Short Block vs Long Block vs Crate Engine — What's the Difference?
If you are shopping for an AMG engine build, you have probably seen three terms: short block, long block, and crate engine. They describe different levels of engine assembly — and choosing the right one depends on the condition of your current engine, your budget, and your power goals. This guide breaks down exactly what each one includes, when to choose it, and how they compare.
Quick Comparison
| Build Level | What's Included | You Supply | Best For |
|---|---|---|---|
| Short Block | Block, crankshaft, connecting rods, pistons, bearings, internal seals | Cylinder heads, intake, exhaust, turbos, accessories, wiring | Healthy heads, bottom end needs rebuild |
| Long Block | Short block + cylinder heads (fully assembled) | Intake, exhaust, turbos, accessories, wiring | Complete internal engine replacement |
| Crate Engine | Same as long block — complete assembled engine | Turbos, accessories, wiring (bolt-on items) | Turn-key drop-in, fastest path to power |
Note: In AMG engine builds, "long block" and "crate engine" are used interchangeably. Both refer to a complete assembled engine — block, rotating assembly, and cylinder heads — ready for your accessories.
Short Block — The Bottom End
A short block is the engine's lower half: the block casting, crankshaft, connecting rods, pistons, bearings, and all internal gaskets and seals. It does not include cylinder heads.
Choose a short block when:
- Your cylinder heads are in good condition — no cracks, warping, or excessive wear
- Your bottom end has failed — spun bearing, cracked piston, worn cylinders
- You want forged internals but want to save cost by reusing your heads
- You plan to pair with separately purchased CNC-ported heads
At YPG Motorsport, our forged short blocks use a billet crankshaft, 4340 H-beam connecting rods, and forged pistons — balanced and blueprinted to race tolerances. Available for the M156 6.2L V8, M177 4.0L twin-turbo, and M178 4.0L dry-sump.
Long Block / Crate Engine — The Complete Engine
A long block adds cylinder heads to the short block — giving you a complete, fully assembled engine. In the AMG performance world, this is commonly called a crate engine: an engine that arrives ready to install. You bolt on your turbochargers (on M177/M178), intake, exhaust manifolds, accessories, and wiring harness.
Choose a crate engine when:
- Both your bottom end and heads need work
- You want the fastest path from stock to race-ready
- You are swapping a complete engine (failed motor, track build, engine swap project)
- You want everything assembled, tested, and ready to drop in
Our crate engines include forged short block + CNC-ported heads with upgraded valvetrain — the full package. Available for the M156, M177, and M178.
Ported Heads — The Third Option
Not every build needs a complete short block or crate engine. If your bottom end is strong but your heads are tired or restrictive, you can order CNC-ported cylinder heads separately. Our ported heads are flow-bench validated, assembled with upgraded valves, springs, and titanium retainers, and sold as a matched pair. Available for the M177 and M178 as well.
Cost Comparison
In general terms across the AMG engine build market:
- Short block — lowest cost. You save money by reusing your heads, but you need a qualified shop to assemble the top end.
- Ported heads (pair) — mid-range standalone purchase. Can be combined with a short block for a DIY long block.
- Crate engine — highest cost, but you get a complete, assembled, tested engine with no assembly risk.
For a detailed breakdown of what AMG engine builds cost in 2026, read our AMG Engine Build Cost Guide.
Which AMG Engines Do We Build?
| Engine | Displacement | Type | Found In |
|---|---|---|---|
| M156 | 6.2L | Naturally aspirated V8 | C63 W204, SLS AMG, CLK63, C63 Black Series |
| M177 | 4.0L | Twin-turbo V8 (wet sump) | C63 W205, E63 W213, GT63, GLC63, GLE63 |
| M178 | 4.0L | Twin-turbo V8 (dry sump) | AMG GT, GTS, GTR, GT R Pro, GT Black Series |
All Builds Include
- Forged internals — billet crankshaft, 4340 H-beam rods, forged pistons
- Race-spec bearing clearances, balanced rotating assembly
- 1,500 HP+ capability with forced induction
- No core exchange required
- 7–21 day build time
- FedEx / DHL shipping worldwide to your door
- Race / off-road application
How to Order
Browse our AMG Engine Builds collection or contact us at sales@ypgmotorsport.com with your vehicle, current engine condition, and power goals. We will recommend the right build level for your project.
Frequently Asked Questions
Is a long block the same as a crate engine?
In AMG engine builds, yes. Both terms refer to a complete assembled engine — block, rotating assembly, and cylinder heads. The terms are used interchangeably.
Can I build a crate engine by ordering a short block and ported heads separately?
Technically yes — a short block plus ported heads equals a long block. However, you will need a qualified shop to assemble the top end. Our crate engine includes full assembly, so you get a tested, ready-to-install unit.
Do I need forged internals?
If you are adding forced induction or pushing beyond factory power levels, forged internals are essential. Stock cast pistons and powder-metal rods are not designed for elevated cylinder pressures.
Do you require a core exchange?
No. All YPG engine builds are assembled fresh. No core needed.
Which build level is right for me?
Contact us with your vehicle details and goals. We will assess your current engine condition and recommend the most cost-effective path to your power target.