Gear ratio question on an engine change 30 CB

BillD

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25 Terry Jason with Cummins 370 power
I have an owner who asked me a question. I figured I put it out here.

He has a 30 South Shore with a 230 Isuzu. He has a "new" 6BT 230 (yes a 230) Cummins he's wants to install over the winter.
Right now with the Isuzu he's spinning a 22X22 square prop with a 2:1 gear and a 1.5" shaft.

Some guys, maybe Cummins, mentioned he may want to consider a 1.75:1 gear with the "new" Cummins power and maybe pick up some "pitch".

IMO it's not worth the hassle or cost to drop from a 2 to 1.75 gear.

Not sure if he runs a cage or not on the 30 CB

What do you guys think ????

Thanks, Bill D
 

steveinak

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I'm no expert but i'm running a over square wheel (24x26) and all seems well and i agree with you why go to all the trouble and expense when maybe just playing with the prop will do the same ??
 

BillD

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25 Terry Jason with Cummins 370 power
I have an owner who asked me a question. I figured I put it out here.

He has a 30 South Shore with a 230 Isuzu. He has a "new" 6BT 230 (yes a 230) Cummins he's wants to install over the winter.
Right now with the Isuzu he's spinning a 22X22 square prop with a 2:1 gear and a 1.5" shaft.

Some guys, maybe Cummins, mentioned he may want to consider a 1.75:1 gear with the "new" Cummins power and maybe pick up some "pitch".

IMO it's not worth the hassle or cost to drop from a 2 to 1.75 gear.

Not sure if he runs a cage or not on the 30 CB

What do you guys think ????

Thanks, Bill D

I'm no expert but i'm running a over square wheel (24x26) and all seems well and i agree with you why go to all the trouble and expense when maybe just playing with the prop will do the same ??

That's my thought. He's talking 30 hp increase, why mess with everything.
 

captainlarry84

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KristenFormer Charter Captain
The Cummins makes its 230 hp at 2,600 rpm. What rpm does the Isuzu make its 230 hp at? Until you answer that question, every one is shooting in the dark.

David
Agreed this is the magic question we need the RPMs of both motors.
 

WoundUpMarine

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WoundUpMarine

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WoundUpMarine

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