How to determine hp rating programmed into engine

[Dan Hughes]

I have a pair of QSB engines in my boat, which had been repowered in 2006. One is original with 800 hrs, one has been replaced due to a failure and has 185 hrs. The original has a sticker rating of 355hp and the replacement has a sticker rating of 380hp. I borrowed a scan tool from a friend and looking at the ratings programmed in the ECM. Both engines say rating is 476hp @ 2800. Is this even possible? Screen shots of the ECM data for both engines included.

Topic

[Tony Athens]

Reading SAE J-1939 ECM output data

Something is not kosher.

How are your controlling the Engine throttle position ??

You need to find your throttle position readings–Your ECM is transmitting that data any basic troubling requires that you should be able to “see it” on any displays that reads SAE J1939 ECM output data

Post a picture of your display(s) — Smartcrap 1.0 is not a display, that’s a Mercury translation of SAE J-1939 data into some foreign language.

I looked up your Simrad, and it should have it———-If not, then bad on them…Knowing throttle position is BASIC

[Dan Hughes]

Hi Tony,

What is a CPL?

Both engines are showing 2850 in neutral at high idle, so I’m not sure how I can get 2875 FL.

The previous owner of the boat, unfortunately, passed shortly before I purchased, so I never got the full story as to what happened. I have been told that the vessel was kept in South Carolina, on a lift. I don’t believe that it was winterized. One winter, they had a cold snap, and the aftercooler froze and busted. The previous owner didn’t know when they went to use it in the spring and started the engine up and ran it for a bit, before it failed.

My gages are the smart craft 1.0, but I also have a Simrad IS42J installed. I’m not sure if engine throttle is an option to monitor, but I can try it next time I’m on the boat. I got all the data on the previous post’s chart from the simrad system.

2400rpms I’m at 12.6 Gph port and 12.2 starboard. Is this a problem?

[Tony Athens]

60271573 (RECON) is programmed as a 380 and should make 3075 N.L RPM

46433590 is programmed as a 355 and should make 2875 RPM NL

Both share the same CPL..

Be sure both engines are propped to reach not less than 2875RPM (vessel fully loaded) and at 2400 RPM, both engines are using about 10.4 GPH or less–then things will take care of ( balance) themselves.

Why did you lose an engine as such low hours? In case you have not figured that out, that could be the moat important part of the entire exercise, if you want to think long term..

Why exact displays do you have?

Can you “see” throttle %?

[Dan Hughes]

Here’s what I got over the weekend.

Speed, Port Gph, Stbd Gph, kts
1700, 7.5, 7.3, 15.3
1800, 8.4, 8.3, 17.0
2000, 9.6, 9.1s, 18.5
2100, 10.4, 10.1, 21.0
2200, 11.3, 11.1, 25.0
2400, 12.6, 12.2, 27.5
2600, 14.2, 13.9, 29.0
2800, 17.1, 16.8, 32.0
2850 top end on both 32.5 kts

High idle in neutral is also 2850

[Steve Lewis]

You also need to take into account that one of the transmissions has extra gearing to spin the opposite way so that can account for the small difference. Nothing will be perfect in the real world so a little difference is not a problem.

As for you question about the 25 extra HP…. I still think you have 2x 355’s as opposed to 1 355 and 1 380. A 380 would spin to 3065 so you might give that a try while making your chart. Disengage the sync and manually advance both throttles to WOT and see if the one in question will go higher. If not then you have twin 355’s.

All of this is theoretical as the propeller is what loads the engine and determines how much fuel is required to spin at any particular RPM. So your actual chart, once complete, will be the ultimate authority of what you have.

[Dan Hughes]

Thanks for the reply. The port engine is no question a reman as it has a white sticker for the engine serial tag.

Both engines reach a governed speed of 2850 @ 32kts. I will have to make a chart next time I am out. What I have noticed is the newer engine (port) burns just a little bit more fuel than the stbd, has more load than the stbd (71% vs 68%) and always seems to be 20-30 rpms difference when cruising while symc’d. Now, that may just be a factor of my props, but could it also be from the 25 extra hp?

[Steve Lewis]

I looked the ESN 60271573 up using QuickServe Mobile and I get “Engine not found”. What I do see(using your pictures) is that both of the rated RPM Values AND CPL numbers taken together point to both being QSB355. If one were a QSB380 then the rated RPM would be 3000rpm.

Are you able to reach the governor rpm range of 2865 – 2885 on both?

If you want to see what kind of power you are actually developing I would create a performance chart. Create a spreadsheet and plot your RPM, Fuel burn and speed for your on plane cruise range. record the numbers at 2000, 2200, 2400, 2600, 2800 and then record you WOT rpm value.

Bring that back to the forum and we can help you figure out what is what from a real world perspective. The rated RPM on both screen captures leads me to believe you have 2 QSB355’s so I have attached the performance report for that engine. I suppose you can ignore the 476hp value that insite shows………

[Author]

Replies