Offshoreonly.com - 502 or 540 build up ?

Offshoreonly.com (https://www.offshoreonly.com/forums/)

- Do It Yourself, Boating on a Budget (https://www.offshoreonly.com/forums/do-yourself-boating-budget-249/)

- - 502 or 540 build up ? (https://www.offshoreonly.com/forums/do-yourself-boating-budget/194689-502-540-build-up.html)

Quote:

Originally Posted by Dan74 (Post 2675308)

(It has speedmaster 2's)

The speedmaster legs can take the extra hp what about my transmissions ?

Thanks.

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.

Quote:

Originally Posted by Dan74 (Post 2803980)

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 !!!!!

So are you using the stock iron exhaust manifolds?

Quote:

Originally Posted by sandcraft (Post 2683777)

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.

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.

Quote:

Originally Posted by Floatindirty (Post 3258252)

So are you using the stock iron exhaust manifolds?

no he had after market manifolds with ss risers.