Both LT1 and LS1 broke new grounds in terms of automobile engine design when they were released, respectively, in 1992, and 1997. Through this write-up, we explain what makes them differ, and which of the two is actually better than the other.
What is a V8 engine?
The V-configuration, in which the two sets of aligned cylinders make an angle with each other, has repetitively been used in the design of internal combustion engines, since the close of the 19th century. In a V8 engine, the two banks of cylinders that make the ‘V’ shape, have 4 cylinders each, and thus, in all, there are 8 pistons driving a single crankshaft.
Engines having this design are generally seen in sports cars, luxury cars, or heavy-duty cars like pick-up trucks and SUVs.
The small-block V8 engine design by General Motors has not stopped captivating car enthusiasts’ awe since it first saw the light of day in 1955.
In 1992, the LT1 engine with a number of ground-breaking innovations over the prevalent standards, made its debut. Five years later, the LS1, a completely new design that almost didn’t even share a single component with its predecessor, heralded the 3rd Generation of V8 engines, and completely changed the face of the V8 line. Now, almost two decades ahead in time, it is the day of the Generation V LT Series, of which the new LT1 engine was first seen in the 2014 Chevrolet Corvette Stingray.
Despite the momentous evolutionary journey of General Motors engines, right from Ed Cole’s original design in the 50s, to what we have today, car lovers absolutely live for the raging debate about which of the two, the LT1 engines, or the LS1 engines, were better. We feel that before we go that far, it would be a good idea to get a clearer picture of the specifications and abilities of these two kinds of engines.
LT1 Vs. LS1: A Direct Face-Off of Specs
LT1
LT1 by General Motors marked the beginning of the line of the Generation II small-block V8 engine family. It was first seen in the 1992 Chevrolet Corvette. We have summarized all the specifications of the engine, as well as compiled a list of automobiles that carried each of the different engine models.
General Specifications
| Engine Capacity | 5.7 L (350 cubic inches) |
| Cylinder Bore | 95.0 mm – 101.6 mm (depending on the engine body shape and model) |
| Piston Stroke | 76.2 mm – 93.0 mm (depending on the engine body shape and model) |
| Engine Block | cast iron |
| Cylinder Head | cast iron, aluminum in some cases |
| Performance Optimization | dedicated Engine Control Unit (ECU), Powertrain Control Module (PCM- a new and improved ECU) in engine models released after 1994 |
Combustion and Fuel Type
| Fuel Injection | multi-port, batch fire fuel injection in the earliest models, sequential fuel injection in models released after 1993 (the use of mass airflow sensors) |
| Type of Fuel | gasoline |
| Type of Oil | wet sump |
| Cooling Mechanism | water cooled, reverse-flow cooling that cools the cylinder head first to maintain a lower temperature and improve compression |
| Firing Control Mechanism | distributor with vacuum vents |
Different Engine Models and their Rating
| Y – body | Chevrolet Corvette C4 (1992 – 1994) | 1992 model factory rating of 300 hp (220 kW) and 330 lb·ft (447 N·m) 1996 model factory rating of 300 hp (220 kW) and 340 lb·ft (461 N·m) |
| F – body | Pontiac Firebird Formula and Trans Am (1993 – 1997) Chevrolet Camaro B4C, Z28 and SS (1993 – 1997) |
1993 – 1995 factory rating of 275 horsepower (205 kW) and 325 lb·ft (441 N·m) 1996 – 1997 factory rating of 285 horsepower (213 kW) and 335 lb·ft (454 N·m) WS6 and SS (1996 – 1997) factory rating of 305 hp (227 kW) |
| B – body | Buick Roadmaster and Roadmaster Wagon(1994 – 1996) Chevrolet Caprice, Caprice Police Package, Caprice Wagon and Impala SS (1994 – 1996) |
(1994 – 1996) factory rating of 260 horsepower (190 kW) and 330 lb·ft (447 N·m) |
| D – body | Cadillac Fleetwood (1994 – 1996) | (1994 – 1996) factory rating of 260 horsepower (190 kW) and 330 lb·ft (447 N·m) |
LS1
The new Generation III of General Motors V8 small-block engines was brought in by the LS1. It was characterized by its strong, reliable design, and the design of engines of many other brands were also inspired by it.
It made its debut in the 1997 Chevrolet Corvette, however, since then, it has seen a lot of improvement and evolution. We have summarized the specifications of the original LS1 (also known as Vortec) engine.
General Specifications
| Engine Capacity | 5.665 L (345.7 cubic inches) |
| Cylinder Bore | 3.898 inches (99.0 mm) |
| Piston Stroke | 3.62 inches (92 mm) |
| Engine Block | aluminum |
| Cylinder Head | aluminum |
| Rating | earliest model 345 hp (257 kW) at 5,600 rpm and 350 lb·ft (470 N·m) at 4,400 rpm in models introduced after 2000 350 hp (260 kW) and 365 lb·ft (495 N·m) |
Combustion and Fuel Type
| Fuel Injection | sequential multi port fuel injection |
| Type of Fuel | gasoline, E85 |
| Type of Oil | wet sump |
| Cooling Mechanism | water cooled |
| Firing Control Mechanism | no distributor, both firing mechanism and air-fuel mixing controlled by ECU |
Analysis and Conclusion
The LT1 was a huge improvement on contemporary engines. Its most powerful variant had a monstrous capability of around 305 horsepower. Also, it introduced the reverse-cooling mechanism where the coolant flows to the cylinder heads first, as a result of which it can achieve higher levels of compression, a ground-breaking concept at that time. It also came with noteworthy improvements in the control unit. All-in-all, it was proof of the fact that a brilliant design, albeit deduced half a century ago, when improved to meet the needs of the day, can still be relevant.
The LS1 is a completely different story. It was a clean-sheet design, meaning it had little or no similarity to its predecessor. Unlike the LT1, the cylinder blocks were made entirely out of aluminum, making the engine itself lighter. Unlike the LT1, it did not use a distributor-based firing system, but instead the control unit itself handled that segment intelligently. The LS1 also came with other advancements, like the coil-on-plug ignition system as opposed to the then-prevalent spark-plug-and-coil ignition mechanism. But most importantly, in terms of power, it had an advantage of almost 50 horsepower of the LT1.
Putting these two against each other is not a fair comparison, because, the LS1 is more or less the new-and-improved LT1, and hence obviously, in any face-off it will emerge the winner.
However, one must remember that even the LS1 was replaced with the newer Generation IV and more recently, Generation V engines. The best of the engineering in the 90s along with the technological improvements that the last two decades have brought to the world have had inputs in the design of these engines, with features like active fuel management, direct fuel injection, piston cooling jets, oil pump, and many others.