Happy July 4th Weekend!
I’m sure most of you will take advantage of the three day weekend and drive your Subie around. It will be quite hot this weekend so go easy on WOT. I bring it up as the last few weeks I’ve read that a lot of people are experiencing ringland failures in the late model GR/ GV cars especially with the EJ257 engine. I am not an automotive expert by any means but the ringland failures on a Subaru is its achilles heel. Similar to the infamous 1998-2002 Honda Accord transmission issue, it was something to be aware of. This article is to educate potential and current Subaru owners that this can happen on stock cars and modified ones and why it is occurring.
When I first bought my STi back in 2012, all I heard about was this ringland failure. It didn’t deter me from buying the car but was always in the back of my mind to never beat the car to death.
The main question from everyone is “What Is Ringland Failure?”
To get a better understanding of what ringland failure is, we have to understand the parts of the engine and what it does in order to see this failure. It would be very difficult to cover in a single post. For this particular topic, I will be discussing the pistons and their ringlands.
To get a basic understanding of how an engine works, click here.
In this section of the engine, the short block contains a few important parts such as the crankshaft, pistons, rings, and connecting rods. The pistons are where the majority of the issues start from.
In the pictures provided below, it shows what a basic piston looks like and how it functions. Unabomber from NASIOC describes it well here.
The “ringland” are the slots on the pistons that support the rings and their duties. A standard Subaru EJ piston will have three ringlands. The diagram above which denotes section 7, 8, and 9 are the rings (slots).
The compression ring (7) is what seals out the majority of the heat and combustion gases from the crankcase.
The oil scraper ring (8) ensures that the remaining combustion gases do not get past it and scrape about 99% of the oil that has gotten past the oil control ring from the cylinder walls.
The oil control ring (9) pulls or forces about 90% of the oil that gets splashed into the cylinder back into the motor.
What causes ringland failures stems from these pistons and the supporting rings. In the EJ257 engine, the pistons are manufactured by pouring molten alloy into a mold. The advantages of having a cast piston is it won’t expand as much when heated. This will allow the build to be tight and quiet for the engine to last a long time. I’m sure this is something that Subaru wants indefinitely. The downside is that cast pistons are not as strong and do not hold up well to severe stresses of a high performance engine.
A better question to ask is why are the ringlands failing especially if the car is stock with the OEM tunes. The consensus of owners and tuners think its the excess heat and pressure generated by knock or in other terms denotation or pre-ignition.
One theory is that the OEM tune is horrible. It seems to cause knocking when tuning the engine to run on various pump gas in the United States with an average of 14lbs of boost pressure in all climates.
Another theory is how the crankcase breather is setup which back feeds large amounts of oil through the intake. This results in diluting the octane value and knock occurs. The setups with running higher boost, aging turbos, PCV routing, and oil aeration can build too much chamber pressure onto the pistons.
Lastly, a final theory is based on driver induced which is subjective but also holds some truth. It is not to say that the drivers are new to Subarus or are poor drivers but unaware of the load they are putting on the engine and how it correlates to the tune. It is not suggested to put heavy loads on the engine at low RPM. Building 14-18 PSI of boost at 3000 RPM is considered high load. Subaru and Cobb Tuning recommend getting further into the RPM before going WOT (3500 – 4000 RPM).
The only thing I would suggest is to get a proper tune with your upgrades. To take it a step further, if you plan on putting heavy loads on the engine, I would also consider investing in forged internals to support the extra power. You’re bound to go this route anyway if you get any ringland failures.
Our cars are built well from the factory. However, if you plan on more power and torque, do yourself the favor and invest in quality parts and find a well known tuner. You’ll be thankful in the end!
If you had ringland failures in the past, let me know what happened and what you did to fix the issue in the reply comment field.