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Advantages of Longblocks over Complete Engines

When researching an engine rebuild it can be confusing wading through industry lingo and technical jargon. This article should help clear up the differences between short blocks, long blocks, complete engines crate engines and what option is best for your situation.

Short Blocks –

Caterpillar Short BlockShort Blocks are a non-running engine. They consist of an engine block, crankshaft and connecting rods. A short block however does not consist of a cylinder head, liners, gaskets, rings a timed gear-train or any kind of ancillary parts including the fuel system.

Advantages: Short blocks are great for customers who have a non-cracked cylinder head but an un-useable crankshaft. Usually when a crankshaft spins a bearing the entire engine seizes up also ruining the head. Customers with a workable head can save a great deal of time and money just opting for a new block/crankshaft combo.

Disadvantages:Usually short-blocks requests are rare because the customer’s cylinder head is also un-useable. When remanufacturing an engine it might be best just to have the cylinder head work done as well. A new ported head machined back to OEM spec can be a great way to add life to an existing engine. Another disadvantage of a short-block could also be the labor costs. A mechanic will ultimately have to reassemble the engine regardless if it is a short block or a long block which includes re-configuring the old cylinder head. The labor costs to reassemble the engine will be more than a long block or complete engine without the added advantage of a new cylinder head.

Long Blocks –

A long block is a more complete version of a short block. A long block is still a non-running engine but contains more parts than a short block. The biggest difference between a short block and a long block is the inclusion of the cylinder head. A long block will typically include:

• Cylinder Block
• Complete Loaded Cylinder Head
• Crankshaft
• Camshaft
• Followers/Lifters
• Pistons
• Liners
• Rings
• Connecting Rods
• Intermediate Cover
• Timed Front Gear Group

Caterpillar 3306 Reman Longblock Engine Caterpillar 3306 Reman Longblock Engine

Depending on the rebuilder, some long-block engines will include injectors often called a 7/8 engine. It is always advised to get a build sheet before purchasing just so you are completely aware of what you are getting.

Advantages: Long-block engines are perfect for customers looking save some money but wanting the most complete internal gear-train. A remanufactured long-block engine can be as much as 50%-70% cheaper than a complete drop in option from a dealer. Other advantages of a long-block engine include less complications during installation. A longblock is built to the exact engine serial number of the engine being replaced. The flywheel and flywheel housing are already an exact match so that bolting up the engine to transmission will work every time. Longblocks are also built to accommodate the exact fuel system. Some blocks are built for inline fuel systems while others are built for rotary style fuel pumps. With a long-block all someone would have to swap over from the old engine is the water pump, oil pump, turbo, fuel system and ancillary parts such as accessory mounts. It is cheaper on the parts and labor side than a complete engine.

• Upfront Pricing
• Save money re-using good working ancillary components
• Built exactly to engine serial number
• Swap over perfect fitting ancillary components
• Perfect fit every time
• Shorter Lead Time
• More simplistic warranty terms

Disadvantages:The disadvantages to long-blocks engines are few and far between. For those looking to get back to work or on the road as quickly as possible, a long-block will require more labor than a drop-in complete engine. Long-blocks engines warranties also only cover the hard-internal parts of the engine and do not include failures to the ancillary parts which means if your injectors fail they are not covered by the builder.

Complete Engines –

A complete engine is just like it sounds… “fan to flywheel” drop in ready to go. A complete engine includes all of your hard internal parts as well as the fuel system, turbo, pumps, housings and oil pan. A complete engine can be bolted up and attached to the transmission rather quickly and requires no additional labor to work on the engine.

Mack MP7 Remanufactured Engine Mack MP7 Complete Remanufactured Engine

Advantages: A complete drop-in option built to the exact serial number and arrangement number will be the quickest way to get back on the road. Lead time can be a matter of days vs. 2 weeks or more with a remanufactured longblock. Complete engines usually are dyno tested and come with a complete warranty on the entire unit.

Disadvantages: The price of a complete drop-in from the dealer will cost considerably more than a longblock option; sometimes double the price. Complete engines (crate engines) not build to a specific serial number sometimes may not be a 100% exact fit. Some customers will look to swap in a different model or higher horsepower unit but not expect the intensive labor costs associated of not doing a like-for-like swap. Many times complete engine swaps will require different motor mounts, work to upgrade the suspension, axles as well as configuring the ECM of the truck to work with the ECM of the new engine. Compatibility is important when doing engine swaps.

All three options will get you back to work again however it is wise to research the long-term pros and cons of doing each. Overall, the thing to keep in mind when researching replacement engine options is whether lead time or cost more important.