how high of a horsepower range can hyd rollers be used to in a mainly street car and still be reliable. I don't really want to run mech lifters because of having to reset lash all the time. But I am planning on around 600-750 hp and around 650 ft/lbs. Could I use say the 3.1L lifters or even aftermarket hyd rollers (comp,crane, crower) and not have to really worry about one of them failing.

 

About 6500 would be the practical limit, maybe a little more with a rev kit. Failure isn't the issue, they're just subject to the same high RPM limits as all hydraulic lifters.

 

so the 3.1 lifters should be ok? I want to just build something decent and somewhat cheap. I was thinking the Dart Pro 1 heads and eagle 4340 crank and rods and either srp or JE pistons. hoping for around 600 horse. should they be. it will be a 421 so it won't rev to high anyway. 6500 shold be about max limit.