Oh it can be done, and done in a way where you have more torque than you ever thought possible.

Roby

My 1987 RumRunner has about 475 hours on its matched 350s, and they still run great. I have experienced the moisture issue. I just keep the oil fresh, and they keep running.

370s ran over 500 hrs, sold it. New owner overreved a motor about 200 hrs later, holed a piston.
525SCs ran over 300hrs, new owners overheated it at about 400hrs. Burned the head gasket.
My cruiser has over 2000 hrs on the motors, beat that.
My boats seem to run fine when I own them. Hmmmm.

I've got over 200 hours on a 2000 Merc 502 Mag with a Whipple (six pounds of boost). I've broken the "stock" forward gear twice (broke the "floor"). Now I have an IMCO HD forward gear.

I change the oil every twenty hours, and it still runs great!

A friend of mine has a 502 mag mpi with 750 hrs on it and no problems yet..

Stock 502 mags,465 hrs on 1 engine 380 on the other.
run perfect, uses 1/2 qt of oil in 15hrs. Ask wd833,
it was his boat!Bought it with 415 hrs on it.

There's nothing WRONG with an OHC marine motor, other than nobody makes a big un.

Sterndrives were/are limited to under 6000rpm continuous duty due to their oiling requirements. At that ceiling, an LT5 would never make over 450hp in a marine app and was wider than a Big Block once you put manifolds and risers on it.

Cost? Definitely placed it in the "novelty" division.

I remember reading magazine articles of two different LT5 powered "concept" boats. There must have been more, but I don't recall knowing about them. It was tried, and the LT5 didn't offer much more than an expensive way to put a motor in a boat that all normal marinas were afraid to touch.

Toyota. Yep, they use the VVTi Lexus V8 in ski boats. Same story. Lots of hype, no true performance benefit over a big block.

And no packaging benefit whatsoever.
(remember, that with the large valve covers on a DOHC, you end up with a very WIDE motor with risers that must go above the motor).

Now, if somebody built a 550 inch cast iron SOHC motor (SOHC would be a good compromise between the benefits of losing pushrod and lifter mass, yet retaining normal widths of valve covers), then you got something to discuss.

Any foundries interested in this??? It's a good idea. Just an expensive and very limited application.

Probably end up with the cost of a turbine when it is all said and done.

Marine industry has no choice but to start with automotive cores to marinize from. Its purely a cost issue.

And the auto industry shows no intention of abandoning pushrods in large motors for now.

4.3 V6, I know not real performance, but I guarantee there is over 1000 hours on it, most likely around 14-1500. I drive the crap out of it, 2 speeds, idle and WOT.

My 1979 Scarab had 454/330's in it and one was re-rung and had new bearings in it before I got it and the other motor wasn't touched.....at least as far as the previous owner and myself new of....anyway the motors were stock bore still and had 1,800 hours on them....last I knew it was still running fine.....Fred

Fred you should have kept the 30!!!