Originally Posted by
supertib
Actually it is not done inside the sleeve !
The results are actually quite good as not only dos it reduce breakin time but it also trues the piston which is often not perfectly round....What we end up with a lower friction piston that makes a better overall seal....Just lapping the piston alone makes a measurable increase in power over a traditionally broken in engine !!! In fact a few of the factory tuned engines feature fitted pistons ..
I know you don't lap the piston inside the liner... But in my eyes, taking material off of a piston will to some degree shorten the life of that piston and liner set. Does it have some benefits? Sure... But any modification to a model engine has to be a compromise. In a racing environment where likely an engine will last a season... Maybe two - and get replaced, I can see it being beneficial. For someone who isnt going to replace it in a year or two, the benefits go away. At least the way I see it. If lapping ABC Pistons is standard practice for all modified engines, I wouldn't get an engine done. Not trying to beat you up Neal... Just not on the same team as far as this goes. If we were working with an aluminum liner with an extremely low expansion rate, then I would be on board.
If these engine companies were really "into" innovation and wanted to bring something more advantageous to the table, they would use hard chrome plated aluminum liners. They weigh less and don't lose their fit nearly as quickly. The fit feels the same warm as it does cold. You don't get that kind of fit with a high expansion metal like brass.
Sorry for for the off topic rants.