Couple reasons -

1. low end torque.

2. Marine Parts availability is huge between small and big blocks.

3. At or above 500 HP - Hp per HP a big block is cheaper---I had 500HP/ 500Ft LB 406 for decades that finally blew up for what it cost to rebuild from scratch I built a big block.

Those are the reasons you dont see them as much , but I still love them and had a ball putting big block on the trailer with my small block.

UD

Simple! Lots of cubes, lots of torque, move heavy lard azz boats better than high strung small blocks.

Simple! Boats are not cars. Big grunt rules in this deal.

For me its weight, cost and dependability. Im building a 525sc clone currently.

1. THats a proven dependable motor. There is no guesswork, the recipe and improvements are well known and have withstood the test of time. Im not trying to figure out cooling, wondering about reversion, trying to make sense of the computers and sensors, trying to figure out the "right" cam etc..

2. Weight. Weight isn't always the enemy. In a 22 foot boat weight in the right place can help the ride.

3 Cost. BBC/merc stuff is everywhere. If your a poor bastard like me, decent used parts, mag cores etc... are readily and cheaply avail. here, on FB, from friends etc.

But I have a small single...its relative. If I had something like a 28 cigarette, replacing big blocks, trannies and trs drives with a couple 550 hp na ls motors hooked to bravos , that could get fun in a hurry.

I yanked the all iron 454 out of my Checkmate and replaced it with an all aluminum 408ci LS2. The motor made almost 600hp and 550lbft N/A and really isn't very radical at all. It also weighs 500lbs less than the big block I took out. They say there is no replacement for displacement, well I respectfully disagree. I believe technology is a very good replacement.

Simple,,,,,lack of low end torque.

Peak numbers dont tell the whole story.

Two scenario's

1. Hey man what you got in that boat " its a 350 " ......O ok
2. Hey man what you got in that boat " its a 632 " ......hell ya let me take a look :santa:

This is so true, got compliments all the time on my Pachanga 22 which ran a warmed over cammed SBC. People loved the sound, loved the look, but the minute I said 350 they looked completely disappointed almost acted embarrassed that they dare think an SBC sounded "killer" :lol:

My 408 started making 500ftlbs at 3100 rpm's and doesn't drop back below 500 till 5900. I think that's more than enough torque to get a 4000lb boat on plane and out of the water.

SBC seems like a good fit for small singles and even some smaller twin applications. Formula built a 353 a few years ago with the Ilmor 570s SBC. Haven't seen another one from them since. In person it sounded good but there was no performance advantage.

Overall just cheap and easy to get 500 horse out of a big block.

I think the SBC advantage is weight and accessibility with twins, especially 30 feet and below.

Add to the mix the LS platform and it gets even better.

But like I said my 2 cents about little light weight diesels, when it comes to moving a 15000 pound boat there is no reason not to go with simple displacement if the hull can handle the weight.