Prop pitch 38 Tiara open

[William Walter]

read Corey’s article about ovever propping on 480 ce engine .i have 3 bladed 24 by 30 props which register right on the power curve or slightly higher .i have some browning on my turbo and aftercooler. Was planning to have props reconditioned this winter as it’s my first with boat and one prop has a slight nick.what conversation should I be having with my prop guy to get me under the curve

Topic

[Rob Schepis]

Hah, what a co-inki-dink, small world..Yes they survived and have been growing like weeds ever since!

[William Walter]

Yes Rob she is one and the same.she is now the proud owner of a tiara 38 open. Hope your girls survived kindergarten with Mrs Walter.Bill

[Rob Schepis]

Wow, yeah, welcome to FL!

Bill,

Interesting that you bothered to include your home town which really had little to no relevance to the topics at hand.  Why that’s so interesting is that I too live in WR and a “Mrs. Walter” taught both my girls Kindergarten and I know my wife and her spoke about cruising, Shelter Island, etc… My wife even recalled that Mrs. Walter had a Tiara….

Same “Walter” ?

I’ve used Mark for outboards, always went well, but I have no experience with him as far as inboard diesels go..

 

 

 

[William Walter]

Rob I live in wading River and keep boat in greenport.i was going to use Long Island propeller in rocky point.used mark before and seems like he will work with me.boat was really fouled when we did survey.had to insist on pressure wash and scrape as the boat was in Fort Lauderdale.boy have they got some nasty barnacles down there.since then I had bottom repainted and running gear cleaned again.i have been running 2100 and getting a 13.5 burn on my 480ce yeilding a 23 knot cruise since then.this may still be a bit overproped so I was thinking of a slight adjustment.i have 24 30 props and noticed the tiara 38s with 450s have 24 28 props.regards bill

[Rob Schepis]

Long Island….my neighborhood.  Who is your prop guy?

[Tony Athens]

William,

As much as I like to tell you you have another solution to long term 480CE longevity, you do not.. The “insides” of your engine are no different than a 450 Diamond which should be propped to 430 BHP at 2700 + RPM..

In so many words,  the engines head and valve gear are the weakest point on the engine and you need to prop your engine so when at CRUISE RPM’S in the 2100-2300 RPM range, you are at or BELOW the 450 Diamond prop curve.. It come down to this, nothing else..

It’s you call who you want to listen to.. Me , “dock talk”, some school trained Cummins Tech with zero long term field experience, or  your prop guy with zero experience with the internal construction of your engine.

Tell him you need your props to absorb no more than about 250-260 BHP at 2200 RPM ( about 13 GPH)…Then the rest will take care of itself. Let’s see how good he is

 

Tony

 

Propping the Cummins 6CTA 8.3 480CE vs. 430/450 Diamond Engine

 

 

 

[Corey Schmidt]

Bill, at 2200 cruise RPM you’re burning ~16 GPH which is way over the curve and your are over-propped. If you want your engine to last and play it on the safer side, you need to re-pitch the prop to match the curve of the 430C Diamond which has a target GPH @ 2200 of 13.6 GPH.

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