Yes, the machine shop needs the pistons to bore a block. Most of your piston manufacturers have never heard the word "uniform." The piston sizes are all over the place. Every once and a while you will guess wrong. You order a set of .30 and have to have a .40, so what, the dist. will swap them.

 

Just curious as to what kinds of pistons some of you guys have been buying that have had all these problems with random piston sizes in your sets. I am assuming ( I know where that can lead) that these are very cheap pistons that I might not be familiar with. The cheapest pistons I have ever used are the KB Hypereutectic sets and even those are extreemely consistent. As I said before in all my experience with street and race engines I have yet to see any pistons from one of the good name brand manufacturers vary more than a couple ten thousandths.

 

also I think it would be cool to get an actual technical discussion going on this board. There doesn't seem to be much talk of actual engine performance.

 

The last set that I used, were K.B. Hyperutectics. There was enough difference in the set to matter. It was nothing that could not have been taken care of with the hone, but why not just bore to the piston in the first place. I have also seen some variance in TRW.