Engine Blown [Turbo]
 

Hi guys, sadly my engine blew last week.

Context:
- Stock internals
- Ptuning Turbo kit , Garrett GTX2867R turbo
- 298whp @ 10psi [DynoJet]
- Tuned by Toan @ptuning

- Full Blown Oil Cooler
- Motul 300V 5W40


Car was running great for 6 months and a dozen of track days.
During the last track day, the cylinder #1 Rod cracked in two parts, and damaged the short block badly. It was a very hot and humid day

Im not here to blame anyone, I was quite happy with the tune, no signs of detonation seen on logs.... I will just ask you to help me do some forensics , because I will rebuild the engine and dont want this to happen again.

Bearings were in perfect condition, if you look into the lower half of the broken con rod it was spinning on the crankshaft just OK. This makes me think Oil starvation was not the cause. Maybe bad Gas -> Detonation?


Pictures:

https://i.imgur.com/KnJuqPp.jpg

https://i.imgur.com/AmJzWlE.jpg
https://i.imgur.com/CwFAz05.jpg
https://i.imgur.com/IXPUSVa.jpg
https://i.imgur.com/3MHx7SH.jpg
Looks like a crack in the piston... detonation?

https://i.imgur.com/4k6nWW6.jpg

Imo you just had a weak rod or one that wasn't as strong as the others anyway. 300whp is way beyond what they were designed for.

Should put a valve spring in there and fight for a recall. In all seriousness, this sucks, very sorry to hear that. I think metal fatigue happens gradually, and it finally gave out. As you said, given that it lasted this long, it may not have been the tune or any one specific issue.

I think really to avoid this, you need to address the rods themselves. There will always be a weak point, engine failure is never something you can guarantee won't happen. You just have to choose the risks you can live with and the ones you can't.

Do you have catch cans / oil cooler?

Well, I will blame your tune. I would get a different tune next time. Sorry about the fail though. Hope you fix it quickly

Of course, i just want to build a new block as "reliable" as possible. I know that 100% is utopic. Even 90% :lol:



I have a Full Blown Oil Cooler, Oil temps where steady, never north of 260F
No catch cans, but venting to the air.

If that rod bearing isn't scuffed then I'll guess that the piston was the first part to let go.

edit: On second thought, if the piston let go first, the small end of the rod would be beaten to shreds.

I'm jumping in to hopefully get schooled by the experts. Maybe it's impossible to really tell.

Good luck with the rebuild.

Too much boost, too much bang. Thats all there is too it. Should have bought a crawford shortblock instead of relying on those pencils for conrods to hold out

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These engines have weak conrods have a look on youtube under mrt performance they talk about it and have made stronger rods for the fa20, also u thing it would be possible to swap the turbo wrx fa20 motor �� just a thought

Its not as straight forward a swap as you might think, lots of fiddly wiring stuff, suffers from the same problems as LS swaps in that regard and some custom stuff has to be made up (like gbox adapter) and the starter doesnt fit but depending on where you live it might be a lot more cost effective than an LS swap. Where I live FA20dit's are half the price of an LS3 (the law here requires the engine be the same age as the car or newer so no LS1/2). In theory if I do all the work myself I could have it done for a similar price as the FBM kit with all the goodies but things never turn out that way

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When did the engine go?

High load low rpm?

High load high rpm?

Curve exit at the track.. I would guess around 4000RPM

If you look at most of the stock motor failures with boost it is the connecting rods that fail.



Next two most common causes of failure are spun rod bearings (from low oil and/or oil starvation), and valve train failures (from over revving the motor and/or manufacturing defects in the rocker arms).



Depending on your budget and goals, I'd say at a minimum you'd want to rebuild with forged rods and pistons. A damper pulley is also a good idea in my opinion.

If you were under high load, being the exit of a turn and that low of RPM was finally able to snap the rod. 10PSI at 6500RPM is not too bad for these rods but 10PSI at 4k is asking a lot of them. Multiple track days with this finally fatigued the rods enough to snap, that's my guess. These rods were not meant for such a high load at lower rpm's. If the block is still good, get a set of rods and pistons and your good to go. With that said you will be setting yourself up for more boost later if that's the route you decide.

Possible detonation but i would lean to the metal fatigue as you have had multiple track days and im sure you have logged for that and the tune was solid before.

Sorry for your loss. I always worry about this myself on the track, so I run 101 octane and even turn down the boost a little, especially hot summer California days.



Have you reviewed any of his logs? If so, what did you see that makes you blame the tune? He says he's tuned by Toan at PTuning. In my personal experience tuning with Toan, he's one of the best tuners out there. His tunes have even saved my own engine from mechanical installation problems that would have blown my engine (i.e. wrong map sensor in, switched vacuum boost reference lines). I've done more than 2 dozen track days with Toan's tunes and several over 100+ degrees F days included. I know there are bad tunes and bad tuners out there, Toan is not one of them I assure you.