When to shift; safe max RPM question?

turbokinetic

Member
Joined
Jan 29, 2008
Finally got a "real" transmission that will allow the shift points to be set higher than 4500 RPM! What is a safe maximum RPM for this motor? This is in my "hybrid" 84 Century. Engine is a year 1987 3.8 SFI, with stock crank (rolled fillet) and rods; forged Sealed Power pistons, Comp 258HR cam, and port work. Has Turbonetics GTK450 turbo.

It will pull like a freight train right to the rev limiter at 5500 RPM. Only bumped it once. It was pulling so well I had no idea I was redlining it.

I know this is a "no clear answer" question. What I am looking for is what someone with a similar engine would consider a safe RPM.

Thanks,
David
 
This may seem like a dumb question, but did you have the rotating assembly rebalanced when you changed the pistons? What kind of hardware? Billet caps? Need more info.
 
This may seem like a dumb question, but did you have the rotating assembly rebalanced when you changed the pistons? What kind of hardware? Billet caps? Need more info.

Not dumb questions!

Hardware is new stock bolts. Caps are stock caps. Pistons were installed on the rods by a machine shop and they were matched set. Rods were weighed and matched but the crank was not balanced.

Hope this helps.

Thanks,
David
 
I would be afraid to run it over 5000. Without a rebalance on the rotating assembly, you'll destroy the main bearings at high rpm. Ask me how I know.;)
 
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