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The GM/Chevy LS Series of engines are a popular donor for swaps in muscle cars, trucks, street rods, and racecars. With so many available on the used market, these cheap LS motors provide affordable options with healthy horsepower and modern performance. It is important to learn as much as possible when preparing for a junkyard LS build. Below are answers to the most common questions about LS engine builds to transport your powerplant from the junkyard to your mean machine:
How to Build a Junkyard LS Motor / How to Build an LS Engine
With the GM LS-Series family of engines in widespread use for over 20 years there is a large supply of engines to choose from for your next junkyard LS build. When hunting, as with any other used engine, be sure to communicate with the owner all of the known history and if it ran well to avoid potential problems and costly repairs before purchasing. A warranty agreement would also be helpful.
The most abundant and lowest-priced LS engines are the 4.8-liter and 5.3-liter version found in Chevy / GMC trucks and SUVs from 1999 to 2013. If you’re looking for a cheap LS build, these engines are the best candidate. The only exception is the LS4 (made from 2004-2009), which was used in front-wheel drive cars and has a shorter crankshaft. This configuration can cause engine swap problems for belt-driven accessories and flexplate/flywheel spacing to the transmission components.
The 4.8 and 5.3 engines look identical externally, so do your homework on the vehicle providing the engine. This can be done using the eighth VIN digit or engine RPO code from the vehicle build sheet (if available) to confirm which motor you are looking at. Otherwise, you will have to use a borescope through the spark plug hole to identify and confirm the difference. If the piston tops are flat, it is the 4.8-liter engine; if the piston tops have a slight dish, it is a 5.3-liter motor.
Both engines provided factory output between 270-320 horsepower and torque from 315-340 foot-pounds over the years, making them very similar in potential for junkyard LS options. Once you have selected your engine, you can begin the build. The first decision to consider is how the engine is going to be controlled. One option is to retain all of the original engine wiring, computer controller, sensors, and everything else needed for the engine to run, including a matching transmission. With this option, the engine essentially does not know that it has been transplanted into a different vehicle.
However, most of the time, all of the wiring has been cut around the engine and matching components are not included. If this is the case, there are two options for engine control: carburetion or an aftermarket fuel injection computer. JEGS offers a large selection of carbureted intake manifolds and kits to complete this carb conversion. An ignition controller will also be required to tell the individual coil packs when to fire. A 600-650 CFM carburetor is ideal for the 4.8-5.3 liter engines to complete the setup. To keep fuel injection, you will need a fuel injection kit to manage ignition and fuel.
Most Popular LS Engines
Many of these kits will include a fuel pump with the correct pressure required to run the fuel system. Otherwise, be sure to buy one separately. If you would like to boost horsepower on your 4.8/5.3 engine, the best option is a camshaft swap, which amazingly can provide up to 100 additional horsepower. Another option, which would provide “horsepower-on-demand”, is a nitrous system limited to 100 horsepower or less to prevent engine damage. Make sure it is designed to work either with your carburetor or fuel injection setup. Also, retard ignition timing between 2-4 degrees when in use, depending on the horsepower setting you have.
Upgrading rocker arms, fuel, air induction, exhaust, and other parts can make additional horsepower. Improving beyond the mentioned components requires changes to the LS engine block, cylinder heads, and rotating assembly. Once the engine has been built, it needs to be adapted to your vehicle. One part you most likely will need to change on the engine to fit your vehicle chassis is the oil pan. JEGS offers a large selection of LS swap oil pans to help you fit your LS engine under the hood. LS swap motor mounts also will be required. A JEGS technical specialist can help you with any questions you have on your junkyard LS build.
Where to Buy Used LS Engines
There are several options for locating a used LS engine. The first is locally at a salvage yard. Finding a LS engine in a wrecked vehicle that did not sustain damage to the engine bay would be one possible source. Keep in mind and communicate with the salvage yard the engines running condition, mileage, and any other important information before making a decision on purchasing. Another option is a local newspaper or online advertisement from either an engine seller or a private seller. Again, ask the same questions before making a purchase. You can also research online vehicle owner’s forums for the engine you are looking for.
What is the Best LS Engine to Build?
The answer to this question depends on the application the engine will be used for. If you are looking for a stock engine, without any modifications, nearly any of the LS engines will be a good candidate. If you are looking for the lowest cost LS engine to build, the 4.8 and 5.3-liter platforms will meet your needs. If you are looking to modify an engine, you will need to decide or prepare for engines that have variable valve timing, active fuel management / displacement on demand. These engine systems reduce the ability to modify the engine camshaft and other components. They can be disabled or removed however, either through software programming and physical part removal. While looking for an ideal LS engine build, there are some engines with known problems that you should be aware of. Based on research, avoid cylinder heads with a casting number “706” from 2001-2006 5.3 liter engines. Many (not all as different manufacturers cast them) of these cylinder heads fail due to leaking through a defect in the actual casting (which is porous) around the oil drains in the cylinder heads. This issue is not repairable. Also note that LS1 engine blocks are only compatible with LS1, LS2, and LS6 cylinder heads. Using heads designed for larger engine will cause valve-to-block interference. Another concern to look for or avoid is with early LS engines (prior to 2005) that have “piston slap” when the engine is cold that goes away when it warms up. The reasoning cited involves the heat cycling of the hypereutectic pistons and possible defective piston rings during warm-up. A leak-down test can help to detect issues caused by bad piston ring seals. A machine shop can confirm cylinder bore size and resolve any issues. This can be done by repairing the cylinder walls in the block and installing matching pistons to the repaired bores as a solution for piston slap. In the end, the most common factors that will anchor your decision on the best LS engine build will be availability, price, and horsepower / torque output to fit your budget and needs.
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Most Popular LS Engine Camshafts
