Hi new to this site I'm in the process of turbo charging my 1978 Hawaiian jet boat. It has a almost stock Harman marine 460 ,signal 76mm turbo, 750 CSU e85 blow thru carb, a1000 fuel pump and twin 38mm gates, question is what spark plug to run thinking around 10psi boost. I don't know if this matters but it has a Berkeley 12jc stainless a impeller. Any help would be appreciated

Are you getting help for this project?? Or do you understand what to do here??? Turbo motors are a lot of work and require a lot of knowledge! You can't just throw a turbo on a motor and hope for the best . The result will be really bad!


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You can find a lot of info here. Wish I could help. Pretty rad to think out of the box...


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Engine doesn't have stock valve train and it the 4 bolt main block. I'm running an old msd 6albtm with 5800 chip in it. Boats still the family cruiser I know I could turn it a lot harder but reliability goes way down. Anyone with knowledge with marine turbo setup s?

Its not the RPM that will kill it, it is the substantially increased torque output at a much lower RPM.  If you are making 1000 HP at 10,000 RPM, that is a lot of little hits on the rotating assembly vs. if you are making 1000 HP at 1 RPM, that is one big bang.  I bet that the best factory crankshaft will let go first.

It really isn't worth it unless you run at least 6 lbs of boost.  Seriously consider a 4340 crankshaft.  How are your tuning skills?  If you have it, I would take advantage of Kevin and Dennis's knowledge.

If your goal is only 5500 RPM, you might try a AA or AAA impeller.  AT offers up to a 5A before the blades start to hit the bowl vanes.  Seems like a lot of work to make an A impeller turn 5500.

Cheers,

Joe

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Getting close.

What are your plans for keeping the oil cool?


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Had the boat out the other day it accelerates so fast. Don't have mph yet but I'm spinning my "A" impeller to 6000rpm were it hits my rev limiter that's with 8psi of boost. Boat cruises nice still, installing boost controller this weekend try to limit boost at lower rpm. Hopefully boat makes through the season started building a new short block for next year so I can turn it more lol. Running very little timing and boost and boat still fast and fairly stable no ride plate or pump mods. Big improvement from last summer pulling 4200rpm

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I'm at 5psi at 2500rpm. Boat jumps out of water when you go from zero full throttle. Yes stock Harman marine bottom end (it's I time boom)first bbf for a boat.chevy guy boat cam with 460

I bet that the best factory crankshaft will let go first.

...Seriously consider a 4340 crankshaft.  How are your tuning skills?

The OEM Ford 385 Series crankshafts can take a turbocharged 1000 hp without issue provided the tune is good.   We've known them to handle quite a lot more than that.  But that's not to say that a forged crankshaft won't let you sleep better at night.

The OEM rods are the weak link in such an engine.

Boats still running got the boost under control just need to install new cam #7 exhaust lobe is at half the lift as every thing else been like this for awhile  still runs good I beleive its a comp marine cam. Has any one had good luck with another brand or I'll just put same cam in minus the bad lobe of course.