Difference in 9 vs Y N*'s..

[Nikolai]

What's the difference in the 2000+ cars? Cams, gears and intake or is there tuning different too? The intakes look identical, but what else is there? Just looking for the cut and dry facts about that, always been a little confused about what is different.

[Bruce Nunnally]

If you mean the diff between the 275hp and 300hp engines, it is cams, cam lobe profiles, and calibration (Programming), and final drive ratio in the transmission.

If you are asking about what the redesign was in 2000, here was the specific press release on the Northstar redesign in 2000. There have been year by year changes to the engine after that, but this was the 2000 redesign:

MAJOR NORTHSTAR V8 DESIGN CHANGES IMPROVE EMISSIONS, MILEAGE, OPERATION

The 2000 DeVille introduces a significant redesign of the renowned Northstar V8, enabling it to operate cleaner, quieter and more efficiently with a 2 mpg increase in highway EPA mileage estimates. In addition, the redesigned powerplant can now run on regular octane fuel.

The design improvements build on Cadillac’s long heritage as a leader in engine technology. Cadillac introduced the world’s first mass-produced V8 engine in 1915; brought out the revolutionary overhead valve, lightweight high-compression V8 engine in 1949 models (including the very first DeVille); and set new industry standards with the debut of the four-valves-per-cylinder Northstar V8 in 1992. The 2000 DeVille ushers in the next step in modern engine design in the form of an improved Northstar V8.

While the basic engine architecture remains a predominantly aluminum 4.6-liter DOHC 32-valve V8, major design improvements have been incorporated to deliver lower emissions, excellent mileage with regular fuel, and smoother, quieter operation.

The list of new Northstar V8 features includes:

Roller-follower valve train design

Improved combustion chamber configuration

Center-feed intake manifold

New pistons

Coil-on-plug cassette ignition system

Siemens powertrain control module (engine/transmission control computer)

Exhaust manifolds with integral air-injection passages

Flex pipe between the exhaust Y-pipe and the catalytic converter

Twin electrically driven, two-stage air pumps (LEV applications only)

Direct mounting of all engine-driven accessories (power steering pump, AC compressor, electrical generator)

Integrated coolant crossover and throttle-body support

The DeVille’s fuel recommendation changes from premium (93 octane, lead-free) to regular, resulting in a major reduction in operating expense. To facilitate this gain, the Northstar’s compression ratio was lowered from 10.3:1 to 10.0:1.

One result of these improvements is that the 2000 DeVille will be certified for sale in California and certain Northeast states as a low emissions vehicle (LEV). This was achieved by means of a reaction-heated catalyst, pistons with reduced crevice volume and a new combustion chamber design.

DESIGN CHANGES

Revised combustion chambers are superior to previous designs in terms of both tumble motion of the incoming fuel-air mixture and burn rate. The intake and exhaust valves have been resized. Larger intake valves improve the engine’s breathing ability, while smaller exhaust valves increase flow velocity, an aid to catalyst light off.

While the new combustion chamber design helps maximize fuel efficiency, even larger gains are made by the addition of roller-follower devices between each cam lobe and valve stem. Compared to the previous Northstar’s direct valve actuation, the result is a substantial reduction in friction. During moderate driving conditions, the torque necessary to turn Northstar’s four camshafts is reduced by 50 percent or more, translating directly into a 0.3 mpg fuel economy improvement.

The Northstar also benefits from a new ignition system that delivers power to the spark plugs directly instead of through wiring. A cassette containing four ignition coils linked by short secondary leads to adjoining spark plugs now attaches atop each cylinder head cover.

In addition to improved reliability, the new ignition system permits scheduling the magnitude of the voltage sent to the spark plugs. High voltage is used during full-load, high rpm and heavy EGR (exhaust gas recirculation) conditions to guarantee complete combustion. The energy level is reduced to minimize electrical loads and radio frequency interference during light-load conditions, such as medium speed cruising. The result is extended spark-plug life and a peak energy capacity that is 130 percent higher than the system it replaced.

CONTROL MODULE

Northstar’s new powertrain control module is a single circuit board device housed within a sealed aluminum case engineered to withstand the harsh underhood environment. The module contains dual microprocessors to monitor and direct engine and transmission operations.

Noise and vibration improvements are the result of adopting a center-feed design for the composite-plastic intake manifold, as opposed to the previous end-feed design. The new design facilitates a near equal-length induction path for all eight cylinders. In contrast, the previous design provided a long path to the front cylinders and shorter paths to rearward cylinders. With the reduction or elimination of many harmonic tones, the resulting induction sound is more of a hum.

A molded-plastic cover backed with acoustical foam rests above the intake manifold to reduce induction, fuel-injector and other noises radiated by the engine. Direct mounting of accessories eliminates flex and vibration inherent with extra brackets. A flexible connection in the exhaust system en route to the catalyst helps quell another source of noise and harshness.

Engine cooling fans in DeVille operate so quietly that they can’t be heard by interior occupants. DeVille uses two acoustically designed fans, with curved blades that move air with minimum disturbance. The fans are individually controlled, so each is switched on only as needed.

POWER AND TORQUE

The 4.6-liter dual-overhead-camshaft Northstar V8 installed in the DeVille and DHS generates 275 horsepower (205 kW) at 5600 rpm and 300 lb.-ft. (407 N· m) of torque at 4000 rpm. The sportier DTS is equipped with a retuned version of the Northstar V8 producing 300 horsepower (224 kW) at 6000 rpm and 295 lb.-ft. (400 N· m) of torque at 4400 rpm. Redline for both models begins at 6500 rpm through 7000 rpm.

The Northstar engines offer 100,000-mile (160,000 kilometers) durability and limp-home mode in case of total coolant loss. The Northstar’s maintenance-free design requires no tune-ups — only changing the oil, oil filter and air filter — until the DeVille logs 100,000 miles (160,000 kilometers). In limp-home mode, the engine can operate on four cylinders at speeds of 50 mph (80 kph) for about 50 miles (80 kilometers), giving the driver an opportunity to reach a safe location. The engine accomplishes this by alternately delivering fuel to four of the eight cylinders. The remaining four cylinders do not fire, but continue to pump air, which cools the engine.

On all DeVille models, the 4T80-E transaxle is linked to the engine via a viscous converter clutch, which ensures smooth operation by reducing torque variation when the torque converter clutch is applied. The 4T80-E also features equal-length drive axles, which limit torque steer by minimizing angle differences from side to side as the car accelerates

[Nikolai]

Thanks. I new there were alot of 2000+ changes, but do you have any specific/technical differences between the 2000+ and the differences between 275/300 HP N*'s?

[JasonA]

Bruce listed both the differences between the 2000+ and earlier engines and the differences between an LD8 and an L37. The intake cam profiles are different, and the PCM mapping to accomodate that. And the final drive ratio in the transaxle. The differences between the LD8 and L37 remain through the 2000+ redesign, even though there were a lot of "base changes" to the engine.

[Nikolai]

Oh ok, I guess I just read through it too fast. Thanks.