k24u

I built my 454 330hp to a 420 last year motor runs excellent even though I have my bottom end balanced I still have the cast crank stock rods but forged pistons. I have been worried about running it to hard with my current crankshaft I bought a stroker kit for it balanced with H beam rods forged pistons and forged crank it would turn the motor into a 489 and raise my compression up to 9.3-1(up from 8.79-1) would it be worth it to remove the cast bottom end and install it and would it make a differnce in performance?

Elite Marine

Performance no, longevity probably. You have to change cranks anyway so upgrade to the forged crank. We offer rotating assemblies and full line of Scat parts. Call us if we can help.

Kirk
Ateco Engine and Dyno Shop

ghittner

Longevity, Yes. I had the exact setup you had and made the change to the exact bottom end you have now. 4340 with H beam rods and SRP pistons. I did it because I was making over 600 HP on the stock assembly and oblonged the crank due to the power. Never wiped a bearing but did some damage to the two in the crank center, it was stretching. I am now running blown 489 @ 800 HP and it runs and lives perfecly. Do it for piece of mind and you can squeeze all you want from it with no worries. Good luck.

KAAMA

Going from a 454cid engine and stroking it to 489cid...yes, you should definately see some kick in the pants performance gains---especially in throttle response/torque.

Also, back in the 80's we had some Merc 330hp engines in a 1978 Scarab and we decided to upgrade the performance of the engines. We kept the stock 3/8" rods only we had them shotpeened, reconditioned, ARP rod bolts, and ran the same stock cast cranks, same 2-bolt main blocks only we used studs and had them align honed on the mains, and the entire rotating assembly was balanced. We used straight Pennzoil 40wt oil, and the only thing we changed on the bottom ends was going to new forged pistons and cam upgrade. We turned the engines at right around 5400rpm, probably about 450hp, and they lasted for about 6 years right until my friend sold his boat.

Maybe we were lucky running those cast cranks, but having correct, competent machine work on the rotating assemblies may have been what saved us and lasted so long.

1BIGJIM

I will pass along some advise that was given to me years ago when I was going to do a 383 project.

Keep your good 1 year old short block or sell it.

All you need it a block to do your stroker project.
I put together a 496 last year and it worked great.
This week I am putting together a 454 with left over parts from a couple of years so I can swamp the 496 if I sell the boat.

k24u

Since I have the kit maybe I should just get a block and build it the way I want and use my current engine (it only has 24hours on it)over the next year and then finish it up next winter and really surprise some people and have a 420 as a spare