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4 cylinder engine with one piston oversized with 0.5mm

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Hello All,

On the dyno during WOT ramp runs 1 piston melted due to injector failure, on a Lada engine.

This is a 4cylinder 1.6 liter naturally aspirated engine and it is fitted with ITB, and heavily modified with cams, compressions, etc. it produced before 175 hp, the factory performance is 75hp.

This engine had 79.5 mm pistons, and only one suffered damage.

We have 1 spare piston from an old project with 80 mm bore.

To keep the rebuild costs low, we are thinking to repair it by fitting this old piston, but than the bore sizes would be different.

Did someone do a similar repair project? If yes, what was the experience and result?

Would you reccomend this way of repair or we should buy a new set of a pistons?

Cheers,

Tibor

Hello, I am laughing because I have done this type of repair before but kept it pretty quiet until now.

it is not common practice or good practice, it will have its own set of complications and new challenges that come with it.

i would do it as a last resort to get a car out of the pits to win a race or just because I did not care, Other than that I would not do it. the engine I did it to may still be going to this day I really do not know.

Regards Ross

As Ross said, sometimes you have to do things like that to get the car out for an event. Not something recommended,though, to put it mildly.

If you can't wait, do it, and pick up another block you can bore to suit a new set of pistons, or just pick up a replacement and re-use the 3 good ones in a virgin bore. I have known one instance with several mm difference (undersize), that ran for some years - but that was a lightly stressed, low rpm engine.

Hello Ross and Gord,

Thank you for your replies, I really appreciate it.

Based on you comments, we will not choose this route :)

We will order 1 new piston and prepare another block.

Cheers,

Tibor

You could also buy a set of four more oversize pistons and bore the block you have to suit, then you'll have a fresh engine and a spare piston. You're going to have to balance costs and circumstances - for you, a block may be cheap and plentiful but pistons expensive, for others it may be the other way round.