8cyl gpu convert or not

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NDWIND
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8cyl gpu convert or not

Post by NDWIND » Mon Sep 26, 2016 5:05 pm

Hello I'm new to this site and am wanting to build a boat. I have a chance to buy a 8cyl gpu I hear a lot about the 520 conversion is it worth it or not and approximately how much does it cost to convert one?

slidingforhogs
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Re: 8cyl gpu convert or not

Post by slidingforhogs » Mon Sep 26, 2016 5:20 pm

The fuel burn alone on a stock 8 cyl is bad enuff.. Very expensive. .. But if you have the pockets for it i guess anything is possible... Good luck with the build..
11'7 gore ,
220 gpu swinging a woody...

Stomp on it!!!!

GMAC 76
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Re: 8cyl gpu convert or not

Post by GMAC 76 » Mon Sep 26, 2016 5:44 pm

wow would that then be a 693...lot of engine....wonder what the hp would be if ya had gitsu cyls?

barhopper
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Re: 8cyl gpu convert or not

Post by barhopper » Mon Sep 26, 2016 5:56 pm

Like this?
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helicsher
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Re: 8cyl gpu convert or not

Post by helicsher » Mon Sep 26, 2016 8:00 pm

450hp?
"Success Requires No Excuses"

NDWIND
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Re: 8cyl gpu convert or not

Post by NDWIND » Mon Sep 26, 2016 9:42 pm

Does anyone have a estimated cost of converting one or is a sbc and gearbox cheaper

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John Fenner
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Re: 8cyl gpu convert or not

Post by John Fenner » Tue Sep 27, 2016 8:50 am

Well, the conversion I'm doing the parts alone on a 6 cyl was @ $4000.00 not including boring the case, getting crank ground, assembly and cylinder overhaul.
I never finish anyth,,,.

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Deano
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Re: 8cyl gpu convert or not

Post by Deano » Tue Sep 27, 2016 9:00 am

If I were in your position of making that decision, I would call Tom Jeffords (Speed Wheelie on here) and talk to him about what you propose and the associated expense. I have his number as being 863-956-3030, if that's changed, I'm sure it's on the board here.
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but it is not the path to knowledge; it has no place in the endeavor of science."
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Olf Art
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Re: 8cyl gpu convert or not

Post by Olf Art » Tue Sep 27, 2016 4:28 pm

Nothing sounds cooler out in the marsh than a 720 though. You can recognize the sound of one a long way off. I guess it mostly depends on how fat your wallet is, but they sure sound and look cool. Rather than changing the cylinders, you might want to study the intake setup. Some mods there would cost a lot less than cylinders and could reap some big benefits. Just a thought. :glasses7:
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broncobill
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Re: 8cyl gpu convert or not

Post by broncobill » Tue Sep 27, 2016 5:09 pm

Most ground powers cranks are not very strong. I would be a little hesitant on converting an 8 cyl because of the crank and extra length.

fletchster76
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Re: 8cyl gpu convert or not

Post by fletchster76 » Tue Sep 27, 2016 8:09 pm

Before JC Stanley passed (the original gpu converter) I was talking to him about this. He said the torque was unreal. He did say it loved fuel but you would have 400hp with some serious torque. My experience with gpu cranks are that they are plenty strong...until they are turned.
14’ Viking, 520 conversion, 72" 3 blade ngh

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OneBFC
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Re: 8cyl gpu convert or not

Post by OneBFC » Tue Sep 27, 2016 8:45 pm

Good torque for sure. Around 750 to 800lbft at the prop shaft.

A little less than a good running 2.0 ecotec. :angel4:

:stirpot:

Cool engine for sure. Have seen a few in the marsh over the years.

Good luck with it!
-Russ
-----------------------------------
The only thing stopping you is FEAR
400+hp Ecotec, 12x7.6 DBDO, 80" 3B Maximus, 2.3 OX,85+mph, water = purely optional
Life begins at 2 BAR, Just a good ole boy

Olf Art
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Re: 8cyl gpu convert or not

Post by Olf Art » Tue Sep 27, 2016 9:00 pm

fletchster76 wrote:Before JC Stanley passed (the original gpu converter) I was talking to him about this. He said the torque was unreal. He did say it loved fuel but you would have 400hp with some serious torque. My experience with gpu cranks are that they are plenty strong...until they are turned.
You can't build any house on anything less than a strong foundation. It's not only a question of whether or not the crank has been turned, but who turned it? There are lots of engines out there that have strange harmonics in them because the reciprocating assembly wasn't properly turned, and afterward was never rebalanced ..... and that goes for A/C as well as car motors.
If I could afford it I'd never build another engine again that hadn't been dynamically balanced. Riding in front of or behind a balanced bottom end is like driving a big electric motor. You gotta experience it to believe the difference.
"I know not what tomorrow may bring, but I know Who brings tomorrow."
Member: KRVSA, FAA, TAA, and life member NRA and VFW

NDWIND
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Re: 8cyl gpu convert or not

Post by NDWIND » Tue Oct 11, 2016 3:31 am

I sure would like to find some 520 pistons and another mag

helicsher
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Re: 8cyl gpu convert or not

Post by helicsher » Tue Oct 11, 2016 4:05 pm

I know Wayne and his dad out at brown's camp in 3a both have 720s
Wayne has Lycoming and his dad has a continental both fuel injection
On 14' all David hulls
I ride with them when ever I see them and there bad ass
When Steve at warrior built my 520 gitso I asked him about building me a 8 cylinder and he laffed and said I will build you one in a heartbeat I have cases laying all over the place but no one wants them
"Success Requires No Excuses"

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