LS Engine Codes Explained For Beginners


There is a lot of confusion when it comes to the LS engine. You might wonder what all these LS engine codes mean, or where the LS engine even came from. Gen III and Gen IV GM V8s are considered LS engines. GM has produced so many variations of the LS engine that it will make your head spin. All of these engines are the same family, use compatible parts, and use similar engine codes. LS1, LS6, LS4, LS2, LS3/L99, LSA, LS9, and LS7 are the main ones you need to know. There are also many other LS-based engines out there such as various truck engines, and different versions to these already existing engines. To wrap our head around all these different engines we will break them down and go over the specifics.

First here are some things you should know about the LS engine;

  • All LS engines are pushrod V8s with aluminum cylinder heads.
  • Vortec series iron-block late-model truck engines (1999 and newer) are also LS based motors. They use different engine codes, but they are part of the family. Engine codes for these motors look like this; LM7, LM4, L59, LQ9, and so on.
  • LS engines can have an aluminum or an iron block.
  • LS engines are ALL considered small blocks. Though some have a big-block displacement, like the LSX 454 crate engine (Exception being the 8.1 Vortec which is a big block).
  • There are two very different generations of the LS engine, which are the Gen III and Gen IV.
  • LSX is a term used for Chevrolet Performance LS racing crate engines but has become “slang” for modified LS engines in general as LSx.
  • LS engines use electronic fuel injection. New Gen V LT engines now have direct injection.
  • LS engines use coil-over-plug ignition rather than a distributor.
  • LS Engines have 6 bolt main bearing caps.


This Gen III 346-cubic-inch 5.7-liter small block V8 was the first LS engine put into production under the hood of the 1997 Corvette. Later  the Camaro and GTO also received this powerplant until 2004. There is controversy over if this engine was the replacement for the Gen II small-block 350 engine or if the 5.3 iron block is the new 350 as it is more common and less expensive.

This all new engine  featured an aluminum block and cylinder heads (cathedral port) 10:1:1 compression, a bore of 3.898 inches and a stroke of 3.62 inches. Originally the LS1 made 345 horsepower and 350lb.-ft. of torque.

In 2001 GM decided to bring more power to the table and created  the LS6 for the C5 Corvette Z06. A brother to the LS1, the Ls6 shares displacement with the LS1 but features a new block casting with a new oil passages and water jacket design for better cooling and oil flow. LS6 engines also had a more aggressive camshaft and better cylinder heads that bumped up compression to 10:5:1. The LS6 had a better flowing intake manifold, as well as other subtle changes such as injectors, valve springs, and exhaust. This made for a higher revving more powerful engine. The Ls6 produced a then impressive 385 horsepower and 385 lb.-ft. of torque, but in 2002 was bumped up to 405. You can find the LS6 in the 2001-2004 Corvette Z06 and first generation (2004-2005) Cadillac CTS-V.


This 364-cubic-inch 6.0-liter engine  was the start of the Gen IV engines. Now don’t confuse this with the iron block 6.0 truck engine. This all aluminum performance engine features 10:9:1 compression, a 3.62-inch stroke, a 4-inch bore, and redesigned flat-top pistons. With a 6500-rpm redline this engine produces 400hp, and 400 lb.-ft. of torque.  The Ls2 was found in base 2005-2007 C6 Corvette, 2005-2007 CTSV, 2005-2006 GTO, Trail Blazer SS and even the SSR roadster pickup.




This Gen IV 376 cubic inch 6.2-liter engine is very similar to the LS2 with bigger numbers. With a bore of 4.065 inches, a stroke of 3.622 and L92 style cylinder heads, This one produces 430 horsepower and 424 lb.-ft. Exhaust is one of the biggest variables in the output of the LS3. The factory exhaust manifolds hide horsepower and by adding the Zo6 factory exhaust, power numbers increase to 436 horsepower and 428 lb.-ft. of torque in the C6. The LS3 can be found in the 2008-2013 Corvette, 2009 Pontaic G8 GXP, 2014-2016 Chevy SS, and 2010-2015 Camaros equipped with a manual transmission. Automatic-equipped 5th-gen Camaros have their own version of the LS3 called the L99. The L99 is essentially the same as an LS3 but features active fuel management (AFM, also known as displacement on demand [DOD] or cylinder deactivation), variable valve timing, and a different camshaft. The L99 produces 400hp.

gm-6-2l-v8-supercharged-lsa-engine-4 fixed


A monster 376-cubic-inch 6.2-liter engine with a 1.9-liter supercharger. Now you need to understand that this is not just an LS3 with a supercharger, there is more to it than that. Don’t confuse this with the LS9 either.  GM was looking for a more powerful engine for the CTS-V and ZL1 Camaros. It was later decided to build a supercharged version of the LS3 and it has less compression at 9:1:1 to run safer under boost.  GM used a forged crankshaft, oil-spray cooled Hypereutectic pistons, and a hydraulic roller camshaft made to handle boost. There was many other little things that were done to make this engine superior to the LS3, but what your probably wondering is what kind of number it puts down. Well it makes 556 horsepower and 551 lb.-ft. of torque at 9 psi of boost!


Different from the rest, the LS4 is a transverse -mounted Gen IV 325.1 cubic inch 5.3-liter engine designed for the front-wheel-drive line up. These vehicles include ’05-’08 Grand Prix, ’06-’09 Impala SS, ’06-’07 Monte Carlo SS, and ’08-’09 Buick Lacrosse. Different from the 5.3 truck engine this block is aluminum with Ls6 style cylinder heads. Built as compact as possible, the LS4 features a flattened water pump, a different bell housing, a shortened crankshaft, and a redesigned front belt accessories. This engine produces 303 horsepower and 323 lb.-ft. of torque and has active fuel management (AFM). If you were to swap this beast into a mid-engine Pontiac Fiero you wouldn’t be disappointed.



The big legendary LS7 has the classic 427-cubic-inch (7.0-liter) displacement in its aluminum block. The largest  factory LS engine with a bore of 4.125 inches, and 4-inch stroke. With sleeved cylinders, a forged-steel crankshaft, titanium connecting  rods, CNC-ported cylinder heads, 2.20-inch intake valves, and 11:0:1 compression, this engine produces 505 horsepower and 470 lb.-ft. of torque. What is truly amazing is its 7,000rpm redline. The LS7 is a very special kind of crazy and it can be found in 2006-2013 Corvette Zo6, as well as the very unique 2014-2015 Camaro z28. GM also produced an LSX style racing version of the LS7 called the LS7.R , not intended for the public. LS7.R was build specifically for the C5-R/C6-R Corvette in the American Le Mans racing series.




The top dog, the most powerful, the Ls9! Similar to the LSA in displacement with more power. Built stronger to accommodate extra horsepower achieved by a larger 2.3-liter supercharger, as well as a more aggressive camshaft. With the addition of an extra 82 horsepower over the LSA, GM added a forged crank, pistons and rods, as well a better air-to-water intercooler to keep it all cool. What is really special about this engine is they are all hand built in Wixom, Michigan. The LS9 debuted in the 2009 specifically for the Corvette ZR1 and is rated at 638 horsepower and 604 lb.-ft of torque.





Designed and built for the purpose of racing, LSX engines come as several sizes and options. The LS7.R is the odd one out with an aluminum block. All other LSXs are built with a cast-iron block to withstand over 2000 horsepower with forced induction! You can order your LSX crate engine from Chevrolet Performance, or from any authorized Chevrolet Performance dealer.

Vortec Series:

The Vortec name has been used a lot in the Chevy engine line-up. It was not until 1999 and newer body GM trucks that these engines  became LS based. You should know that all Vortec truck engines use an iron block. They are built and tuned differently than a true LS engine. Over the years GM has produced so many versions of these engines that it is hard to list all of them, but they are all similar. 4.8, 5.3, 6.0, 6.2, and the often forgotten 8.1 big block are now available. Because trucks are so common in America, there are hundreds of thousands of these engines out there, making them cheap and easy to find parts for. They are also very simple and easy to get reliable horsepower out of making it a very common engine to swap into a project car.

As you can tell there are many styles of the LS engine. It’s now clear the differences between various versions. And now that you know some history behind the LS Engine, you can tell engines apart and share our knowledge with others such as friends and family, growing as one big LS family. The LS engine has become so popular that people are swapping them into the most ridiculous machines; pretty much just about any make and model of car you can think of. Reason for this being is simply because the LS engine is the best engine out there, blowing the competition away. We hope this information log on the LS engine gives you a full understanding of the line-up GM offers, so you can LS swap the world.

About the author

Cole Clark

A Canadian, Cole Clarke eats, sleeps, and breathes cars. His love of cars started at 3 years old watching the General Lee in The television series Dukes of Hazzard. In his spare time, Cole attends car events and enjoys his new Camaro SS. Most performance knowledge is self-taught, but he has worked in various automotive fields as well. Cole respects all types of cars, from off-road to street machines, domestics, and imports.
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