Sounds awesome! Very nasty.

Oddly enough my insurance agent asked me if I had modified car engines in my boat when I got it insured

Noobie first post :whistle: Cool thread! Ive spent the past 6 years modding and beating on LSX based engines in my race car, they are amazing! Im surprised I havent seen more of these engines in high performance boats, they are light years ahead of the old gen I & II designs.

The ls3 "top end" is an upgrade to the cathedral port heads anytime your running a 4" or larger bore. The rectangular ports flow alot better and are cheap considering the price of a set of aftermarket cathedral port heads. The only drawback is the 2.165 inch intake valve and 15 degree valve angle can limit your cam choices due to clearence issues.

They are not popular because mercury has not used them. They are very committed to the bbc and would have to rework there line up for it make sense to use ls based stuff. IMO it would make more sense if there engines were ls based up to the 700.

5.0mag becomes 4.8l ls, 350 mag becomes 5.3l ls, 377 mag becomes 6.0l ls, 8.2l becomes 6.6l ls (408) different cams get you your h.o. version. 525 efi 6.6l with ls3 heads and mild cam. add a tvs1900 blower for you 600+ motor and tvs2300 for you 700 motor. these could be iron or aluminum based all the blocks are available. the price for ls stuff goes way up if you plan on an engine larger than 418, you have to have a stroke deeper than 4in which I don't like on most production blocks. Aftermarket and ls7 push the price way up and in most cases are not needed.

A thread I started last year to discuss this topic. Some interesting discussion.

http://www.offshoreonly.com/forums/g...rs-hiding.html

I agree. Very Nice!

thx guys !

It s real fun to drive and very easy hardly any chine walk up to 96 mph and what there is you steer easily out it whit the dual ram steering .

that nasty engine even get the boat to 90 mph @5000 rpm whit my big 32 maximus on it !

my next project will be a 26-28 cat whit 2 ls in the back making 550-600 hp probaly a little bigger diplacement that way I can use normal bravo xr and everything keeps in one piece and still go fast !
and not to forget pretty light weight !

This will solve your problem if you want to drop the $$$

http://www.mastmotorsports.com/2010/news-view.php?id=74

Talk to Scott. He used to work for Ilmor for quite some time. He left Ilmor and went to Mast Motorsports. He was a major part in the development of this engine. Nice guy.

Don't get me wrong the mast stuff is super nice as a matter of fact I have some of there heads going on a mile land racing 427tt motor for a rx7 as we speak. with a goal of 1500-2000hp, best heads on the market for ls stuff hands down. (I just sold a set of ETP's to go this route, Cary's stuff is top notch)( I drive a 6.0l powered 2500 I have built multiple LS powered swaps, I talk anyone who will listen into ls powered car, Im looking into a cts-v, and im looking for a 24-26 hull for a ls swap.

but for the most part the mast engine is not what this guy is looking for. Its not even where the ls will do best in the marine market especially with what people are going to spend these days. for the same money teague, croket,GT etc will eat mast's lunch. The ls stuff shines when you want to make up to about 600hp cause it can be done cheap.(production block and heads etc) add in a set of 3k+ mast heads and aftermarket block and that evaporates. I can't figure out why no one is making 450hp to 600hp ls engines using mostly gm parts. once you go past a 408cid the price goes way up for little gain.

trying to go toe to toe with a bbc is foolish imo. I would not pay the same price for a small block, when I could get a BBC make more power and torque for less money.

what size cam are you running? What are the cam specs?