Toyota spent considerable effort establishing the "i-Force" name for the V-8 engine it shoved into the first Tundra. Toyota will use the name again on both V-8s it's loading into the all-new 2007 Tundra. But with an output of 381 horsepower and 401 pound-feet of peak torque production at 3600 rpm, the new 5.7-liter i-Force V-8 deserves its own name altogether. After all, this is the most powerful engine--car or truck--Toyota has ever sold in North America. And it's the highest-horsepower engine currently offered in any new 2007 light-duty pickup truck.
Called the 3UR-FE within the confines of Toyota, the new 5.7-liter is built around the same structural architecture as the 4.6-liter V-8 in the Lexus LS 460 introduced last year. However, while the Lexus engine is produced in Japan, the only plant in the world building the i-Force 5.7-liter is Toyota's plant in Huntsville, Alabama. And the aluminum engine block and heads are cast by Bodine Aluminum (owned by Toyota) in Troy, Missouri. So this is the engine with the most North American content Toyota has ever built. Japan, however, had plenty to do with the design.
There are truck engines out there with dual overhead cams and 32-valve heads and others with variable valve timing. But throw in aluminum-block construction and variable intake lengths, and the Tundra's i-Force 5.7-liter V-8 rates right up there as one of the highest-tech truck engines ever made available to the public. There's more to come from this engine: Adopting direct injection as used on the Lexus could easily boost output up over 400 horsepower.
• Aluminum block and heads, cast-in iron cylinder liners
• Four-valve heads, DOHC, and intelligent valve timing
• Conventional fuel injection with injectors spraying into intake tract
• Bore size identical to that of LS 460's 4.6-liter
• Tundra's stroke length almost 25 percent longer than 4.6-liter's
• 5.7-liter V-8 uses butterfly valves in intake manifold to adjust runner length
• Adjustable runner length based on throttle position and engine speed