And Then… Don't forget the 800-hour sludge tests run with low-quality bargain oil—one quart low, of course—or engines left to idle for hours at extreme angles to mimic police use, or intake-valve-deposit tests with non-detergent Chinese fuels . . .
It used to be that caring about your car meant you had to care for it. Engines, in particular, were viewed as semi-fragile. They needed to be warmed up, shielded from thermal shocks, and allowed to cool down before being turned off, particularly if they were turbocharged. But such quaint notions of mechanical sympathy are long gone, which is why modern engine tests venture well beyond what even the most insensitive driver would do.
Resist the urge to blame appliance-minded Americans for the added engineering workload. Mike Herr, Ford's engine-durability specialist, says that as engine portfolios become globalized, companies want to avoid the time and expense of separate testing for each market. "This 'commonization' has often resulted in simply incorporating the most-extreme tests from each operation," he says.
For Ford's global thermal test, for example, engineers run an engine up to peak power, and when the water temperature hits 230 degrees Fahrenheit, they shut it off and pump minus-22-degree coolant through it for 15 minutes. Then they start the frost-covered engine, allow it to idle for 20 seconds, and rev it to the power-peak rpm until the temp hits 230 degrees again, which takes about 10 to 15 minutes. During this test, the oil temperature goes from about 5 degrees to more than 280. Engineers repeat the process five consecutive times. Throughout the full durability-test regimen, an engine undergoes 350 such cycles, with other grueling programs in between.
- 10 Things You Didn't Know About the 2015 Ford F-150
- Instrumented Test: 2013 Ford Taurus 2.0L EcoBoost
- Instrumented Test: 2014 Cadillac CTS 2.0T
GM's thermal test moves engines between room temperature and 239 degrees at max power in less than 10 minutes, thousands of times. Its global-engine durability test sounds even tougher—and more fun—than its thermal test: "Think of it as drag racing from stoplight to stoplight on Woodward Avenue, starting at Eight Mile Road in Detroit to downtown Pontiac, about 17 miles north," says Adam Kwiatkowski, director of engine development and validation. "Then turn around and drive at top speed back to Eight Mile, and repeat the cycle about a hundred times." GM shuts down the turbocharged engines it's testing once an hour for three minutes immediately after a wide-open-throttle run in order to subject the turbo bearings to a nice heat soak.
As engines get more complicated, such extreme exercises become more important. Jeff Kolodziejczyk, a Ford engine-development supervisor, says: "Our EcoBoost engines have more-complex cooling systems to cope with integrated exhaust manifolds, turbochargers, and local hot spots. Our 1.6-liter has four separate valves to regulate cooling flow." Making sure those systems will work properly for a long time under all conditions makes for a lot of man hours logged, to say nothing of the fuel bill.
from Car and Driver Blog http://ift.tt/nSHy27
Put the internet to work for you.
No comments:
Post a Comment