i understand what you are saying but a 557 and a 572 both have a 4.5 in bore.

It's probably because they get a good deal on parts. Aren't big companies all about the bottom line anymore? Who knows maybe in the next couple of years those motors will be assembled in China.

Probably many factors involved, target horsepower based on out drive rating, availability and cost of components, durability of combination etc.

i don,t think that,s it,a4.375 and a 4.5 stroke crank from callies cost almost the same.as far as [assembled in china],the mentioned engine manufactors would not last long if they sold foreign junk,we are talking about high end packages here not chinese junk.

Maybe it can. Does anyone know what the actual bore spacing and deck height is?

LT5s can be taken to 415s or even 440s with new liners a guy developed years back. It will be cool when the aftermarket starts boring and stroking the QC4V and adding bigger turbos. But it won't be cheap.

Virtually everything for LT5s was custom and cut from a billet when they got heavily modded. Like 5k for crank, 3-5k for cams, and 2k for headers. Expect the same but worse.

Hmmmm. Thats interesting. Wouldnt they design the drive AFTER the engine to meet its HP demands?

I know. I've just been on a bash China kick lately. I would imagine it has to do with wall thickness, rod stroke ratio, ect. And now a days you have to throw in the "green" factor. The merc stuff has converters don't they?

im with you on bashing the chinese junk,im not sure of the number but i believe the converters are only required below 500 hp.

mercury did . m8 drive.

Our 632's in the 33 have been great but a little high strung before the detune.
We have a 572 in the deck jet boat that took a s#$t after less then 1 season with a 1071 on top on pump gas so we pulled the tired 496 tall deck bus motor of the shelf and put the 1071 on top and bolted her in to finish the year,the 496 runs harder sounds better and go'es 8 mph faster then the 572 ever went.