Basic Diesel engine question

[madhatter1]

Just found out since we pulled injectors from port side for testing that this engine has different injectors than the starboard side. Not sure of actual part numbers but port side has less fuel flow at max. Dave Disesia rebuilt the port side and must have known the difference. Supposedly the larger injectors on starboard side were discontinued.

Should I be concerned or just keep running as is. I have perfect injectors now so why would I chance a new set? I have heard bad things about new injectors but maybe that's a myth.

So in a pair of 650 HP 8-92's the port is technically a lower HP. Both make full RPM. Has been this way for 900 plus hours of operation. Mechanic recommends changing starboard to the lower flow injectors to match the engines HP. Not pushing me hard, just saying. My question is do I even need to give this a consideration? I cruise at 1800-1850 RPM's. Sometimes bump up to 1950 for fast cruise and maybe 2100 once a year or so to catch a bridge opening. At these RPM's I believe that each engine is being fueled enough to make whatever HP is needed for those cruise RPM's. Therefor making equal HP. The only difference in HP and loading would be after the port runs out of HP at full throttle and the starboard is maybe pushing harder. I only ever hit full RPM once a year with mechanic onboard for PM sea trial.

My reasoning in leaving as is comes from what I do in my 34 which tends to clog fuel filters. If one engine goes out of synch due to low fuel flow from filter I simple throttle down 50 RPM's where fuel flow is good and engines stay synched perfectly. Just brought the engine with better fuel flow down to match the other. So both making same HP at same RPM even though one has a limitation.

 

[Bob Quinn]

I'm no mechanic but everything you are saying makes sense.
I would personally find it hard to want to match them side to side so that throttles could be in same exact position for an hour a year. Perhaps someone in the know will have answers to any possible negative to not having them matched but I sure don't see the issue. Sounds more like one of those things that will just bug you knowing they are not the same.

I drove most of the summer with one messed up / bent prop. I could tell more in responsiveness when turning or idling around. Couldn't really even tell when at 10 mph or throttling up (other than the impending vibration if I was to continue to throttle up).

Sounds like your saying "If it ain't broke don't fix it" . Might be good not to kick the hornets nest and risk possible new injectors not working right. I would think injectors are tested and flow tested when new though?

Do she hook to the right ? LOL.

Good luck, hopefully some mechanics chime in.

 

[Avenger]

Propeller demand means both engines fuel the same pretty much everywhere except max RPM. So unless you're running in the corner you'll never see any difference.

We replaced the injectors in the port engine with the same spec after the un-Reliabilts burned a piston on Dave. He did a full rebuild on that engine which included our injectors. They're correct and I wouldn't F with them.

What injectors do you have in the starboard engine that are different?

 

[madhatter1]

I can ask what each is on Monday. I have a good mechanic who takes care of me so not going to bug him on the weekend. Dave ran the boat the whole life of the new starboard engine as well as the port after he rebuilt it. He ran it at 1800 as well. So I'll just stick with what is not broke.

Is there one part number for 650HP version of 8-92?

 

[Avenger]

No worries. You're bugging me on the weekend too.

Detroit is,... funny,.. when it comes to things like that because they had so many dealers making up their own specs. It was kind of a free-for-all sometimes.

 

[q240z]

I 100% back Avenger: if it ain't broke, leave it alone.

 

[Captain Ralph]

J&T, Covington and other had some trick injectors made or special ordered. These part numbers are not available. However, close matches can be had.
A better shop can still change the nozzles to help match them.
Still, Timing height can be a simple adjustment for that old (real old) Detroit guy to make and help even the engines up.
So, anybody check the height before removing the injectors?