what rpm can it take?

[Capri306]

Hydraulic (and especially hydraulic rollers) are a significant limiting factor regarding engine speed limit. I've seen this on engine dynamometers and heard it by word-of-mouth from local gearheads. I can't say I've ever had my motors up that high since I've usually built mine for low-end torque and reliability...plus there's that darn 6250 RPM limiter on the Mustang's EEC-IV.

It makes perfect sense if you have ever had a hydraulic roller in one hand and a regular hydraulic in the other. The mass difference is amazing (relatively speaking), and if you've ever seen the internals of an engine while it's running, you'll better appreciate the abuse engine parts must withstand. Imagine having that lifter in your hands and shaking it back and forth about 3000 times a minute (equivalent to 6000RPM). Honestly, that's not even close to the stress the lifter undergoes, but you get the idea.

Hence why I'm going solid roller when my project takes off after college.