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Moving engines forward

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Old 09-06-2025 | 01:37 PM
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Default Moving engines forward

We are still in the planning stages of our repower and wondering if it would be beneficial to move the engines forward a few inches? 40ft Hustler single step hull switching from Yanmar diesels to Cummins. Currently spinning 32 pitch 5 blades on #8 Arnesons. One issue the current setup has is it starts porpusing when trimming up. It'll run flat then a small boat wake can set it off and I have to bump the tabs or drives down to make it stop. If you let it continue it'll start hopping the boat out of the water. Would moving the new engines forward make it better or worse? Currently cruise at 70 to 72 with drives at zero with no porpusing. Top speed 83 but thats trimmed way up and hopping her fat heavy ass out of the water. Lol I have roughly 12 inches of room to move forward.
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Old 09-06-2025 | 03:04 PM
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Is there a weight difference between the two motors, that might factor into that also.
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Old 09-06-2025 | 03:10 PM
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have you tried adding weight in the nose in the current config, moving engine location affects several things......... if the manufacturer is still in business Id be getting them on the phone
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Old 09-06-2025 | 03:21 PM
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Originally Posted by Craney
Is there a weight difference between the two motors, that might factor into that also.
They both weigh 1,400ish give or take a few pounds.
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Old 09-06-2025 | 03:24 PM
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Originally Posted by F-2 Speedy
have you tried adding weight in the nose in the current config, moving engine location affects several things......... if the manufacturer is still in business Id be getting them on the phone
I'll give then a shout next week. I'm curious what should I expect in moving forward? The engines are heavy so a minimal movement could make a big difference for better or worse.
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Old 09-06-2025 | 04:15 PM
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The two biggies I see is drive coupling and exhaust reconnect, I assume this is a side by side
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Old 09-06-2025 | 05:20 PM
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I don't think moving them forward +/- 6 inches will have any significant results. I would lean toward trying different props with more rake.
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Old 09-06-2025 | 05:41 PM
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Originally Posted by F-2 Speedy
The two biggies I see is drive coupling and exhaust reconnect, I assume this is a side by side
I'll be the one doing the swap and fabrication. The turbo design is completely changing so exhaust already has to be redone. The coupling will just require a longer driveshaft.
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Old 09-06-2025 | 05:52 PM
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A friend of mine had a 1995, 46' Post. Twin 6v-92's. Moved the engines forward one foot. He was very happy with the performance.
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Old 09-06-2025 | 06:03 PM
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ya I keep forgetting its a repower.........
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