ENGINE BLEW UP ON ME! HELP!!

RHaas said:

I now have mixed feelings about these engines being able to handle these tunes. After much research I found there are many examples of this happening but then there are others who have yet to have any issue at all?

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Nodnarb said:

Can anyone point me in the direction of where to find info on engine builds. I will be building the bottom end of my R very soon and was wondering what rods/pistons are most commonly used and how they made out with them. I’ve heard differing opinions on using stock 82.5 pistons or honing out to 83 for a better fit.

I read of a guy local to me who used IE rods and JE pistons(stock size 82.5) and something is definitely not working out for him. Said the JE pistons slap a ton (make noise) when cold and has loads of blow by. Filling a catch can in an hour.
I imagine he will be rebuilding again very soon.

Also wondering if the Mahle slap a lot too. They use a propriety alloy and I don’t believe they’re forged like JE

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WhyNotZoidberg? said:

Our ECUs run load-based maps, not boost-based, so it should adapt to elevation changes.

These are not Subarus

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littco said:

This is not true.. they are boost based .

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Ed @ EQT said:

They’re actually largely torque based. There’s a MAP ceiling the gets set, but until it hits that, the ECU is actually targeting torque. So in theory boost levels can vary with altitude.

— Ed

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Hoon said:

If he's filling a catch can in an hour, something is very wrong. It's not the piston, it's the moron who did the machine work. Your machinist is much more important than your components. Personally I'd run the IE stuff if building one of these motors, but JE makes a damn good piston also.

These motors have thin walls to begin with, I would avoid going with a larger bore if at all possible. The additional strength is much more important than a negligible bump in displacement.

I've run various forged pistons in other applications. When you build a motor loose they drink a bit of oil, but that comes with the territory on 500+whp 4 bangers. That said, forged pistons expand a lot more than cast or hypereutectic, so they do need more piston to wall clearance, but they shouldn't be loose to the point of loud piston slap...if anything, it should be a light tick for the first few minutes after cold start.

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navindralr said:

My understanding is is IE and mahle pistons are the go to option. Usually stock size is good if the piston walls are still perfect. Most engine builders only hone out if there are defects in the wall that need to be removed. I think blow by is from improper engine break in and rings not seeing correctly. I'm not an engine builder but this is what mechanic friends have told me.

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navindralr said:

I should have said cylinder walls, not piston walls.. but either way...

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Nodnarb said:

Thanks for the info! I’ve had forged pistons in a Chev v8 and like you said I could hear a tick and wouldn’t beat on it till it warmed up. I’m pretty sure I’ll go with IE rods and Mahle pistons. Not sure on h beat or Tuscan yet. I’ll get the rifle drilled as well for better oiling. Waiting on a quote from Carrillo/cp to make a final decision.


I’ve had 2 suggestions to stay stock bore if at all possible because of the thin cylinder walls like you said, and one builder recommended 83 mill to get a proper clean and round hole. I think I might have to wait till the engine is apart to decide. That’ll slow down the process, but I’m thinking it’s the right way to go.

Also I had a 2 builders suggest to deck the block, and one say definitely do not deck the block because it could fuck with the timing which is finicky in the 2.0 as it is. Still undecided on that one.

Thanks again

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ChronicSPD said:

Honestly, you say you like the car. If that's true, repair it as cheap as you can (but correctly) and drive it stock or do research and mod it correctly with a safe tune. Blown motors aren't too common on these cars. Many cars run with some serious power with no major issues.

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Gti jake said:

This thread is useless without pictures.

I saw another thread about a blown up gti on the FB page today, it was also APR stage 2 without an intercooler upgrade. When the weather gets hot and IAT sky rocket you’re asking for trouble, especially with stock heat range plugs (if that’s the case) on a stage 2 tune.

Anyway, find a salvage yard with a mk7 and pull the engine. Replace yours and be done with it. That shop suggested to rebuild the replacement engine...why? To make more money off you. There’s tons of bone stock low mileage mk7 totalled from collisions out there...

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