What’s the difference between short and long block engines?
Most replacement engines can be ordered as short or long blocks. Despite their labels, both engine types are similar in size. They only differ in the components they carry. A short block package typically includes the engine block, crank and pistons. It is called a short block because it has a shorter list of components and usually comes with a shorter warranty. A long block engine has all the parts of the short block package. To the skeleton that is the short block, it adds a cylinder head, camshaft and valve-train.
A "turn-key" or crate engine is a fully assembled engine that is 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 bits and pieces.
If you need a new engine, you can either buy a drop-in from your car manufacturer or get one from an automotive machine shop. Sourcing from an independent shop or dealer can save you money and potentially get you more extended warranty coverage. If you buy your engine from an independent dealer, you will need to know what is included in a short block vs. long block engine package so you do not end up with unnecessary replacements.
Short Block Engine
A short block 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. Because there are usually slight variations in the packages that companies dealing in automotive parts offer, some short blocks may come with camshafts and timing belts. All short blocks require additional parts such as gaskets, cylinder heads, and oil pumps which have to be purchased separately.
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, valve-train, and cylinder head. A long block may also come with an oil pan and valve covers. It is 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 package. It does not include, among other parts, the fuel system, intake and 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.
A short block engine is usually cheaper than its long block counterpart. As of 2018, a long block engine cost anything between $1,500 and $5,000. The price difference depends on the make, model and year of the car for which the engine is designed.
However, a short block requires the purchase of additional components which come as standard equipment on the long block. It also needs more installation time because of all the parts that have to be fitted. When you factor in the additional components required and labor costs, the long block usually turns out to be a better bargain.
Warranties on long blocks are usually longer and more extensive 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.
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 that come with a long block wear out evenly and, consequently, 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 to be installed 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 engine if the major internal parts of your old engine have been damaged beyond repair but other external parts are functional. If these parts are damaged as well, and the total cost of purchasing the short block and additional components approaches the cost of buying a long block, consider getting a long block 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 make a purchase, get and compare quotes for both short and long block engines from multiple dealers. The quotes should include the specifications of each engine type and the estimated installation costs.
As a rule, you should get an extensive diagnostic test 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 the engine failed due to overheating, for example, it is possible that the fan relay and sensors for coolant temperature are defective. Until you fix this primary problem, you risk getting stuck with another seized engine.