you can get a brand new general motors crate 454 minus carb for well under 5, so in theory it shouldnt cost much difference for marine complete with carb.

WOW under $5000 for a brand new GM 454 motor making 500hp . Ill take 2.

Am I missing something here?

Real Motors Cost Real Money If You Want To Go Canal Cruizing Go To Gm

Yeah to what Whiteknuckle said.

Also, Has anyone used a "GM crate engine" right out of the crate, and installed it in a boat for marine use with any success?

I have always heard that if you plan on using a crate engine for marine use that it's best to take it apart and check all the bearings and have them clearenced for marine application engine---same goes for the rings. I don't always trust everything the way it comes from the factory so, if I have to take it all apart and check their work, then I might as well have it built properly for marine use by a precion machine shop that is familiar with hi-perf engines destined for marine offshore use----and a shop that also has a good reputation for making them stay together so they don't come apart. I am not so sure I would trust a factory crate engine just because it's new, and comes from the factory. Of course that's just my own .02, but it's at least worth thinking about.

Keep in mind though a "crate 454 h.o" IS IDENTICAL other than camshaft and oil cooler bypass valves to a 454 mag long block. Same pistons,rings,lifters,valves,springs,CLEARENCES,ma chined on same exact machinery,same gaskets,oil pump,bearings,fasteners etc,Smitty

Smitty how much is a new 454ho $ ? Then How much to have someone go thru it $ ? Then how much HP are you getting ? Round numbers would be great. I know my guy get $1000 for labor without any machine work.

I have been waiting for some one to bring up this point! I was a trainer for GM back in the STG days then moved to Melior to do there fleet training. I have used 3 create motors 2 502/502 in Jet boat applications. One was sold after a year, one was sold after 5 hard seasons on it. Both sold in the boat they where originally purchased for.

Even though I was not part of it I was told from numerous people involved that most of GM performance motors R&D was done in conjunction with Mercury. I now have a 502short block that was a GMPP that had a cam change and a set of Edelbrock heads set for marine use. I will tell you I do agree that you are rolling the dice if you trust a mass produced performance motor. But so far I have had a good track record with them.

Now lets talk about the $25k I spent with B&B performance out of Redding CA for a blower motor (I supplied the blower. A 871 set up). That was a joke. My JE pistons turned out to be SRP’s , Cola crank was a Scat, and my Manely rods where eagles. So lesson learned. I used this company because of some good recommendations. To fix this mess I used a well known shop to the NJBA’er DNE Motorsports in Costa Mesa CA. So its all in who you trust.

Same situation with the Merc 496's, right? Plus they are running hyper, not cast pistions, right?

I can’t tell you about the 496's but my 502 block has Forged Aluminum. I have never been a fan of Hype-pathetic pistons after a set of Sterling’s we put in a low hp 454 has the pin boss break off. but do know a lot of builders have used them with good success