PatriYacht

Sure , tall deck is better but the short deck 540 is a very popular engine. I have two of them and I haven't had any problems related to the angularity. A set of good cylinder heads is going to be 2500.00 + per engine. A fully prepped Eagle crank and set of rods is less than 1500.00 per. While you're at it, bore it to 4.560 and build a 555. The Gen 6 has thick cyl. walls and most can go 4.600 so you would still have room for a couple of rebuilds. I'm quite sure it will take 600 hp to reach your goals. A friend of mine had an Executioner with No. 2's and Gale Banks turbo engines. It made 650hp per engine and went 90mph lightly loaded.

Chris Sunkin

The SSM II uses the upper from the 2 drive. Lowers are diferent and don't handle TRS power levels. They were somewhat fragile, which is why they weren't around long. You break one, you'll be shocked at the parts pricing- if you can find them at all.

Me- I wouldn't fool with it unless you're willing to drop some serious coin into your transom in the near future.

PatriYacht

Standard Gm rod is 6.135. Going to the Eagle 6.385 rod gives you a stronger rod and cuts the angularity. It ends up being 1.502 vs. 1.533. Not really a noticable difference. The piston ends up being shorter which can lead to piston rocking if you set it up with excessive piston to wall clearences. The plus side to this is a much lighter piston which makes for easier crankshaft balancing. SRP has a line of small dome pistons with an up to date design that works well with these engines. Without decking the block, compression works out to 9.7 to 1, just about right if you have access to 93 octane gas.

sandcraft

My current engines are 622ci bowties. 4.6 stroke. In regards to "bang for the buck" engines, I will never build another large stroker engine, its just too expensive. (at least mine were) Maybe because I used Callies cranks and Oliver steel billet rods to give me piece of mind. I currently have plans for a 509build that will give the same hp with less cost. Maybe a short deck 540 isnt that radical, I havent built or even researched that combo. I have noticed that some of the builders go to a tall deck when they build 540 or larger. My guess is its because they have to warranty their engines. You said the the short deck 540 is a common build. Would that be the Merc Racing bulldogs? If thats the case, then I would feel better about building that combo. I still think a 600 hp 509 (iron head) would be a less expensive build.

Dan74

I'm not sure exactlly of the merc spec's bore x stoke and what decks over the years in thier bulldog's 500's &525's efi's. I havn't owned a boat with them YET !!!! I have no problem at stroking the short deck with only a 600hp goal and 5800 redline. At the moment I'm looking at callies comp star cranks & rods and je's. I have to rebore both and buy one original crank anyway so its really just the price of rods and one crank extra to stroke it, Why not ? Except for fear of $$$ when the speedmaster 2's fall off the back . Im aware the difficulty of getting spares for them .Ive already got one complete TR in stock at home.Thanks for all your info.

Chris Sunkin

Regular oil changes will help them live. Eliminating the holeshots and good throttle discipline leaving and re-entering the water even more so.

Bob280Silencer

I would re build what ya got,put some good al heads(AFR,Dart,etc)the custom cam and let 'er rip.The heads alone are 50-75 hp per side.With the compression bump and the cam you should be close to 600 per side.The al heads will handle the compression bump better and out perform the iron heads.I have a 540 making 650hp.I love it but I only had to build one and except for the machine shop,I did it myself.Still was a few $$. Just my .02 Good luck Bob

Dan74

Thanks for all the info, It was a hard call but went for the 509 and not to stroke it , final decision came down to the speedmaster 2's, not the short deck height. I think people dont realise when longer rods are used the piston pins are much closer to the crown so the agle is very similar as patri yacht pointed out.my 2 cents anyway. If its not enough then in a few years (after drive upgrades) will buy the afr heads. Ive had the boat nearly 10 years now, just wish I knew about this site before. Will post my results when its back on the water.

Dan74

Yep back on the water and all good.

Kept with the 509ci after all. Decided to go with new 305cc AFR CNC bowl blend heads. RM Builder , Bob Madera spec'd the cam and valvetrain. I told Bob what I wanted and got exactly that. He was an Invaluable help with advice on other components and issues as these were the first modified big blocks I 'd built.

DYNO DAY, Ran the engines in on the Dyno and only had time to a Basic tune on them.
Ran them Fully assembled as in the boat with sea water pump and heat exchangers. Couldn't use my Exhaust so I used an old set (a little more restrictive). Peak Hp was right where I asked for it 5800 and 577hp. Dyno is the lastest model and apparently is the most savage around town (giving the lowest numbers).

Back in the boat engines idle great at 700rpm no reversion. Plan was to keep the same props and rev them more for the speed. Boat used to run WOT at 5000-5200, now swings out to 5700-5800rpm. Picked up a solid 10mph on the speedo !!!Will do some runs with a gps soon.

Thanks Rm Builder !!!!!

Jammin'

Congratulations! It's great to hear how a project turned out.