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First-time Subaru STI owner -- found out my engine is going to pop!

62K views 11 replies 6 participants last post by  turmic 
#1 · (Edited)
Hey guys,

So this is my first Subaru...a 2013 STI. My previous AWD vehicle was a fully built 2006 EVO 9 MR with 475 AWHP and full wheel and suspension upgrades that I regretfully sold for a GT500. I got to the point that I missed the EVO experience so much that I decided to get another AWD vehicle and decided to give Subie's a try, and it's been quite eventful to say the least.

Now that brings me to my question...all the while the car was down I was reading about the car and found out that my pistons are going to fail (ring land cracking) at any given point in the future because of the use of hypereutectic pistons in the EJ257 motor...coupled with a lean condition at boost and a knocking factory tune. From what I can tell I can't pre-emptively fix it with a better tune because that gives SOA the opportunity to deny any warranty claims on the drivetrain in the future, and a stage 1 or 2 build can still end in a blown engine. Am I understanding that correctly? It's amazing that these cars have this problem and it hasn't been more widely discussed in the general car world. How does a company build a car model with this sort of a problem and NOT have it turn into a public shitstorm? Crazy. The 4g63 engines never had such issues so this is all new to me on having to cope with the idea that my engine will likely have a premature death.




Thanks in advance. I look forward to learning as much as possible about these cars and the community.
 
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#2 ·
It's amazing that these cars have this problem and it hasn't been more widely discussed in the general car world. How does a company build a car model with this sort of a problem and NOT have it turn into a public shitstorm?
:rolleyes: Because everyone crying about it are making a much bigger deal of it than it actually is. The number of cars experiencing problems is exceptionally small.

ZOMG MY CAR BLEW UP ON THE STOCK TUNE? HEY EVERYBODY, ALL OF YOUR CARS ARE ABOUT TO EXPLODE AND KILL EVERYONE WITHIN A 500 FT RADIUS!! RUN FOR THE HILLS!
 
#3 ·
But my understanding of the problem is accurate? I've been reading a lot and it seems to come down to the fact that the pistons are simply more sensitive to knock. My understanding is that guys who get safer tunes in the way of adding fuel and reducing knock will be less likely to have it happen vs those that do not?
 
#4 ·
It seems I've heard that too. Just stick to 91+octane and you should be good. I'm at 93000mi in my 03 and I haven't had a problem but I'm hardly modded at all. (stock tune)
 
#5 ·
I didn't think the earlier models were prone for the same problems that the late models have. Are the same piston alloys being used then? Are the tunes as lean as today?

There was a few reasons I went to Subaru...one was because I liked the company's environmental image and charitable donations. Two, I wanted AWD that was true AWD. Three I needed something with at least 300 crank HP that would last for a long time. It seems that last bit is more hype than reality it seems.

I'm hoping the issue is more internet explosion than reality. I just have to make a decision on doing a stage one tune over at Cobb in Austin or just buying Accessport.
 
#6 · (Edited)
All WRX/STis are prone to knock. This is why it says "premium gas only" and not just "recommended".

Other than that, the US 2.0 WRX was much lower power and the pistons being small where plenty strong. The rods are weaker than the pistons in the EJ205 engine. The EJ257 has bigger pistons thus they are a bit weaker. That added to more power makes this sound like it might be true.

Actually, I am way out of my element here. All I can say is It's a SUBARU. They are the some of the most reliable cars on the road today. Consumer Reports will back me up over the last 10 years.

To be on the safe side I'd get a protune. They should be aware of the knock situation. Although people have been using the Cobb Accessport for many years with great success. If you think you will need to reflash the ECU multiple times get the Accessport

All I can do is direct you to someone who knows more about this than me. Post #14 Clark Turner. I seriously don't think your engine is "going to pop" any time soon.

What is up with the STI rings lands? - NASIOC
 
#11 ·
Oh wow. Thanks for that post. I didn't find that one yet. I surmised that to be the case after all this research. If the piston is the known weak link, and that's backed up by inherent qualities of the allow, the known knock levels in the factory tune, and physical evidence from owners...it cannot be un-true

I'll just wait for the thing to pop in factory spec (if it even does)...and have it warrantied. Hopefully chunks don't damage the turbine on the way out. But if it's going to get cracked open then just replace it with forged pistons and a more smooth and safer tune with regard to AFR's. I'll probably get a compression tester as well to run checks on the cylinders every so often.
 
#9 ·
There are plenty of folks on here who have owned 4G63's in the past. If you think it was a more reliable performance engine than the EJ257, you're nuts. More power potential maybe, but not more reliable.
 
#10 ·
I only say that based on my experience. I built that car up at the 1000 mile marker, and had zero problems on stock internals for 5 years and daily use. That's increasing PSI to 23 lbs, bigger turbo and all piping replaced, larger injectors, better fuel pump, cams, AMS tune, intake, full exhaust, etc. That makes me believe the engine internals are reliable, and I never saw that the car/engine had a single reoccurring/common issue even at factory spec. So there's that.

I love the car...I just don't like reading about the damn pistons being inherently sensitive to a factory tune.
 
#12 ·
The biggest worry is how good or bad your aftermarket tune is. It seems over the years a lot of professionl tuners have wrapped their heads around this confusing Boxer layout and can eliminate knock a lot better these days vs when the cars were new. Its all in the tune when you go aftermarket and yeah. I'm not so sure I'd beat the piss out of the car on a stock tune either.
 
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