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500 HPs in a 312 fastech

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Old 10-22-2006, 04:58 PM
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Default 500 HPs in a 312 fastech

I sold my Formula 312 this summer but a local mechanic I know is installing 500EFI's in a 312. The boat had the 454/330's and he is asking if I can suggest a prop pitch. Mine with 502 mags and 1.65 bravos (1.65 was standard) ran a 30 pitch 4 blade.
I seem to remember someone had put 500's in a 312 but don't remember who. Anyone familiar with a 312 that had the power upgraded? Looking for prop suggestions.
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Old 10-22-2006, 05:01 PM
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Default Re: 500 HPs in a 312 fastech

If it has 1.50 Bravos then I would start with a 32" Bravo 1.
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Old 10-22-2006, 05:58 PM
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Default Re: 500 HPs in a 312 fastech

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If it has 1.50 Bravos then I would start with a 32" Bravo 1.
1.65.....I asked if they were changing it to 1.5 and he was planning on discussing that with the owner.
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Old 10-22-2006, 06:05 PM
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Default Re: 500 HPs in a 312 fastech

Strongly suggest 1.50 gears. 1.65's will require way large props that will be very ineffieciant on a 312. We Procharged a 312 with 454 Mags several years ago and the 1.65's just would not work. We wound up with 1.50's and 34 Bravos labbed down to 33's.32's might be about right with 500's.
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Old 10-22-2006, 06:54 PM
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Default Re: 500 HPs in a 312 fastech

Did Phantom Chaos have 500s in his 312?
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Old 10-22-2006, 07:03 PM
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Default Re: 500 HPs in a 312 fastech

What kind of speeds will a 312 w/ 500's run? That seems like a lot of hp for a 31 Formula. How do they handle at those speeds?
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Old 10-22-2006, 07:37 PM
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Default Re: 500 HPs in a 312 fastech

The Procharged boat ran low 90's if I recall,but that was maybe 8 or 9 years ago,my memory is really bad. I do recall it handled well up to high 80's, a little loose above that,but customer ran it hard for several years with no issues.
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Old 10-22-2006, 07:38 PM
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Default Re: 500 HPs in a 312 fastech

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Originally Posted by mpally
What kind of speeds will a 312 w/ 500's run? That seems like a lot of hp for a 31 Formula. How do they handle at those speeds?
I expect it will run near 80, maybe more on a "good" day. I remember reading somewhere that the 312 would chine walk from the low 70's to the high 70's then it's fine. Mine would chine walk at 72-73, but that's all I could get out of her.
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Old 10-22-2006, 09:04 PM
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Default Re: 500 HPs in a 312 fastech

I would have thought it would run north of 80. How much does the 312 weigh?
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Old 10-22-2006, 09:18 PM
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Default Re: 500 HPs in a 312 fastech

my old 311 had 502's and had 26's, straight hull older and heavier, I would start at at least 30's...
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