It's been documented that the new Boss is set from the factory for some serious on-track antics. In the right hands, it can run 11s stock and cut corners with some of Europe's best.
Can you really double the...
Can you really double the power output of your Boss 302 with one simple bolt-on? You can if that bolt-on is Kenne Bell’s 3.6L Twin-Screw supercharger!
Under the hood, the 11.0:1 DOHC 5.0L received CNC-ported four-valve heads, revised cam timing, and a trick new intake manifold. Also part of the package are forged rods and upgraded valvetrain components. The mods push the output to 444 hp at an amazing 7,500 rpm. The new valvesprings allow the Boss motor to rev cleanly to 8,400 rpm (when the factory rev limiter is bypassed). Those changes actually dropped peak torque from 390 lb-ft at 4,250 rpm to 380 lb-ft at a slightly higher 4,500 rpm, but the fun zone in the Boss motor can be found at the top of the rev range.
Examining the word Boss, we discovered that it is very close to a word near and dear to our hearts-namely, boost! But in this case, there were a few concerns, including the static compression and variable cam timing. How would these respond to positive pressure? To find out, we took a Boss to Kenne Bell, one of the leaders in supercharger technology for decades.
(Thanks to Tracy Keller and Maximum Velocity Performance for use of its Boss for this test. Tracy even drove from San Antonio to KB's home is Rancho Cucomunga, California.)
Having previously run testing on the new supercharger kit for the 5.0L Coyote, we decided the Boss needed something special. In this case, special meant the installation of the big 3.6L blower kit just introduced for the Boss 302. Truth be told, the standard 2.8L blower is likely more than enough for most applications, as the 2.8L twin-screw is capable of supporting 1,000 hp. But for some owners, the idea that "more" is available is reason enough to step up.
Capable of supporting over 1,200 hp, the 3.6L features liquid cooling to minimize the temperature differential between the hot (discharge) and cool (inlet) sides of the supercharger. This differential makes life difficult on the rotors, as the growth rate of the rotors is a function of temperature. The hot and cool sides grow at different rates based on temperature, and the result can be changes in tolerances at both ends. Kenne Bell's exclusive (patent pending) liquid cooling minimizes the temperature differential, which in turn improves both power and reliability, especially at elevated boost levels.
Though the 3.6L Twin-Screw blower is the major power producer of the Kenne Bell Boss kit, it is the attention to detail on the remainder of the components that allows the Coyote motor to take full advantage of that glorious boost. Tucked under the blower inside a high-flow intake manifold is an efficient air-to-water intercooler system.
The system also features a dedicated circulation pump, reservoir, and front-mounted heat exchanger. Cooling the charge temperature is important on any boosted application, but critical on a motor sporting 11.0:1 compression.
Having a big blower is all well and good, but not if you restrict the airflow going to it. When it comes to supercharging, less air in means less boost (and less power). Recognizing that positive displacement superchargers are sensitive to inlet restrictions, KB went to great lengths to maximize the airflow of the sub systems positioned in front of the blower.
Knowing that, just one restrictive component can severely limit a perfectly good supercharged motor, Kenne Bell designed the Mammoth intake manifold to maximize airflow. In addition to offering tremendous airflow (upwards of 1,800 cfm), the Mammoth intake is designed to accept either the stock 80mm or the Kenne Bell 168mm throttle body. Testing at 15 psi on the Boss motor demonstrated that the throttle body upgrade alone is worth over 40 hp. Tested at higher boost levels, where the stock throttle body would represent even more of a restriction, the gains would be even more pronounced.
One thing sure to entice Boss owners is the dedicated Boss/Mammoth plaque attached to each system, replete with individual serial number-as if a Boss Mustang wasn't exclusive enough!
Boss 302-NA vs. Kenne Bell...
Boss 302-NA vs. Kenne Bell 3.6L (15.5 psi) Only from forced induction do you see power gains of this magnitude. The already impressive Boss motor produced just under 400 wheel hp (rated at 444 flywheel hp) and 350 lb-ft of torque. The variable cam timing ensured a broad torque curve, which continued once we added boost. Installation of the Kenne Bell supercharger kit (at 15 psi) resulted in a jump in power to 722 hp and 556 lb-ft of torque. Nothing beats the wail of a supercharged mod motor running at 7,500 rpm!
KB SC Boss 302-Stock vs. KB...
KB SC Boss 302-Stock vs. KB 168 throttle Body Obviously Ford never envisioned its 80mm throttle body supporting over 700 rwhp, so an upgrade was in order. Installation of the Kenne Bell 168mm throttle body resulted in a jump in boost from 15 psi to 16.6 psi, and a sizable jump in power. The throttle body swap increased the power output from 722 hp to 765 hp (over 40 hp). The gains from the high-flow throttle body are even more impressive at higher power and boost levels.
KB SC 302-16.6 psi vs. 21...
KB SC 302-16.6 psi vs. 21 psi Though we ran other boost levels, the final pulley swap (3.50 inches) brought a peak boost reading of 21 psi. It’s amazing that the bone-stock Boss motor (and clutch) was not only capable of withstanding 21 psi of boost, but seemed to thrive on the pressure and pump out an impressive 854 hp and 643 lb-ft of torque—more than doubling the factory power on the way.
Feeding the Mammoth intake and 168mm throttle body is nothing less than a 4.5-inch air intake and MAF assembly. The stock air filter and MAF system were never designed for the elevated power levels offered by a supercharged Boss motor. The cavernous Kenne Bell air intake is fed by an equally massive air filter. It's important to note that the air intake positions the filter down in front of the inner fender, well behind the front bumper cover-a position that guarantees a constant supply of fresh, ambient, and not heated, underhood air.
With plenty of airflow into and out of the 3.6L blower, the kit also supplies the necessary fuel. The combination of a new MAF assembly and the presence of boost (to say nothing of the 168mm drive-by-wire throttle body) naturally required custom programming. The custom programming was combined with a fuel system upgrade that includes a set of 75-pound injectors and a Kenne Bell 20V Boost-a-Pump. We were impressed that these simple fuel system changes allowed us to more than double the power output of the factory Boss motor!
Since we were looking for big boost from the Boss, we elected to upgrade to the new eight-rib drive system. Belt slippage can become an issue at higher boost and power levels, so KB designed a dedicated eight-rib drive system that features an optional ATI damper. The ATI damper is available in a variety of different sizes to adjust the boost level, but our testing was run with the smallest Kenne Bell-modified 6.6-inch crank pulley (included in the standard eight-rib kit).
Before installation, we ran the Boss motor in normally aspirated trim. As with previous testing, the 444hp Boss pumped out just a hair under 400 rwhp (and 350 lb-ft) on the DynoJet. Torque production exceeded 300 lb-ft from 2,600 rpm to 6,800 rpm, making for a broad and useable power band.
After the installation, the blower was configured with a 4-inch blower pulley and run through the stock throttle body. The remainder of the Boss was all stock, including the stock exhaust manifolds right back to the factory mufflers. Equipped with the 4.0-inch blower pulley, the intercooler 3.6L Kenne Bell produced 15.2 psi of boost. The supercharged Boss pumped out 725 hp and 558 lb-ft of torque. That, my friends, is serious power.
Replacing the stock throttle body with the 168mm unit from Kenne Bell resulted in a jump in peak power to 765 hp. Pulley swaps eventually produced 21 psi of boost, and a peak power output of 854 hp and 643 lb-ft of torque, all from an otherwise stock 5.0L. That, my friends, is screwing your Boss!
1 The Boss Mustang is a heavy...
1 The Boss Mustang is a heavy hitter right from the factory. Combining upgraded internals with revised cam profiles, CNC-ported Four-Valve heads, and a trick intake manifold increased the power output of the 5.0L Coyote motor from 412 hp and 390 lb-ft to 444 hp and 380 lb-ft. The mods increased peak power production by 1,000 rpm, and we’ve heard of Boss motors spinning safely to 8,500 rpm!
2 The gang at Kenne Bell...
2 The gang at Kenne Bell fed our need for speed with the new liquid-cooled 3.6L supercharger. Capable of supporting over 1,200 hp, the 3.6L was easily capable of doubling the power output of the 5.0L Boss motor. Feeding the big blower was a Kenne Bell Mammoth intake manifold. Restrictive intakes reduce the airflow, boost, and power potential of any supercharger, so Kenne Bell designed an intake system to keep pace with the flow rate of its massive 3.6L blower.
3 Working with Lucas Oil,...
3 Working with Lucas Oil, Kenne Bell designed synthetic supercharger oil to maximize lubrication, cooling, and longevity.
4 Given the minimal hood...
4 Given the minimal hood clearances of modern Mustangs, Kenne Bell designed these trick motor mounts to lower the engine. Dropping the engine provides the necessary blower-pulley-to-hood clearance.
5 Naturally, the extra airflow...
5 Naturally, the extra airflow supplied by the blower requires additional fuel. The Kenne Bell supercharger kit includes 75-lb/hr injectors. Kenne Bell magic tuner Ken Christley was the man responsible for the difficult job of tuning the supercharged combination
6 The only other fuel system...
6 The only other fuel system upgrade was to install a 20-volt Kenne Bell Boost-a-Pump. The combination of the stock fuel pump, larger injectors, and Boost-a-Pump provides sufficient fuel for over 850 wheel horsepower.
7 Knowing high boost and...
7 Knowing high boost and big power levels were in the cards, we opted to install the new eight-rib system from Kenne Bell.
8 The eight-rib system includes...
8 The eight-rib system includes a modified stock six-rib damper/crank pulley from Kenne Bell. Available as an option in a variety of different sizes from stock up to 7.88 inches, the ATI damper can also be used on 6- to 10-rib applications.
9 Here is a shot of the new...
9 Here is a shot of the new eight-rib system installed on a mock-up motor. A great deal of time and energy goes into the development of a new blower drive system.
10 The Kenne Bell supercharger...
10 The Kenne Bell supercharger kit will accept the stock 80mm throttle body, but big power came with the Kenne Bell 168mm oval unit. Tested at 16 psi of boost, the throttle body upgrade was worth over 40 hp. The gains would be even greater at higher boost and power levels.
11 Completing the free-flow...
11 Completing the free-flow inlet system is a 4.5-inch air intake/MAF assembly. Just one restrictive component ahead of the blower can severely limit power and boost. The combination of boost and a revised MAF assembly naturally required custom programming.
12 Boost supplied by the...
12 Boost supplied by the blower can be adjusted with simple pulley changes. The largest (4.0-inch) blower pulley provided over 16 psi of boost, while the 3.5-inch pulley stepped the boost pressure up to 21 psi. There is much more power to be had from this combination with even higher boost levels.
13 Keeping things cool is...
13 Keeping things cool is an efficient air-to-water intercooler. The intercooler system features a front-mounted heat exchanger. Note also the massive air filter supplied with the kit.
14 Run at just over 15 psi...
14 Run at just over 15 psi with the stock throttle body, the 3.6L pumped out 722 hp. This number jumped to 765 hp after the installation of the 168mm throttle body (boost went up to 16.6 psi). After cranking up the boost to 21 psi, the supercharged Boss motor pumped out an amazing 854 rwhp, more than doubling the factory output of 400 hp.