Despite their names, both engine types are similar in size. They only differ in the components they carry. A short block engine package typically includes the engine block, crank, and pistons. The term short block originates from the engine's shorter list of components and usually comes with a shorter warranty.
A long block engine includes all of the parts of the short block package with the addition of a cylinder head, camshaft, and valve-train.
Most aftermarket and replacement engines can be ordered as short blocks or long blocks. But there are numerous other factors that could affect which type of engine to go for in a specific vehicle — and for a specific budget.
A turn-key or crate engine is a fully assembled engine usually shipped from the manufacturer to the installer in a crate. All the installer has to do is fit it into a vehicle, turn the key, and drive off. In addition to the parts that come with a long block, a turn-key engine package usually includes a throttle pedal, spark plugs, airflow sensors, and other various bits and pieces.
If you require a new engine, you can either buy a complete drop-in engine from a manufacturer or get one from an automotive machine shop. Sourcing from an independent shop or dealer can save you money and potentially get you longer extended warranty coverage. If you buy your engine from an independent dealer, you will need to know what is included in a short block versus a long block engine package, so you do not end up with unnecessary replacements.
Short Block Engine
A short block engine is the bottom end of a vehicle's engine. It includes the cylinder block and a few other critical parts of the engine, such as the crankshaft, cam pistons, and connecting rods. These pieces are also known as the rotating assembly. Because there are usually slight variations in engine builder companies' packages, some short blocks may come with camshafts and timing belts. All short block engines require additional parts such as gaskets, cylinder heads, and oil pumps which have to be purchased separately.
Short block engines are ideal for individuals who desire to learn the engine building process on their own. Building a short block engine is a great learning experience and provides a more involved and hands-on approach to engine replacement.
Long Block Engine
A long block engine is, in a sense, a complete version of a short block. In addition to the assembled block, it features a camshaft, lifters, valve-train, and cylinder head. A long block may also come with an oil pan, water pump, and valve covers. Long blocks are usually used when diagnostics indicate that a vehicle needs an engine overhaul.
Despite having more components than a short block, a long block engine is not a complete engine package. A long block does not include, among other parts, the fuel system, intake manifold, exhaust manifolds, or electrical components. If you need to replace these components or every other part of the engine assembly, consider ordering a "turn-key" engine.
Some people confuse short block and long block engines with small block and big block engines or refer to them interchangeably. There are significant differences between these terms, starting with the classification of small block or big block engines is a description of engine size. Short block or long block refers to the number of assembly parts included.
A short block engine is usually cheaper than its long block counterpart. As of 2021, a long block engine costs anything between $1,500 and $5,000, while short block prices are around $1,000 to $3,000. The price difference also depends on the make, model, and year of the car the engine is designed for.
However, a short block engine requires purchasing additional components that come as standard equipment on the long block. A short block also requires extra installation time because of all the parts that have to be fitted. When you factor in the additional components needed and labor costs, the long block usually becomes a better bargain.
Warranties on long blocks are usually longer and more comprehensive than those on short block engines. Since warranties only cover the parts included in the original purchase, the additional components installed on a short block are not covered. Warranties for either engine type do not cover issues arising from faulty fittings, so consider hiring a professional mechanic to do the engine installation.
Any additional parts needed for a short block can be purchased with a separate warranty depending on the company you are buying from. However, if you buy a short block engine, comprehend the parts warranty and any installation warranty a mechanic may offer to guarantee their work.
Choosing the Right Engine Block
Generally, a long block engine offers better and more reliable performance than a short block engine. Since long blocks come with more parts preinstalled, they are less likely to malfunction due to faults in the fitting process. Additionally, the components included with a long block wear out evenly and minimize replacement costs.
As with other sub-assembled auto parts, not all long blocks will work well with the make and model of your vehicle. To match the performance of the stock engine, you have to ensure the long block that you are installing is compatible with the electronic control unit and the transmission system of your car.
On the other hand, a short block engine gives you more choice over the range of external parts you can install. You can expect a short block to perform better than a long block if you invest in quality parts and accessories. Consider, for example, cylinder head assembly, which directly affects the engine's horsepower output. Unlike a long block, a short block does not come with a preinstalled cylinder head. It gives you the freedom to choose whichever head fits the performance you would like. A great head on a great short block can produce more power than a stock engine.
Consider going for a short block over a remanufactured engine if the significant internal parts of the old unit have been damaged beyond repair, but other external parts are functional. If these pieces are damaged, and the total cost of purchasing the short block and additional components approach the cost of buying a long block, consider getting a long block for your engine swap instead.
Knowing what comes with a short block versus a long block engine package can help you find the perfect fit for your car. Before you purchase, acquire and compare quotes for both short and long block engines from multiple dealers. The quotes you receive should include the specifications of each engine type and the estimated installation costs.
It would be best always to get an extensive diagnostic test done on the faulty engine to avoid needless replacements in the future. Understand why your engine failed in the first place, then have a professional mechanic fix the problem when he or she replaces the engine. If you experience engine failure due to overheating, the fan relay and sensors for coolant temperature may be defective. Until you fix this primary problem, you risk getting stuck with another seized engine instead of fixing your original problem.