Cadillac 4.9 Engine Technical Informationby Rob Wagner
The 4.9-liter Cadillac engine was a short-lived compact V-8 that predated the more popular 4.6-liter Northstar engines that debuted in 1993 and remain in production as of 2010. The 4.9-liter version was used in most Cadillacs between 1991 and 1995. Today, it’s a popular engine to swap with non-Cadillac cars, such as the Pontiac Fiero and other GM models.
The 4.9-liter V-8 was developed as a larger version of the 4.5-liter Cadillac engine used in the 1987 to 1993 two-seater roadster Allanté. It was almost identical in every way to the 4.5-liter version. The exception was that the 4.9's displacement was larger, and power output was increased by 20 horsepower through a port fuel injection system. However, the 4.9-liter V-8 in effect served as an interim powerplant until the more compact and considerably more powerful 295-horsepower, 4.6-liter Northstar was launched. The Northstar saw the Allanté through its final production year and was installed in the Eldorado and Seville.
The 4.9-liter Cadillac engine is a square motor with a 3.623-inch bore and stroke. It features a 9.5:1 compression ratio and a port fuel injection system to generate 200 horsepower at 4,100 RPM and 275 foot-pounds of torque.
The 4.9-liter engine was used in the Fleetwood, Eldorado, Seville and DeVille models. The Allanté was not equipped with this engine version. The engine block and intake manifold were made of aluminum, and the heads were made of iron. The 4.9 also featured a new oil pump, which increased oil flow by 13 percent and oil pressure by 18 percent. A new oil pan accompanied the oil pump. Also added were improved pistons to minimize engine noise during cold starts. The 4.5-liter V-8s were notoriously noisy when running cold. A new camshaft and crankshaft balance minimized engine vibration.
Port Fuel Injection
The Cadillac 4.9-liter engine can be identified by the “V8 PFI” embossed in red on the forward valve covers. “PFI” is an acronym for port fuel injection. This new sequential port fuel injection system was equipped with larger ports, throttle bores and larger valves over the previous throttle body injection (TBI) system. Instead of the two fuel injectors on the throttle body versions, the PFI had eight injectors in the intake manifold. The eight individual fuel injectors provided more power, better fuel efficiency and superior emission controls over the TBI engines.
The 4.9-liter V-8 was replaced by the Cadillac Northstar engines, but some Cadillac owners probably felt a little nostalgic for the 4.9 version. Early Northstars, especially the 1993 and 1994 models, suffered from oil leaks at the rear main crankcase seal. Cadillac enthusiasts turned to the 4.9-liter version to power older model Cadillacs while non-Cadillac owners swapped out their GM engines for the 4.9. Early concerns that the PFI system would not work on non-Cadillacs were unfounded, but the 4.9 usually had to be mated with the Cadillac 4T60E and 4T60 automatic transmissions to avoid major modifications.
- Thinkstock Images/Comstock/Getty Images