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Short Block vs. Long Block: Which One Is Right For You?

Posted by IAG Performance on Mar 1st 2024

Short Block vs. Long Block: Which One Is Right For You?

There are a lot of factors to consider when choosing between a short block and a long block. It’s not just about the price tag- factors like your own mechanical ability and the types of components you’re wanting to include in your build will also play a part in the decision making process. In this article, we’ll go into depth about the differences and advantages of each option. Not sure what a short block is, much less a long block? Don’t sweat it, we’ll start from square one.

Photo of uninstalled bare block.


The difference between a bare block, a short block and a long block refers to how complete they are. Starting with the bare essentials is the bare block. A bare block is as pared down as an engine gets, it is literally just the engine block all by itself. This means no pistons, no rods, no crankshaft. If you’re starting your build with a bare block, chances are you’re one of those mechanically inclined types that doesn’t shy away from a challenge. While a bare block allows you complete control over your choice of internal components, it also means you’ll be building from scratch.

From oil filters to engine blocks, we have everything you need to rebuild or maintain your Subaru engine-


The next step up is the short block, which is made up of an engine block that is outfitted with the crankshaft, connecting rods and pistons. A big advantage of starting a build with a short block is that there is a lot of opportunity to incorporate some upgrades that are capable of handling increased power. While you’re able to purchase a short block direct from the factory complete with OEM components, it’s definitely worth checking out short block options that are set up for higher performance applications.

IAG Performance has a great selection of engine build options, click here-

Photo of COBB short block.
Photo of IAG short block being build by technician.


Where Subaru is concerned, we think we’ve pretty much nailed the perfect short block. Taking into account all the common failure points of the factory short blocks, we’ve built a series of blocks to accommodate a range of high-horsepower applications. From forged JE pistons to structurally optimized rods and stronger bearings, our specialty short blocks provide a solid foundation on which to build from.

Click here for cylinder heads and parts for your next build-


A short block is a great option if you already have a good set of cylinder heads to dedicate to your build, or you want to customize your engine to better suit your specific needs. Keep in mind that you’ll still need to have a fair amount of mechanical experience to finish out your build, but you won’t be starting from scratch like you would with a bare block. Our own IAG short blocks come pre-assembled and ready to install, making it easy to upgrade your Subaru engine.

Click here to check out our turbo and supercharger upgrades-

Photo of IAG short block, uninstalled.
Photo of IAG long block, uninstalled.


Engine upgrades take time, that is, unless you go for a long block. Long blocks include everything the short blocks have; an engine block, crankshaft, connecting rods and pistons, but they don’t stop there. They also come with the cylinder heads, camshafts, and valvetrain components, all installed and ready to drop into your engine bay. While most professional long block builders do not allow for much in the way of customization, IAG offers high-flow oil pumps and closed deck blocks, just to name a couple optional upgrades.

Take a look at our long blocks and upgrade options here-


A long block is ideal if you don’t have the necessary tooling to rebuild your own long block, or you just don’t have the time to take on a big project. The IAG long blocks for Subaru make it especially easy to change out your engine in no time at all; just drop in the new long block and swap over your manifolds. To make it even easier, IAG now offers timing kits and timing kit installation for a truly straightforward engine swap. Best of all, since we don’t require a core, you can recoup some of your investment by selling off your original long block.

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Photo of IAG long block, uninstalled.
Photo of IAG long block and short block.


So, which one is right for you? Budget can be a big factor; a short block is a pretty good deal if you have the time and skills to finish out the build. A long block is a bigger investment right off the bat, but can actually end up saving you money on upgraded internal components if you take advantage of a discounted price package. Of course, as previously mentioned, things like tooling, mechanical expertise and time constraints will also play a part. Lastly, whether you’re going for a short or long block, you’ll want to make sure to choose one that will get you into the power range you’re looking for.

IAG Performance has everything you need to maintain your Subaru engine, click here-

Of course, if you’re still uncertain about which option is best for your project or if you have any questions about your next build or swap, don’t hesitate to reach out to us at 1(410)840-3555 or send us an email at Our team of experts is here to assist you every step of the way, we’re always happy to help!

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