Start with a junkyard 5.3
The iron LM7 and LY5 5.3 are cheap, everywhere, and take a cam, a tune and even moderate boost on stock internals. Most people's first swap should start here.
Plan your LS swap before you buy a single part.
Pick your car and your engine, then choose every part from mounts to boost. You get horsepower, torque, total cost and shop hours as you go, plus warnings when parts don't play well together.
Engines covered22
Swap platforms18
Build stages17
Cost to useFree
Build to a number
Tell us the power you want. We'll spec the parts.
Type a goal in plain words. We test the part combinations for your car, find the cheapest one that reaches your number without fitment problems, and load the full parts list below.
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Which LS engine should you swap?
Every common Gen III and Gen IV LS, from the $700 junkyard 4.8 to the supercharged LS9. Prices are rough used-market figures. Tap a row to drop that engine into your build.
| Engine | Size | Came in | Block | HP / TQ | Crank trigger | Used price | What to know |
|---|
Before you pull the old motor
The parts that kill swap budgets are rarely the engine. These are the calls that matter most.
Match 24x or 58x
Gen III engines (LS1, LM7, LQ4) use a 24-tooth crank reluctor. Most Gen IV engines (LS2, LS3, LY5, L92) use 58x. Your computer and harness must match the engine, or you need a converter.
Watch the hood line
Truck intakes sit tall. In a Miata, 240SX or RX-7 you'll usually want a car-style intake to clear the hood. The calculator flags this for you.
AFM engines need a delete for cams
Many 5.3, 6.0 and L99 engines have Active Fuel Management lifters. Running a performance cam means an AFM delete kit and a tune to shut it off.
Budget the boring parts
Mounts, oil pan, fuel pump, wiring, cooling and accessory brackets often add up to more than the engine. Price them first, then decide on power parts.
Size fuel for the power you want
Boost raises fuel demand fast. The calculator checks your injectors and pump against estimated power, so you buy the right size once.
LS swap questions
Short answers to the questions people ask before their first swap.
How much does an LS swap cost?
It depends mostly on the engine and how much work you do yourself. A junkyard 5.3 swap done at home can come in at a few thousand dollars before power upgrades. Shop labor, a fresh transmission and boost can push it well past $15,000. Use the calculator above to price your exact combination.
What is the best LS engine for boost?
Iron-block truck engines like the 5.3 LM7 and LY5 and the 6.0 LQ4 are the usual choice. They're cheap, the blocks are strong, and the lower compression handles boost well. The LS7 is a poor boost candidate on stock internals.
Can I keep my current transmission?
Often, yes. Adapters exist for common GM automatics like the TH350 and TH400 and some manuals, but you'll need the right flexplate, crank spacer or pilot bearing. Check the torque rating against your build; the calculator warns you if it's too low.
Will a 4L60E hold my build?
A healthy stock 4L60E is generally considered good for roughly 350 to 400 lb-ft. Past that, people move to a built 4L60E, a 4L80E or a 6L80E. The calculator flags builds that exceed the transmission you picked.
Do I need a tune?
Yes, once you change the cam, injectors, intake or add boost. A stock engine in a new car still needs its computer set up for the swap, for example to turn off the anti-theft system and set transmission settings.
What's the difference between Gen III and Gen IV?
Gen IV engines (2005 and later, starting with the LS2) moved to a 58x crank trigger, a rear-mounted cam sensor, and on many trucks, AFM and variable valve timing. Parts like heads and intakes often interchange, but the electronics don't.
Ask a fitment question
Not sure something fits? Send it in. Answers go to your email, and good questions become guides on this site.