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Focus ST OEM Short Block vs. Built Motor

October 11th, 2023 | 3 min read

By JP Alonso

Most days around here, someone asks us something about putting a built motor in their Focus ST. Generally, those interested are in two different categories: either they're planning for the future or they're reacting to a failure, the latter being pretty darn inconvenient.

You're reading this because you're interested in improving the performance of your Focus ST engine, or trying to get the performance back in it. When you push the boundaries of performance, things fail. Shoot, sometimes things fail regardless. Fortunately, it's rare to see an untuned, unmolested car have an engine failure, but it does happen in a variety of platforms, and for no good reason.

In the case of the Focus ST engine, you get pretty lucky, the OEM engine can take quite a beating! But there are limits. 400whp is reliably achievable, however, the way you drive changes the "reliably" in that scenario. A 400whp Focus ST can last a long time, as long as it is well maintained and mildly street driven.


If you are building your engine, high quality off the shelf engine parts to reinforce the Focus ST are abundantly available from brands like Manley, Mahle, Brian Crower, Supertech, Wiseco, Boostline and more. The process to rebuild is fairly straightforward - removal, disassembly, inspection, machining, assembly, installation. It's a simple process, but not an easy one. And unless you can find a company with a built short or long block sitting on a shelf ready to ship, it's going to take a minimum of 6-8 weeks, based on my experience. There are always exceptions to the rule, but if an engine shop says they can have your motor done in one week, you probably need to keep looking.

Let's pretend you were making somewhere in the neighborhood of 375whp-425whp and you just cracked a ringland (i.e. failed piston). Or maybe you didn't blow up yet, but you want to replace the engine before it happens. It makes sense to upgrade to better components if you're doing the work of engine removal anyway, but what if you don't have enough time, funds, or both?

Here's another idea: What about a new OEM block? 

Is it the best option for purely handling power and abuse? No.

Is it something you can brag about at the next cars and coffee? Mehhh, not really.

Could it last 60k-70k miles with only mild use at the 400whp range, cost about $1,000-1,500 less than a built block, and be able to get up and running again in a matter of 1-2 weeks? Yes.


OEM-SmallBlock (1)OEM-Head (3)

The Ford OEM Focus ST short block comes fully assembled with rods, pistons, rings, bearings, and crankshaft. It's balanced, machined, and ready for action. It does come with the balance shaft fitted, so if you want, you can choose to take this off. Keep in mind, this would create the need for an oil baffle in the pan and a balance shaft delete. You can reuse your old oil pan on the new engine, as long as it's in good shape. And an oil pump is basically mandatory when you're installing a fresh power unit. Head gasket, rear main, head bolts/studs, valve cover gasket, and handful of other gaskets can be found in the Ford OEM Complete Gasket Kit and that's all you'll need to reassemble and get back on the road.

For some, there is no way they'd sacrifice going with high end, forged components if they're putting a new engine in. And by no means am I saying OEM is the best option. I'm not even recommending it. If you have the time, money, understanding, and need for making a built motor come together, that's definitely the way to go.


What I am saying is, it's perfectly acceptable to go the OEM route if you're not racing your ST every weekend or putting 500whp through it regularly. A well tuned (this is important), well maintained stock engine can hold up pretty well under most street driven applications. A poorly tuned engine will fail, even if it has h-beam rods and 2618 pistons. We regularly tune 400whp stock engine cars that hold up for a good amount of time.

In the right situation, don't be afraid to "upgrade" your Focus ST engine with a brand new OEM block. They're usually available for quick delivery and assembled by a pretty reliable engine manufacturer (Ford). Tens of thousands of miles of abuse can really deteriorate the performance and reliability of an engine. Setting the clock back that much with a fresh unit is a game changer, even with an OEM setup.

JP Alonso

I'm the founder of Edge Autosport and I remember first getting into cars in high school. I read all the magazines, bought a bunch of technical books, and finally got to start wrenching around the age of 19. I really enjoy modding and being able to live out a passion is truly awesome. I wouldn't change a thing.