Program Main Cap question.

A 2 bolt Program block with caps on #1-4 and studs will hold up to 600hp. Like Skrews I don't bother with 4-bolt caps and I don't use girdles. But I do use the Program 2-bolt caps with main studs. I use them because the caps can deform under load at those levels and if any detonation creaps in. the effects of the movement is visible on the mating surfaces and the bearings. Studs alone will hold up to 550 with a good crank and good machining. Beyond 600 you start to get issues with the head gaskets and cylinder integrity in addition to the cap flex and at that point just get a better block.