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What to do: Piston Ring and head gasket failure

2430 Views 19 Replies 8 Participants Last post by  Raakaar
Hi All, Been a member for awhile, but i think this is one of my first posts.

Got into a perdictament today, tuner told me my 2014 STI has a #4 Piston failure and a head gasket failure. Currently my car is running an AP w/ pro tune and Cobb Turboback exhaust. They are doing a tear down to see what else is going on.

I am trying to figure out what I should do, go OEM or go with a built motor. I don't have power goals, other than wanting to have some fun with the car. My primary goal is reliability and relatively normal maintenance. Can anyone offer any advice on what I should do? Below is what my tuner recommended I do while I am in there making changes.

Start with:
  • IAG Stage 2.5 closed deck short block
  • Cobb Intake
  • IAG or Cobb Fuel Lines and Rails.
  • Cobb/ID Fuel Injectors (1050x or 1300x2 depending on power level)
  • Fuel Pressure Regulator
  • Fuel Pump
  • EBCS
  • AOS

  • Bigger Turbo
  • Turbo Inlet
  • MAP Sensor
  • Ethanol Set up
  • Header
  • External Wastegate
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it's hard to say without defining your goals. if you plan on staying stock turbo forever, the type ra oem block will do just fine.

If there is ANY chance of you going bigger turbo, the IAG block mentioned is a wonderful block. it's damn near exactly what mine is (mine is just the 2, not the 2.5, difference is the 2.5 is closed deck). for reference i'm on a blouch 20g xtr turbo running 23psi on pump 93. on iag's dynojet i put down 377whp/401wtq, although i have had a different tuner than what iag had retune the car and i may be just under that now.

either way i'd suggest getting arp head studs for it. and if you can go with a better valve/spring combo, as with just doing a shortblock tthe valve/springs will be the weaker point if you ever wanted to run higher boost.
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there is a chance that I would go bigger turbo, just don’t know the timing, not in a rush to go big power.

My goal is really about reliable and daily drivability power. I don’t want to be daily driving a beast of a car every day.
to be honest having a car with that much power daily driving it wasnt bad at all. everyone makes it out to be like it is terrible or hard to handle. especially with turbo lag, it drives just like stock till you step on it. as long as you are aware of how hard and when you can step on it it's not a big deal at all.
? What does that even mean ?

My built 05 was far more driveable after it was fully built. Stock my 2020 does not run as poorly as the 05 did stock.

Any block (so most IAG blocks) with 2618 pistons will have shorter than stock lives. Think 60K+ high performance miles. You might get to 100K, but you'll know its not new . . .
i get that. there are plenty of 100k+ iag blocks out there that are daily driven though. you may be a little down on power but the car can still be strong and fun at higher milage with iag blocks.
I just don’t want another piston ring or head gasket failure again. One time is heartbreak enough
that's all going to be in the tune. if you can run e85 that is safer. and you can make more power.

the reason you need to define your goals is because you may be ok with the type ra block. you may need an iag stage2, or you may be needing to go with an iag stage 4 extreme long block. without knowing or at least having a general idea of what turbo/fuel/power you would like to be at, it's hard to make the proper suggestion.
Just curious - I autocross heavily. SCCA, which is usually the most restrictive ruleset, now says,
"Boost regulation systems, either electronic or mechanical, and electronic fuel cuts referencing boost pressure may be modified, replaced,
or removed. This does not allow for changes to the turbocharger or wastegate (including wastegate spring). "
This changed a couple of years ago. So my new tune is allowed, which does have some increased boost. Otherwise, Perrin downpipe, Cobb intake. On CA 91 premium ☹ it rolls ~300whp/300wtq.
BUT, if you're interested in autocross to the SCCA ruleset, you may not substitute an aftermarket block like a closed deck. Just sayin'.

Also, just for a datapoint, this car was used once/twice a month for autocross and was not hammered on at all other than that. It had a mild tune that did not increase boost at the time. It blew a head gasket at ~90Kmiles and lost compression at ~100K miles, so I got a new OEM block. On teardown there was significant cylinder wall wear on the #4 and a little on the cylinder in front of that, and I heard two different stories about whether one of the ring lands had broken down. In any case I was pretty disappointed with that engine life. And I believe stories about higher performance builds having shorter lives....
within scaa you should be able to get stronger head gaskets, so far as the low compression, that could be quite a few things. mine lasted for +/- 40k miles (from 58k-98k ish) before it blew. when it blew it was 100% my fault (DO NOT GET POWER HUNGRY). cooling mods (dom cyl4 cooling, oil cooler, aos, etc) can help the motor last longer. So can an equal length header, as the stock header keeps alot of heat around clylinder 4. may be something to think about it.
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