calculating load

[Jeffrey Fontes]

Hi all,
First post but been getting my motor supplies from SB. Love the service!!
This is the first year ive ever run a diesel boat. Im used to gas I/O’s, inboards and mostly outboards. I am extremely handy and a good wrench.
enough of that though.
We just picked up a 31 Eastern (down east hull) with a cummins 6bta 330 with 1700 hours with a 22×24 4 blade wheel. 15Kt cruise at 2600, 2850 WOT 17 kts if i am lucky. Im getting about 1.3 NMPG (based off of miles/gallons) at 15 kts that is about 11.5GPH.

What is my load at 11.5 GPH 2600 RPM and 15Kts?

I know that the Aftercooler needs a good cleaning but otherwise it has new injectors and a rebuilt injector pump..sadly the mechanic prior to us owning it couldn’t stop the timing gear from slipping so he keyed it.

I miss the speed of the outboard boat since it got the same exact MPG’s with 247 more HP and twice the speed as what we do now, but this is a beast in most sea sates. Its clear that the motor is turning the correct RPMS with the WOT at 2850.
Is it safe to assume that is all i am going to get out of this motor terms of fuel burn and cruise speed? or can i change the prop and or transmission and prop for more speed and relatively the same GPH?

Topic

[Rob Schepis]

That’s fine, just make sure there is only one! There’s plenty of youtube demo videos on all sorts of equipment and different units, including the cheaper units in case you want to save a few bucks.

[Jeffrey Fontes]

That would explain the reflective square on my crank pully, its on the face of the pully is that ok?

[Rob Schepis]

I use this Laser unit by Extech (model 461920), might be cheaper units out there but this has served me very well for many years. Just used it last night checking out a pair of 3208 CATs.

It comes with the reflective tape, just put a small square on the crank pulley. Here’s some shots using it on my 330B’s. At the time I had the starboard belt guard off but the port engine had the guard on and you can shoot the pulley through an access hole.

[Jeffrey Fontes]

OH any work instructions on verifying the tach?

[Jeffrey Fontes]

Thank you. I was fairly certain we were getting what we could out of it. I’m not terribly concerned with the speed although I miss it. I was just hoping to know if its loading correctly or if I had room for adjustments.

[Rob Schepis]

I think you are “on the edge” already and asking all that engine has to offer for any decent life to be expected. if you want to run at the high cruise you should back off on the prop and get her north of 2,900 FULLY loaded and consider installing boost/EGT. Has the tach been verified? Perhaps a new “hi-tech” prop could get you better performance but since it appears you lost 15knots in your boat swap I don’t see how a knot or so will really make a difference… The best way to get used to a slower boat is to only go out on snotty days 🙂

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