0-liter powerplant was built by San Diego’s Sport Car Motion using stock-sized 86mm Arias pistons pushed by a quartet of Brian Crower connecting rods in a re-sleeved block, clocking in with a lowered 9.5-to-1 compression ratio. The factory K20Z1 crankshaft and rotating assembly friction surfaces benefitted from a set of ACL bearings. Up top the cylinder head was opened and upgraded with a set of Drag Cartel 2.2 camshafts while the remainder of the valvetrain got the Supertech spring and retainer treatment. The single cylinder head and block are mated with a set of ARP studs with a JE head gasket sandwiched in between.
Replacing Displacement
Of course, the answer to reducing overall displacement by 33-percent is to increase air intake efficiency – in Bentatou’s build, that meant the addition of boost. The harbinger of power in this case was the Garrett G30-770 turbocharger. Featuring a 58 mm inducer and 65 trim, the K20 takes in ambient air from its mid-engine placement via a custom intake system, then feeds the collected, compressed air first through a Koyorad water-to-air heat exchanger and ultimately through a Pracworks intake manifold via a 70mm throttle body. Spent gasses exit through an RS Motorsport manifold and exhaust system, with some boost modulated at the Turbosmart wastegate.
On the fuel, ignition and control sides – the E85-drinking K20 gets its liquid sustenance from an Aeromotive A1000 fuel pump feeding four Injector Dynamics ID1700X fuel injectors.A Koyorad cooling system setup developed through much trial, error and reverse engineering of the necessarily long distance between front-flowing radiator- cooling air and the mid-ship engine placement keeps things cool and cavitation-free. Engine management is handled by a KPro unit tuned by team member Kristian Wong. On a Mustang dynamometer, the setup was good for 424 horsepower at 7,500 rpm with 392 lb/ of torque.
Best Supporting Actors
Anyone can throw parts at a car, but it takes skill and knowledge to set those parts up properly. Much of the appeal of this trophy and championship-winning street class car is just that; the parts are reasonably available for most people that aren’t professionally funded race car teams. Transferring power from the K20 to the ground is currently
the work of the Samsonas 6-speed dog box transmission, McLeod Twin clutch and flywheel setup, KAAZ 1.5-way Limited Slip Differential, and Insane Shafts driveshafts, The suspension consists of KW Competition shocks with KW springs, a 1-inch front swaybar and ambient air in the rear swaybar position, and an RS Motorsport 6-point
roll cage to shore up the fi h wheel. Rolling stock consists of 18 x 10.5 and 18 x 12 Rays ZE40s wrapped in the requisite Yokohama Advan A052s (265/30 in front and 295/35 in the rear). Late-braking apexes are possible with Stoptech brake lines, calipers and rotors squeezing Winmax W5 brake pads.
Racing Suit
While “race car bits as fashion” aesthetics are in the eye of the beholder, Bentatou went to great lengths
to ensure the car was universally visually appealing in addition to being the fastest in class at the track. Rather than a laundry list of unobtanium aero parts, the aero combinations on the NSX were carefully curated and then color-matched for a show-car quality racer that attacks on all fronts. In front, a Spoon Sports R-GT front bumper wears an RS Future front splitter and end plates. These meet with Yokota Bodycraft front fenders on the side and and factory NSX-R bonnet up top. Marga Hills side skirts lead to Marga Hills rear fenders and the NA1 missile terminates with the Spoon Sports R-GT rear bumper down low and an RS Future LM Wing up top. The entire body is covered in a hue called “Midnight Purple 2”, sprayed on by ABS Autobody.
Thank You, Next
In its current form, Bentatou says that the development on the street-class level of competition is over and the time is now or never for solidifying its place in history with as many track and competition records as possible. By the time this reaches publication, the NSX will have attacked time in its last street-class version. “The development for the street class has come to an end,” Bentatou explains. “We will be at Road Atlanta with Global Time Attack (in May 2022). From there we start the unlimited build.” Whatever new trophies and accolades it may come home with, you can bet that Bentatou’s development in the unlimited class will progress steadily forward, and Bentatou and his NSX will become the next overnight unlimited class sensations.
