Engines and Transfer Cases
The Chevrolet Avalanche is powered by the Vortec 5300 V-8. Measuring in at 5.3 liters, or 327ci, the Vortec uses a bore and stroke of 3.78x3.62 to develop 285 horsepower at 5,200 rpm and 325 lb-ft or torque at 4,000 rpm. The block is constructed of iron. Aluminum heads with two valves per cylinder top it off. Compression ratio is 9.5:1, and fuel is fed into the combustion chambers by a sequential electronic fuel-injection system.
The Avalanche uses a New Venture 246 transfer case. This uses an aluminum case and features a low-range of 2.72:1. A unique feature of the 246 is Autotrac, a system that, when selected, keeps the truck in two-wheel-drive until tire slippage is sensed. When that happens, the system transfers power to the front axles until traction is restored.
Our Dodge Ram 1500 test vehicle appeared in our parking lot wearing a 4.7L (287ci) engine that produces 240 horsepower at 3,200 rpm and 300 lb-ft of torque at 3,200 rpm. The block of this engine is made of cast iron and features a bore of 3.66 inches and a stroke of 3.40 inches. On top of the block sit aluminum heads that feature a total of 16 valves controlled by a single overhead cam for each head.
Splitting the power front to rear on our Dodge Ram 1500 is a New Venture 241 transfer case. Made with an aluminum case, it is chain-driven and features low-range gearing of 2.72:1. A manual shifter controls this easy-to-shift transfer case, a feature that was appreciated by our testers.
We found the biggest engine of our bunch this year under the hood of the Ford F-150. Measuring in at 5.4 liters (330 ci), the Triton V-8 produces 260 horsepower at 4,500 rpm and 350 lb-ft of torque at a nice-and-low 2,500 rpm. Other specs include a 3.55x4.16 bore-and-stroke and a compression ratio of 9.0:1. The valvetrain is composed of single overhead cams controlling two valves per cylinder. A sequential multi-port electronic fuel-injection system supplies the fuel.
A Borg-Warner 44-06 transfer case sends power to both axles. This aluminum transfer case is part-time, and is chain-driven. Low-range for the 44-06 is a respectable 2.64:1 and our test vehicle featured an electronic shifter.
Powering our Nissan Frontier was the optional supercharged 3.3L V-6 engine. It uses an Eaton M62 Roots-type supercharger that delivers a maximum of 7.5 pounds of manifold pressure to boost output to 210 horsepower at 4,800 rpm and 246 lb-ft of torque at 2,800 rpm. Also helping produce horsepower and torque are heads equipped with 24 valves and controlled by dual overhead cams. Running 91-octane fuel is recommended.
The job of transferring power to both axles is handled by Nissan's corporate two-speed transfer case. It is similar to the other transfer cases in this test in that it is made of aluminum and is chain-driven. However, it does feature the highest low-range gearing of our group, at 2.02:1.
Toyota designates the engine powering the Tacoma as the 5VZ-FE. The 3.4L V-6 uses a compression ratio of 9.6:1 and a bore and stroke of 3.68x3.23 to help it create 190 horsepower at 4,800 rpm and 220 lb-ft of torque at 3,600 rpm. More power-producing parts come in the form of 24-valve aluminum heads with dual-overhead cams. A distributorless ignition system sparks fuel that is fed by an electronic fuel-injection system.
Controlling distribution of power is a transfer case built by Aisinseiki, a subsidiary of Toyota. Constructed of aluminum, the part-time transfer case features a low-range of 2.56:1. Shifting the T-case is a lever that uses a button to engage high-range and a rearward pull of the lever itself to find low-range.
Our favorite engine of the test was the 4.7L i-Force V-8 that produces 245 horsepower at 4,800 rpm and 315 lb-ft of torque at 4,800 rpm. Lots of technology can be found on this mill. It is the only V-8 of our test to feature four valves per cylinder and double overhead cams. Its block is constructed of cast iron and features a 3.70x3.31 bore-and-stroke and a compression ratio of 9.6:1. Aluminum heads top off this high-tech engine.
Another Aisinseiki transfer case is found under the Tundra. Like the Tacoma's, it is constructed of aluminum, is part-time, and features a 2.56:1 low-range. However, unlike the Tacoma, the Tundra uses a fully electronic system that utilizes buttons to shift the transfer case.