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Bbc blower motor help!

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Old 10-11-2018, 09:11 PM
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Exclamation Bbc blower motor help!

Currently running a 509 bbc with a b&m 250 blower, ready to do some upgrades and looking for advice on which way to go?!!
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Old 10-12-2018, 12:27 AM
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You are going to need to be a little more specific on what you want and what your budget is to get any decent answers.
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Old 10-12-2018, 06:46 AM
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Budget $10000 give or take a little,

current motor was in the boat when I bought it and said to have 12hts since dyno fresh when I bought the boat, dyno 660 hp at 5lbs boost at 6100 rpm and was still climbing. Known parts list is gm block 509 cubic inches, dart pro 1 aluminum heads, crane gold rockers, unknown cam assuming decent size as it was still building power at 6100rpm, b&m 250 blower with intercooler, twin 750-850 carbs with Nickerson stickers on them, msd ignition. Was thinking I’d do leak down and compression test first along with pull timing cover to research cam per number, then assuming the cam is a good blower grind move up to a 1071 intercooler and twin dominators setup.

Or option #2 is a motor for sale locally it consists of a new gm block setup at 540 cubic inches 8.5-1 has eagle crank and rods floating pins je pistons, afr 357cc heads, Jessel shaft mount rockers, solid roller cam haven’t seen cam card but assume it would need switched out to hyd roller marine grind, has 871 blower shop blower and intake with dominator carbs has brass freeze plugs and marine grade head gaskets less than 500 miles.. Can buy it for 15000 or less

Motor #2 seems to be the way to go, after selling current motor it puts me in the upgrade for 5000 give or take and with a 540 vs 509 also has a lot better hardware afr vs dart heads, shaft mount rockers, bigger blower and carbs ect, it can be bought for 15000 or less and after selling my current motor has me into the upgrade for 5000 plus any parts needed to make it boat friendly, besides a possible cam and lifter swap what else would need to be done to motor #2 to make it boat friendly?? Does a boat motor have different clearances on valves, bore, and lower end bearings than a car motor? Seems if I buy a blower for my current motor I’d have around the same investment with less cubic inches, less cylinder heads ect??
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Old 10-12-2018, 08:44 AM
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Not sure of all your internals, but I had a pair of 509's. Dart Blocks, Dart Aluminum CNC Heads, T&D Rockers, Crane Cam, Callie Rods and Crank. 10-71 blower shop, Intercoolers, msd, And my first pulls with 7lbs of boost made almost 980HP at 6000. I detuned them to 5lbs of boost, 5600 RPM and they were making about 875. Reliable. I am no expert but block geometry is better on a 509 then it is on a 540. I have also had 540's but they were NA.

Seems like your base motor Idea is the way to go. but LOTS OF VARIABLES in your ideas.
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Old 10-12-2018, 09:45 AM
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I’m looking to make 850-900hp on a safe tune and have reliability that will last several seasons without a lot of maintenance? If my heads are just factory castings is that an achieve able goal??
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Old 10-12-2018, 10:32 AM
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Originally Posted by Daytona25 View Post
Im looking to make 850-900hp on a safe tune and have reliability that will last several seasons without a lot of maintenance? If my heads are just factory castings is that an achieve able goal??
I had 335 runners on my CNC heads. You can always get yours hand ported a little if needed, but I assume you will have plenty of flow if they are 335 or bigger. Especially forcing air with 10-71. 850 could be possible. I am sure Mild Thunder will jump in, he has done many reliable combos. And this seems right up his alley. Might depend on intake too. I can't remember what I had, it might have been a victor Jr. Intake. Can't seem to recall
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Old 10-12-2018, 12:43 PM
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Nice heads rockers and pistons in that 540. Could use more blower but sounds like a nice setup.

A blower swap on your motor would be pretty simple too.
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Old 10-12-2018, 01:05 PM
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I was just thinking the 540 seemed like a better package all around and possibly the better deal $ wise if I sell my motor complete to return most of the purchase price vs spending the money it would take to swap mine to larger blower and carbs and all.
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Old 10-12-2018, 07:43 PM
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My opinion, more cubic inch in a boat, I would go to the 540.
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Old 10-12-2018, 11:11 PM
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Kinda what I was thinking along with better flowing heads!!
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