If you look around at daily driver type hypereutectic pistons (like Speed Pro, Silvolite, Mahle hypereutectic, etc) for a rebuild, you can’t help but notice that they all have a lowered deck height compared to OEM pistons. The result? Unless you deck the block, mill the heads, and/or use thinner head gaskets, you WILL lose compression if you use these pistons.

I have always wondered why nobody sells stock compression height hypereutectic pistons, as these would be desirable for people who have no interest in nitrous and/or forced induction. The other day, I brought this up while taking my block to the machine shop, and he said that there is a reason why ALL hypereutectics are reduced compression height. Quite simply, he said it is a federal law. Specifically, this is done to keep compression from being easily increased during rebuilds in order to keep emissions in check. The reasoning here is that hypereutectic pistons tend to be used in vehicles that are driven more on a regular basis than forged pistons (which are often used on non-daily driven high performance vehicles). So the government targets hypereutectic pistons rather than forged pistons (which are often sold as ‘for off-road use only’). Is this true?