what to do about my crankshaft
 

I took my 454 twin turbo engine apart to freshen it up. The engine has been sitting about 4 years because of not having the time to rebuild it after pinching a ring in cylinder 7. The machine shop said they can hone the cylinders and 0.30 pistons will work again. ( the block was bored 0.30 before). They recommended line honing the mains and installing main studs. They also said they would want to cut the crank to 0.20 (it was cut to 0.10 on the rods and mains before) The crank is a factory GM forged 4.0 stroke LS6 crank. These are mercruiser twin turbo 475 HP engines that are LS6 long blocks with Rayjay turbos. I am going to make about 5-6 psi of boost and spin them to 5400 rpm. Is 0.20 safe to cut the forged crank too? If not would a cast steel crank handle about 550-600 hp?

phughes69,,,,,what machine shop????

i have been going to dynamic speed and marine since late 70's.
located at hall and Jefferson, talk to Ron or mike.

Automotive Machine in Fraser. I talked to Jack directly about this yesterday. Im going to go there today and get all the details and weigh my options. 1: I either have the crank cut and nitrated or 2: I get a stroker kit.
My rods are the stock 7/16 rods but have ARP rod bolts put in them. The existing pistons are Speed Pro L2453F dished turbo pistons No mater what I still have to get pistons

once the crank is ground .020 the case hardening is gone,by the time you send a stock stroke crank out for re hardening you will spend more than just buying a new crank.

local crankshaft repair shop tells me they can cut it down to 0.20, nitrite it and straighten it for $440 vs $950 for a new forged, balanced 4" stroke crank. At Summit a new Scat 4340 forged crank is 743 but would also require balancing.

You might look at the Lunati Voodoo crank

the machine shop will say tuff chit if it comes apart, an extra 300 buck to go back to standard is the way Id go,,,,jmo

I wouldn't go more than .010.

Why do they want to cut it another 0.010" and align hone it? Was it that major of a failure that damaged the crank? If not tell them to polish it and be done with it.

a few months back i sent a 4.375 stroke bbc callies crank to shafteck to get welded,reground and re hardened,1100 bucks.still way cheeper than a new one but for a 4 inch stroke gm crank it would not be cost effective to have it done.what shop will re harden a forged crank for 440 bucks?

phughes69,,,,
i dont think i have ever run greater a 0.010 crank in all my race engines..
i ran a super gas camaro back in 80's

i changed my motor from 4.0 stroke 4.25
ron, (dymanic speed) got all my parts scat crank , eagle rods srp pistons.
i dont know auto motive history , but i can tell you dymanic puts out alot race and marine stuff..

gw

Ron at Dynamic did the motor for my street car, I highly recommend them.