Keith Atlanta

After all this time why is the 557 bore and stroke so desirable?

Sterling 1550 & 1150 & 1700 Turbo are 557's
The New Chief 1900 turbo is a 557
Merc 850, 1075, 1200 yep they were 557
The Merc 1350 & 1650 are 552 (not 557 but why limit your flagship product when you did a clean sheet redesign?)

Sonny's is making bigger and bigger N/A power out of monster bore & stroke. Why arent marine guys doing it? What is this MASSIVE benefit that cant be overcome by displacement? The technology is there, what is the magic behind the 557?

Why not 598 or 632? Or like Sonnys 762, 770 or 864?

mike tkach

iTrader: (3)

2 reasons that come to mind,1 the 4.375 crank is less prone to breaking than a 4.5 crank.2 more room for a nice ring package.these are things to concider in a high horsepower endurance engine.

pqjack

not so long ago, 572 was the way to go.

mike tkach

iTrader: (3)

it still is for me!

Keith Atlanta

Exactly my point. Why arent we up to 632 or BIGGER now?

Fenderjack

iTrader: (2)

I would think it has something to do with piston speed and the amount of reciprocating weight.Them big car engines only do high RPMs for a short time.Boats do it for for longer periods.I would think they have a bigger chance of self destruction.Just my 2 cents JOHN SR

ThisIsLivin

It also has to do with cylinder wall thickness, 4.5" bore verses 4.6" or larger. That's the reason the ZR1 is a smaller displacement than the Z06, they needed thicker cylinder walls for durability under boost. The big Pro Stock motors are billet blocks and 5" bore spacing or more. If you were looking to go NA than the 598's make more sense. You have a lot lower cylinder pressure and less stress.

hotjava66

Agree with all of above and will include the question of drives. Not much that will live behind the torque of a monster displacement engine.

Also the added mass of bigger everything moving at faster speeds would generate some serious loads on components.

TylerBurich

A similar question came up 2 years ago. My take was that 557cubic inches netted the most reliable setup with readily available parts (as if that even applies to this industry). Curious also why merc stayed around that same displacement on their brand new stuff. Only thing I can think of is keeping the deck height within reason to keep the engine package within a certain dimension.

Keith Atlanta

I agree with all of you, but the question behind the question was the 1350/1650. If you are going to go with a clean sheet engine design why so "small'?

Shouldnt that SOB been about 100 cubic inches more?