With so many choices in components from the aftermarket or factory performance shops, engine builders have numerous options in designing their next bullet. Whether taking advantage of parts laying around the garage or building an engine specific to rules or a tight budget, the engine builder may need to make numerous calculations to make sure everything fits right–especially when it comes to the rotating assembly.

The website for United Engine & Machine offers an information-packed tech section that includes a set of handy calculators. Since the company’s expertise is in pistons (Silv-o-lite, KB Performance and Icon), there are calculators to help the engine builder figure out compression ratio, convert measurements, establish the proper ring gap, make sure there’s enough deck clearance and determine final displacement.

Another excellent calculator is the effective compression pressure ratio calculator. Many first-time builders don’t realize how much of the actual compression is lost when installing an aggressive camshaft. In addition to providing a calculator to handle the math, UE&M’s chief engineer John Erb also gives a detailed explanation of this engine dynamic.

So, don’t take any chances. Proper planning and measuring will save time and money, and the tech reps at the various aftermarket companies will be grateful that you’ve done your homework. They can double check your numbers before ordering the part or make additional suggestions. And this is a good time to emphasize that you should really be honest with your intentions for the engine. Don’t order a lumpy cam and high-compression pistons if 95% of your driving is on the street.