502 or 540 build up ?
02-22-2009, 09:45 AM
#21
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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.
Last edited by ROTAX454; 02-22-2009 at 09:53 AM.
11-21-2010, 07:14 PM
#22
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Location: Wild n Reckless From North Texas
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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 !!!!!
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?
11-27-2010, 05:26 PM
#23
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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.
Last edited by AIR TIME; 12-05-2010 at 12:17 PM.
