An good engine dyno will put the same amount of load on an engine as a boat will. (They can hold an rpm at wot. Just like a boat, as chassis inertia dyno is different story) a 6.0l with l92 heads and a 224/230 cam will hit 500hp around 5000rpm and peak at 525hp around 6000rpm. 600hp will require more cubes, boost or more cam and rpm. BTW I would not even consider 7000 rpm the moon for these engines.

There is a 32 Skater with twin LS7's. Hear its awesome

Never said that 7000 was the moon on these but I still don't care to be twisting those rpms on my boat engine constantly when its factory gm parts. Plus on top of that I don't know how many rpms you can turn a bravo1 before it starts wanting to eat itself.

Sprink, I have a '93 ext cab stepside mark III that I bought new, I'm going to be re doing after I'm done with the boat. I have thought of doing that LS swap with it. But now after building the Vortec engine for the boat, I've learned some secrets for the truck, I'm not sure which way to go with it

With just a cam and a tune ill be putting out damn good numbers. You'd need a fully built sbc to lay down compairable numbers.

I've read this whole thread and find it a very interesting read. I'm restoring a Magnum 27 sport and will eventually go with twin SB's. What kind? I'm not sure yet, but If I decide to go with LS power where do I start the search? ......and what does it take in "real dollars" to get a pair of LS engines in my Bilge? ......I'm not a wrencher so some of the stuff discussed in this thread fly's
right over my head, but I'm very interested nontheless.
From researching boats simular to mine & because there heavy they need 400 - 450hp a side to cruise well..........I priced a short & long block starting point (Dart 427 SB) before I even got to the cams I was priced out........................can LS engines be even discussed with a moderate budget?.......one thing I'm certain of is, B1's will be at the back of whatever I choose.

the early 2000's 6.0 iron block from trucks are about the best to start with, even stock will make great power, all marine parts available now...

You can nab a lq4 for around a grand each, toss in a custom cam 450 or so new valve springs 300 to 500. Carb it with msd control box. 550. And then exhaust 800 to 2500. That would have you running 80 bucks for motor mount adapters. Thats the basic way to get it done. Efi is tougher on the wallet if you don't know electrical. 550 for harness then 240 for basic tune to make it run. 8.1l marine injectors run 400 to 500. Carb is simple but you don't get the efficiency of efi. Both are comparable for power. No real gain either way. I chose to rebuild my engine from top to bottom. Many people have just simply ran the motor untouched without any issues. so add in 2000 to 2500 for a full rebuild if you go that way.

What are you running for accessories and seawater pump? What about drive coupler and bell housing? Been watching and gathering info on LS for a while, kicking around doing a pair. Right now I think starting with donor lq4 or lq9 is the most cost effective. To build from scratch is just too expensive and you have a lot of nickel and dime stuff that adds up to a ton of cash. Would love to discuss with anyone who has done or is doing an LS for marine use. Feel free to PM me for contact info.

Bellhousing will bolt right up with the exception of one bolt but not a big deal. They make a crank driven sea pump that will work great. The flywheel just needs the spacer ring to push it back to the old chevy distance so the couple will be fine. Bolt holes are in the same location. Use the accesories that are in the motor. The starter is a gear reduction and is sealed from the factory. Its the exact same as the marine starter. Now remember the lq9 is 10:1 comp the lq4 is 9.5:1. 2005 and up both motors use the same rods just dished vs flat top pistons. The early lq4 had a slightly lighter rod. Now that being said they are still very strong rods. They will hold 600-700hp untouched. Upgrade rod bolts is recomended however if they are cracked metal rods they need resized. The cost of arp bolts and resizing the rods you can buy aftermarket rods with arp bolts in them. So if you're building major hp get the rods upgraded. Just remember these engines are internally balanced. So you need to balance the motor with new rods.