Olds Cranks It Up with New Northstar

NEW YORK - Making bold moves to revive what many believe is a dying franchise, General Motors Corp.'s Oldsmobile Div. will get the long-discussed, Northstar-derived 3.5L DOHC V-6 for its Intrigue at the start of 1999 production. The new all-aluminum V-6 - dubbed "Shortstar" by GM insiders - only will be available in the Intrigue GLS at first, but it will become standard by the end of the calendar year as the OHV 3800 V-6 is dropped from the Intrigue.

If early GM press material is an indication, the new engine apparently will be called the 3.5L Twin Cam.

Olds has the new 24-valve engine exclusively for the '99 model year, while the 3800 will be retained by other midsize GM cars. The new engine is designed by the same team that developed the V-8 Northstar exclusively for Cadillac. GM claims the team used the greatest amount of computer analysis in the company's history to create the Shortstar, which has been designed to run on regular-grade unleaded fuel.

"This engine will provide plenty of power for passing and merging, along with ambitious performance under all normal driving conditions," says John Zinser, chief engineer for Premium V engines. The new 3.5L V-6 is rated at 215 hp at 5,600 rpm and 230 ft.-lbs. (312 Nm) of torque at 4,400 rpm. Mr. Zinser says 90% of peak power is available in a broad range from 1,600 to 5,600 rpm. Like the Northstar V-8, the new V-6 has a limp-home capability in the event of a sudden loss of coolant. Normally, the coolant warms rapidly to help emissions and fuel economy.

Maintenance is designed to be minimal, with no service other than oil and filters for the first 100,000 miles (162,000 km). The oil filter allows complete draining of engine oil and has no metal filter casing, meaning all the lubricant contained in the filter can be completely drained. The engine uses 100,000-mile platinum-tipped spark plugs to help achieve the 100,000-mile interval before significant service is required.

The Northstar team used a two-piece aluminum block to create strength and stiffness. At the same time, noise is minimized and durability is maximized with a relatively low 9.3:1 compression ratio. Individual cast iron cylinder liners are permanently cast into the block for a durable interface with the aluminum pistons.

High-voltage spark plug wires are not required because a "coil-on-plug" arrangement, controlled directly by the powertrain control module (PCM), makes such wires unnecessary. Other features that help durability include a nodular iron split crankshaft that provides even firing for smooth power, while roller chains and sprockets keep valve timing synchronized for life.

Powder metal is used for the connecting rods, cam drive sprockets, camshaft bearing caps, valve guides and valve seats. GM says powder metal helps create high precision parts.

GM engineers also used a simplified fuel injector design, along with a fuel rail design that uses top-feed injectors that are smaller and lighter than traditional injectors.