Correct performance curve and pyro gauge

[Robert Greig]

I wanted to confirm that I have the correct Performance Curve for my twin QSB 5.9’s, 425HP. Data Plate pictures attached.
I believe the correct curve is M-93262.
Also, is there any advantage to installing pyro gauges on these electronic motors ?
I am still dialing in the props based on rpm/fuel flow.
I wasn’t sure if the pyro gauges would assist in any way to monitor the performance or health of the motors.
If so, what would the optimum temp probe location be ? I have some test ports at the exit of the turbos or would I need to drill and tap holes in the exhaust manifold leading to the turbos ? Pictures attached.
Thank you.

Topic

[Steve Lewis]

Warranty Question

Tony forgive my ignorance. I just looked up the the published warranty for both HO and non-HO ratings and they are both 24months but HO is 1000 hours and INT is 3000 hours. Does the QSB425INT engine cost more than the QSB425HO rated engine? If they have the same HP and fuel burn numbers but different warranty periods, I am guessing the extra liability for Cummins is offset by a higher initial cost?

[Tony Athens]

Engine Ratings

You are leaving “Warranty” ( time, or “months”) out of the ratings question.. That is the major part as to why they do it that way when the HP ratings are the same on seemingly identical engines..

Tony

[Steve Lewis]

Looks good to me

Robert,

I looked at the reports for the INT(M-93263) and HO(M-93262) spec’d 5.9 425 and the fuel burn at each rpm interval is the same. Maybe Tony can add some context as to why the CPL 1860 would have INT and HO ratings and have the same fuel burn yet different duty ratings. Maybe Cummins rated it HO first then tested longer and figured that CPL could run INT as well. The difference are below as per the fine print on the reports.

CPL 1860 HO – Rated power 1 out of every 8 hours and <500 annual hours
CPL 1860 INT – Rated power 2 out of every 8 hours and <1500 annual hours

Your data plate shows 425HO so M-93262 looks good to me. As for the Pyrometer……

Yes a Pyrometer and a boost gauge will give you the extra data that can help a prudent operator stay within parameters and start to see the early warning signs of anything wrong. Good base line data plotted on a graph and then recorded on regular intervals will help detect issues. Based on the articles below, exhaust flange is the correct location.

Boost, EGT, and Horsepower

Cummins Marine Exhaust Flange Pyrometer (EGT) Location

Boost Fitting Locations for B & C Series Marine Diesels

Cheers!

1 user thanked author for this post.

Robert Greig

[Author]

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