gavriil

GM pushes pushrod engines -- and reaps savings - - Engines allow company to save $800 per unit sold - - By DAVE GUILFORD | Automotive News



GM pushes pushrod engines -- and reaps savings
Engines allow company to save $800 per unit sold


By DAVE GUILFORD | Automotive News

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Performance buffs belittle pushrods as crude and outdated.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."

gavriil

With all the talk about the 3.8 V6 in the Monte Carlo SS thread, I thought this would be interesting. Sheds some light as to why GM is still persisting with pushrods. Many many times I brought cost as the major factor as to why GM pushes for pushrods and this article reinforces that.

chef chris

To them it's probably just as easy(cost-wise) to add a supercharger to make up the difference in HP(GTP for instance).

Python2121

yeah and they dont need to design a whole new engine, plus its better for the consumer (though they probably dont think of it this way) in terms of modding

edit: i mean adding a supercharger

cusdaddy

GM pushrod engines also get outstanding fuel economy too (for their displacement) which is another plus

kansaiwalker1

The path of least resistance....

crippler22

If you think about it using a pushrod engine makes more sense than using overhead cam engines. A pushrod engines operating range is from 0 to 5500 or 6000 rpm, and the power band starts at around 2500 rpm and goes to 5000 to 5250 rpm. A an overhead cam engine may rev to 9000 rpm, and most all have a power band starting above 3500 rpm some don't kick in till 4500 rpm or higher even with vtec. At those rpm's you are not getting any kind of gas mileage. And the engine is really working to make power. Whereas the pushrod engine doesn't have to work that hard to make power. And I would put a 3800 up against any v-6 for smoothness.

CLUofI

that is a bold statement my friend

CLUofI

Accord v-6 240 hp and EPA 21 city, 30 mpg highway

Grand Prix GT 3800 V-6 200 hp and EPA 20 city, 30 highway.

am I missing something here?

dozorca

I think that when someone looks at a smoothness of an engine they forget that its not just the engine... The tranny, and many other parts play a roll in the smoothess of an engine...

You can have an awesome engine but if the components transfering that power are shit, you're not gonna score any points...

cusdaddy

Yes... The Accord V6 is 3.0L and it gets almost exactly the same mpg as a 3.8L GM V6... Yes, the Accord makes more HP, but less torque.

Look at the GM 3.5L pushrod engine in the new Malibu, which is a better comparison:

EPA: 23mpg city, 32mpg HW... And this engine makes more torque than the V6 in the Accord. and is still has .5L more displacement.

Their HP is less, but as I stated, for their size, they produce excellent fuel economy. The same with the LS1/LS2/LS6