LS1 Vs. LSx Engines: What Is The Difference?

If you’re shopping for a crate engine to drop in your classic car or street rod, an LS is often an excellent choice. A problem you may face though, thanks to the naming convention used for GM engines, is this: Do you want an LS1 or what engine builders like us refer to as an LSx?

LS Engines Take Many Forms

GM’s small block V8 engine designations are confusing. The LS1 of 1997, for instance, was followed by the LS6 and not, as might have been logical, the LS2. (That didn’t show up until 2005.)

Complicating matters, more than two dozen engines have carried the LS designation, plus more that were LS engines under different names. On top of that, there was an engine GM called the LSX.

LSX and LSx

The LSX (note the capitalized “X”) is a race variant of the lightweight LS7 engine. This 7.0L (427ci) version of the Gen IV small block went into the 2006 Corvette. In contrast to the ‘vette motor, the LSX has a cast-iron block that handles a lot more horsepower. Indeed, there are reports of LSX engines making as much as 2,000 horsepower.

The LSx (note the lowercase “x”) is not this engine. Here the “x” indicates an engine is of the LS family. At the risk of getting mathematical, “x” could stand for 2, 3, 6, 7, 9 or even “A.” Of course, “x” could equal 1.

Two Generations of LS

Arriving in 1997, the LS1 was the last of GM’s Gen III small block engines, but also the first LS. Like previous small blocks, it was a compact 5.7L (350ci) V8.

Keeping things simple for any Chevy or Pontiac owner wanting a more powerful engine, this retained the bellhousing bolt pattern from those predecessors. Thus, it’s pretty safe to say, if an older small block came out of a car, a new LS1 will fit the space vacated. As mentioned earlier, the next engine in the LS series was the LS6. This too was a Gen III small block, but the LS engines that followed were all of the fourth generation. Major differences were a 58-tooth reluctor wheel for improved ignition timing, plus the addition of variable valve timing and displacement on demand, also known as Active Fuel Management (AFM).

Gen IV engines also grew in displacement, achieved through larger bores and longer stroke. Bore spacing remained at 4.4 inches, so overall length was virtually unchanged.

LS1 or LSx?

Better questions might be, what vehicle is the engine going into, and how much work do you want to do? We sell an LS1/LS6 crate engine that makes for a relatively straightforward transplant into an older GM vehicle.

Available as short blocks, long blocks and complete engines, these let you carry over many, if not all, of the ancillaries. That makes them an alternative to stripping, machining and rebuilding the existing engine and gets you back on the road faster.

One downside of choosing an LS1 is that you’re not getting the latest and greatest in engine technology. You’re also not getting the bigger displacement of the Gen IV. Our LSx crate engines can give you from 6.0L (364ci) up to 8.2L (502ci). These give you a lot more power, but also mean more work and money.

How to decide? If you need a new small block V8 for a classic car or something custom you want to drive every day, an LS1 crate engine could serve you (and your budget) well.

If, however, you’re building something special for street or strip and want a lot of horsepower, take a look at our line of LSx crate engines. We’re sure there’ll be something to suit.

Power or More Power?

A true LSX engine is a rare beast. LSx, however, indicates that an engine is of GM’s small block LS family, although it could be either third or fourth generation. The Gen III LS1 and LS6 engines make straightforward transplants in older small block-powered vehicles but are somewhat limited in horsepower.

If big horsepower is what you want, talk to us about a Gen IV LSx crate engine.

Call or email Golen Engine to learn more – 1-800-591-9171.