Cadillac V8 engine

Cadillac was the first automobile maker to mass produce a V8 engine. The company has produced eight generations of V8s since 1914, and today is the only General Motors division to retain its own V8 design.

L-Head

The Type 51 was the first Cadillac V8. Introduced in 1914, it was the standard engine for 1915 Cadillac models. It was a 90° design with an L-head (sidevalve) configuration and was water cooled. Bore was 3.125 in and stroke was 5.125 in, for a total of 314 in³ of displacement. Output was 70 hp (52 kW).

The engine was refined for 1923 with a new split crankshaft that introduced the (now standard) 90° offset for each pair of cylinders. Power was up to 83.5 hp (62 kW).

The L-Head was on the Ward's 10 Best Engines of the 20th Century list.

Cadillac created a new V8, the 341, for 1928. It was a 341 in³ engine and produced 90 hp (67 kW). The same year saw the introduction of the synchromesh transmission.

In the 1930s, Cadillac increased displacement to 353 in³ (5.8 L) with a 3.38 in (85.7 mm) bore and 4.94 in (125.4 mm) stroke.

LaSalle

In 1937, displacement was reduced to 346 in³ for 135 hp (101 kW) for LaSalle. A smaller 322 in³ version was also introduced at 125 hp (93 kW). In the 1940s, these were paired with Cadillac's new Hydramatic automatic transmission. These engines were produced through 1948.

OHV

331

For 1949, Cadillac and Oldsmobile shared a new V8 design, Olds at 303 in³ engine and Cadillac at 331 in³. This was the first OHV V8. Output was impressive at 160 hp (119 kW). The American automakers competed throughout the 1950s to produce the most powerful V8. Cadillac quickly added four-barrel carburetors and dual exhausts to their V8 models, boosting output to 250 hp (186 kW) for most by 1955. The Eldorado used twin four-barrels for 270 hp (201 kW).

365

Displacement was up to 365 in³ for 1956, and the 1957 version produced 300 hp (224 kW).

390

A longer stroke pushed displacement to 390 in³ for 1959, yielding 325 hp (242 kW), while the Eldorado six-pack reached 345 hp (257 kW).

Redesigned OHV

Cadillac and Oldsmobile redesigned their V8s for 1963. The new engine was smaller and lighter but still stronger.

390

A special 390 in³ was produced for 1963 only.

429

Displacement kept growing, with a 429 in³ version producing 340 hp (254 kW) introduced in 1964.

472

The largest V8 engine to date appeared in 1968 when Cadillac unveiled their 472 in³ version. This huge engine delivered 375 hp (280 kW) but specialized in torque, with 525 ft.lbf (712 Nm) produced at just 3000 RPM.

500

But the company was not finished with huge V8s. In 1970, Cadillac introduced the largest modern V8, the 500 in³ (8.2 L) Eldorado motor. It produced 400 hp (298 kW), but the emmissions and economy restrictions of the 1970s (as well as the switch from gross to net ratings) dropped output to 235 hp (175 kW) (for the Eldorado) and 220 hp (164 kW) (for the rest) in 1971.

Downsized OHV

The market of the 1970s forced Cadillac to downsize its vehicles and engines. The newly-downsized deVilles and Fleetwoods of 1977 featured a redesigned V8 with a new 4.08 in bore and 4.06 in stroke, for 425 in³ (7.0 L). Carbureted output of the L33 version was 180 hp (134 kW), but electronic fuel injection was also available on the L35 for 195 hp (145 kW). (The Eldorado would keep the 8.2 L V8 until its' 1979 redesign; the Seville would keep its' fuel-injected, Oldsmobile 5.7 L V8 until its' 1980 redesign.)

1981 L62 V8-6-4

The most notorious engine in the company's history appeared in 1981. The 425 had been reduced to 368 in³ (6.0 L) for the previous year's L61 Seville, but the improvement in mileage was minimal. Desperate for an engine powerful enough to move the immense Cadillac sedans, but efficient as well (especially in light of CAFE mileage standards), General Motors decided to make the fuel-injected 6.0 L V8 a variable displacement engine. General Motors subcontracted for the creation of the variable displacement technology to the Eaton Corporation, the end result being the L62 V8-6-4.

This engine sequentially shut down pairs of cylinders when load was low, improving emissions and economy. The system was designed to reset to eight-cylinder operation when accelerating from rest or when the throttle was opened at cruising speeds. Cadillac hailed the L62 as a technological masterpiece, and made it standard equipment across almost the whole Cadillac line (the Seville retained its standard Oldsmobile-based 5.7 L diesel V8).

The L62 proved troublesome, both mechanically and electronically, the latter due in part to computer technology that was much too slow for the task. The V8-6-4 departed from the main Cadillac line after the 1981 model year, but remained the standard engine for factory Cadillac limousines for another four years (due mainly to the insufficient power of the HT4100 V8).

No automaker attempted the same trick again until Mercedes-Benz experimented with it on their V12 in the 1990s. It was not widely deployed until the 2004 DaimlerChrysler Hemi and 2005 GM Generation IV small-block. All of these later systems work by deactivating a bank of cylinders, rather than opposing pairs.

Aluminum OHV

HT-4100

Another new V8 appeared in 1982 as the HT-4100 (option code LT8). This engine was originally designed for transverse front wheel drive use in the planned downsized 1983 Cadillac sedans. However, delays in General Motors' BOC (Buick-Oldsmobile-Cadillac) large sedan program and the colossal failure of the L62 V8-6-4 caused the HT-4100 to be rushed into production for the 1982 model year.

The 4.1 L HT-4100 featured an unusual aluminum block with iron head construction. Bore was 88 mm and stroke was 84 mm; in most applications, it was equipped with throttle-body "digital" fuel injection. Initial output was a paltry 125 hp (93 kW), not nearly enough to provide Cadillac-level acceleration in the heavy Cadillacs of the early 80s (which were designed for a much bigger V8); early models were plagued with reliability problems. Later versions of the HT-4100 were used in the originally-planned front wheel drive configuration throughout the Cadillac line (with the exception of the limousines and the Cimarron).

The version found in the 1987 Cadillac Allante featured port fuel injection, with output of 170 hp (126.8 kW) and 235 ft.lbf (319 Nm) of torque. The 4.1 was superceded by larger models and ceased production in 1988.

HT-4500

Engineering allowed the company to begin to raise displacement and output again. A bored-out (to 92 mm) 4.5 L HT-4500 version was introduced in 1987 with 155 hp (116 kW). Various versions were built between this introduction and the end of production for this engine in 1992, including a high-output LW2 with multiport fuel injection version for the Allante which produced 200 hp (149 kW) and 270 ft.lbf (366 Nm).

HT-4900

An even larger version, the L26 HT-4900, debuted in 1991 at 4.9 L with a square 92 mm bore and stroke. Power was the same as the 4500 at 200 hp (149 kW) but torque was up slightly to 275 ft.lbf (373 Nm). The engine was produced until 1996.

This Cadillac V8 series was used in the following models:

This engine was phased out in favor of the newer Cadillac Northstar engine in the mid-1990s.

Rear-Wheel-Drive Cadillacs

From 1982 to 1985, all RWD Cadillacs (except for the limousines) featured the HT-4100 V8, though this could be replaced with a 4.1 L Buick LD5 V6 or a 5.7 L Oldsmobile LF9 Diesel V8. From 1986 to 1989, the rear wheel drive Cadillacs - the Fleetwood Brougham and Brougham - used a 5.0 L (307 in³) Oldsmobile 307 carbureted V8 (replacing the HT4100). In 1990, a 175 horsepower, fuel-injected 5.7 L (350 in³) Chevrolet Small-Block V8 became available to coachbuilders. In 1991, the Oldsmobile 307 was replaced with a 5.0 L (305 in³) fuel-injected Small-Block V8; the 350 in³ Small-Block became available in non-coachbuilder vehicles as well. In 1993, the 180 hp (134 kW) 350 in³ V8 became standard in the newly-renamed Cadillac Fleetwood; in 1994, this was upgraded to a detuned Corvette LT1 V8 with 260 hp (194 kW), which the Fleetwood would use until it was discontinued in 1996.

Northstar

Cadillac's most technologically advanced engine since the original OHV V8 bowed in 1992. This new DOHC Cadillac Northstar engine is documented elsewhere. Today, this engine is the only one at General Motors to be closely associated with a single marque. Although Oldsmobile and Pontiac have borrowed the Northstar architecture for their V8 (and even V6) engines, it was not until the 2005 Pontiac Bonneville that a non-Cadillac car used the Northstar name.