Does this mean overbore?

[LKWTSI]

I'm pretty sure this means it's been overbored by 0.50.

Am I correct??

Been sniffing too much carb cleaner. Just realized that's 0.50 not 0.050.

What could this mean??

 

[BogusSVO]

the block has been boared by .5mm or appox a .020 bore

are those even turbo pistons? I thought the the turbo ones had 63DT cast into them.....

 

[ramsack]

those are not turbo pistons as indicated by the missing t

 

[LKWTSI]

Thanks you guys for en-lightning me!!!

What are the biggest problem running this in a turbo engine?? strength?? or what?

 

[JEFFREYCASTGSX]

The ring lands are higher and thus the pistons are weaker, detonation though is what is gonna kill them. On the bright side compression is higher, just watch out for detonation though.

 

[LKWTSI]

The ring lands are higher and thus the pistons are weaker, detonation though is what is gonna kill them. On the bright side compression is higher, just watch out for detonation though.

That's a new expression for me

Can you explain what that means in terms of what the difference in ring lands are?

I get the weaker part and how the detonation will be a prob'. But what's so different that the CR changes. From what I can see the piston comes to the same TDC as my old block. But again I'm just using my eyeballs not high tech measuring device

 

[JEFFREYCASTGSX]

There is less cc in the piston making the compression higher, 9:1 i believe. The ringlands are higher in the pistons, detonation is gonna kill the piston rings due to them being higher, on a turbo piston the compression is lower to combat detonation and the ringland are lower for if detonation hits then the piston/rings will not be damaged, as easily. The difference visually in the pistons is not very obvious though.

 

[donniekak]

Simply put, the stock setup is tuned for 7.8:1 compression. 9:1 compression requires a different tune. Even with a good tune, any detonation will damage the weaker pistons.

 

[ramsack]

i really don't think detonation will automatically and instantly kill the non-turbo pistons. plenty of people have run them and i'm sure during tuning they didn't have 0 counts of knock to get it tuned safely.

 

[BogusSVO]

Simply put the ring is closer to the top of the piston, with that being done, more heat is transfered to the ring.
with more heat in the ring, the ring expans faster and more, the ring end gaps close up, butting the ends together, causing the rings to flex, that force cracks/breaks the ringlands.

also that being a NA engine, the ring end gaps are smaller than the turbo ring end gaps...

so all in all, get some stock replacement turbo pistons and rings, in the proper over bore, and have them hung on the rods....

seems that the NPR rings and pistons are an afforadable choice... they also seem to have a good rep on the board...

Check with the supporting vendors, I am sure a new set of pistons and rings would be around $100 or so

 

[LKWTSI]

Thanks for the info, guys. I actually tracked down the guy that sold me the block. He is going to get me a replacement set of turbo pistons. He was cool about the whole thing and it appears it might have been the machine shops screw up and even then, who knows. So I'm stripping this thing back to bare parts and rebuilding everything, so I know everything is torqued and appropriate spec'.