502 or 540 build up ?
 

I have a 33 Fountain Executioner which I'm re building the engine's and would like to get some more speed. The boat now runs approx 75-80 mph @ 5000-5200 rpm. I would like to keep the same props as they are hard to find and run up to 5500 - 5800. (It has speedmaster 2's)

The current engine combo has been in for 5 years no problems with water reversion or oil temps etc.

Gen 6, 450hp 502 crate engines (stock) iron rectangular port 118 cc heads, forged crank, forged pistons 8.75 :1,
Power flow Exhaust Maniflods & stainless risers
MSD Billet distributor with Msd 6m box and rev limiter.
Standard dual plane manifold & 800 Holley.

This is what Im thinking of doing, JE 9.5:1 pistons, camshaft crane 731 or similar ? The heads are getting a clean up and 3 angle job and will be match ported to a new hp 500 single plane style manifold and fit roller rockers.

Will this get me to 5500-5800 rpm or shall I go bigger on the cam?
Shall I keep the hydraulic lifters or go solid?
I have to replace one crank & rebore both so I was thinking to make them both 540's using eagle cranks and rods with Je's
The speedmaster legs can take the extra hp what about my transmissions ?

Thanks.

From those numbers it sounds like you have a great setup already. Is the 75-80 mph GPS?

I always have RMBUILDER (do a search) grind mine per the application. Well worth the extra money.

If you plan on running 9.5 CR with iron heads you better make sure you have good gas available or you will have problems.

Big question, what exhaust are you running?

As per going to a 540 that just depends on how deep your pockets are $$$$. If you only need one crank I would replace the one crank. Otherwise you are looking at new cranks and rods and you have the block machined for the additional stroke. I have built three stroker motors and love them. Again its on how much do you want to spend.
I think you would be money a head putting on some AFR heads and a custom grind roller:D

Good Luck

I agree. I would at least have RMBuilder/Bob Madara of Marine Kinetics design a cam for your engines. He will custom design a cam for YOUR specific application and what you want. You will get a custom ground cam for about the same price for what you would pay for an "off the shelf" cam. Bob is an excellent consultant on marine performance stuff. Bob's number is 585-654-8583 in N.Y.

The Exhaust's are imco powerflow manifolds and stainless riser's, which for now we will run with. We always use premium 96. As for the speed we run a solid 75 most days which I checked with a handheld gps a few years back when I installed a new speedo. Lightly loaded on a good day up 80. I forgot about getting the block machined for the stroker. thanks

You'll need to get to 600 hp if you're going to gain that much speed. 540's and the 741 cam will get you close with the iron heads. The 731 and 502 ci will make a little over 500 hp. Not nearly enough. Btw the No.2 Speedy is not very strong. Be gentle with 600 hp.

No substitute for Cubic inches........But I have seen some stout 502's built that run realllll good!! Do what you can afford but do it right either way.:p:cool:

You need to gain about 80-100hp for 500rpm gain. I think you will be close with boring to 509's and without stroking it with the other mods you posted. I would also go with a 741 cam or similar for a 509. Stay with a hyd roller.

Thanks for the Info guys, have been in contact with Bob and will be getting him to do cam for me for sure. Before I decide need to find out more about strengh of the speedy no 2's. PatriYacht any more info would be great how gentle?.

The Speedy No. 2 uses all the internals from the TRS. I would guess it can handle up to 600 hp with a fair degree of reliability. But just like a Bravo, flying the boat or doing holeshots will kill it in a hurry.

I would never stroke to 540 using a standard deck block. To much rod angularity. Tall deck only. 509 as griff pointed out would be the way to go. And go with aluminum heads for the amount you would save on a stroker crank.

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.

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.

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.

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.

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.

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

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

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.

Back on the water
 

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 !!!!!

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

ou

I am confused. Why are u going to be adding power when the Speedy II's may not take it? And if you hurt one, better get your credit card out because you don't have that much cash. Why not be looking into upgrading your rear powertrain first, then go for more power up front. Nothing will kill your boating season faster then taking out an outdrive. Like snapping a prop shaft and having your 1k prop drop to the merky bottom of the lake.

Update-----just saw your latest post. Glad your build-up worked out. Solid numbers with solid equipment. Don't forget about my first paragraph. Hate to see your boating come to a "crunching" stop. In the meantime, easy on the sticks.

So are you using the stock iron exhaust manifolds?

no merc used tall decks for the 540 500hp and 575hp and its not that common. the two builders I have used only build 540s with tall decks they said the short will not last as long as a tall deck in the long run. I made 600hp with my merc 502 and 650 670 with a change to 509 9.5 to 1 comp useing merlin marine heads. my both my stock and merlin heads were pocket ported. talk to biggus on here about konrad drives there good to 800hp.

no he had after market manifolds with ss risers.