Difference Between LS1 and LT1 (With Table)

LS1 and LT1 are small-block engines created by General Motors. They are deemed popular among automotive enthusiasts for their reliability and power. LS1 was introduced in 1997 as an advanced version of LT1, while LT-1 was first introduced in 1970.

LT-1 Chevrolet First Generation small-block was the progeny of TURBO-FIRE small block V8. It had a Holley four-barrel carburetor and a power output of 255-370hp @ 5,600 RPM.

Thereafter, the LT1 GM Second Generation small-block was introduced in 1992. This was an engine with 350hp @ 5,700 RPM, a batch-fire fuel injection configuration, and features like reverse-flow cooling.

LS1 vs LT1

The main difference between LS1 and LT1 is that LS1 is made out of aluminum while LT-1 is made out of cast iron. However, LS1 engines for trucks are also made with cast iron to ensure maximum strength and durability.

Due to its build, the LS1 engine is lightweight and thus has a better performance compared to LT-1. LS1 initially had a power output of 257-345hp and a torque output of 335-365 ft. /lb. after which it was upgraded to 390-400hp and 400 ft./lb.


Comparison Table Between LS1 and LT1

Parameters of Comparison




LS1 was introduced in 1997 by General Motors.

LT-1 first-generation small-block was introduced in 1970.

Horsepower rating

The first-generation engine had 257-345 horsepower.

LT-1 engine had a power output of 255-370 horsepower.

Torque rating

335-365 ft. /lb.

330 ft. /lb.


Aluminum cylinder block (except the truck engines which were built with cast iron).

Cast iron cylinder block with aluminum cylinder heads.

Engine capacity

5.7 liters

5.665 liters


Lighter weight and better performance.

Heavier build and lower performance when compared to LS1.

Fuel Efficiency

More fuel-efficient than LT-1 as when there is not enough air to burn, the amount of fuel fed to the engine will reduce.

Lower fuel-efficiency than LS1 as the fuel being fed always remains the same; the fuel that does not burn gets wasted.


More power than LT-1.

Less power than LS1.


More expensive than LT-1 but cost-efficient.

Cheaper than LS1.


What is LS1?

LS1 is a small block that was introduced by General Motors in 1997. The engine was an advanced version of its predecessor – LT1. The machine was made out of aluminum and had 6 bolt mains.

LS1 had a power output of 257-345hp and a crank fire distrubutorless ignition system with one coil per cylinder. Due to its build, the machine was light in weight and thus performed well.

Over the years, General Motors introduced newer versions of the LS1 small-block named LS2, LS3, LS4, LS5, LS6, LS7, LS8, and LS9. The newest version of the engine is LSA.

LSA is a 6.5-liter engine that is standard for the 2009 Cadillac CTS-V. It has a horsepower rated at 556. Other features include a compact 1.9-liter supercharger, hypereutectic pistons, and a different charge cooler design than its predecessor LS9.

Talking about the price, LS1 is more expensive than LT-1, but the performance is worth the cost. The small block is lighter, stronger, has more power as well as better heat dissipation than the latter.


What is LT1?

LT1 was the first-generation small block that had a power output of 225-370hp and torque output of 330 ft./lb. The machine was made out of cast iron and had aluminum heads. This ensured strength, durability, and reliability. 

The engine featured a reverse-flow cooling system that its predecessor lacked. This system cooled the heads of the machine first which in turn allowed a higher compression ratio and thus increased the power output of the engine.

LT1 was racing-inspired as it had a high-lift camshaft, solid valve lifters, and a high winding personality. Other features included four-bolt main caps, a forged aluminum piston, a baffled oil pan for reduced windage, a high-rise aluminum intake manifold, high-volume oil, and fuel pumps as well as transistorized ignition system.

The latest of these engines is the General Motors Fifth Generation LT1 with an engine capacity of 6.2 liters. It features a cast-aluminum block, oil-spray piston cooling, and redesigned main caps.

Main Differences Between LS1 and LT1

  1. LS1 has a horsepower rating of 257-345 and a torque rating of 335-365 ft. /lb. while LT1 has a horsepower rating of 255-370 and a torque rating of 330 ft./lbs.
  2. LS1 is made out of aluminum while LT1 is made out of a cast-iron block and aluminum heads.
  3. LS1 has an engine capacity of 5.7 liters while LT1 has an engine capacity of 5.665 liters.
  4. LS1 is lightweight and thus has better performance while LT1 has a heavy body that ensures strength and durability.
  5. LS1 reduces the fuel being fed to the engine when there is no air to burn while LT1 feeds the same amount of fuel to the engine irrespectively. This leads to wastage as the fuel does not burn.
  6. LS1 engines have better heat dissipation compared to LT1 engines.
  7. LS1 engines produce more power than LT1 engines.
  8. LS1 engines are more expensive than LT1 engines.



LS1 and LT1 have many differences between them, be it the specifications, materials used to build the engine, power, performance, or price.

A major difference between LS1 and LT1 is that LS1 is made of aluminum while the latter is made of cast iron. Aluminum is a lightweight material that ensures better and smoother performance.

Even though LS1 is more expensive than LT1, its features compensate for the cost. The newest version of LS1, named LSA, has a horsepower rating of 556, a compact 1.9-liter supercharger, and hypereutectic pistons.

The latest fifth-generation LT1 comes with a cast-aluminium build and redesigned main caps ensure maximum power and strength. The oil-spray cooling system ensures efficient heat dissipation.