We're all hot rodders here, so let's ignore that a new 5.0-liter Mustang with a Kenne Bell blower already has the capacity to fry the tires at will. There is always a "need" for more.
In this case, the literal choke on the Kenne Bell party has been the stock throttle body. This is no surprise as the Kenne Bell blower kits for the new 5.0 engine all feature the company's aptly named Mammoth air inlet. Large enough to swallow a housecat, the Mammoth intake effectively eliminates intake restriction. Thus, the stock throttle body--a mere 80mm in diameter--can't fully sate even the standard Kenne Bell 2.8 blower's appetite, much less efficiently feed a 2.8H pullied for track action.
For clarity we’re showing...
For clarity we’re showing just four of the six combinations of throttle bodies and pulleys tested. The light blue/dark blue lines represent the largest pulley run with the stock and Kenne Bell throttle body. The red/green lines are the smallest pulley (highest boost) paired with the stock and Kenne Bell throttle body. As expected, the missing middle test would plot equally between the tests shown. Clearly Kenne Bell’s blower system allows dialing in the desired power, and these tests peak at just 13.4 pounds of boost. There’s a whole gaggle of steeper curves to be had once the supporting oil pumps and supporting hardware is available.
So, Kenne Bell has done the logical thing, developing a monstrous 168mm throttle body as an optional upgrade to its blower kits. This correctly sizes the new throttle body to the Mammoth intake found standard on all Kenne Bell 5.0 kits and so it's no surprise the new throttle body proved more efficient in its first magazine test. At $799, it's one of those big parts that a casual guy could do without for awhile, then add down the road as he steps up his program. Of course, according to our test, he'll have to be content with a mere 591 rwhp compared to the 637 rwhp he could have with the KB throttle body, but then, life just isn't fair.
Kenne Bell's supercharger kits for the '11-'12 Mustangs center on the 2.8 and 2.8H twin-screw blowers. Regular readers will recall the 2.8 blower is optimized for 8-15 pounds of boost, while the 2.8H does best from 15 pounds on up. Until now only the stock throttle body was available, and as the photos show, it is entirely overwhelmed by the huge Kenne Bell Mammoth air inlet.
As the dyno tests illustrate, the stock throttle body is a bit of a choke in the entry-level 8- to 9-psi range, albeit not a catastrophe at such easy-going boost levels. But, as expected, at higher boost and power the greater the stock throttle body lags. So, the more power you make the better the Kenne Bell throttle body pays off. It's tough to draw a line and say that above such-and-such boost you must have the big KB throttle body. To a great extent this depends on how you're using the blower. Street fans could wait a little--the track-oriented customer is more likely to want all he can get right away.
The situation is pleasantly complicated by the easy Kenne Bell blower pulley changes. Using inexpensive pulleys and tools, it's a 4-minute snap to swap KB pulleys. In practical terms, that means easy 8 to 12 pounds of boost on the street, then swapping the pulleys and moving up to race gas and something like 18 pounds of boost for some rowdy track action. Reversing the process puts the car back in still-powerful street trim for the drive home.
This also means that up to the 600-rwhp threshold, you can make the same power with the stock throttle body and a smaller blower pulley as with the big throttle body and a larger pulley. Considering the throttle body is $799 while the pulley and changing tool are $94, this might be a good way to go. On the other hand, the big throttle body is definitely more efficient, and if you're interested in over 600 rwhp, you'll definitely want or need it to meet your goals.
In the end, it's up to you. Just starting out with a standard 2.8 Kenne Bell kit for your pride and joy street 5.0? You'll be happy with a big pulley and the stock throttle body for a good long while. Buying a 2.8H kit for track action? Better factor in the cost of the big throttle body. In between you'll have to make the call depending on your hunger for power and fiscal leverage.
Ricardo Topete of GTR (left)...
Ricardo Topete of GTR (left) and Ken Christley of Kenne Bell (right) pulled all the levers, did the dyno driving, and made the tuning changes during this cooperative Kenne Bell/GTR test. Ken is putting final torque on a blower pulley change here; the whole procedure takes maybe five minutes.
Frank Lanzas’ ’11 GT wears...
Frank Lanzas’ ’11 GT wears its liquid-cooled Kenne Bell 2.8 blower and 168mm throttle body like a natural. The cavernous Mammoth air inlet casting at the rear of the supercharger, along with the culvert-like chrome air inlet tube, are part of the stock Kenne Bell blower kit for Coyote engines. Pricing for a black-finished KB Coyote blower such as this starts at $6,599 for the non-liquid cooled version; the LC blower shown here retails direct from KB for $6,899, plus $799 for the big throttle body. With the large 4.125-inch pulley seen here, this combination put 550 hp to the tires in a walk.
Kenne Bell has flexible adapters...
Kenne Bell has flexible adapters to fit the stock or KB throttle bodies to the KB inlet tube. The molded adapters—this one is obviously for the stock throttle body—are easier to install than many of the silicone pieces found in typical cold air inlets, cone filters, and the like. Note how the stock throttle body is installed with the electronics re-clocked upward for clearance. We didn’t have this sort of flexibility with cable-operated throttle bodies.