Differences between engines. Concern or not?

[aviator]

Yes I'm aware of this. The engines in the F53 I'm looking at have had heat exchangers changed at about 600hrs

Interesting thread as I have similar situation with Volvo TAMD75Ps although I know exactly when the situation changed.

I had a new stbd turbo fitted at 650 hours and immediately the fuel flow increased on that engine, previously it had been even between both engines pretty well. Volvo said the turbo had to run in etc etc but all was well.

FWIW small diffs between the props will also give a difference in fuel flow due to differences in engine loading, but in my case I knew it was definitely a change in the turbo.

These days I have stopped worrying ;-)

 

[jfm]

Interesting. So you had a new tight stbd turbo and increased lph in that engine. And lower boost pressure in that engine we can safely assume. That's exactly the symptoms in Deleted User's putative boat. So I reckon this freti has a duff (tight bearing) turbo on stbd side as said above. Or the data is wrong as MapisM said

What was the difference in lph that you got with the volvo 74s?

I don't think it is duff or mismatched props despite many suggestions of that. That wd cause increased turbo boost in stbd engine, not reduced

 

[aviator]

I'll dig out the log and post the info. I watch LPH like a hawk tight thing that I am hence spotting it at once.

Thing is that the port engine fuel flow remained the same, well as much as is ever the case with different loading conditions at sea and this was my concern. Why just changing the turbo increased fuel flow on sync'd engines. You'd have thought it would be more efficient with the new turbo.

Anyway my comments about the props also came from personal experience. I had a little contratemps on a sand bank in the Thames estuary and grounded the props, this at the end of a round Britain trip when pressonitus had set in silly thing that I am. I returned to Felixstowe and used the local firm to fix the props since they claimed to be experts. After the repair I set off without a sea trial and realised that the props were badly out as the whole thing vibrated over 1800 rpm so took a slow route back to the Hamble where there are better facilities that I know about and have confidence in. Hamble props did them again and all was well except that fuel flows didn't match whereas in long experience they did. The boat had to come out of the water again for another reason and Sealine suggested that the props go back to the original manufacturers where they indeed produced a better match. I just paid up in each case since I am not the arguing sort - my wife may think differently of course!

So this long winded story just to show that actually small differences in props do make a difference and without the previous trend in fuel flows being known it is difficult to say if there is any mechanical prob with the original query. All suggestions are valid but prop fixes yet another line of enquiry.

The story of going back to the original Levington dealer when I reported that their prop fix well, wasnt a fix will wait for another day.

 

[MapisM]

I just paid up in each case since I am not the arguing sort - my wife may think differently of course!

Well, I must sympathize with your wife on this one!
And even more so for VP repair: I don't think a turbine really needs a break-in these days, and if it does, it should be a matter of a few hours. Having a worse performing engine after such fix is unacceptable imho.
If you find the numbers, it'll be interesting to check them against VP specs.
In the case of Deleted User, we shouldn't forget that it's the more thirsty engine which actually matches the specs nicely.

 

[Deleted User YDKXO]

Update

Thanks to aquapower of this forum hereabouts who gave me a contact at Finnings UK down in Poole, I was able to send them a copy of the test report and here is a summary of their reply

All parameters recorded on the sea trial documents sent fall within Caterpillars acceptable limits, the boost and fuel consumption will be higher on the Port engine as it is carrying more load. This is normal as one propeller will be driven against rotation which creates more load. All temperatures and pressures look good the fuel consumption looks good and engine speed which are 1% over the 2300rpm rated speed. You will also get a difference in fuel pressures and engine oil pressures as the filters on Cat engines are handed so one engine will have longer fuel lines and oil lines than the sister engine. I have listed the major facts below for your reference with Cat specs I hope this helps.

I'm not able to copy and paste the table Cat also sent me but all the measured test parameters fall within Cat's limits so it looks like these engines are fine. Interesting comments about differences port v starboard fuel consumption and fuel/oil lines?

 

[MedDreamer]

A nicely straightforward reply Mike and in this case well worth asking the experts.

If you had been guided by this post you would have

1) Changed props
2) Fit new turbochargers
3) Removed the fuel tank and replaced it with seperate ones for each engine
4) New fuel pump
5) Serviced Injectors
6) Fit bigger satellite dish - eh? shum mishtake shurly



So is this the green light for change of boat then?

 

[DAKA]

All really good news mike , hope your change goes well

Now totally unrelated and dates back to a discussion with jfm 2-3 years ago

the boost and fuel consumption will be higher on the Port engine as it is carrying more load. This is normal as one propeller will be driven against rotation which creates more load.

Interesting comment, one tank runs out of fuel early reducing the usable range , Hurth ZF produce some of their range of gear boxes with slightly different ratios, the 63 as used commonly by Volvo Penta for example .......could this be a deliberate attempt to overcome this ?

My current boat had slightly different propeller pitches , I have often thought this could be an attempt to balance the engines ?

Do you know what gear boxes are fitted to your cats and do you have ratios slightly different for clockwise/anticlockwise ?

 

[Deleted User YDKXO]

A nicely straightforward reply Mike and in this case well worth asking the experts.

If you had been guided by this post you would have

1) Changed props
2) Fit new turbochargers
3) Removed the fuel tank and replaced it with seperate ones for each engine
4) New fuel pump
5) Serviced Injectors
6) Fit bigger satellite dish - eh? shum mishtake shurly



So is this the green light for change of boat then?

Heh, heh, thats a bit sarcastic.

It's not quite all systems go yet. They've done a survey/seatrial on my F46 in Sardinia and gave it a clean bill of health so they've agreed to accept it as a p/x. I've got a survey and seatrial on the F53 fixed up for Saturday week so fingers crossed on that. The big problem is my F46 is in Sardinia and their F53 is in Lignano on the northern Adriatic. As part of the deal, I had to agree to pay for my F46 to get to Lignano. Their are 2 ways of doing this, either by sea but it's an awful long way around the toe of Italy and up the Adriatic, or I get the boat to Rome which is about 200nm from Sardinia and then truck it to Lignano. The truck option is slightly cheaper overall but the flybridge has to be dismantled first to comply with height regs. Either way I'm looking at a total cost close to €10k but the p/x deal is very fair so I'm going to have to stand that.
I'm quite excited about the prospect though. If it all goes through, I will probably base the boat in Croatia. It's a fabulous coastline which I rode with some mates on a motorbike tour last year and, since then, I promised myself that I'd take my boat there some day. That day may arrive a lot sooner than I thought

 

[Deleted User YDKXO]

Do you know what gear boxes are fitted to your cats and do you have ratios slightly different for clockwise/anticlockwise ?

All I know is that they are Twin Disc boxes. Don't know ratios or anything else

 

[MedDreamer]

Best of luck Mike, I hope it all goes well. Croatia sounds and looks fabulous.

 

[aquapower]

Glad to hear you bot the results you needed, while I was on a training course at Volvo last year we were told of a lot of fitting of new parts at great cost when guessing at what might be wrong, instead of looking at the obvious which in this case was perfectly normal and not what it seemed.

If you have the twin disc boxes thats another bonus as they are a lot stronger than the ZF ones which are prone to giving up due to being borderline on the HP limit for that box, (usually the port one)

I would favour moving boat by sea rather than dismantling things to get height for road transport as its usually quite a lot of work to remove masts and if any thing breaks when undoin it thats extra hassle

Good luck and hope the purchase goes through smoothly

 

[jimmy_the_builder]

Heh, heh, thats a bit sarcastic.

It's not quite all systems go yet. They've done a survey/seatrial on my F46 in Sardinia and gave it a clean bill of health so they've agreed to accept it as a p/x. I've got a survey and seatrial on the F53 fixed up for Saturday week so fingers crossed on that. The big problem is my F46 is in Sardinia and their F53 is in Lignano on the northern Adriatic. As part of the deal, I had to agree to pay for my F46 to get to Lignano. Their are 2 ways of doing this, either by sea but it's an awful long way around the toe of Italy and up the Adriatic, or I get the boat to Rome which is about 200nm from Sardinia and then truck it to Lignano. The truck option is slightly cheaper overall but the flybridge has to be dismantled first to comply with height regs. Either way I'm looking at a total cost close to €10k but the p/x deal is very fair so I'm going to have to stand that.
I'm quite excited about the prospect though. If it all goes through, I will probably base the boat in Croatia. It's a fabulous coastline which I rode with some mates on a motorbike tour last year and, since then, I promised myself that I'd take my boat there some day. That day may arrive a lot sooner than I thought

Uh-oh, sounds like another forum delivery trip adventure! Need any crew?

Cheers
Jimmy

 

[petem]

Mike, your maths aren't very good, at 2100 revs the diff is more like 20%. Apols if this has already been suggested or may be a stupid suggestion, but are both engine driving the same alternators etc?

Pete

 

[Deleted User YDKXO]

Mike, your maths aren't very good, at 2100 revs the diff is more like 20%. Apols if this has already been suggested or may be a stupid suggestion, but are both engine driving the same alternators etc?

Pete

Yeah you're right, seems a big difference but the figures are within Cat tolerances according to Finnings so You've got to believe them. Yes I believe that the alternators are the same

 

[Deleted User YDKXO]

Uh-oh, sounds like another forum delivery trip adventure! Need any crew?

Cheers
Jimmy

Maybe but I'm favouring trucking her at the moment

 

[MapisM]

A nicely straightforward reply Mike and in this case well worth asking the experts.
If you had been guided by this post you would have...

I saw only now the updates from Mike, and your reply above.
With all due respect for the "experts", at least those who tried to contribute to the request from Mike actually READ the numbers.
Now, do you think the same can be said of the "experts" who sentenced that the boost and fuel consumption will be higher on the Port engine as it is carrying more load?
If so, think again.

 

[Deleted User YDKXO]

I saw only now the updates from Mike, and your reply above.
With all due respect for the "experts", at least those who tried to contribute to the request from Mike actually READ the numbers.
Now, do you think the same can be said of the "experts" who sentenced that the boost and fuel consumption will be higher on the Port engine as it is carrying more load?
If so, think again.

Mario, yes I agree there does seem to be a discrepancy in the figures but all the same, I sent the figures to 2 different 'experts', one of whom is the UK Cat dealer, Finnings, so you would expect them to know what they're talking about, and both experts confirmed that all readings were within Cat's stated tolerances. I had a sea trial on the boat on Friday and certainly, the engines showed no signs of any problems. The boat reached a max speed of 31kts even with a dirty bottom and that is only 1kt less than Ferretti's stated max speed. Both engines reached slightly more than their rated max rpm, all the instrument readings were normal and there were no other signs of any leaks or other issues. I do know that the surveyor identified a shaft misalignment problem on the port engine which may have been slightly affecting the engine parameters but I don't know really.
It was interesting to compare the 2 engines which were not a mirror image of each other. In order to locate all the main service items on the inside ie 'handed', Cat have moved the position of many items. For example the fuel and oil filters are in a different position on each engine. Maybe this bears out what the Finnings expert was saying in that different fuel and oil pressures could result from the engines being handed.
I don't know what else to do now. The experts say the engines are within tolerances, the boat goes fine so I guess I have to believe that the engines are OK

 

[MapisM]

I don't know what else to do now. The experts say the engines are within tolerances, the boat goes fine so I guess I have to believe that the engines are OK

Yup, I see your point Mike.
And I can't imagine any further sensible check you should/could do.
31kts with a dirty bottom is a great result for that boat, btw.

I'd just be curious to hear how Finnings justifies the releveance of a general theory for the port engine burning more fuel (according to which, btw, that should happen in ANY boat, whilst it doesn't seem to be the case, according to the experiences of other posters), in a boat where the port engine actually burns (or seems to, anyway) less.