red line

You guys need to state your engine size. The 225 has a 4.12 stroke and the 170 is exactly 1" shorter and higher revving. I think the NASCAR hypers turned 7000.
I doubt my 225 will ever see 4500. (unless my son borrows it without me riding shotgun] Didn't build it for that. I have a small Autometer tach around but it hasn't turned up yet.