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Estimated HP output - Build Sheet attached

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Old 04-30-2018, 10:51 AM
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That engine combo isnt going to make power much past 5200rpm. Not with that camshaft and exhaust.

Hows the tune? What timing set to? What carbs/jets?
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Old 04-30-2018, 07:42 PM
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Originally Posted by MILD THUNDER
Not with that camshaft and exhaust.
Are you saying that those Stainless Marine manifolds won't support 500HP?
just curious
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Old 04-30-2018, 08:28 PM
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A 33 Powerplay with 500hp will need 28 pitch prop with 1.50 gear. Will run 78-82 mph gps. The short deck version like that will run those speeds with 465hp. Check the engine carefully or dyno to check actual power.
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Old 04-30-2018, 08:48 PM
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Originally Posted by Rookie
Are you saying that those Stainless Marine manifolds won't support 500HP?
just curious
I think he's saying 5200 is close to max rpm.
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Old 05-03-2018, 10:00 AM
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I'll put some time in and get to know the boat. I have a set of labbed 28P bravo 1's ready to go in boxes - which I bought before I even paid for the boat and just as I started this thread. Coming to the relative conclusion this build package can make 500+HP, I figured it could've swung the 28s - like most Powerplays with 500s. After sea trial, it makes me second guess that, but I'll run the 24s or Mirage Plus 25s the boat has and work from there.

The engines were built by Precision Automotive in CT if that helps.
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Old 05-03-2018, 05:04 PM
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Run it and enjoy it. That is a beautiful boat!
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Old 05-03-2018, 08:24 PM
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What ignition system are you running? Any chance its hitting the rev limiter? What total timing are you running?

what carb is on it? Was it dyno tuned, or how was it tuned? The engine should make over 500hp, but only if tuned properly. If its short on timing, carbs not tuned right, it will be down on power
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Old 05-04-2018, 08:48 AM
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Originally Posted by MILD THUNDER
What ignition system are you running? Any chance its hitting the rev limiter? What total timing are you running?

what carb is on it? Was it dyno tuned, or how was it tuned? The engine should make over 500hp, but only if tuned properly. If its short on timing, carbs not tuned right, it will be down on power
These are all excellent questions, which I will dig into once the boat is in my possession. Awaiting delivery at the point.

As far as carb, build sheets indicate a rebuild - not replacement, so I'd have to look into it but its a Holley. Maybe pros know what it is based on sight:

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Old 05-04-2018, 01:17 PM
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I’m still quite new to the bbc power boat thing so I’ve had quite the learning curve, but I’ve found most of my gains in the rigging and tuning. Stupid stuff like finding a neglible kink in my fuel line, the wire to my ignition was too small, the fuel pump was too small for my upgrades on so on. I put a wideband on what I thought was a great running engine and found wot to be low 10s. Jetted it for mid 12s and found 600rpm. It’s all in the details.
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Old 05-04-2018, 08:54 PM
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That flame arrester isn't big enough for a stock 454.
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