They say you can never be too rich or too thin--or have too much horsepower. You're on your own for the first two, but to address the third, Toyota Racing Development has introduced new supercharger systems for the 2007-2009 Tundra and new Sequoia equipped with the 5.7-liter V-8.
The TRD division chose an Eaton Roots-type supercharger Twin Vortices system with a liquid-to-air aftercooler that uses a low-temperature heat exchanger. A TRD performance air-intake system is included along with iridium spark plugs, high-flow injectors, and a high-capacity fuel pump. In addition, there's a TRD calibration that reflashes the engine-control computer and a tidy single-belt drive system. All kits are 50-state emissions legal.
The superchargers pump out a substantial 8.5 psi of boost, which really wakes up these engines. The 5.7-liter engine's horsepower is bumped 25 percent to a whopping 504 horses at 5500 rpm (up from 381). Torque also makes a sizeable jump by 27 percent to 550 pound-feet at 4000 revs (up from 401).
On the down side, premium fuel is required. Also, the TRD reps state that, in EPA-mileage testing (which is predominantly light-throttle low-speed driving) the supercharged engines get approximately the same fuel-economy numbers as stock. However, we should note that, in real-world driving, owners typically report about a 1 mpg loss. As usual, fuel economy depends on how you drive.
As part of its strength and durability testing, Toyota spent a lot of time towing with this particular full-size-truck performance upgrade. Towing aficionados know that a supercharger gets more air into the engine at higher altitudes and also helps when pulling a heavy load up a grade. Throughout testing, temperatures of key components were monitored, including the catalyst, transmission, intake, and coolant. Likewise, TRD has supercharger kits for other smaller vehicles like the current-gen Tacoma and FJ Cruiser. Performance gains for the 4.0-liter V-6 top out at 302 horsepower and 334 pound-feet of torque, up from 236 and 239, respectively.
We had a chance to flog the supercharged trucks on the half-mile oval and 1/8-mile dragstrip at Irwindale Raceway outside Los Angeles. The superchargers worked flawlessly, providing a strong, linear gain throughout the rpm range. From off idle to redline, the engines pulled hard and seamlessly, with no pinging, lag, surge, or peakiness. Other than the serious increase in power, about the only noticeable factor is some supercharger whine, but even at higher rpm, it's not objectionable.
When installed by an authorized Toyota dealer, the superchargers and drivetrains carry the same five-year/60,000-mile warranty as the stock components, or the balance of the new vehicle warranty, whichever is greater. When not installed by an authorized dealer, the supercharger is covered by a one-year, 12,000-mile parts-only warranty. Suggested retail price of the TRD kit is $5875 plus labor. Installation time is estimated at eight to 10 hours if you know what you're doing, longer if you don't.
Source:Toyota Racing Development800/688-5912www.trdusa.com