Change prop size on a 6BTA

[Clint Reigh]

I have a 6BTA 315/330 at 2950 RPM with a ZF280A 2:1 gear from sbmar that I installed in my commercial fishing vessel in 2018. I kept the same prop which is a 21:22 on a 6 ft 1.5 inch shaft with a single cutlass bearing. At the time I did not want to change too many things at once but I am now interested in trying to squeeze a little more power out of my setup. I have room to add at least another inch in diameter to the prop. Could I increase my power by installing a 22:22 prop without risking damage to the drive line or engine?

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[Clint Reigh]

Pretty sure it is analogue but my boat is out of the water and inaccessible for the next couple months.

[Clark Leighs]

What is the tach? Is it an analogue unit or a digital unit? If it is digital it likely can be believed.

1 user thanked author for this post.

Tony Athens

[Clint Reigh]

Tach came with the engine in 2018. I have an egt gauge from sbmar also. I do not have a boost gauge.

[Tony Athens]

How accurate is your tach?

It really take 2 measurements to see if you left too much power on the table..

An accurate tach and a boost gauge.. EGT measurements are also nice when you want to “ask it all”..

[Author]

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