Back in the days of the musclecar, Pontiac introduced the first four-barrel carburetor, the Rochester Quadrajet. The spreadbore design allowed their big V-8s to swallow an ungodly amount of air and fuel at wide open throttle, and returned good throttle response, fuel economy, and performance as well. For the '60s, that is.
Times have obviously changed. Gas no longer costs 35 cents a gallon, carbs are only for NASCAR, and a new musclecar era is upon us. But with every new generation comes a new set of problems. With the introduction of electronically controlled fuel injection it seems to some as if the link between the right foot and forward motion has been mucked up with electrons.
Enter Jimmy Hoekstra and Fuji Racing. They have developed an individual throttle body kit to make throttle response razor sharp, as well as increase power and torque throughout the powerband. The NA Miata before you is equipped with just such a kit. Designed to increase the velocity of the intake charge, individual throttle bodies more effectively suck in the incoming air. Although individual intake volume is smaller, it is collectively much larger. Throttle response is increased through the reduction of the total volume of air inside the intake manifold.
The result is better combustion and instant acceleration, which can be tuned depending on the user's need. The length of the air horns and diameter of the velocity stacks regulate the amount of air coming in at different rpm, essentially allowing for better low-end torque or high-rpm horsepower. Longer air horns and smaller diameter velocity stacks yield an increase in low-end twist at the expense of top-end power, while shorter air horns and larger diameter velocity stacks let the engine breathe better at the northern end of the tachometer.
The kit (sold through Hoekstra's web site: www.fuji-racing.com) comes complete with the throttle bodies, air horns, intake manifold, throttle position sensor, vacuum canister, and throttle linkage. Weighing in at only 9 pounds, the individual throttle body kit is ideal for anyone interested in increasing power and torque without adding the weight of a supercharger or turbo. Intercoolers, plumbing, and all the associated parts of a forced-induction kit can upset the balance of a car as perfectly weighted as the Miata. Fuji Racing claims an hour for installation, and any stock motor can utilize the kit, with no additional modifications necessary.
But, as anyone who likes to make cars go fast will tell you, what's "necessary" is in the eye of the beholder. With his head mechanic, Raul Rodriguez, in charge of installation, Hoekstra decided to throw on a few other goodies. Even though the majority of the engine is stock, Rodriguez and Hoekstra felt comfortable advancing the timing to 14 degrees before top dead center. It's a minor step up from the stock 10 degrees, but the effect can definitely be felt. Coming out the hot end of the engine is a Racing Beat 4-2-1 header, which feeds a feathery light 7.7-pound Fuji Racing cat-back exhaust. A Fuji Racing fuel pressure regulator and Fuji Racing fuel rails were installed to ensure proper delivery when the individual throttle bodies really started to go off. A Toyota MAP sensor is utilized to monitor the hyped-up intake. Rounding out the supervision of incoming air is a Fuji Racing inlet air temperature sensor.