These are interesting as well:

http://www.mastmotorsports.com/2010/...=Marine&id=396

Pricewise, Ilmor 570 packages are pretty close to Merc 565 packages.

That is a 416ci with cnc mast heads....their 550hp VVT airboat engine is great also and does not need long tube headers. I'm starting to like a 700hp whipple 416ci. Seems like you can make enough TQ out of boost for cruising and have similar longevity as a 502/509 whipple engine with lighter weight and better fuel consumption???

I'm really a huge fan of the LS engines, coming from cars, before I purchased my first boat last season. As a couple of other people have said, the ideal application would be in a cat or a smaller single engine boat. Somewhere around 600 N/A and 800hp with a blower are about the most i would ever try and do before a big block likely gets more economical and reliable in a marine application.

I think a stroker L92/LS3 (416/417 CID, 427 CID if you bore it) , factory heads and intake, some aftermarket valve springs, custom cam, hardened pushrods, and a roller bearing upgrade on the stock rockers could make 550 on 87 octane no problem with a lot of that power and torque under the curve.

Many of you are looking for a lot more ponies than that though. Parts are a dime a dozen and theses motors are laying around in junkyards everywhere. I can stop in at my local chevy dealer or late model speed shop and pick up anything i need in most cases.

Anybody know what those Mast 600 horse motors sell for?

For the do it yourselfer LSx enthuisiest, another hard core LSx site with alot of information.

http://www.yellowbullet.com/forum/forumdisplay.php?f=36

$27K if I remember right

Just saw this from the Boattest.com guys

353 Fastech with 570 Ilmors:

http://www.boattest.com/boats/boat_v...D=2507&ID=2814

We are building a pair of these right now.

L92 with a good stroker rotating assembly, stock heads with good valves and valve job, proper valvetrain, custom cam.

Should do right around 600hp.

Closer to 550hp with a smaller cam and 87 octane if you go that way.

Did some searching and they have that boat at 81 and cruised at 52 with a 35gph fuel burn and there's still some more dialing in to do. When those numbers where published there were only 7 hours on the boat including the 45 minutes boattest.com had it.

For comparison, the same boat with 525's tops out about 78 with the same 52mph cruise and 35 gph fuel burn at cruise. Looks like wot burn with the 570's in about 90gph and wot on the 525's is about 82gph.

Sounds to me like that's very similar numbers between the motors, with almost identical cruise, yet 3-4mph on the top end. The 570 speeds where with 23P Maximus props.