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Old 06-29-2015, 03:42 AM   #1
UnknownAlly
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Default How to Avoid Blown Ringlands in your Turbo Subaru

I found this helpful. Thought I'd share this article. This is my first turbo car.
Source: VikingSpeedShop.com
I did not write this article

The Problem | Ringland Failure on EJ20 and EJ25 Series Engines

While largely limited to the late model WRX and STI with the EJ255 and EJ257 motors, theres been some concern raised about the shear numbers of ringland failures being reported on the forums. Our goal with this article is to address why this is likely occuring and how you can guard yourself from it happening to your Subaru. Some of these may seem like common sense to most, but for many younger or first time turbo car owners it may be new.

The “ringland” is the portion of a piston that supports the ring itself. The standard Subaru EJ piston will have three ringlands per piston. The first is the most susceptable to damage because it is supporting the primary compression ring. This ring is what seals out the majority of the heat and combustion gases from the crankcase. The second ringland supports the secondary compression ring which is shaped differently from the first ring. It is tasked with ensuring that the remaining combustion gases don’t get past and also to scrape any oil that has gotten past the third ring off the cylinder walls. The last ring is known as the oil control ring. It is shaped completely different from the two compression rings because it’s duty is to force oil into the various parts of the piston to help cool and lubricate it.

Ultimately for one reason or another the ringland is cracking and failing.

Why do the Ringlands Fail?

There are many theories out there as to why the pistons are failing. Many hold weight with common reasons found in other piston failures, some are model specific, and others are a shot in the dark. Ultimately, the excess heat and pressure generated by knock (aka detonation or pre-ignition) is the culprit. The causality of the knock is what is at odds in this theories.

Theory #1 – The OEM Tune is Terrible

Subaru has had continous problems with it’s OEM tunes causing knock since the first USDM WRX rolled off showroom floors. To their credit, tuning an engine to run on all sorts of pump gas with 14+ lbs. of boost pressure in all climates is not exactly easy, especially when you have to conform to vague emissions standards for 100K+ miles. There’s strong evidence showing that the failure prone 08+ WRX / STI do run exceptionally lean during a high load moment (read: under boost). In fact, a couple dozen completely 100% stock and well maintained WRXs / STIs have had ringland failure within 40,000 miles.

Counter Point – It seems that tuning the cars doesn’t make you immune to the failures as people with tuned stock turbo cars have had similar failure rates.

The Fix – Get the car tuned after most mods to take full advantage of the mods, make more power, get better fuel economy, … JUST DO IT.

Theory #2 – The Crawford Oil Vapor Dilution – AOS Theory

According to Crawford and a few other shops a major source of engine failure can be traced back to the crankcase breather setup backfeeding large amounts of oil through the intake. This in turn dilutes the octane value and knock occurs.

This is a valid theory since there is considerable amounts of blow-by generated by turbo engines in general. Running higher boost, aging turbos, questionable PCV routing, crankshaft oil aeration, and a multitude of sources can feed oil vapor through the PCV. This vapor dilutes octane value, which causes pressure to rise quickly in the chamber. Once the pressure rises the rate of the reaction also quickens, thus you have a large rise in chamber pressure before an ideal crank position which imparts heavy loads onto the piston. Subsequent latent heat from this will cause continuing detonation, even as the ECU begins to pull timing in reaction. The result is detonation until significant heat is pulled from the chamber, ie. lifting, or the reduction in timing is sufficient to reduce hot-spots.

The Fix – Run a proper AOS system that re-routes the PCV and breather systems to a catch-can. Ideally this should be back fed to the intake, vacuum side, but you can also feed it to the downpipe for a blown suction effect. Grimmspeed makes a good and simple unit, but Crawfords V2 AOS is ideal.




Theory #3 – Driver Induced Failure

I believe that a large amount of failure is due to the driver. Even the most cautious of drivers can cause significant amounts of knock on any tune. This isn’t to say that the drivers are dumb or have poor skill, it’s simply that most drivers are unaware of the load they are putting on the engine and how that correlates to the tune.

Simply put, one of the worst things you can do to your turbo engine is to load it up at a low RPM on the highway in a high gear. Building 14 – 18 PSI of boost at 3000 RPM is a high load : low RPM moment that may not have been properly tuned for your vehicle. Most tuners don’t bother sticking the car in 5th or 6th and road force testing it for knock at low RPM. Subaru and Cobb both recommend getting further into the RPM range before going WOT (3500 – 4000 RPM).

A special consideration for GRs is also the fact that our cars have a fueling harmonic issue around 2800 – 3200 RPM.

It also goes without saying that driving the piss out of the car for prolonged periods of time will cause engine failure. The engine is designed for short bursts of speed. Contrary to whatever you might think or have read the engine does not like prolonged racing. If you are at a track event, have fun, but remember your cool down laps and be sure you are using a quality oil and monitoring coolant temps.

If the car is completely heat soaked from sitting in traffic, don’t rip it through the gears the first chance you get. Slowly get up to speed and let the radiators / intercooler shed off some of the heat. In 118 degree Texas summers I’ve logged 180+ degree inlet temps before the turbo with the A/C running. The engine was misfiring even under light throttle until I could get up to speed and bleed off the heat.

The Fix – Downshift … get up in the RPM, 3500+ before going WOT. You’ll see far less knock. Lastly, don’t drive like an idiot.

Theory #4 – The Pistons are Weak!

The EPA and Congress have more to do with ringland failures than Subaru. The ever increasing emissions requirements have pushed many OEMs to leave no stone unturned when it comes to reducing emissions. The piston crown has been weakened because the ring pack was moved further up the piston. Subaru did this to avoid fuel from being trapped between the piston and cylinder wall above the first compression ring. This would increase hydrocarbons in the emissions and necessitate additional catalytic converters (and cost and power reduction). Trust me, Subaru would MUCH rather install a nice forged piston with beefy ring lands.
I recommend you guys read up on the Federal emissions testing requirements for OEMs. It’s very involved and includes testing the vehicles into 6-digit mileage figures with remote accessible emissions equipment that the EPA can request/access at any point in the test. Failure would set back Subaru not only in time, but in significant costs as well. These costs would be forwarded on to you.

Ultimately, the pistons might be weak, but the real cause is pre-ignition and detonation. Remove the knock and the pistons work just fine.

The Fix – Forged pistons … unfortunately.

Theory #5 – Latent Combustion Heat

An observation I’ve made is that nearly all of the failed pistons are failing at the skirt end of the piston. This is also in line with the quench pads on the head which work to squirl and squeeze the air / fuel mixture into the chamber center. However, these pads are also prone to building up hotspots, especially the sharp ridge at the end of the pad. These hot spots can create pre-ignition and localized heat rise. This heat weakens the piston and causes the failure / melting that you see.

Since the gasket is 0.6mm the quench effect is largely reduced, but when you add carbon deposits and rod stretch at high RPM you can start to greatly reduce the distance. Especially on an engine that is consuming poor grade gas and oil vapor.
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Last edited by UnknownAlly; 07-02-2015 at 09:24 AM.
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Old 06-29-2015, 08:03 AM   #2
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Very nice write up! I wasn't aware of the ringland failure. I've most read about the bearing issues. My last performance car was an RX-7, so this was very educational.

Thanks!
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Old 06-29-2015, 02:23 PM   #3
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Excellent analysis...I enjoyed reading it. However, this part "Trust me, Subaru would MUCH rather install a nice forged piston with beefy ring lands..." doesn't account for other manufacturers using forged pistons in similar vehicles (Evo). After all, they need to meet the same EPA requirements as Subaru. I personally think not using forged pistons is purely a cost-saving measure on Subaru's part.
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Old 06-29-2015, 02:36 PM   #4
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Some good points, but if the tune was really that terrible there would be a lot more blown stock engines than there are. I still believe oil choice is a major factor in these engines, ie 5w30 is not the right oil...
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Old 06-29-2015, 04:28 PM   #5
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Quote:
Originally Posted by JordanM9 View Post
Some good points, but if the tune was really that terrible there would be a lot more blown stock engines than there are. I still believe oil choice is a major factor in these engines, ie 5w30 is not the right oil...
It is more dependent on the specific oil than just the weight of the oil. 5W30 can be the right oil. Mobil 1 5w30 is not it. It all depends on the specific oil and how well it handles our turbo engines. Rotella T6 5W40 seems to do great in our cars (I use it) but that doesn't mean any type of 5W40 is just as good.
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Old 06-30-2015, 01:28 AM   #6
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I really wish people would ask before they copy / pasted my entire article on a forum ...

When considering other engines, like the Evo's 2.0L, you have to remember that they use a much smaller diameter piston which affords them certain luxuries. The ring land area is considerably smaller as well. The smaller chamber and bore also improve emissions and efficiency.

Subaru has to go to a big bore in order to maintain engine width limits.

You are better off finding similar cylinder pressures among similarly sized pistons and power outputs.

You have to keep in mind that Subaru really doesn't care much about their performance image. They never really have, outside of Japan and maybe Europe. Subaru NA is a tight wad of a company that got saved by being the green, "we care about families, trees, and puppies" image that sold Outbacks by the boatload to people. The WRX and STI fly in the face of their image, and it would not surprise me one bit if Subaru killed the STI in the US and neutered the WRX even more.
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Old 07-01-2015, 11:39 AM   #7
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Quote:
Originally Posted by JordanM9 View Post
Some good points, but if the tune was really that terrible there would be a lot more blown stock engines than there are. I still believe oil choice is a major factor in these engines, ie 5w30 is not the right oil...
Explain further. Why do you think 5w30 is not ideal for our engines? How does it cause ring land failure?
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Old 07-01-2015, 11:41 AM   #8
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Originally Posted by JordanM9 View Post
Some good points, but if the tune was really that terrible there would be a lot more blown stock engines than there are.
Most people that own stock tuned cars are not gearheads. They are not subjecting the cars to the same loads. The stock tune also runs much lower boost pressure, which means knock is not as hard on the lands. It's also just as likely that many people are driving around with cracked ring lands.
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Old 07-01-2015, 11:56 AM   #9
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Quote:
Originally Posted by Subaru_Freak View Post
I really wish people would ask before they copy / pasted my entire article on a forum ...

When considering other engines, like the Evo's 2.0L, you have to remember that they use a much smaller diameter piston which affords them certain luxuries. The ring land area is considerably smaller as well. The smaller chamber and bore also improve emissions and efficiency.

Subaru has to go to a big bore in order to maintain engine width limits.

You are better off finding similar cylinder pressures among similarly sized pistons and power outputs.

You have to keep in mind that Subaru really doesn't care much about their performance image. They never really have, outside of Japan and maybe Europe. Subaru NA is a tight wad of a company that got saved by being the green, "we care about families, trees, and puppies" image that sold Outbacks by the boatload to people. The WRX and STI fly in the face of their image, and it would not surprise me one bit if Subaru killed the STI in the US and neutered the WRX even more.
You have some good points about the hipsters buying up the Outback and Forester market for go green environment blah blah. But stating Subaru doesn't favor the STI is not true. They always show Launch Control on their homepage every wednesday. They always support the Subaru Rally Team on wins they have. Subaru has even mentioned how well the Team did racing in this years 24hrNBR. So..that's an understatment about not showcasing the STI/WRX market.
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Old 07-01-2015, 12:02 PM   #10
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tune/oil/driver plenty of these cars running around with 350+whp (myself included) for years with no issues
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Old 07-01-2015, 12:28 PM   #11
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Quote:
Originally Posted by shoots808 View Post
You have some good points about the hipsters buying up the Outback and Forester market for go green environment blah blah. But stating Subaru doesn't favor the STI is not true. They always show Launch Control on their homepage every wednesday. They always support the Subaru Rally Team on wins they have. Subaru has even mentioned how well the Team did racing in this years 24hrNBR. So..that's an understatment about not showcasing the STI/WRX market.
It's still (as with most mfrs) a small percentage compared to their total sales. Subaru does more PR absolutely which has helped fuel the enthusiast image and aftermarket support. But by and large, their business is selling cars that appeal to the mainstream.
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Old 07-01-2015, 12:38 PM   #12
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Had a buddy send me this article last week. Great read!
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Old 07-01-2015, 01:07 PM   #13
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Thanks for the write up great read.
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Old 07-02-2015, 04:19 PM   #14
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Default How to Avoid Blown Ringlands in your Turbo Subaru

Guys I didn't write this article. I got it from Viking Speed Shop


Quote:
Originally Posted by BigRob74 View Post
tune/oil/driver plenty of these cars running around with 350+whp (myself included) for years with no issues
My WRX with 146,000 miles runs better than my mom's 1997 Q30 with 135,000 miles.
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Old 07-09-2015, 04:39 AM   #15
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My WRX with 146,000 miles runs better than my mom's 1997 Q30 with 135,000 miles.
Those old VG30's will run forever. My buddy had one with something like 230K on it by the time he finally just scrapped the car. It burned a touch of oil, but still ran well.
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Old 07-09-2015, 04:54 AM   #16
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Quote:
Originally Posted by shoots808 View Post
You have some good points about the hipsters buying up the Outback and Forester market for go green environment blah blah. But stating Subaru doesn't favor the STI is not true. They always show Launch Control on their homepage every wednesday. They always support the Subaru Rally Team on wins they have. Subaru has even mentioned how well the Team did racing in this years 24hrNBR. So..that's an understatment about not showcasing the STI/WRX market.
The SRT and Enduro teams are all supported by Subaru Japan/Euro. Subaru US on the other hand, just piggybacks off of it. They actually are extremely tight with their money in the US, and that's saying a lot considering Subaru brings in quite a bit higher profit margins than other manufacturers.

It's important to know that Subaru Japan and Subaru US are two very different organizations. They operate autonomously and have vastly differing structure / leadership.

From a marketing perspective, there's a reason why Subaru is only in the WRC and Enduro. WRC conveys prowess in any condition, a cornerstone of the backbone AWD selling point. Enduro conveys reliability, another major selling point of all Japanese brands since the 80s.

It's so the defeated 30-something year old dad can feel happy about owning a gutless 2.5L H4 backed with a CVT to appease his wife and have room for the 80 billion pounds of baby equipment.

Why do you think Toyota races in NASCAR? You think they are mining valuable standardized steel tube-frame chassis data, or gaining tricks for their next gen Prius from the high RPM pushrod V8? ... It's to be associated with "domestic", and to be shown in competition with traditional US brands such as Ford and Chevy.
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Old 07-09-2015, 04:56 AM   #17
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For the record, I'm open to edits, changes, or answers to questions that need to be added to the article.
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Old 07-09-2015, 08:07 PM   #18
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Default How to Avoid Blown Ringlands in your Turbo Subaru

At first I thought the article was pretty good. But then I realized that it's many different ways of saying that it's either a bad tune or poor piston design. So it's not very informative. I definitely applaud the undertaking of trying to answer this question but perhaps exploring those two ideas further might be more beneficial. Like how many of the engines that experience ring land failure see other evidence of knock? Maybe an in-depth look at the Subaru piston dimensions might help. I personally would like to see something along the lines of: I think the majority of the ringlands fail due to low rpm detonation because_______.

Sorry, not trying to be an asshat just stating that I'm interested I this topic and would like more information.

Last edited by Bad Noodle; 07-09-2015 at 09:20 PM.
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Old 07-10-2015, 04:27 PM   #19
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Quote:
Originally Posted by Bad Noodle View Post
At first I thought the article was pretty good. But then I realized that it's many different ways of saying that it's either a bad tune or poor piston design. So it's not very informative. I definitely applaud the undertaking of trying to answer this question but perhaps exploring those two ideas further might be more beneficial. Like how many of the engines that experience ring land failure see other evidence of knock? Maybe an in-depth look at the Subaru piston dimensions might help. I personally would like to see something along the lines of: I think the majority of the ringlands fail due to low rpm detonation because_______.

Sorry, not trying to be an asshat just stating that I'm interested I this topic and would like more information.
Your best bet would be to get ahold of the guys at Viking Speed shot. They're somewhat active on one of the Texas fb groups, but I'm not sure they go to more regional groups around the country. Doesn't hurt to find them and ask though.
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Old 08-02-2015, 08:41 PM   #20
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Quote:
Originally Posted by Bad Noodle View Post
At first I thought the article was pretty good. But then I realized that it's many different ways of saying that it's either a bad tune or poor piston design. So it's not very informative. I definitely applaud the undertaking of trying to answer this question but perhaps exploring those two ideas further might be more beneficial. Like how many of the engines that experience ring land failure see other evidence of knock? Maybe an in-depth look at the Subaru piston dimensions might help. I personally would like to see something along the lines of: I think the majority of the ringlands fail due to low rpm detonation because_______.

Sorry, not trying to be an asshat just stating that I'm interested I this topic and would like more information.
So I've been wanting to expand the article more. I just haven't had a ton of time to invest into the article. I'll try to get something done soon.
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Old 08-02-2015, 08:42 PM   #21
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Quote:
Originally Posted by J_mythsuby View Post
Your best bet would be to get ahold of the guys at Viking Speed shot. They're somewhat active on one of the Texas fb groups, but I'm not sure they go to more regional groups around the country. Doesn't hurt to find them and ask though.
I'm the author (and owner of the website)
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Old 08-03-2015, 04:15 PM   #22
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Quote:
Originally Posted by Subaru_Freak View Post
So I've been wanting to expand the article more. I just haven't had a ton of time to invest into the article. I'll try to get something done soon.

That would be awesome. I look forward to reading it.
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Old 08-03-2015, 04:36 PM   #23
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so basically....


you're regurgitating several theories around a myth that doesn't exist.
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Old 08-03-2015, 05:02 PM   #24
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I was a little amused reading this that the issue of owners not being cognizant of oil consumption and oil shearability issues with EJ series motors doesn't even come up. Average owners often believe they're following maintenance procedures using a U.S.-spec 5w30 oil without knowing that depending on the brand, it can shear down to 5w20.
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Old 08-05-2015, 03:11 AM   #25
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Originally Posted by Smurftastic View Post
I was a little amused reading this that the issue of owners not being cognizant of oil consumption and oil shearability issues with EJ series motors doesn't even come up. Average owners often believe they're following maintenance procedures using a U.S.-spec 5w30 oil without knowing that depending on the brand, it can shear down to 5w20.
Shearability isn't really the concern here, or even the viscosity of the oil. That really comes down more to a bearing protection concern. Which arguably is a problem with any turbo motor.

The primary source of the oil vapor is mechanically aerated oil from the rotating assembly. The PCV system is not designed well for an engine naturally prone to blow-by (flat, turbo motor). Even my SR20DET from the 90s had a baffled catch can from the factory.

I suppose a much heavier viscosity oil would slightly reduce this, but that comes with it's own issues.
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