Satisfied with our baseline, it was time for boost. Off came the TFS intake and on went the dedicated lower manifold for the Kenne Bell Mammoth kit. Designed to accept a 2.6L or 2.8L supercharger, the intake offers exceptional flow and a dedicated air-to-water intercooler. The intercooler was important as we planned on running serious boost. Feeding the beast were billet fuel rails and Injector Dynamics 85-lb/hr injectors fed by an Aeromotive fuel system. We chose a 2.6L supercharger for this application, but the Mammoth system also features a revised intake manifold, massive single-blade throttle body, and 4.5-inch air-intake/MAF assembly. Airflow into the blower is critical, as inlet restrictions result in a drop in boost (and flow) out of the blower. Why restrict your 1,000hp supercharger with a 600hp inlet system? The Mammoth system was designed to maximize flow into and out of the Twin-Screw supercharger.
Installation of the Kenne Bell Mammoth blower required use of the front accessories. We installed the alternator (in its revised location), the A/C and power steering pump along with a Meziere electric water pump and idler pulley. Pulley swaps on the Kenne Bell were a snap, allowing us to start with a 4.25-inch pulley that provided over 10 psi, and finished the day with 22.6 psi using a 3.0-inch pulley. Belt slippage was eliminated with the use of the eight-rib upgrade from Kenne Bell. This required swapping out the stock six-rib pulleys on the alt, PS and A/C along with the installation of a 7.5-inch, eight-rib crank pulley. Running the 4.25-inch pulley increased the power output to 552 and 482 lb-ft of torque. The Mammoth offered a slightly rising boost curve, starting at 8 psi (at 3,000 rpm) and finishing at 10.7 psi at 6,700 rpm. In typical positive- displacement fashion, torque production was impressive, exceeding 450 lb-ft from 3,400 to 6,200 rpm.
9 Before running the blower,...
9 Before running the blower, we did a quick intake test by first running the naturally aspirated engine with a stock PI intake and Accufab throttle body. Equipped with the PI induction system, the low- compression 4.6L produced 348 hp at 5,900 rpm and 349 lb-ft of torque at 4,700 rpm. All testing was run with a set of 1-3/4-inch long-tube headers from Kooks feeding a pair of Borla XR1 racing mufflers.
10a Next up, we tried the...
10a Next up, we tried the Street Burner intake manifold from Trick Flow Specialties. To ensure adequate flow, the Street Burner intake was run with a 75mm Accufab throttle body.
10b Equipped with the TFS...
10b Equipped with the TFS Street Burner intake, the 4.6L produced 371 hp and 331 lb-ft of torque. The TFS intake increased peak power by as much as 45 hp but lost out to the long-runner PI intake below 5,300 rpm.
After dialing in the supercharged combination, it was time to crank up the boost. We installed smaller and smaller pulleys on the 2.6L, stepping down in 0.25-inch increments. The 4.0-inch blower pulley brought 586 hp, while the 3.75-inch pulley stepped things up to 627 hp. Equipped with the 3.5-inch pulley, the 4.6L produced 670 hp at 17.5 psi. Stepping up to 20 psi with the 3.25-inch pulley brought 698 hp, but our final pulley swap to 3.0-inch pulley netted 742 hp. We tried a new radiused air entry designed by Kenne Bell on the oval throttle body that pushed the peak power output to 749 hp at 22.6 psi, but we stopped our testing there.
The blower will support considerably more power, but what we needed was more engine to start with. That would simultaneously increase power and decrease boost, making the blower even more efficient. Don't get us wrong, 750 hp is serious power from a supercharged Two-Valve, and we can't help but think there is even more power lurking in the Wooly Mammoth.
11 Now that we were done...
11 Now that we were done messing around with the normally aspirated combination, it was time to get screwed-twin screwed.
12a The new Mammoth kit for...
12a The new Mammoth kit for the 4.6L PI motor featured a dedicated lower intake manifold.
12b The lower intake both...
12b The lower intake both maximized flow and featured an efficient air-to-water intercooler core to keep intake charge temperatures down under boost.
13 The Mammoth system featured...
13 The Mammoth system featured custom billet fuel rails feeding 85-lb/hr injectors. We installed the larger injectors in anticipation of elevated boost levels.
14a Since boost and flow...
14a Since boost and flow out of the blower is a function of the airflow into the blower, Kenne Bell went to great lengths to design a new (high-flow) Mammoth intake manifold.
14b The Mammoth intake was...
14b The Mammoth intake was designed to accept a variety of different throttle bodies, ranging from stock to this massive single-blade throttle body said to flow up to 2,350 cfm.
15a Maximizing airflow to...
15a Maximizing airflow to the throttle body and Mammoth intake manifold was a 4.5-inch air-intake/MAF assembly.
15b Kenne Bell even had custom...
15b Kenne Bell even had custom air filters designed to feed their Mammoth system.
16 The Liquid-cooled 2.6L...
16 The Liquid-cooled 2.6L Kenne Bell Twin-Screw system featured a patented "external spring" bypass valve to minimize heat buildup under cruise conditions.
17 Running the blower on...
17 Running the blower on the engine dyno required installation of the front accessory drive system, including the A/C, power steering, and Meziere electric water pump (with idler pulley). Note the use of the 7.5-inch crank pulley, eight-rib pulley upgrade system from Kenne Bell, and new (reversed) position of the alternator.
18 We started out testing...
18 We started out testing with a 3.75-inch blower pulley, which produced a peak of 10.7 psi. The boost supplied by the intercooled supercharger kit increased the power output of the 4.6L to 552 hp and 482 lb-ft of torque.
19 Pulley swaps were quick...
19 Pulley swaps were quick and easy on the Kenne Bell, allowing us to test pulley sizes ranging from 4.25 inches down to 3.0 inches.
20 We stepped up the power...
20 We stepped up the power with each pulley change, but finished up the day at 22.6 psi with a peak of 749 hp and 685 lb-ft of torque after installing a 3.0-inch blower pulley and radiused entry on the throttle body. Look for a new, more powerful test engine that will push the Wooly Mammoth Two-Valve past the 750hp mark in the very near future.
NA 4.6L PI vs. TFS street...
NA 4.6L PI vs. TFS street Burner Intake. Prior to installation of the Kenne Bell Mammoth kit on the 4.6L, we took this opportunity to run a quick intake test. The modified 4.6L was run first with the stock PI intake and Accufab throttle body and then again with the TFS Street Burner intake. The TFS intake offered substantially more peak power, upping the peak numbers from 348 hp and 349 lb-ft to 371 hp and 331 lb-ft. The long-runner PI induction system offered more power up to 5,300 rpm, but the TFS intake offered as much as 45 hp at 6,500 rpm.
4.6L NA vs. Kenne Bell Mammoth...
4.6L NA vs. Kenne Bell Mammoth (10.7 psi). Adding the Kenne Bell Mammoth supercharger kit offered substantial power gains, increasing the power output from 348 hp and 349 lb-ft (with PI intake) to 552 hp and 482 lb-ft of torque at a peak boost of 10.7 psi. For this first test, we equipped the supercharger with a massive 4.25-inch blower pulley to work with the 7.5-inch crank pulley. Torque production exceeded 450 lb-ft for most of the curve, but we were just getting started.
Kenne Bell Mammoth--10.7 Psi vs. 22.6 psi. The great thing about forced induction is the ability to crank up the boost. Stepping down in pulley size from the 4.25-inch blower pulley to the 3.0-inch pulley increased peak boost pressure from 10.7 psi to 22.6 psi. Naturally the increase in boost had a positive affect on power, pumping up the output of the 4.6L from 552 hp and 482 lb-ft of torque to 749 hp and 685 lb-ft of torque.