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BEAUTIFUL BOAT!
That's got to be one hell of a ride. What a sweet motor too.
What do you think you saved in weight with the aluminum heads, intake and exhausts? I've got a 454 crusader in my Whitewater and have toyed with the idea of putting it on a diet. How are you getting close to 3 mpg at 45 mph? My rig burns 15 gph at 3000 rpm. How does your setup do idling around for hours? I know it's apples to oranges (inboard fishing / to i/o cruiser) but it looks like you really have it sorted out.
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Thanks guys/gals for all of the kind words.
The Aluminum heads saved around 50 lbs, however the 502 weighs about 50 lbs more than the 454. When I converted it to fresh water cooling, that added about 45 lbs. The mini starter will save a few lbs over the old bulky style. I don't know the weight difference on the exhaust manifolds as they were on the boat when I got it, I would guess another 50 lbs. The engine will idle all day long with out fouling any plugs but I would not recommend it due to the possibility of water reversion from the valve overlap. One could have a custom cam made to prevent the water reversion but it wouldn't have the lope to it and might not make as much HP. As a result I try not to let it idle very long and if I do, I'll rev it to 1400 RPM's for a couple of minutes before I shut it down. I wouldn't recommend this exact set up for a straight inboard fishing boat.
The fuel economy is due to the engine having almost a 10:1 compression ratio, conservative head ports, conservative camshaft, and a perfect air/fuel ratio (tuned by a FAST wide band O2 meter). I don't remember the exact numbers without going to the GM Performance Parts web site, but if I recall it makes 567 ft lbs of torque at 34-3500 RPM's and 502 HP at 5250 RPM's. If you have to run the boat less than 3,000 RPM's it will start to burn more gas. The engine seems to be most efficient around 3,500 RPM. Also by going to the four blade Bravo 1 prop gave me about 3/10ths better MPG.