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.

If I go this route I will be doing strokers so internals will be new. Not sure yet about how much stroke 4 or 4.1 but worried 4.1 might cause issues with short piston and some wobble due to BDC coming out of the bore. Probably do LS3 or L92 heads, custom cam. Not sure yet on carb vs EFI, if stock EFI would work with reprogram I would do it but buying new intakes would be a bit pricey. Maybe a Victor intake and carb to simplify things. Still way ahead buying a complete engine either way to get all the accessories etc.

Just watch the compression ratios. The stock injectors are damn near maxed out in stock motors. The injectors are the only weak point on the ls engines. Carb set up is easy but get the msd box seperate not in the edelbrock kit. The msd is programable where the one in the eddelbrock kit only has plug in chips. And oddly its cheaper to buy them seperate??? I can't figure that out...lol. yes the used engine is the best way to go for parts wise. Unless you're building 2k plus hp then a stock block will be fine. The lsx block is awesome for boost due to six head bolts vs 4 around each cylinder.

Will those engine mount adapters allow direct bolt up to offshore style mounts and do you have a link for them?

The ones I've seen bolt up to mine off of my scarab. They convert from the ls 4 bolt to the old sbc or bbc 3 bolt. Then you just use the mounts you had on you previous engine. Hmm not letting me copy a link?? Google ls engine mount. They come up with tons of them. Holley dirty dingo. All kinds you can move the motor forward up to 3 inches or keep it in stock location.

ezstriper, sdg0080, hotjava66,

Thanks for the feedback, but I'm realizing quick this won't be easy!...........(my) limited budget + (my) limited engine knowledge = finding somethin in the swap shop :cartman:

The exhaust is a big part of the budget. Haxby speed has new take offs you can buy. Yeah its not super cheap but in the end it is worth it... well for some of us...lol. the stock lq4 puts out around 335hp. The stock cam will work fine. I just want some more grunt out of it...lol.

Do you have a link or other info on the crank driven water pump? How does price compare to Hardins piece that goes on the a/c bracket?

Price isn't even half of the harden one. That harden is 800 the crank driven is around 250. The link is a few pages back ill see if I can find it and repost it.

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I would imagine picking the perfect "donor" would be critical ...what are the signs to look for when separating a junk block from a good 'donor" block? .....and after your out of the machine
shop with honing the bores and what not, are you any better off than buying a block from say.....Summit , Dart???

Do a google search...it will hit on several sources quickly.

No real secret to it. The iron blocks are very solid. I just picked one with 120k miles. It should just need a hone job and not bored. The bores looked great. Still seeing cross hatching in the bores. The 2005+ have beefier rods buy they are cracked metal rods and need resized if you put arp bolts in them. If you go efi get the ecu from the doner and the tac module for the drive hy wire throttle body. Otherwise the 2002 is pretty much the last year of drive by cable. And no benefit from buying summit block. The junkyard one will have all your brackets anf odds and ends. My machinist quoted me 1200-1500 in labor for doing everything.

What should I expect to pay for a good donor block? ... 4 bolt main? .... what parts should be forged for 450hp?....... what's "everything" mean with the machinist quote? .......Merry Merry!

Around 1100 bucks for most engines. They are all six bolt mains. 450 is nothing. Just throw in a cam and springs and run it. Again these bottom ends will handle 600 -700 hp in stock form. They pumped 1200hp out of a turbo 4.8 l out of a junkyard. Stock bottom end on it. Everything from tear down to rebuilding. Thats all the labor to clean hone assemble it all.

I'm going probably a little overboard with my build... I decided to go scat I beam rods with arp cap screws. Its not much more than than reconditioning the old rods and adding the arp bolts.

Well i finally got to go pick up my 6.0 out of a 07 2500. It has around 87,000miles on it and i picked it up for $1150. So since it was an automatic i need to get a flywheel for it, fab som brackets to put my seawater pump where the AC comp was and figure out what brackets to go with to convert it from the 4 bolt motor mounts to the old 3bolt. So my 1st question is should i buy a flywheel from GM or from jegs/ Summit? 2nd question is what is this spacer that i need to bolt the coupler up to the flywheel? 3rd question is where do i go to learn about trimming this wiring harness down cause i would like to do that myself.

lt1swap.com has everything you need to know about the harness... Bought my flywheels from Jegs and I didn't need a spacer. You can get the motor mount adapters pretty much anywhere.
ebay has a ton of them.

see on mine I have the flat 6.0 flexplate. from what I'm reading I guess that one should bolt up without any issue. I guess time will tell...lol

flexplate won't work, need a manual flywheel, the drive coupler bolts to the pressure plate bolt holes...

I've got the flywheel off my 350. But I don't know if that will bolt to my ls crank

No. They are different. You can get a LS flywheel from Jegs for $99.

yeah I was looking at that. is jegs one really much different than the stock ones? I know I dont want to run a lightweight flywheel...lol

I don't know that they are any different, just much easier to find.
I've actually been thinking about some light flywheels on mine...

see I was worried about a lightweight flywheel not having enough momentum. I've done a lot of 4 wheeling over the years and with big heavy tires having a light flywheel can hurt performance. yes you gain in the top end but it can stall the motor when you hit heavy resistance. Thats my concern with a boat. you have so much reistance with the water that I would worry about stalling out whenever you changed gears. I know in small engines, I use to race a honda civic... dont laugh to hard on that one... but with the small motor if you did any road racing any increase in corse elevation would actually slow the motor down. it just didnt have the momentum to keep the rpm's up. I would talk to haxby speed or bob madara and see their thoughts on flywheels. On a smaller lighter boat it may not be as big an issue on say like a 32' or bigger boat. I honestly dont know how it would affect the engine on a boat, I'm just going off of what I have delt with in the auto world.

so talked to Bob Madara and he said that the lightweigh flywheel isnt a bad idea in lighter boats. Like I said the flywheel is an energy storage device, but he stated that instead of storing that energy the lighter flywheel allows it to be directly applied to the propeller. he said it really helps pulling out of turns and also instead of making the bow point to the sky when getting on plain it helps to get the boat on top of the water faster. good info, so it looks like I'll get getting an aluminum flywheel for my engine. I gotta give a big thank you to both Haxby Speed and Bob Madara. you guys are simply awesome. I don't think this project would be near what it is without the help I have recieved from them.

okay so I just ordered a fidanza 12.5 lbs aluminum flywheel so I'll report back on how well it works... LOL gotta love amazon... so much stuff on there. Also anyone keeping track this swap is not for the faint of heart. by the time I have the headers for this monster I will be around $8300 invested in the engine. all for a boat I paid $2000...hahahaha. could this swap be done cheaper? absolutely. I just chose to go with the better option of investing money into it the first time.

Exciting new developments on the LS front.

https://www.facebook.com/photo.php?v=633227006737195

gotta love twins... lol I'm planning a single turbo ls for my bmw swap thats coming as soon as i have my boat running. i love boosted ls engines. the 5.3's love boost, and can support a damn good amount of HP in stock form.

http://i776.photobucket.com/albums/y...ps49fa8699.jpg
http://i776.photobucket.com/albums/y...psd2281f8e.jpg
http://i776.photobucket.com/albums/y...ps6c74065b.jpg

Motor mount adapter plus coil relocation. Brand new to the market and straight from haxby speed. These things look killer and its about time some one has made something like this. If anyone wants more info contact alex at haxby speed.

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