Which LS Engine Should You Swap in Your Car?

Posted by Alan MacDonald on

Which LS Should You Swap in Your Car? 

LS Engine Family Swap Options 

The world would be an awesome place if everyone could afford to put an LS9 in their car, but that’s not how it works. There are quite a few choices when it comes to which LS you should swap into your car. If you have the money an LS7 or LS9 are awesome options. The LS7 produces a ridiculous amount of horsepower naturally aspirated. The LS9 produces a ridiculous amount of power with its supercharger.


GEN III - LS1 Engines

GM first introduced the LS family of engines in the 1997 Corvette. They called it the “Gen III small-block” now known as the LS1. The LS1 engine is a 5.7L, and it featured an all-aluminum design. It also featured coil near plug ignition, and various other new engine management features. These new features made it vastly greater than the previous generation's small block. In 1998 the LS1 replaced the LT1 found in Camaros and Firebirds. Chevrolet then began producing an iron-block Gen III small-block that came in the pick-up trucks and SUVs. Because of their comparatively small bores, LS1 blocks can only use LS1, LS6 and LS2 heads. Larger heads will cause valve-to-block issues. Transplanting an LS1 could be difficult because the 1997-2004 Vettes came with throttle by wire throttle bodies and electronics to operate them. You must have the accelerator pedal and TAC module from a 1997-2004 Vette that match the PCM programming to use the stock throttle body.

NOTE: Since 1989, many GM fuel injection systems have incorporated a Vehicle Anti-Theft System (VATS) programmed into the stock EPROM or PCM. This means the engine will not run if it is transplanted into a vehicle without the original vehicle steering column and decoder module. 1998-2002 Camaro and Trans Am LS1 cars used a VATS system as an anti-theft device. If you have one of these engines and your computer has the factory programming, you need a Painless 64024 Vehicle Anti-Theft (VATS) defeat module, applicable to 1992 and up GM vehicles. Painless VATS computer chips allow you to bypass the factory programming, making the wiring in your engine swap a snap.




Gen IV LS Engines - LS2, LS3 (LS4)

Chevrolet Performance later produced the “Gen IV small-block,” which featured MPG-boosting cylinder deactivation. Gen IV also featured larger displacements compared to Gen III and re-engineered camshaft sensing. These were all great improvements for the LS engine family, making it a word-class engine. The Gen IV family includes the LS2, LS3, supercharged LS9, supercharged LSA, and the all-mighty LS7.

Roughly in 2003, GM upgraded the LS into its Gen IV configuration with a number of changes. The upgrades included a 58x crank trigger wheel with the cam sensor moved to the timing chain cover. A quick way to differentiate between a Gen III and Gen IV engines is by looking for the camshaft sensor at the back of the engine. On Gen III it is just behind the intake manifold. On Gen IV engines, the sensor was moved to the front of the engine. Gen III engines use cathedral port heads while later Gen IV engines employ larger, rectangular intake ports. Each configuration requires its own specific intake manifold although there are adapters available to bolt rectangle port intake to cathedral port cylinder heads.

Variable Valve Timing (VVT) became available with certain Gen IV engines, allowing an amazing 62 degrees of potential cam movement over the entire range of engine operation. Part of the Gen IV package included a faster and more powerful ECU that controls a hydraulic servo that advances or retard the cam based on engine speed and load (engines equipped with VVT). The ECU advances the cam at idle and low rpm engine operation to improve low-speed torque and throttle response. As rpm and load increase, the ECU will begin to retard the camshaft to enhance peak power.

Another step in the evolution of the LS was the integration of what GM calls Active Fuel Management (AFM) that is often been called displacement-on-demand. In the Gen IV version of AFM, four cylinders (1, 4, 6, and 7) are selected to be “dropped” during light load, highway cruising situations. This turns a 6.0L V8 essentially into a 3.0L V4 during AFM operation and the conversion in and out of AFM is seamless to the driver.

All LS engines use a composite intake manifold and there are several variations on this theme. Truck engines generally employ a taller manifold to accommodate longer runners that emphasize low-and mid-range torque for hauling heavy loads. Passenger car manifolds are much lower in profile with shorter runner lengths that offer more top-end power potential. In both cases, Gen III manifolds use three-bolt throttle bodies while the Gen IV versions use larger diameter four-bolt throttle bodies. As an example of size, the 1997 5.7L LS1 was fitted with a 75mm electronic throttle while it’s later and larger 6.2L cousin breathes through a 90mm throttle.



LS2 Engines

Introduced as Corvette's new base engine in 2005, the LS2 uses a different intake manifold and a larger 90mm throttle body. The LS2 block is compatible with LS1/LS6 or the high flowing and desirable L92 cylinder heads.

LS2 engines from 2005 Corvettes and 2005-2006 GTOs and Chevrolet SSRs with engine codes ZJA, ZJB, 5MC, YTA and 6MC all had 24X crank position sensor reluctor wheels. These LS2 engines can be operated with a Painless 60520 2005 GM LS2 Harness, along with an LS1 Corvette style accelerator pedal and TAC module.

LS2 engines in 2006 and later Corvettes were equipped with a 58X crank position sensor reluctor wheel. These engines can be operated with a Painless Performance 60524 2006-08 GM LS2/3/7 Throttle By Wire Harness, an E-38 ECM and 2006 and later Corvette accelerator pedal.



LS3 Engines

In 2008 the LS3 was the Corvette's new base engine, producing 430 hp @ 5,900rpm and 424 lb-ft @ 4,600 rpm. Other features included offset rocker arms, high flowing intake manifold, a slightly stronger block than the LS2 and larger injectors from the LS7 platform. The LS3 also used the highly desirable L92 cylinder heads and a more aggressive camshaft and revised valvetrain. The stock LS3 is fitted with a 2001 LS6 camshaft that is modified with more intake lobe lift. The LS3 block can use any head except for the LS7 and C5R.

LS3 engines in 2008 and later Corvettes were equipped with a 58X crank position sensor reluctor wheel. These engines can be operated with a Painless Performance 60524 2006-08 GM LS2/3/7 Throttle By Wire Harness, an E-38 ECM and 2006 and later Corvette accelerator pedal.



(LS4 Engines)

Steer clear of the LS4 as it is designed for transverse front-wheel-drive applications. Unless you're modifying a front-wheel-drive car, the LS4 platform is of little value to hot rodders looking for an engine swap, as it's difficult using it in anything but what it originally came in.



LS6 Engines

Originally only used in the high-performance C5 Corvette Z06 model, the LS6 was later used in the Cadillac CTS-V for two years before being replaced by the LS2. The initial LS6 in 2001 was rated at 385 bhp and 385 lb·ft, but the engine was modified the next year to produce 405 bhp and 400 lb·ft of torque. The LS6 is basically a high output LS1 engine with better heads. Key features are its higher compression ratio, sodium-filled hollow stem valves and revised oiling system. LS6 blocks can only use LS1, LS6 and LS2 heads because of their "small" (3.89 inches) bores. You can NOT use heads designed for larger engines as that will cause valve-to-block interference.

NOTE: The 2001-2004 LS6 Corvettes use a serial VATS system. The ECM and BCM use serial communication which is not defeatable by an add on VATS module. The best option on these is to use a different throttle body / ignition system or carburetor.

Where to look: 2001-2004 Chevrolet Corvette C5 Z06 and 2004-2005 Cadillac CTS-V.



LS7 Engines

The LS7...what an impressive normally aspirated engine with over 500 horsepower and not using a supercharger or turbocharger! These engines were hand-built by the General Motors Performance Build Center in Wixom, Michigan. The bad news? You're probably not going to find one of these in your local wrecking yard.

The LS7 was influenced by Corvette's Le Mans racing program and incorporated some serious race engineering in the engine's development. The block itself has larger sleeved cylinders with a longer stroke. The crankshaft and main bearing caps are forged steel for strength and the connecting rods are forged titanium with hypereutectic pistons. Heads feature Del West 2.20" titanium intake valves and 1.61" sodium-filled exhaust valves. The LS7 features a dry-sump oil system and CNC ported 12-degree head castings. The cylinder heads, with the larger valves, flow an incredible 370 cfm. LS7 blocks should be matched with heads designed for at least 4.10-inch bores; and 4.125-inch bores are preferred.

LS7 engines in 2006 and later Corvettes were equipped with a 58X crank position sensor reluctor wheel. These engines can be operated with a Painless Performance 60524 2006-08 GM LS2/3/7 Throttle By Wire Harness, an E-38 ECM and 2006 and later Corvette accelerator pedal.



LS9 Engines

Good luck finding a wrecked ZR1 Corvette at the wreckers! These factory supercharged engines are based on the LS3 block. Looking for an emissions-legal motor that pumps out around 600 horses, and will last for 100,000 miles? Buy this crate engine from GM Performance Parts at a price tag just north of 24K.

If a stock supercharged LS engine just isn't enough power for you, why not go all out and get an Edelbrock Supercharged LS 416 Crate Engine with an astounding 720 horsepower and 695 ft-lbs. of torque! 



How to Identify LS Ports


LS Truck Engines

These are some of the most affordable options for an LS engine. The major difference is that they are cast iron instead of aluminum. NOTE: All trucks manufactured with Gen III & IV engines have a serial anti-theft system. This serial anti-theft system is only defeatable through ECM reprogramming. You should plan on having the ECM re-flashed when installing this into your transplant vehicle.

But on a budget then the truck LS engines are a great option. You can purchase an aluminum or cast iron 5.3L or 4.8L LS for a reasonable amount of bucks. Install a cam and do a little head work and you’ll easily be making 400whp or more. If you’re planning on boosting your project the 4.8L truck engine will be perfect for you. The 4.8L can take insane amounts of boost completely stock and will really perform well.

If you don’t want a barebones 5.3L or 4.8L you could always step up to a 6.2L truck block which is based on the LS3 engine. With the larger displacement and slightly better cylinder heads, you can get your project in the neighbourhood of 500rwhp or more. 



LQ4 Engines

Based on the LS engine, this 6.0 Liter truck engine was designed to bridge the gap between the new LS small blocks and Big Blocks for the truck applications. The major difference in the LQ4 engine is that they are cast iron instead of aluminum. Bolting a set of LS6 heads to the iron block, the LQ4 was born. The 1999 and 2000 model year engines had cast iron heads with all other model years sporting the cast aluminum heads. The beefy iron block and the 4.000" cylinder bores that can accommodate the GM L92 heads, make for some serious horsepower at budget prices. For junkyard engine builds, these are a very desirable engine. The LQ4 and LQ9 are the most common Gen III LS blocks, and are very desirable due to the big bore and durable iron construction. Some have made 1,500+ HP on this block.

Where to look: 1999-2004: Chevrolet Express/GMC Savana, Chevrolet Silverado 2500, Chevrolet Suburban/GMC Yukon XL Denali, Hummer H2.



LQ9 Engines

Marketed as the Vortec HO 6000 and later as the Vortec Max, the LQ9 was a higher output version of the LQ4. Specially designed for the Cadillac line, the engine found it's way into GM's truck line as the Vortex Max in 2006. The main difference between a LQ4 6.0L and the more desirable LQ9 is the LQ9 has a high static compression ratio. The easiest way to differentiate them? The LQ9 uses a flat top piston while the LQ4 uses a dished piston. The LQ9 featured a bigger cam and higher compression flat top pistons for an extra 10 horses and 10 lb-ft output over the LQ4. Like it's predecessor, the LQ9 is a highly valued engine for budget rebuilds of stock engines that can be pushed to a higher horsepower level.

Where to look: 2002-2006 Cadillac Escalade, Cadillac Escalade EXT, 2003-2006 Cadillac Escalade ESV, 2003-2007 Chevrolet Silverado SS, 2004-2005 Chevrolet Silverado and GMC Sierra (Vortec HO Edition only), 2006-2007 Classic Chevrolet Silverado and GMC Sierra VortecMax Option.



LY6 Engines

Another cast-iron truck block, the LY6 is the replacement for the LQ4. Sharing the same bore and stroke as the LQ4, the LY6 added variable valve timing which makes the powerband a little broader. These engines came from the factory with the high flowing L92 heads and increased compression. They may be too new to readily find in the wrecking yards, but patience and a lot of searching could reward you with a stock 352 horsepower block.

Where to look: 2007 to present: Chevrolet Silverado HD, GMC Sierra HD, Chevrolet Suburban 3/4 ton, GMC Yukon XL 3/4 ton.



L76 Engines

Also referred to as the new Vortec Max, the L76 is often considered the replacement for the LQ9 engine. The L76 is an aluminum block version of the LY6 that incorporates features like variable cam phasing and active fuel management. Other differences include a higher compression ratio and bigger camshaft. A second version of the L76 was manufactured with an LS style intake for the Pontiac G8 GT which dropped the variable valve timing feature.

Where to look: 2007-2009: Chevrolet Suburban, Chevrolet Avalanche, Chevrolet Silverado, GMC Sierra, GMC Yukon XL and 2008-2009 Pontiac G8 GT.





LS Engines - Summary

Here’s the bottom line; the LS is cheap, light, compact, and makes a ton of horsepower. It can fit into nearly anything you want, and it can be done on a tight budget. From the average Joe to a professional racer, the LS engine is perfect for nearly anything. 

The easiest way to get your motor running is with something like FiTech’s Ultimate LS induction kit. FiTech has built a simple, short runner-length fabricated aluminum intake configured for both the 24x cathedral port (LS1, LS2) and the 58x rectangular port (LS3, L99) engines. FiTech calls it the Ultimate LS induction system and the base kit includes everything needed, including the intake manifold, throttle body, ECU, complete wiring harness, injectors (either 36 or 66 lb/hr), fuel rails, fuel hose, fittings, and nearly every sensor you’ll need to easily bolt the system onto an LS engine. This is great news for those with LS engines, either built or sourced from a salvage yard, who want an affordable way to get it running in their Chevy project.

The beauty of this approach is its simplicity. Once you’ve plugged in the wiring harness to the engine and powered it up, all that’s left is to input the engine size and your preference for idle speed, air/fuel ratios, timing, and a couple of other parameters and the engine is ready to run. It’s literally that easy.

Books to read before an LS Swap:




Products to help your LS Swap:

Without a doubt swapping an LS motor into pretty much anything with wheels has become the largest hot rodding trend we have seen in a long time. Performance Improvements has some of the top LS swap components that you are looking for to make it easy to get your motor running.



LS Swap Articles and Tech Tips:



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