In today's world, the amount of power a bolt-on part can add to your Mustang or fast Ford is amazing. Whether it's an exhaust system, supercharger pulley, or custom tune, the technological advances that have been made can allow you to make some sick power without ever breaking a seal on the long-block.
Case in point is the BBK throttle body that we installed on a willing Shelby GT500. In a matter of about an hour, the Shelby picked up 16 rwhp just by swapping the factory throttle body for the larger and more refined BBK piece. Amazed? We sure were.
The GT500 is owned by Jim LaRocca, and had previously graced the pages of MM&FF when we swapped the factory Eaton supercharger for a Ford Racing TVS huffer in the October issue ("Eaton Up The Competition," pg. 132). Prior to the TB swap, the rear-wheel horsepower figure came in at 605. According to LaRocca, though, the stock throttle body served to be a restriction. "It doesn't matter if it was the stock blower, the TVS, or a TVS with a set of pulleys on it," he says. "The stock throttle body is a restriction at this power level."
The BBK unit features twin 65mm bores, as opposed to the stock 60mm sizing. The throttle body is CNC machined from a 356 aluminum casting, and comes with OEM die-stamped throttle linkages, double sealed bearings, O-ringed throttle shafts, and new electronic controlled injection molded plastic gear assemblies for the drive-by-wire. For those of you who own a Mustang GT with the 4.6L Three-Valve engine, rejoice as BBK has a twin 62mm throttle body available to replace the 55mm stock item. As with the GT500 throttle body, the GT part is another easy swap-and-replace deal.
As stated, the install itself was a breeze, as the only items needing attention were the drive-by-wire controls and the initial setup of the throttle body's blades. "Before I took the old throttle body off, I measured the voltage going to the throttle position sensor, which was 1.31 volts," LaRocca explains. "When I put the BBK piece on, I adjusted the bronze set screw until the blades were in the proper position to read 1.31 volts. Other than that, it was an easy installation, and the power that came of it was astounding."
With the BBK throttle body in place, we strapped the car to Krazy House Customs' Mustang chassis dyno for some validation. Keep in mind, the numbers appear low due to the difference between the Dynojet the car was run on when the blower was swapped, and the Mustang Dyno rollers for the throttle body swap. Regardless, you can see that the blown mod monster picked up the 16 rwhp, going from a before figure of 527 to an after figure of 543. Not too shabby for a part that costs $319.99 and takes an hour to install. If you do the math, minus labor, it equates to a touch under $20 per horsepower. And that sounds reasonable to us.
Here you can see the difference...
Here you can see the difference between the stock 55mm twin-bore throttle body and the BBK 65mm throttle body.
The mouth of the BBK throttle...
The mouth of the BBK throttle body is more refined and open, as well as being 10mm larger. The BBK piece was good for an increase of 16 rwhp, simply because at elevated power levels, the stock GT500's throttle body is a restriction.
The installation was as easy...
The installation was as easy as could be. Simply remove the air inlet assembly, undo the throttle position sensor (TPS) and drive-by-wire connections, and remove the four bolts and the throttle body. To put the new BBK piece on, simply reverse that order.
Before we removed the stock...
Before we removed the stock throttle body, we took measure of how much voltage the TPS was seeing at idle, which was 1.31 volts. Once we had the BBK throttle body on, LaRocca adjusted the gold set screw (arrow) until the TPS was seeing the same 1.31 volts with the new throttle body. Once there, he locked down the set screw, and the Shelby was ready to roll.
Other than setting up the...
Other than setting up the proper TPS voltage, there was no tuning involved in swapping to the larger BBK throttle body. Once on Krazy House Customs' Mustang chassis dyno, the snake cracked off 543 rwhp, as compared to the baseline 527 rwhp figure. While lower than the dyno figures listed for the car when we swapped on the TVS blower, the before and after difference clearly shows the 16 hp the BBK throttle body gave us.