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Old 05-02-2013, 12:45 PM   #101
MaddMax
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SSS4-

The data certainly seems to suggest that ringlands failures are more common on the STIs. There are differences in the piston design, variable cam timing, and most imporantly, the tuning. The STI's require more octane. With that said, I think the chances of a ringland failure in stock 2011+ STI are very low.

Ringlands break because of detonation, usually multiple events. The most likely time where you would break a ringland is during high load, high boost situations. That typically means high gear, full throttle, and full boost such as mashing the throttle in 4th at 2000rpms. IMO, it's stupid to do such a thing. If you want max acceleration, the nselect the appropiate gear to reduce the load on the motor. Going WOT at a low rpm in a high gear could spell bad news for an ill-tuned motor because it labors longer in the rpms, therefore, there's more time for more detonation events. These aren't high displacement motors. They need to revving above 3500rpms to make any meaningful acceleration.

Lastily, if you're on the fence about the WRX or STI, keep in mind the WRX is generally the faster of the two in 0-60 and 1/4 mile and the revisions to the 2011+ WRX put it squarely on the heals of the STI. There use to be a huge difference in performance between the WRX and STI. Now that difference is next to nothing. Read this article if you want to see what the 2011+ WRX is capable of:

http://www.motortrend.com/roadtests/...on_first_test/
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Old 05-02-2013, 01:46 PM   #102
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If money is not a factor, get the STI. If it is, get the WRX. IF something happens, MOST likey it'll happen under warranty(if you are not modding). Get one. Enjoy it and don't worry.
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Old 05-02-2013, 06:10 PM   #103
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I would bet a lot of money that most ring land issues are cars that were over-revved. People miss gears and bounce off the limiter, do it too often and stress weakens parts. Add to that gas that may be a little watered down from sitting, and there goes piston #4. The people who have stock cars were most likely at high load in the lean part of the stock tune.
Overall, it's ridiculous to think that Subaru would not make a change if there was an issue with the pistons or anything else. I don't need to know exact percentages to know that Subaru would not be as profitable as has been in recent years by releasing defective motors!
SS, I would suggest a new STi or if price matters WRX, used ones are a gamble and cost nearly the same as new. Another benefit of new is this is possibly the last year of this generation and it is pretty cool to have the last year of a specific model.
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Old 05-02-2013, 06:59 PM   #104
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Quote:
Originally Posted by MaddMax View Post
SSS4-

The data certainly seems to suggest that ringlands failures are more common on the STIs. There are differences in the piston design, variable cam timing, and most imporantly, the tuning. The STI's require more octane. With that said, I think the chances of a ringland failure in stock 2011+ STI are very low.
It seems that its a problem with ALL turbo EJ25 motors.

And the current WRX uses a single AVCS system identical to the 02-07 sti's. They were still experiencing ringland failures then as well, but not as many as during the 08-09 years (which seemed to be the most problematic).

As far as the sti requiring "more octane", i dont believe it.
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Old 05-02-2013, 07:37 PM   #105
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they require the same octane.
The STI runs higher compression which is probably why they pop more often.

I blame the cheap cast pistons regardless. Subaru is the only Japanese import that runs hyper cast pistons in a boosted engine. There is a reason why all the other imports ran some variation of forged internals or even used ceramic coated pistons in their boosted engines ever since they started producing them in the 80s. its better to over engineer than to do just the bare minimum. Apparently Subaru missed the memo.

You would think Toyota owning part of FHI would share some of their experience with Subaru. The only boosted engine they ever had problems with was the 7M-GTE and that was because the heads weren't torqued down properly from the factory. All of their other boosted engines were bullet proof. Its not like sharing info would hurt when in the end they profit from everything Subaru sells.
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Old 05-02-2013, 08:21 PM   #106
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Hmmm... Actually, the STI engine runs lower compression at 8.2:1 and a tad more boost.
The WRX engine runs higher compression (Subaru says 8.4:1, but I believe gurus in these forums have actually measured something closer to 8.6:1).
Regardless, I believe most of the issues start with the tune.
Going to any sort of competitive event (especially hot summer track days) with a bone stock STI and its bone stock EPA/CARB-approved tune is going to be hard on the engine.
Then, add things like improper oil used during these events (weak sauce energy conserving oil), failure to monitor oil level, failure to monitor water temps, insufficient octane level in the gas given the extreme conditions encountered during these events and it's easy to run into trouble with these engines.

No doubt, forged factory slugs would have been nice especially when relatively inexpensive cars like the Fiat 500 Abarth have factory forged pistons.
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Old 05-02-2013, 08:25 PM   #107
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Originally Posted by Lrn2Corner View Post
they require the same octane.
The STI runs higher compression which is probably why they pop more often.

I blame the cheap cast pistons regardless. Subaru is the only Japanese import that runs hyper cast pistons in a boosted engine. There is a reason why all the other imports ran some variation of forged internals or even used ceramic coated pistons in their boosted engines ever since they started producing them in the 80s. its better to over engineer than to do just the bare minimum. Apparently Subaru missed the memo.

You would think Toyota owning part of FHI would share some of their experience with Subaru. The only boosted engine they ever had problems with was the 7M-GTE and that was because the heads weren't torqued down properly from the factory. All of their other boosted engines were bullet proof. Its not like sharing info would hurt when in the end they profit from everything Subaru sells.

Funny. All my engines in all but one of my Justys have been bulletproof. And I don't blame Subaru for that one either. The guy who owned it before me ripped apart the electrical and the thermo wasn't working and the engine overheated a lot. But, it still ran for 1 1/2 years on a warped and cracked head(before I traded it in, so no clue how long after)...

That was 93-94 and even though our family had rock solid Subaru's for over a decade before that, THAT is where I developed my love of the taste of the Subaru koolaid. Haven't found a taste good enough for me to change since.
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Old 05-03-2013, 06:36 AM   #108
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Originally Posted by neg_matnik View Post
Hmmm... Actually, the STI engine runs lower compression at 8.2:1 and a tad more boost.
The WRX engine runs higher compression (Subaru says 8.4:1, but I believe gurus in these forums have actually measured something closer to 8.6:1).
Regardless, I believe most of the issues start with the tune.
Going to any sort of competitive event (especially hot summer track days) with a bone stock STI and its bone stock EPA/CARB-approved tune is going to be hard on the engine.
Then, add things like improper oil used during these events (weak sauce energy conserving oil), failure to monitor oil level, failure to monitor water temps, insufficient octane level in the gas given the extreme conditions encountered during these events and it's easy to run into trouble with these engines.

No doubt, forged factory slugs would have been nice especially when relatively inexpensive cars like the Fiat 500 Abarth have factory forged pistons.
Funny, I could have sworn that the larger dome on the STI pistons would result in a higher compression ratio if everything else remained the same, must not be the case then. Thanks for the info, I never pulled up the factory specs before and just went with what an engine builder told me.
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Old 05-03-2013, 12:49 PM   #109
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Originally Posted by sc00by4life View Post
It seems that its a problem with ALL turbo EJ25 motors.

And the current WRX uses a single AVCS system identical to the 02-07 sti's. They were still experiencing ringland failures then as well, but not as many as during the 08-09 years (which seemed to be the most problematic).

As far as the sti requiring "more octane", i dont believe it.
On this site and iwsti.com you don't read about ringlands going nearly has often on 08+ WRXs unless the car is usually pushing beyond Stage II mods. I believe even running Stage II in a 08+ WRX over the long term can be risky especially if you're racing.

As for the octane requirements for the STI, the manual recommends 93 and requires at least 91. For the WRXs, the manual requires 91, but says you can run 87-89 in certain situations/elevations, but that you may see reduced power.

For any turbo Subaru, I'd recommend running the highest octane available.
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Old 05-03-2013, 01:08 PM   #110
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Originally Posted by Lrn2Corner View Post
I blame the cheap cast pistons regardless. Subaru is the only Japanese import that runs hyper cast pistons in a boosted engine. There is a reason why all the other imports ran some variation of forged internals or even used ceramic coated pistons in their boosted engines ever since they started producing them in the 80s. its better to over engineer than to do just the bare minimum. Apparently Subaru missed the memo.
Nissan (GTR and Juke), Hyundai/Kia (2.0T motor), BMW (N20, N54, N55 motors), and many others runs cast pistons in their turbo motors.
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Old 05-03-2013, 04:42 PM   #111
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Quote:
Originally Posted by MaddMax View Post

Nissan (GTR and Juke), Hyundai/Kia (2.0T motor), BMW (N20, N54, N55 motors), and many others runs cast pistons in their turbo motors.
Do you think this is because of emissions/oil consumption due to the tolerances that the forged pistons require?

My wrx will definitely not see higher than stage two power levels, from what I've seen it can handle that level just fine and remain very reliable granted maintenance is done correctly. The only thing I see the STI brings as far as increased reliability is the tranny, ringlands can't handle much more if anymore than the wrx. If going for high power levels I say buy a used STI for a good price and build the motor. Otherwise go EVO, that being said, my stage 2 wrx has plenty enough power for me and I don't forsee any reliability issues with it in its current state.
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Old 05-04-2013, 11:33 AM   #112
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Originally Posted by MaddMax View Post
Nissan (GTR and Juke), Hyundai/Kia (2.0T motor), BMW (N20, N54, N55 motors), and many others runs cast pistons in their turbo motors.
They also run direct injection which makes running cast pistons less problematic by a large margin. Show me an EJ255/257 running direct injection and a turbo that I can buy from subaru. You can't can you? If it was available or an option I can guarantee you we wouldnt be having this conversation.

You can't compare engines with superior fuel management and delivery which heavily reduces the chances of detonation to something running outdated fuel injection tech. Not to mention the lame PCV system that lets oil into the intake charge during spirited and competitive driving.

With the combination of those two things, until Subaru got its hands on DI tech they should have been running forged pistons from day one. Then none of us would ever have heard of anyone busting a ring land and this conversation would never exist. Instead we would still be poking fun at blown mitsubishi transfer cases rather than seeing threads like these.

Before direct injection you had every boosted engine out there with some form of forged internals for a reason. I agree as tech gets better forged internals will be seen less often in production cars. The GT-R is a testament to the improvement in technology that has come in recent years. It shows that with better tech engine component durability improves without having to use more expensive materials or forged components.

But the current STI using the EJ257 is not a GT-R with the best that automotive tech has to offer. It is outdated and is finally going to catch up the rest of the performance world with this next coming model in terms of engine tech. <---that's the bright side out of this whole rant. Unless you dont want a sedan lol.

/end rant
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Old 05-04-2013, 11:10 PM   #113
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Originally Posted by Plasmabluewrx View Post
I would bet a lot of money that most ring land issues are cars that were over-revved. People miss gears and bounce off the limiter, do it too often and stress weakens parts. Add to that gas that may be a little watered down from sitting, and there goes piston #4. The people who have stock cars were most likely at high load in the lean part of the stock tune.
Overall, it's ridiculous to think that Subaru would not make a change if there was an issue with the pistons or anything else. I don't need to know exact percentages to know that Subaru would not be as profitable as has been in recent years by releasing defective motors!
SS, I would suggest a new STi or if price matters WRX, used ones are a gamble and cost nearly the same as new. Another benefit of new is this is possibly the last year of this generation and it is pretty cool to have the last year of a specific model.

Hitting the rev limiter = ringland failure? Please explain, I'd really like to hear that one. Gas that may be 'watered down'. Really, how often do 08+STi owners not drive their car? It would have to sit for quite a while before the quality of the gas would be a real issue.
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Old 05-04-2013, 11:57 PM   #114
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Originally Posted by PearlRex11 View Post
Do you think this is because of emissions/oil consumption due to the tolerances that the forged pistons require?
The EVO X 4B11T engine and Boss 302 Roadrunner engine both use Mahle forged pistons so I don't buy that tolerances have anything to do with it. It's probably $$$ that is the biggest reason. Had Subaru gone with something similar chances are the these engines would be much more reliable at least at stock levels and stage 2.
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Old 05-05-2013, 05:33 PM   #115
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Hitting the rev limiter = ringland failure? Please explain, I'd really like to hear that one. Gas that may be 'watered down'. Really, how often do 08+STi owners not drive their car? It would have to sit for quite a while before the quality of the gas would be a real issue.
Hitting the rev limiter does not mean ring land failure, however missing gears often and over-revving an engine often does stress ring lands. The force built up has to go somewhere, seeing as the easiest place for it to go is past the rings (putting all the force on the ringlands) this causes failure. No I did not say every time someone hits 7500 rpms on their stock motor it will break parts, but over time I guarantee you it will weaken them.

I know of several BP stations and some cheap stations that were known to give out old, watered down gas. Did I say it will water down in the tank, no I didn't. When you think your putting in 91 and its 89 due to whatever reason, this damn sure will lead to detonation on this motor, hence piston failure.
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