Max RPM for da slant?

Read this about the 170.
http://www.valiant.org/sixup.html



Other slant six performance notes

The 170's relatively short stroke allows it to rev high. Both Russ Shreve and Steve Remington - a Valiant engineer and expert - agree that the 170 is the engine to use if you will turn over 6,000 rpm frequently. According to Russ, a 170 CID slant six HyperPak would deliver a comfortable 182 hp, and turn 8000 RPM if you kept the cam lobes lubricated. He also said that:

It had a shorter stroke than the 225, but the same head and valves. Low end torque was less, but ultimate power was the same. In addition, with the lower block height it was a sturdier engine, and with the shorter stroke could rev higher with less chance of an rpm failure. The Achilles Heel was the cam lobes.

If he [someone upgrading their six] is going for higher power and RPM he is going to need the HyperPak clutch and special clutch bolts. Otherwise he is most likely to have a clutch explosion. I also recommend an explosion shield. A clutch explosion can cut a car in half.