Back in April autoblog brought you an initial report of the upcoming "Ironman" edition Toyota Tundra, and full details have now made their way into cyberspace. The package will be comprised of a number of dealer-installed accessories and components aimed at pumping up the testosterone levels in Toyota trucks. The special-edition is named for Ivan "Ironman" Stewart, who has raced Toyota trucks to an unparalleled 10 championships and 84 career victories.
Not only will there be an Ironman Tundra, but also Ironman editions of the smaller Tacoma truck and the retro FJ Cruiser beachcomber. Whereas the previous reports suggested that engine output would remain unchanged, the Ironman Tundra will actually offer a supercharger that boosts output from 381 hp to a whopping 504, and torque from 401 lb-ft to a stump-pulling 550. The Tacoma and FJ Cruiser likewise have their power increased from 239 hp to 304 and from 278 lb-ft of torque up to 334. Other components on offer for the Ironman Tundra are a Magnaflow cat-back exhaust, Bilstein shocks, Hella lamps, a Hurst pistol-grip shifter and 20-inch Alcoa aluminum-alloy rims with General tires. Similar accessories will reportedly be available for the Tacoma and FJ Cruiser as well.
With Toyota truck sales slumping, the company's performance division TRD hopes that the new Ironman packages will help boost sales. However, most buyers are not expected to pony up the $20k for the full monty, with most anticipated to spend between eight and ten grand on Ironman accessories from the pick-and-choose menu. The components are supplied directly by California-based Halo Special Edition Vehicles, which hopes to sell 500 Ironman packages this year before increasing targets to 5,000-10,000 packages in 2009.
Calculating the final drive ratio is easy. Understanding the difference between “higher” and “lower” gears is a little more difficult.
The final-drive ratio is so named because it’s the last time gears are used to multiply power as torque is transferred from the engine through the drivetrain to the drive wheels. This ratio is the numerical relationship of the ring and pinion gear found in the rear differential on 2-wheel-drive trucks and both the front and rear differentials on 4-wheel-drive vehicles. The final-drive ratio is calculated by dividing the number of teeth on the ring gear with the number of teeth on the pinion gear. So a ring gear with 43 teeth and a pinion gear with 10 teeth equates to a 4.30:1 ratio.
Tundra offers three final-drive ratios, depending on the engine choice and other equipment: 3.91:1, 4.10:1 and 4.30:1. With the 3.91:1 ratio, that means the driveshaft turns 3.91 times for every complete rotation of the drive wheels. With the 4.30:1 ratio, the driveshaft turns 4.3 times for every rotation of the drive wheel.
To move the truck the same distance—one rotation of the drive wheels—the engine turns over fewer times with the 3.91:1 ratio than the 4.30:1 ratio. A lower numerical ratio tends to offer better fuel economy, especially at highway cruising speeds because the engine doesn’t work as hard. The higher numerical ratio provides greater torque multiplication for more pulling power and quicker acceleration. The engine works harder when trading speed for torque, therefore fuel economy can suffer.
Confusion often surfaces when talking about final-drive ratios with customers, especially enthusiasts. The terms “higher” and “lower” may have different meanings at different times. A customer looking over a Tundra with a 3.91:1 final-drive ratio may ask for a “lower gear” to go off-roading. Toyota doesn’t offer a numerical ratio lower than 3.91:1, but in reality, the customer is asking for the 4.10:1 or 4.30:1. To this customer, lower means a higher numerical ratio because that provides more torque for off-roading.
Another customer might be considering a Tundra with the 4.30:1 final-drive ratio and ask for a “higher” or “taller” gear to help improve fuel economy. Again, Toyota doesn’t offer a numerical ratio higher than 4.30:1, but the customer is really seeking the 4.10:1 or 3.91:1 to reduce the engine speed.
The full-size pickup truck woes continue to worsen, leaving even mighty Toyota little choice but to slow production of its Tundra model. In fact, Toyota's brand new plant in San Antonio that was built just for the Tundra will be shutting down a total of 14 days between now and October. Full-time workers at the plant will be able to use vacation days, take the time off unpaid or find something else at the plant to do while the assembly line is halted.
Unfortunately, temp-to-hire workers aren't so lucky. Two-hundred employees who were hoping to land full-time positions at the plant will be laid off this summer. Toyota spokesman Mike Goss says, "We have a very long-term view of that factory in Texas. We're trying not to overreact. We're trying not to shut it down." Whoa... back up. Shut it down? We hadn't heard any such thing until it was spoken by Goss. Sounds like things are just as bad for Toyotas with beds as they are for pickups from Detroit.
All Toyota Tundra engines feature dual overhead camshafts (DOHC). This means there are two camshafts placed at the top of each cylinder head for a total of four camshafts on V6 and V8 engines. One camshaft on each head opens and closes the intake valves while the other camshaft operates the exhaust valves. (Actually the valve springs close the valves but the camshaft lobes control the operation and determine when valves return to the closed position.) Each cylinder has four valves: two intake and two exhaust.
This is the standard engine design in almost all high-performance cars and racecars. Some trucks like the Ford F-150 have a single-overhead-camshaft (SOHC) design with a single camshaft located on top of each cylinder head. On the Ford, this cam can operate a single intake and single exhaust valve per cylinder, or on the 3-valve motors it operates two intake valves and one exhaust valve. Other ½-ton trucks like the Chevrolet Silverado, GMC Sierra and Dodge Ram use a cam-in-block and two-valves-per-cylinder design in most of their engines. This means a single camshaft operates all the valves through a complex and heavy arrangement of lifters, pushrods and rocker arms.
Because the Tundra’s camshafts are placed almost directly over the valves, the valve operation is much more precise, even at high engine revs or RPM. Engine breathing is also more efficient over a wide range of engine speeds with four valves controlling airflow into each cylinder. Remember, an internal combustion engine is an air pump in its simplest form. Multi-valve engines allow more air and fuel to enter the cylinders, which in turn produces more useable power and increases fuel economy.
DOHC makes it much easier to implement variable valve timing. To operate at peak efficiency, the airflow in and out of the cylinders must be carefully managed. Proper valve timing is critical to engine operation. Too much air or not enough at different engine speeds will adversely affect performance and fuel economy. Variable valve timing adjusts... [Read More]
Toyota Tundra Forum
