Polishing diesel pistons.

Polishing diesel pistons.

Customers have asked us about claims that polishing piston bowls reduces cracking, changes compression or improves fuel economy. Those are different claims and need different evidence.

I bought and read SAE paper 902141, 'Effect of Mirror-Finished Combustion Chamber on Heat Loss' (1990). It discusses reduced heat loss from a polished combustion chamber; it does not establish the benefit of partially polishing a particular customer's diesel pistons.

For a claimed compression change, I would want the amount of material removed, the chamber-volume calculation and before/after measurements. A photograph of a polished piston does not provide that information.

Ceramic coating is a separate approach to managing heat transfer. Choose the treatment around the engine's requirements and measured results, rather than assuming any surface finish adds power.