With the auto industry being such a cut-throat business these days, it makes you wonder if Ford might not switch back to a pushrod design for the their trucks, and dare we say it... their Mustang?
----- By DAVE GUILFORD
DETROIT -- A key factor in General Motors' ability to play an aggressive price game often goes unnoticed or even draws criticism - GM's heavy use of pushrod engines.
Performance buffs belittle pushrods as crude and outdated. But pushrods - expected to make up 62 percent of the 5.5 million engines GM will sell in North America this model year - save GM roughly $800 per unit against comparable overhead-cam engines, analysts say.
That enables GM to boost incentives, add standard equipment or offer a V-6 cheaper than a competitor's overhead-cam version.
Edward Koerner, vice president for powertrain engineering operations, says pushrods fill the high-volume, price-competitive segment of GM's engine lineup. Targeted at consumers who want a reliable engine but don't care about its inner workings, pushrods "give you some feature-content opportunities," Koerner says.
"Maybe there are other things that are more important in a segment, and because the powertrain price was down, you can offer other comfort features at that price point," he says.
For example, dual-zone air conditioning is standard in the base Chevrolet Impala. The feature is either lacking or found only in upper-end models of key competitors such as the overhead-cam-powered Honda Accord and Toyota Camry, which outsell the Impala nonetheless.
Japanese automakers overwhelmingly favor overhead cams. GM lines up pushrods against domestic rivals as well.
For example, its Chevrolet Silverado and GMC Sierra full-sized pickups
- sporting pushrod V-8s - compete with the Ford F-150 and its overhead cam V-8s. Dodge offers overhead cam V-8s as standard equipment on Ram pickups but has built a successful marketing campaign for the optional
5.7-liter Hemi pushrod V-8.Overhead cam, or multivalve, engines generally use one or two camshafts per cylinder head to open and close four valves per cylinder. They typically offer better power at higher RPMs and smoother idle and are more suited to variable valve timing, which improves torque range, fuel economy and smoothness and reduces emissions.
Pushrods, also known as overhead valve engines, use a single camshaft placed in the engine block below the cylinders, which have two valves apiece. Typically, they provide better low-end power. The configuration is more suitable for cylinder deactivation.
With fewer camshafts and valves, pushrod engines require fewer parts, which cuts cost and simplifies production. They also have an advantage in weight and size.
Koerner termed the cost difference "very, very significant" but would not give a figure. Brett Smith, director of product and technology forecasting for the Center for Automotive Research in Ann Arbor, Mich., says the difference is about $800, including premium materials often found in overhead-cam engines.
Smith adds that refinements have lessened many of pushrods' disadvantages: "It's no longer a low-tech, low-precision pushrod. It's a low-tech, high-precision pushrod."
Lindsay Brooke, senior powertrain analyst for CSM Worldwide in Farmington Hills, Mich., notes the Chrysler group has created an advertising buzz around its pushrod Hemi V-8s. Pushrods suit much of the U.S. market, particularly trucks, Brooke says: "GM and now Chrysler, with its V-8 Hemi, have a strong value proposition."
GM's engine lineup also includes "high-feature" engines, mostly overhead-cam engines and "image engines" for high-end vehicles, Koerner says. GM's strategy depends on offering the suitable engine for each consumer niche. But matching engines and market segments can be a sensitive business. For instance, GM has pushed the 2004 Pontiac Grand Prix as a performance vehicle. But it is powered by a 3.8-liter pushrod V-6.
That drew the scorn of a reviewer for The New York Times, who contrasted the pushrod to import competitors' "modern, overhead cam, multi-valve engines - many of them with variable valve timing for smoother, more flexible power delivery."
Gordon Wangers, managing partner of Automotive Marketing Consultants in San Diego, says enthusiast-magazine reviewers "are very critical these days of anyone running pushrods."
Wangers says although some pushrods are excellent, they reinforce enthusiasts' sense that GM is wedded to outdated technology. "The problem is the marketing, the image of 'yester-tech,' " Wangers says.
But most mainstream consumers don't care about engine specifications beyond horsepower and the number of cylinders, he says.
"I'm not sure the buyer of a Buick LaCrosse would know or care if the engine was multivalve or pushrod," Wangers says. "I don't think a Camry buyer would know either, for that matter."
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Here's a little NG poll. If you could get a Chrysler-style Hemi or a GM-style LS2 pushrod engine (a Ford design of course) under the hood of your next new Mustang for 800 bucks less than a overhead cam design, what would you do?
1) Buy an OHC Mustang 2) Buy a Hemi/LS2-style MustangPatrick '93 Cobra '83 LTD