Everything you need to know about your Subaru engine (2023)

You look at the title of this blog that we say everything you sayneedknow; versus what we want you to hear or what our opinion is. Here at Crawford, he'll only hear proven facts and information to help you make your own informed decision about what he's doing under his hood.

First we will enter the conditions (inbold) and their meaning and how they relate to the products you buy, so reading this article or any other article on the internet will give you a much better understanding of what you are looking at.

engine parts sources

If your car was delivered new to the dealer, it is 100%stockofOEM(Original Equipment Manufacturer). These terms describe the parts that are factory-installed on your vehicle. if there is somethingafter sales, then it was manufactured or modified by a factory or shop other than Subaru.

Genuine OEM Subaru parts are high quality genuine parts. Many decades of research, development, investment, trial and error have gone into these regions; well over 90% of all aftermarket manufacturers. Yes they are expensive. But think about why spare parts are cheaper. QUALITY. OEM parts are quality checked parts. Most of the counterfeit parts are made in dirty factories in China with low quality materials. In the auto industry, you get what you pay for, so haggling won't make your Subaru reliable. Be sure to research the companies and their components and be willing to invest in your car if you want to get it right then do it once.

Types of Subaru engines

The first Subaru engine to be used in the US is the E-Series. Most Subaru you see on the road today has an EJ, and in 2011 Subaru introduced a completely redesigned engine called the F-Series. EJ engines, leaving only the EJ257. the ITS from 2019.

A short list of popular US models and the engines they use:


  • 2002-2005 Subaru WRX


  • 2006-2014Subaru wrx
  • Subaru STI from 2004 to present.
  • Impreza 98-2011
  • Legacy 1996-2010
  • Legacy GT 1996-2012
  • Interior 1996-2012
  • Forestry 1998-2010
  • ForesterXT 1998-2013


  • 2013-present BRZ/FR-S/GT86/86


  • WRX 2015-present
  • 2014-2018 xt forestry


  • Impreza 2012-present
  • Crosstrek XV 2013-present


  • Forestry 2011–present
  • Legacy 2012 to present
  • Interior from 2012 to the present.

If you want to see the full history and range of Subaru engines, this Wikipedia article has it all:https://en.wikipedia.org/wiki/Subaru_EJ_engine

Most aftermarket engines and power components you'll find are for turbocharged Subaru models. This is because until 2013 there were none.THATModels (naturally aspirated/non-turbo) were adjustable. That means you couldn't adjust the car's computer, orECU, to accommodate changes under the hood, which go through an intake or manifolds. You also don't need to build the engine if it doesn't make great horsepower. There are ways around this, but they are usually expensive and require a complete rewiring of the motor, so it is no longer road legal. For this reason, swaps are popular with NA models, but they require an enormous amount of time and money.

parts of your engine

ohcomplete engineit is what comes out of the engine compartment in its entirety. It's everything but the intercooler, lines, hoses, and fluid reservoirs. Also know askey ready.
Everything you need to know about your Subaru engine (1)

Afull long blockEliminates bolt-on components such as turbo, manifold and heads.

Everything you need to know about your Subaru engine (2)

Along bare blockIt's the same, minus the valve covers, timing components, cams and pulleys.

Everything you need to know about your Subaru engine (3)

ohshort blockis the center of the engine, with thebuttsERASED. Includes internal components: pistons, connecting rods, crankshaft, bearings and rings.

Everything you need to know about your Subaru engine (4)

buttsthey bolt into each end of the short block.
Everything you need to know about your Subaru engine (5)

In the small block you will find the moving parts that make your engine spin. These are known asinternal.

In the middle of the short block is yourcrankshaft (crankshaft), which turns the crankshaft pulley at the rear of the engine. This rocking motion is translated to the drive train that drives the wheels.
Everything you need to know about your Subaru engine (6)
Connected to the pendulum are hiscash, with the correct official name ofIngenuity. Connect the crank to thepiston, which is pressed in and out by the cylindersInternal combustion(explosions).RPMis the number of times per minute that an explosion occurs between all cylinders in your engine. When an explosion occurs, the top of the piston absorbs direct shock and the rod must be even stronger due to its length and direct connection to the piston via apole sharpener.
Everything you need to know about your Subaru engine (7)

the pistonthe ringthey sit in grooves on the top edge of the pistons and seal the small gap between the piston and the cylinder wall to prevent exhaust gases from entering the crankcase. Some even pass through the opening of the ring, and this is known asflying past.
Everything you need to know about your Subaru engine (8)
Everything you need to know about your Subaru engine (9)
Perhaps you have heard the myth:

"EJ engines are just sensitive to thatfailed rings."

This is when the spaces between the ring are broken. This is largely untrue. This myth is used to sell in-house parts and aftermarket music under the guise of reducing the likelihood of this happening. In a way, the myth is true, but not for the simple reason of structural design or factory tuning. This statement is only true if you do not take good care of your engine, i.e. you run out of oil, do not change enough oil, modify your car without the proper adjustment, use the wrong fuel, etc. Knocking and lubrication problems, which can This occurs with an air/oil separator, proper adjustment, and proper maintenance. Read more about our recipe for a healthy engine in the section titled:"What do I need to keep the Subaru engine reliable?".

In reference to short blocks, you may have heard the terms Closed Cover Block, Semi-Closed Cover Block, and Open Cover Block.DiezIt is the space between the cylinder wall and the crankcase where coolant flows to keep the cylinder walls cool. (Show the picture with the platform circled, with the cylinder wall and block labeled.) ohcylindersThis involves the pistons, where internal combustion occurs, so this is the most abused part of the engine. Cylinder walls are subjected to high temperatures and explosions, and they expand and contract when the engine is turned on and off. Therefore, it can be the weakest link in a block, apart from the internal parts, if it does not have sufficient structural support and thickness.
After 2005, all Subaru engines aresemi-dated cover. They have some reinforcement points to increase the resistance of the cylinder wall.open decksit can be seen in early non-turbo engines and the first two generations of the WRX. These are the weakest Subaru engines, as they have virtually no cylinder wall reinforcement.
Everything you need to know about your Subaru engine (10)
closed deckSubaru used it for a long time (early 90s), but it was soon discontinued due to unreliability. Today, the concept is entirely aftermarket, with the coolant passages in the open and semi-closed blocks filled with metal, creating a solid connection between the cylinder wall and crankcase. Sure, it's incredibly strong, which is why it was first practiced in the world of high-powered, extreme-heat racing. It kept the cylinder walls in one piece for an extended period of time, expanding the number of racing miles each engine could last. The downside to this extra resistance is the fact that the coolant passages are closed, causing the engine to run at higher temperatures and often overheat. This causes the internal components to wear out more quickly, even though the block remains intact. There are other ways to cool a modified engine on the market, but they are expensive and detract from the cohesion of the engine compartment. It is an inexpensive solution for those who want to avoid a new engine. The stores that sell these blocks take very old blocks and reuse them. This is why the cost is so low for anyone looking for a powerful EJ motor, which will make it popular later on. They are also popular for their misleading marketing; that OEM semi-closed deck blocks are prone to failure and cannot support high horsepower builds. This is absolutely false if you follow our recipe for a healthy engine in the next section.

What do I need to keep the Subaru engine reliable?

We use that term a lot at Crawford; a little motto: "Don't fix what ain't broken." This is what you should keep in mind when modifying your Subaru with the intention of maintaining maximum reliability. We say maintenance, because there is no safer or more reliable construction than keeping your Subaru 100% supplied, without premium fluids of course, and keeping your maintenance schedule up to date. This may contradict anything you've read about Subarus, but most of what you read is Joe Blow's opinion, based on what? 9 times out of 10 it's a company trying to sell you something you don't need by going to forums where rumors and slander spread like wildfire.

After 24 years of 100% Subaru aftermarket research and development, our trial and error with their engines has given us the following recipe for an efficient and reliable Subaru engine:

1. Don't fix what isn't broken.

We understand that many of you love its huge list of mods. But if you want efficiency and reliability to be the most important part of your build, don't modify a part that works perfectly under the hood unless there is proof that it offers the advertised benefit. OEM parts have to go hand in hand with each other, so if you start removing, adding, or changing certain things, you'll end up with one problem after another. We're sure you've heard stories from many Subaru owners about how their cars are a money pit and always fail... well, they probably broke this first cardinal rule.

2. If you are modifying your car with power-enhancing components, be sure to get a tune-up from an EXPERIENCED, REFURBISHED tuner.

This is perhaps the most important factor in reliability. At any power level... standard, bolt-on or race. If you don't get a perfect fit, your engine will eventually fail. Think of ready-made products orOTS cards. They are made for all cars in the world; without taking into account subtle differences from car to car, weather, altitude, fuel variations, etc. They should only be used to gently roll in an engine or carefully drive from the shop to the tuner to listen to a custom song. Never crash your car on an OTS map.
An experienced tuner means someone who has been around for a while; Not someone practicing in his car. Preferably a tuner with extensive experience with Subaru engines. Reputable means that they have a good public reputation.
If you're looking for a new local tuner, try to attend local automotive meetups and events and just talk to people and hear what they have to say about their tuners and how long your engine has been in one with power mods.
If you can't find one locally, there are several tuners that can play a tune remotely. Again, find someone great and don't settle. This is the most important investment in its construction.

3. Be on top of maintenance.

This is just as important as a solid melody. Subaru engines hate to run out of oil. They are meticulous. Unlike a Honda that can keep leaking oil like an anorexic girl with crumbs, running a Subaru engine low on oil can lead to engine malfunction.
Volume is important, but so is the quality of the oil you use. For turbocharged Subaru engines, definitely go for a fully synthetic engine unless you're installing a new engine. We have been using and appreciating MOTUL for many years. Oil is oil is oil, so as long as it's premium, you can't go wrong. Also, make sure you keep up to date with any changes. Only if you use premium will you be able to cover 4 to 5 thousand miles by keeping it full. Try to replace the filter more often; about every 2000 miles. If your filter is at the bottom of the engine this is difficult but possible. You may lose some oil in the process, but as long as you do it fast, it's possible. Those of you who have a filter at the top have no excuse! Subaru filters are of great quality, but we have always used K&N and completely trust them.

4. Use a good air/oil separator (AOS)

We say appropriate because there are many canisters on the market disguised or marketed as air/oil separators. A good AOS can reduce knocking and oil consumption while allowing the engine to run optimally. Since Crawford designed and built the first Subaru AOS, and the fact that it's our best-selling part, we have a lot to say on the subject.Click here to read everything you need to know about air/oil separators.

    My engine died. Now what?

    The first step is to find out why this happened. Did you generate too much energy? Have you left the car without oil or it's been a while since you changed it? Did you have less than perfect pitch and experience a blowout? Have you lost compression in a cylinder due to broken rings or broken rings (also forms knock)? Has it been lost due to a drop in oil pressure or an explosion?

    All of the above factors are typical causes of engine failure on Subaru. A compression and leak test, along with studying your engine's history, will help find out what's going on. Once you have a reason, better choose your components and path to prevent this from happening again. It will cost you up to 10k depending on the engine you choose. Again, you get what you pay for, so make sure the components and services you choose are premium, unless you want to build from scratch.

    Should I rebuild my current engine or buy a new one?

    This depends on the type of engine you have.

    If it's an EJ, choose a new one to avoid future failures. We know it's expensive, but that's why it's not a good idea to rebuild it.

    The weakest parts of the EJ engine are the cylinder walls. Being a semi-closed cover, they do not have many reinforcements. Especially if your engine has failed due to a blowout, the cylinder walls are probably the cause.out of the round. This means that they are no longer perfectly round. The workshops will measure and verify the disassembled engine. If it's really out of the round shape, offer borders.Sharpenit is the process of making the cylinder walls perfectly round again. They will update and then order each cylinder.oversized pistonsadapt to the new dimension. The big problem with this is that you just took the weakest point of the engine and made it leaner and then weaker.

    If you have an FA or FB engine, the cylinder walls are much stronger and generally do not lose their shape. Rebuilding is certainly another option for these engines.

    Anyway, the most reliable way is a new block.

    And my heads?

    9 times out of 10 Subaru cylinder heads are reusable after engine failure. They're pretty bulletproof. The only exceptions to this rule are:

    • If the engine overheats: This can warp and/or break the cylinder heads.
    • You broke a valve or tagged your tubes. Sometimes you can just replace the cams or valves if they aren't too scarred, but most of the time this means that bits of metal from your engine have lodged in the cylinder heads and it's extremely difficult to remove these bits from all the passages. If any of these fragments enter your new engine, you will immediately have another engine failure. Have your shop carefully inspect your heads to determine if anything needs to be replaced.

    If you are reusing your original headers, be sure to reseal them before installing them on the short block. This ensures a like new seal with the head gaskets and prevents future head gasket failure.

    Should I take this opportunity to rebuild my head?

    If you have turbo the short answer is no. In a turbocharged Subaru engine, the turbo does all the work. The amount of money it takes to build heads is not worth the meager gains you can make, which can easily be achieved on the dyno by increasing the thrust by 1 pound. Aftermarket cameras can make more top-end power, but you sacrifice power where you need it and feel it in the low and midrange. These mods are best suited for an NA build.

    What other parts need to be repaired/replaced on a new engine?

    Anything that has touched the oil should be thoroughly cleaned to remove any metal fragments. These fragments can re-enter your new engine and cause it to fail again. It is impossible to completely clean the oil pump, so you will have to replace it with a new one along with the main oil pump seal. The same goes for the oil cooler. On an FA or FB engine, the oil pump is built into the front cover of the engine, so this entire part will need to be replaced. If your engine has done over 100,000 miles, you may want to consider a complete gasket kit that comes with all of the engine gaskets. If the mileage is lower, reusing a lot of gaskets is perfectly acceptable. That being said, the gaskets that need to be replaced, regardless of the intake, exhaust, water pump and cylinder head gaskets. Make sure your new short block will fit ARP 11mm head bolts. They are reusable indefinitely and are 1000 times better than OEM head pins. Fun fact; They were originally designed by Quirt Crawford. You will also want new spark plugs and we recommend taking this opportunity to upgrade them as well. We recommend NGK Iridium spark plugs with single stage cooler. And finally, of course, new break-in oil for your engine and a new oil filter.

    All of the components listed above (minus the oil cooler because most people have replacement parts) come together in our short block install kit.Click here to see it.

    At what power levels should you consider buying a built-in motor?

    Believe it or not, if you follow our tips for maintaining a reliable engine, an OEM EJ25 can hold up to 400/480 horsepower! We've done this many times with our customer builds. FA20 NA blocks support up to 300hp/360hp, and FA20 DIT blocks match the EJ25 at 400hp/480hp.

    If you have an FA20 NA (BRZ/FR-S/GT86/86) engine, you can swap out your horrible easy-fail dipsticks for the FA20 DIT dipsticks that come on 2015 and newer WRXs. They are perfectly matched and much stronger. This is a great commitment to your wallet as your 86 grows.

    The motor stages built and their resistance depend on the manufacturer. Ours are the following:

    • S2: 450 CV/540 CV
    • S3L-X: 550 CV/660 CV
    • S3l-X with FSR upgrade: 600+wpk/720+pk

    Click here to see our building blocks.

    That's right folks - you don't need a closed platform block for high HP builds!

    What makes Crawford Constructed Blocks unique?

    Every component designed and manufactured by Crawford Performance has been tested for maximum performance and reliability, both on and off the track. For over twenty years we have tested all combinations of upgrades for the EJ20, EJ25 turbo engines and most recently the new Subaru FA20 engines. We push these engines to the limit to determine which parts are failing and to what extent. Based on that research, we created forged internals to keep your engine strong enough to handle the level of power you want.

    Our versions include the following OEM upgrades:


    • Crawford SPEC S2 JE Forged Pistons. These pistons are SCCA approved and stamped accordingly.

    S3L-X (formerly S3L-i)

    • Crawford SPEC S3L JE Forged Pistons. They come with a $250 upgrade option to FSR, an even stronger billet forging. FSR stands for Forged Side Relief.
    • Bastones Pauter CrawfordSPEC X-Beam

    About CrawfordSPEC Pistons

    Each CrawfordSPEC piston has a unique disc design, designed and exclusive to Crawford Performance. Our lead engineer, Quirt Crawford, worked closely with JE Pistons to create a design with the following results:

    • More vacuum manifold at idle, making the engine more compact, healthier and more efficient
    • low crankcase pressure
    • More power at the same boost level with the same support mods
    • All CrawfordSPEC pistons match the OEM 99.5 bore.

    About the FSR Piston Upgrade

    Piston forging developed by Quirt Crawford. While the forged style is publicly available, the skirt length and plate design are exclusive to Crawford Performance. This Blacksmithing Upgrade includes:

    • 100% CNC machined from high quality 2618-T6 forged billet aluminum.
    • Designed specifically for high horsepower trailer and highway engines.
    • Internal and external bracing (bridge design) provides a stiffer construction, minimizing overall weight.
    • Billet means the pistons are machined on all surfaces, allowing all unnecessary weight to be removed during production, reducing excess friction/heat in high horsepower applications.
    • Weight reduction to 32 grams.
    • Includes high quality 9310 steel wrist straps.
    • Reduced skirt width and shorter wrist pin compared to traditional "full round" style forgings. The narrow skirt helps minimize piston-to-cylinder wall contact, which can cause friction and loss of power, while the shortened pins reduce overall weight.

    About CrawfordSPEC rods

    Each CrawfordSPEC rod is designed to a specific length, designed and exclusive to Crawford Performance. Our lead engineer, together with Pauter Rods, produced a design with the following results:

    • A longer length than the standard length not only increases resistance, but also increases the rod ratio, allowing for a smoother and more efficient power delivery.
    • Plug vs... Forged, made from the strongest steel available in the industry: 4340 Chromium Molybdenum.

    Why doesn't Crawford use replacement rods, bearings, rings or gaskets?

    This goes back to one of our mottos: don't fix what ain't broke. Our blocks are expensive due to all the OEM parts included being premium. Many people are surprised that our prices are higher than the blocks of other companies that have more updates. We'll say it again: you get what you pay for. Replacement parts are cheaper because they don't have the same quality standards as OEM parts. They are cheaper for a reason. And we don't replace parts on an engine that won't break, and we won't. For example, we use and test aftermarket connecting rods, which are stronger than OEM connecting rods. Consistently had a higher failure rate than OEMs crank at the same power level.

    But I have changed things. The bearing must be the problem, right?

    To answer this question, we must first explain how bearings work so that the reason for their failure makes more sense. This particular article on bearing failure was written by Quirt Crawford himself:

    Algemene motorlagerstoring 101

    FYI, this is a general letter to anyone who has had a Subaru engine bearing failure.

    The Subaru engine has two sets of bearings, one in the main journals of the crankshaft and the other in the connecting rod journals of the crankshaft. The oil that lubricates and floats these bearings comes from the oil pump through the engine block and is fed to the crankshaft through the main bearings so they see oil first and the connecting rod bearings see second oil. With this fact in mind, it is easy to diagnose whether the connecting rod bearing failure was caused by a lack of oil pressure or knocking/excessive loads.

    In the absence of oil pressure, the main and connecting rod bearings will be damaged by scratches, with the connecting rod bearings being the most damaged as they support the highest loads. Bearing damage is generally even across all four main cranks and journals, so you won't see just one bearing damaged from lack of oil pressure.

    Knock/excessive load on the connecting rod bearings is very easy to diagnose as the connecting rod bearings are the only ones damaged, leaving the main bearings completely intact. Detonation is like a giant hammer hitting the top of the piston and that impact travels straight down through the connecting rod and into the connecting rod bearing, expelling the small film of oil that prevents the connecting rod bearing and connecting rod pin strike the crankshaft. from metal formation to metal contact with each other. Knocking can only damage one connecting rod bearing at a time, while lack of oil pressure will damage all four at once.

    Statistics show that the vast majority of Subaru engines where only one connecting rod bearing is damaged occur in the No. 3 cylinder. There are many different opinions as to why this happens and I won't go into that as it's irrelevant to the topic. of this letter. .

    When you have a bearing failure on your engine, cleaning ALL the bearing material on the engine and turbo parts is paramount! If this is not done correctly, the aftermarket engine and/or turbo will not be able to absorb this residual dirt. Unfortunately, this is also a high statistic in our industry... And the one who suffers from this costly error is always the vehicle owner, as the workshop that performed the work is usually not even aware of the error they have made, so blame something or something else, someone. other. At Crawford we always throw away all vehicle oil coolers as it is impossible to get dirt out of the bearings. The small filters in the cylinder heads must also be replaced; Otherwise the turbo will fail within 1000 miles of the new engine being installed. The oil pump will also be damaged by debris from the bearing, as will the oil pressure relief valve in the oil pump housing; At Crawford we never reuse the old oil pump either.

    - Quirt Crawford, financiero van Crawford Performance

    Still have questions after reading this article? Do not hesitate to contact us whenever you want:

    855-67-SUBIE (78243) Ramal. 1

    Do not leave any questions in the comment section. We cannot answer that we have done this. Instead, send us an email or give us a call.


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