Under-Prop?

[Richard Janek]

I’m considering re-pitching propellers to free up some rpm on a pair of 6CTA8.3 M2’s. These engines have 2000hrs, early C’s. I just replaced the head gaskets due to external coolant leak at WOT. Replaced all sea water components after reading and learning here. Thanks.

The engines make 2700 using optical tachometer on the harmonic balancer. The helm tach actually under reports the rpm by 50/100 rpm.

Any downside to letting the engines run up to 2950?

From what I read on this forum, no problem with under propping by a few hundred rpm. I just want to buy some reserve for high load running, should that occur.

EGT and Boost gauges installed, 800F/875F and 30psi at WOT.

Topic

[Nathan Brady]

The proper way to prop your boat is to load it down to the max that you would ever use it at. Then go do your wot tach check and you’ll want to see it at 2700-2750 for that engine. That way you’ll be safe at any load you use it with. 

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