Michael Galimi
November 1, 2010
Photos By: Courtesy Of Downs Ford Motorsport

If you're scratching your head and wondering why swapping a throttle body requires retuning, the answer is simple. Since the computer controls the electric motor, it's calibrated for the stock throttle body blades, gears, airflow over the blades (open and closed), and airflow through the bores. It knows how much force to exert on the throttle blade to achieve a certain pitch. All those variables are changed when swapping to a new throttle body.

Larger throttle bodies allow greater airflow through the bores, as well as at idle, and even the gear characteristics are different (weight/material, lubrication, mesh, and smoothness) of different throttle bodies. The throttle body motor control can be corrected in the ECU tune, but it requires you take your car to the local chassis dyno and pay to have the re-flash. The L&M throttle bodies don't require the re-tune since they address those points of throttle blade movement, and most importantly, airflow.

LaRocca was the horsepower and tuning expert in the design phase, while Minkin brought his 35 years of aerospace experience to the table. They also brought in an engineer, Mike Long of G-Force Racing Transmissions/Long Machine and Tool, to streamline the manufacturing side of the equation.

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Laminar airflow and velocity is critical in the aerospace industry, and the L&M team applied some simple techniques to create smooth, non-turbulent flow. To achieve the proper airflow, a vortex generator, more commonly known as a splitter, is added. "The vortex generator excites the air," said Minkin. "It's used on some airplanes to straighten and speed up the airflow forward of the control surfaces (ailerons, elevators, and rudder). We've performed airflow testing of the single-blade throttle bodies and found they experience dead airflow in the middle of the opening off idle, and then around 2,500 rpm. The airflow suddenly picks up speed and causes an rpm surge, which accounts for the off and on feeling that so many experience with this type of throttle body, as well as other driveability problems."

The airflow is also enhanced as it goes over the throttle blades due to the front of the L&M blade being chamfered. This technique was derived from airflow going into a jet engine. "It's about enhancing airflow and reducing/removing turbulence," Minkin explained. That was the first step in correcting the problems associated with using the factory throttle body motor controls with an aftermarket throttle body. The next was precision-cut Delrin plastic gears, similar to the factory gears, allowing a smooth control of the throttle blades that reduces the effort on the motor.

We tested two different sized L&M throttle bodies on a modified Shelby GT500-the twin-bore 66mm (LM66) and the twin-bore 72mm unit (LM72). Our test car appeared a few issues ago when Downs Ford Motorsport's technicians installed a Ford Racing 2.9L supercharger on Shay Varrone's '10 Shelby GT500. Out of the box, the blower helped bring output to a stout 675 rwhp with the Ford Racing tune, which left some power on the table due to its safe nature.

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The car was tested on a DynoJet chassis dyno at Big Daddy Performance (Lakewood, New Jersey). Since that article, Varrone had Downs add American Racing Headers long-tube headers and H-pipe (with catalytic converters), larger injectors, and a custom SCT tune from Big Daddy Performance. In this trim, the GT500 blistered the chassis dyno with a stout 703 hp and 659 lb-ft torque at the wheels, which is our new baseline.

The car was equipped with a FRPP Cobra Jet twin-bore 65mm throttle body, which comes standard in the 2.9L twin-screw blower kit. Mike Rozman of Big Daddy Performance did a few back-up runs to ensure our baseline of 703 rwhp was consistent and within 2 rwhp each time.