Harrison wants that engine to perform to its maximum capabilities so that customers of the F-150 SVT Raptor won’t have anything to worry about. In short, if the engine can withstand the rigorous testing Ford demands during the development cycle, it can withstand almost anything the most enthusiastic off-roader can dish out, even desert racers.
The testing is intense. It’s cruel, dusty and dirty. By working in the lab to push the engine to its limits, the process simulates how a customer would use the engine. But then it goes a little bit further.
“Running it over 6,000 rpm for more than 150 hours, which is over the peak power limit of the engine, really puts it through its paces,” Harrison said. “We’ve tested it in harsher operating conditions on the engine dyno than would ever be seen by a customer who races.”
Beginning in fall 2006, Harrison and his team tested more than 50 engines, with each running through a dozen separate tests. Evaluations included high-speed durability, crank-torsional testing, aeration and a thermal cycle where the engine is “shocked” from one temperature extreme to another.
As with all Ford programs, attention to detail was a hallmark of the testing process.
“We did a careful teardown of each engine at completion of testing to ensure there absolutely are no issues with the hardware,” Harrison said. “These are very demanding, very stringent tests – far more stringent than anything you would see on a truck – racing or otherwise.”
Testing in the heat Besides dyno testing, the engine was put to the test in its element – the desert of Borrego Springs, Calif. Important factors such as engine cooling were evaluated on the 62-mile test loop designed by Ford’s Special Vehicle Team (SVT).
Engine cooling is key on Raptor – when the truck is in a desert environment, the hot weather and deep sand put a heavy load on the vehicle, and the engine has to exert maximum power to keep it going through deep sand.
There also is less airflow through the radiator at low speeds, and a large and effective cooling system is required for this extreme environment. To improve airflow to the engine, grille openings were increased by 20 percent.
“We spent a lot of time developing our desert durability test so that it’s very close to replicating the Baja 1000,” said Kerry Baldori, SVT chief functional engineer. “Desert testing proved to be a very quick way to learn about the reliability of the truck and it put another level of extreme loads on the engine that our normal durability testing doesn’t cover.”
Features of the new 6.2-liter V-8 engine include:
Cast-iron engine block and four-bolt main bearing caps, with additional cross bolts, for durability Aluminum cylinder heads, with two valves per cylinder head and two spark plugs per cylinder to more efficiently burn the fuel-air mixture in the combustion Single overhead camshaft with roller-rocker shaft drivetrain, which creates a stiff valvetrain that allows optimized camshaft lift profiles and results in better low-speed torque. The roller-rocker shafts allow valve angles to be splayed, resulting in optimized intake and exhaust port layout for better engine “breathing” Dual-equal variable cam timing means intake and exhaust valve opening and closing events are phased at the same time to optimize fuel economy and performance throughout the engine speed range and throttle positions Core to the improvements is using a larger bore and shorter stroke. This approach to creating power has its roots in storied Ford racing engines from the past. The large bore (102 mm) allows for larger intake and exhaust valves for improved engine breathing, and the shorter stroke (95 mm) allows higher engine speed for increased horsepower. Still, peak horsepower is generated at a relatively modest 5,500 rpm. Piston cooling jets squirt oil on the underside of the pistons to keep the piston crowns cool under extreme operating conditions.
Crankcase breathing is also improved to reduce windage losses and oil aeration levels at very high speeds. “That really helps get a robust lubrication system for the engine,” said Harrison. “It allows us to endure a lot of time at extreme high speeds.”
The 2010 Ford F-150 SVT Raptor launches with Ford’s proven three-valve Triton 5.4-liter V-8 engine. The new 6.2-liter engine will become available in early 2010.