The Pontiac Grand Am (H) 2.5, produced between 1989 and 1991, represented a key iteration of Pontiac’s popular compact sedan. Falling within the ‘H’ generation of the Grand Am, which spanned from 1985 to 1991, this variant occupied a middle ground in the lineup, offering a balance between affordability and performance. It was positioned above the base models with smaller engines and manual transmissions, and below the more powerful, though less common, variants. The Grand Am, as a whole, was designed to appeal to American buyers seeking a stylish, comfortable, and relatively fuel-efficient vehicle, competing with models like the Ford Tempo and Chevrolet Cavalier.
Technical Specifications
| Brand | Pontiac |
| Model | Grand AM |
| Generation | Grand AM (H) |
| Type (Engine) | 2.5 (150 Hp) Automatic |
| Start of production | 1989 |
| End of production | 1991 |
| Powertrain Architecture | Internal Combustion engine |
| Body type | Sedan |
| Seats | 5 |
| Doors | 4 |
| Fuel Type | Petrol (Gasoline) |
| Power | 150 Hp @ 5600 rpm |
| Power per litre | 60.7 Hp/l |
| Torque | 183 Nm @ 3200 rpm |
| Torque (lb-ft) | 134.97 lb.-ft. @ 3200 rpm |
| Engine displacement | 2471 cm3 |
| Engine displacement (cu. in.) | 150.79 cu. in. |
| Number of cylinders | 4 |
| Engine configuration | Inline |
| Cylinder Bore | 101.6 mm (4 in.) |
| Piston Stroke | 76.2 mm (3 in.) |
| Compression ratio | 8.3:1 |
| Number of valves per cylinder | 2 |
| Fuel injection system | Multi-port manifold injection |
| Engine aspiration | Naturally aspirated engine |
| Engine oil capacity | 4.3 l (4.54 US qt | 3.78 UK qt) |
| Coolant | 7.5 l (7.93 US qt | 6.6 UK qt) |
| Length | 4510 mm (177.56 in.) |
| Width | 1690 mm (66.54 in.) |
| Height | 1340 mm (52.76 in.) |
| Wheelbase | 2630 mm (103.54 in.) |
| Drivetrain Architecture | Front wheel drive |
| Number of gears and type of gearbox | 3 gears, automatic transmission |
| Front brakes | Disc |
| Rear brakes | Drum |
Powertrain & Engine Architecture
The heart of the Grand Am 2.5 was the 2.5-liter (150.79 cubic inch) inline four-cylinder engine. This engine, internally designated as the LQ1, was a relatively simple design, featuring a cast iron block and an aluminum cylinder head. It utilized a multi-port fuel injection system, which improved fuel efficiency and throttle response compared to earlier carbureted designs. The engine boasted two valves per cylinder, operated by a single overhead camshaft. The 8.3:1 compression ratio was a compromise between performance and the ability to run on regular unleaded gasoline, a key consideration for the American market. The three-speed automatic transmission, a THM700R4 (also known as the 4L60), was a common and generally reliable unit used in many General Motors vehicles of the era. It was chosen for its smooth operation and ease of use, appealing to buyers who preferred the convenience of an automatic over a manual transmission.
Driving Characteristics
The 150 horsepower and 183 Nm (134.97 lb-ft) of torque provided by the 2.5-liter engine and automatic transmission delivered adequate, though not exhilarating, performance. Acceleration from 0 to 60 mph was typically in the 9-10 second range. The automatic transmission’s gear ratios were optimized for fuel economy and comfortable cruising, rather than aggressive acceleration. Compared to the base 2.0-liter engine, the 2.5 offered a noticeable improvement in power, making highway merging and passing maneuvers less stressful. However, it lacked the punch of the optional V6 engines available in other Grand Am trims. The automatic transmission, while convenient, did result in some power loss compared to the available five-speed manual transmission. The overall driving experience was geared towards comfort and practicality, rather than sporty handling.
Equipment & Trim Levels
The Grand Am 2.5 Automatic typically came standard with features such as air conditioning, power steering, and an AM/FM stereo radio. Interior upholstery was generally cloth, with a choice of color schemes. The dashboard layout was functional and straightforward, with easy-to-read gauges. Optional extras included upgraded sound systems, power windows and locks, cruise control, and a sunroof. The 2.5 trim level generally represented a step up in terms of features compared to the base models, offering a more comfortable and well-equipped driving experience. It wasn’t considered a luxury trim, but it provided a good balance of features for the price.
Chassis & Braking
The Grand Am (H) utilized a front-wheel-drive platform with an independent MacPherson strut suspension in the front and a semi-independent twist-beam suspension in the rear. This suspension setup provided a comfortable ride, though it wasn’t particularly sporty. The front brakes were disc brakes, offering better stopping power than the drum brakes used on the rear wheels. Stabilizer bars were typically included, helping to reduce body roll during cornering. The chassis was designed to provide a stable and predictable driving experience, prioritizing comfort and safety over outright handling performance.
Market Reception & Comparison
The Grand Am 2.5 Automatic was generally well-received by critics as a practical and affordable family sedan. It was praised for its comfortable ride, spacious interior, and relatively fuel-efficient engine. However, some reviewers noted that the performance was somewhat underwhelming, particularly compared to competitors offering more powerful engines. Fuel economy was rated at around 22 mpg city and 30 mpg highway, which was competitive for the time. Compared to the base 2.0-liter Grand Am, the 2.5 offered a significant improvement in performance, but at a slightly higher price point. The V6-powered Grand Ams offered even more power, but they were considerably more expensive and less fuel-efficient.
Legacy
The Pontiac Grand Am (H) 2.5 Automatic, while not a particularly rare or collectible vehicle today, remains a relatively reliable and affordable option in the used car market. The LQ1 2.5-liter engine is known for its durability, and the THM700R4 automatic transmission is also generally considered to be a robust unit. Common maintenance issues include oil leaks, worn suspension components, and corrosion, particularly in areas with harsh winters. Parts availability is generally good, as many components were shared with other General Motors vehicles of the era. The Grand Am 2.5 Automatic represents a typical example of American automotive engineering from the late 1980s and early 1990s – a practical, comfortable, and relatively affordable vehicle designed to meet the needs of everyday drivers.
