A complete LS swap kit includes the engine block, cylinder head, intake manifold, and engine bay brackets, but not transmission, cooling, or fuel system parts
An LS engine swap kit is a bundle of the core engine components needed to drop an LS-series V8 into a vehicle that didn't come with one. The kit typically contains the long-block engine (block, crankshaft, pistons, rods, and cylinder head), engine mounts or brackets designed for your specific vehicle, and sometimes an intake manifold. What it does not include — and what catches most buyers off guard — is the transmission, radiator, fuel injectors, wiring harness, or any of the systems that connect the engine to the rest of the car.
The reason kits are sold this way is that what you need beyond the engine depends entirely on what vehicle you're putting it in and what transmission you want to use. A 1967 Chevelle needs different mounts than a 1982 Camaro. A street car needs different cooling than a race car. Selling a truly "complete" kit would mean selling dozens of different kits, so vendors instead sell the engine and the brackets, and leave the rest to you.
Key Takeaways
- A complete LS kit includes the engine block, heads, and intake manifold, but transmission, cooling system, and fuel system are separate purchases.
- Engine mounts or brackets are usually included, but you need to verify they fit your specific vehicle year and model before ordering.
- You will need to source or adapt a radiator, water pump, alternator, power steering pump, and air conditioning compressor separately.
- Wiring, fuel injectors, fuel pump, and engine control computer are not in the kit and must be purchased or sourced from a donor vehicle.
- Total cost for all supporting systems typically equals or exceeds the cost of the engine kit itself.
What the Engine Kit Actually Contains
The engine block comes as a long-block or short-block, depending on the kit. A long-block includes the cylinder head, intake manifold, valve covers, and sometimes the oil pan. A short-block is just the block, crankshaft, pistons, and rods — you add the heads and manifold yourself. Most complete kits sold as "turnkey" or "ready to run" are long-blocks, which means less assembly work on your end.
The kit will include engine mounts or a motor plate (a bracket that bolts to the block and then to your car's frame). These are vehicle-specific — a kit for a Chevy S10 has different mounts than one for a Pontiac Firebird. Before you buy, confirm the kit lists your exact vehicle year and model. If it doesn't, you may need to buy mounts separately or have them fabricated.
Some kits include a basic intake manifold, though it may be a single-plane or dual-plane design that works for street or strip use, not both. Fuel rails and injectors are rarely included; you'll buy those based on your fuel system choice.
Cooling System Parts You Must Buy Separately
The engine block and heads come bare — no radiator, water pump, thermostat housing, or hoses. You need to source or buy a radiator sized for an LS engine in your vehicle. A radiator that worked for your car's original engine is usually too small; an LS runs hotter and moves more coolant. Many swap shops sell radiators pre-sized for popular swap combinations (LS into a Camaro, LS into a Miata, and so on), or you can have one custom-built.
The water pump bolts to the front of the block. Some LS blocks use a mechanical pump; newer ones use an electric pump. The kit engine will have the correct mounting surface, but you buy the pump itself. You'll also need a thermostat, housing, and bypass fittings — these are inexpensive but straightforward to overlook.
Hoses, clamps, and coolant lines are not in the kit. You can buy universal hose kits or have them made to fit your engine bay layout. Budget time here; hose routing is one of the last things you finalize, after everything else is mounted.
Fuel System Components Not Included in the Kit
The engine block has no fuel injectors, fuel rails, or fuel pump. You choose these based on how much power you want and what fuel pressure your engine management system requires. A carbureted LS (rare but possible) needs a mechanical fuel pump. A fuel-injected LS needs an electric pump in the tank, a fuel pressure regulator, and injectors matched to your engine's displacement and target horsepower.
If you're using a donor fuel tank from the original vehicle, it may not have the right pump or the right mounting point for an LS fuel pump module. Many swap builders install a new fuel tank or retrofit the old one with an LS-compatible pump module. This is not a small job — it involves dropping the tank, cutting or welding, and testing for leaks.
Fuel lines from the tank to the engine are not in the kit. You'll run new lines (usually -6 or -8 AN hose) from the tank to a fuel filter, then to the fuel pump and injectors. This is a safety-critical system; do not improvise or reuse old rubber fuel line.
Wiring, Computer, and Engine Management
The engine block has no wiring harness, no engine control unit (ECU), and no sensors. Modern LS engines need a computer to run — you can't bolt one to a carburetor and call it done. You have three paths: use the original LS computer and harness from a donor vehicle, buy a standalone engine management system (Holley, MSD, or similar), or use a plug-and-play harness designed for your swap.
A plug-and-play harness is the easiest route if one exists for your vehicle. Companies like Painless Wiring and Lokar sell harnesses that connect the LS engine to your car's original dashboard and electrical system. They cost more than a bare harness but save weeks of troubleshooting. If no plug-and-play harness exists for your car, you're either fabricating a custom harness or going standalone.
Sensors — oxygen sensors, coolant temperature, intake air temperature, throttle position — are not in the kit. Some come with the engine block if it was pulled from a running vehicle, but you should not count on it. Budget for a full sensor set and plan to test each one before you start the engine.
Transmission and Driveline You Must Source Separately
The kit is an engine only. You need a transmission, and it must be compatible with the LS bell housing. Most LS engines use a LS1 bell housing (for T56 manual or 4L60E automatic transmissions) or an LS9 bell housing (for different automatics). Some newer LS variants use different housings. Confirm which bell housing your kit engine has, then buy a transmission that matches.
If you're keeping your car's original transmission, you may need an adapter plate to bolt it to the LS bell housing. Adapter plates exist for many combinations (LS to Turbo 350, LS to Muncie, and so on), but not all. Research whether an adapter exists before you commit to keeping the original transmission.
You'll also need a driveshaft, which may need to be shortened, lengthened, or rebalanced depending on where the engine sits in your car. This is not a DIY job; take it to a driveshaft shop and bring the car or detailed measurements.
Accessories and Ancillary Systems
The engine block has no alternator, power steering pump, air conditioning compressor, or serpentine belt. You buy these based on what you want the car to have. A street car needs all three; a race car might skip power steering and air conditioning to save weight and complexity. These are bolt-on purchases, but you need the right brackets and pulleys for your engine and accessories.
Exhaust manifolds or headers are not in the kit. You'll buy headers designed for your engine and your vehicle, or you'll have custom manifolds made. This is one of the last things you install, after the engine is mounted and you can see exactly where the pipes need to go.
Engine oil, coolant, and other fluids are not in the kit. You'll need the correct oil weight for your LS variant (usually 5W-30 or 10W-30), the right coolant type, and brake fluid if you're upgrading the brake system to handle the car's new power.
Frequently Asked Questions
Do I need to buy a new radiator, or can I use the one from my car?
Your original radiator is almost always too small. An LS engine produces more heat and moves more coolant than most engines it replaces. You can try it as a temporary test fit, but plan to buy or build a larger radiator before you drive the car regularly. Many swap shops sell radiators pre-sized for popular combinations.
Can I use my car's original transmission with an LS engine?
Maybe. It depends on what transmission you have and whether an adapter plate exists for that combination. Research your specific transmission before you buy the kit. Some adapters are readily available; others don't exist or are unreliable. If no adapter exists, you'll need to buy a transmission compatible with the LS bell housing.
What if the engine kit doesn't list my vehicle?
The mounts may not fit, or they may need modification. Contact the kit seller and ask whether the mounts are the same as a listed vehicle, or whether custom mounts are available. If neither is true, you may need to have mounts fabricated by a machine shop or welding shop, which adds cost and time.
Is a standalone engine management system cheaper than a plug-and-play harness?
Not usually. A standalone system (Holley Terminator, MSD, or similar) costs $1,500 to $3,000 and requires tuning. A plug-and-play harness costs $800 to $1,500 and works out of the box if one exists for your car. If no plug-and-play harness exists, standalone is your main option.
What's the difference between a long-block and short-block kit?
A long-block includes the cylinder head and intake manifold; a short-block is just the block, crankshaft, and pistons. Long-block kits require less assembly and are usually sold as "complete" or "turnkey." Short-block kits are cheaper but require you to source and install heads and manifold yourself, which is more work and more cost.