Target Revs for 330 Diamond 6BTA

[Stephen Oliver]

Hi Guys

What revs am I looking at achieving WOT for the 6BTA 330 Diamonds ideally (approx 1700 hours)

Boat is back in the water finally with new props (20×21 4 blade mikado) Port engine is topping out just over 3000rpm and starboard side wont run that high as the throttle is at max before it gets there (its out position wise compared to port engine much further forward at same rpms – so think its just a cable issue – something i’m going to look at soon) it only gets to 2750 so I suspect the port engine will get to 3100 if the starboard engine was running up to speed. I suspect a bit underpropped – but would rather have scope to load the boat (not that it was empty) but we generally cruise at about 2200rpm (16ish knots) boat repairer is suggesting cupping the props a bit but i’m looking for advice…

By the way are there any guides to adjusting throttle position etc on SBmar?

Thanks in advance

Steve

Topic

[Stephen Oliver]

HI Guys

Just as a follow up – i believe (although not confirmed yet until new turbo is fitted) that the issue was a well and truly worn out turbo (salt water worn) see https://www.sbmar.com/community/topic/turbo-rebuildable/#post-33525

I suspect there was just very low boost available and therefore down on power – just the STB engine was pulling the port engine along and masking the issue – I also suspect the black smoke couldnt be seen due to the exhaust being submerged when planing. Someone had basically found a worn out turbo – didnt fix it (and here is where i get a bit suspicious) – bogged it full of exhaust cement to get it to seal (no gasket was present) – I also suspect that my issue of tacho being out by 200-300rpm on the port side may have been purposely done so that it appeared both engines were running at same WOT rpm.. very poor work!

Anyway – its forced me to look at a number of things – After-cooler is being bench serviced (but is likely to require repair due to being hammered out of the housing) – I have found my mufflers were designed by someone without a clue (the outlet level is the same as the inlet so they never fully empty – so looking at draining through a spare through hull fitting and NRV as I think the water level in the mufflers is well above the waterline (TBC) but I am yet to read of anyone doing this! (dodgy sketch attached of what I am thinking!) I’ll also try and get a full picture of the exhaust installation – but think I need new mufflers making – again – longer term thing..

I am also going to run rydlyme through the raw water cooling – and then repeat eveything on the stbd side!

As always indebted to all on the site (especially Tony) for all the help and suggestions – and I’ll be back with a full update once I have the port engine operating.

Steve

[Tony Athens]

Until you read and follow the article on this site “low power troubling shooting”, be sure everything is followed 100% as written, and then follow my earlier “one-on-guidance” above, then there is nothing else I can offer……….Until you do all of that, we are both just spinning our wheels and going no where fast…

Tony

[Stephen Oliver]

Ok bit of an update. Changed filters for 10mic racor, the old 30s were not very dirty. Changed last chance filter for the recommended fleet guard. 6 of us came over to a local island for the weekend and to give it a test run.

Came out of the marina, let her warm up and then opened the throttle. Port engine was a bit sluggish accelerating but went beyond 2200 up to past 2400 (didn’t check wide open as we were just cruising over, but proved it would go past 2200 easily, could hear the engine note change also as I throttled up.

We stopped on idle half way over to dump the holding tank. Accelerated back up and port engine was back to being pinned at 2200. No change in noise when throttled up, no noticeable smoke when throttled up.. so seems to be a heat \ time related thing..

Any ideas what else to look for.. I’m still trying to get some gauges for the fuel lines just to see if pick up may be a problem..

Steve

[Stephen Oliver]

Hi Tony

I dont suppose you sell the filter heads by themselves do you? Struggling to find much over here.. so looking at options.. Also what size ports do you have on them? Most I see are 1/2npt – so by the time the fitting is in etc there is quite a restriction going into a 1/2″ hose.

I’m also still trying to find the fittings you use.. with the yellow collars – any pointers as to brand or where they come from?

Steve

[Stephen Oliver]

Thanks Tony

Have been reading it – which is where I got the 5/8 line from – but i’m not going to be anywhere near 15ft line length – probably <10ft so if 1/2″ will do then makes fittings a bit easier and can use the standard fleet guard head which I can pick up relatively cheaply. I’m reading / have read most of your site..

Will go 10mic short term on the racors until I can pull this together. I’ll have several standing by also! The filters have been in the boat for 20 years so although inadequate – they must have a bit of overhead as the boat has done a couple of long journeys with the previous owner – 1200 mile round trips – either way they will be going shortly – as I mentioned earlier – i’m going through the engines Seaboard style as best I can – but with my own business – a little one and life – things take a little time!

Steve

[Tony Athens]

3/8″ return is 100% big enough–Even 5/16″ is fine.. Usually 1/2′ supply is ample unless some odd in in the system..

Have you absorbed this article and understant what it is saying?

Understanding Fuel Line Sizes vs. Fuel Supply Restriction

It’s your 500 FG Racor that is totally inadequate as to flow AND capacity.. Plus, you really do not want a 30 Mic before the engine—- You want 10 Mic..Never rely on the last chance filter to save you the “innards” of your injection pump in a marine application when it it so easy not to..

Tony

[Stephen Oliver]

Hi Tony / Rob

Yep understood – am just looking at options for filtration etc available here so i can remove the racor. I’m hoping that is all it is.. but i’m not generally that lucky and not to mention I dont see how it can fix itself in 3 months on the hard… Either way – I’m going to go grab some filter elements (probably 10mic) to throw in just in case as a short term fix. Winter is good boating here..

I can get the filters really cheap but the heads are proving a little difficult to track down.. the only ones so far are baldwin / fleetgaurd with 7/8’s ORB fittings.

I’m being a bit cautious on spend at the moment as we have just paid our pen fees, have the insurance and also the boat registration payment to deal with this month!not much change from $11,000aud!!

If we didn’t have all that i’d just order the kits straight from SBmar and deal with it..

I am planning on a pressure gauge on the output side of the last chance as previously mentioned – I’m looking for a 100psi gauge for each engine.

I’m also looking at a vac gauge on each filter set once i have sorted that out I figure more info is better in the long run! I’m just trying to find the parts now. Looking at 5/8 hose (16mm) for all feeds – and 1/2 or 3/8 returns to the tank. I’m also trying to work out if I can move the whole filtration to the front of the engines as there is a large bulkhead to mount everything on cleanly – where as there is no bulkhead at the rear which makes things a little hard to mount and access.

working through your fuel filtration posts and absorbing it..

I assume having the filters mounted below tanks is standard practice as they are now (makes priming easy)

Steve

[Tony Athens]

Remember, the Last chance Filter on this engine is under PRESSURE (15-35 PSI or so) , not vacuum.. Again, best to put the gauge on the output of this filter.

You want to “see” the fuel pressure going into the injection pump rail.

Tony

[Rob Schepis]

And add to all that the fact that your Racor 500 is rated to 60GPH and your engine pumps 60-65GPH…

[Stephen Oliver]

Hmm Reading your info on fuel filtration.. I’m probably going to be looking at starting the fuel filtration and pipework from scratch. Currently all copper – nice install – but hard to modify as its 20+years old and pretty green… . Fuel system looks to be fairly simple:-

2x 450l Tanks all feeds are from the bottom I believe (3 valves are in place at the bottom rear of the tank.

3 valves each side – and from what I know I have feed – return and tank link. All pipework is copper to the filters and back until it gets to the engine then goes rubber.

I guess if I went rubber right through it would be a) easier to mod b) easier to replace the existing racors with your recommendations (look at 2 stage primary FS1000 and other) so completely scrap the racor c) ensure I have no crimped shut connections as are present on the way to the genset.. dont ask the previous owners have done some really suspect things..

What fittings do you guys use? looks like hose barbs rubber and worm drive clamps?

Probably worth me starting up a new thread for this as it going away from the OP.

Steve

[Stephen Oliver]

Tony Athens wrote:

1) Remove the solenoid linkage and tie up you fuel stop lever(s) tight at the top unless you are 100% sure the solenoids are doing it.. Just because the solenoid is “sucked-up” to its internal stop, does not mean the fuel lever is all the way up. The linkage is adjustable.

2) Install a fuel pressure gauge ( around 0-60 PSI , liquid filled) on a 5-6 ft hose with a few loops in it and attach it to one on d the unused ports on the last change filter head. Output side on the head is best, but if you know it is “as new”, then it does not matter

Do some testing with that……….Your fuel pressure there will tell you 100% if you are having a fuel delivery issue of some sorts.

Report back

Tony

Thanks Tony will give the fuel solenoid a good going over next week and manually tie it up (load of zip ties on board!) Then i’ll start gauging the engines up.. the last chance filters are remote so easily view able..

Again thanks for your ongoing help…

Steve

[Stephen Oliver]

Rob Schepis wrote:

So no vacuum gauges on your primary fuel filters? That would tell you if something is going on restriction wise from your primaries back to your tanks, dip tubes, etc. What do you have as primaries, Racors?

Hi Rob

No no vac gauges or gauges of any type – and yes – howdya guess I had Racors? haha…. pretty much every boat over here has them. 30mic primaries but only the 500 series so single filter. Gauges are on the list – but just trying to source some filter heads here in Aus to put a bulk primary and gauge prior to the racor.. maybe 30mic primary and 10 mic racor and 2 mic pre injector (which is remote mounted) – Also looking at putting some oil pressure gauges on the motors too.. Slowly going through everything to get it Seaboard style but also fire fighting along the way..

What range vac gauges?

Steve

[Tony Athens]

1) Remove the solenoid linkage and tie up you fuel stop lever(s) tight at the top unless you are 100% sure the solenoids are doing it.. Just because the solenoid is “sucked-up” to its internal stop, does not mean the fuel lever is all the way up. The linkage is adjustable.

2) Install a fuel pressure gauge ( around 0-60 PSI , liquid filled) on a 5-6 ft hose with a few loops in it and attach it to one on d the unused ports on the last change filter head. Output side on the head is best, but if you know it is “as new”, then it does not matter

Do some testing with that……….Your fuel pressure there will tell you 100% if you are having a fuel delivery issue of some sorts.

Report back

Tony

[Rob Schepis]

So no vacuum gauges on your primary fuel filters? That would tell you if something is going on restriction wise from your primaries back to your tanks, dip tubes, etc. What do you have as primaries, Racors?

[Stephen Oliver]

Thanks Tony – I’ll aim for 2900..

I have to solve another issue now before I can test again.. the Port engine issue of limited revs is back.

Boat was doing this prior to being on the hard for 3 months after a reef strike (to starboard side) runs normal up to 2200rpm and then nothing further. No matter where the throttle is pushed no extra – no change in noise – no extra smoke (dont have egt so cant confirm)

Put back in the water – first run all good apart from rev counter being out by a large margin on the port side. That now corrected – first few runs of around 30 minutes – all good – both engines pulling up to 2850.

Took it for a run today – 45 minutes up the coast at between 2200 and 2400 rpm – felt good. Shut down while we had some food and drinks. Started up – dropped 250l of fuel in and the headed back home – port engine wouldnt go over 2200 again. No black smoke – so can only assume boost is ok and not extra fuel is going in when throttled to WOT (until I get boost and egt I’m a bit blind.. on this)

I originally thought it was a fuel solenoid issue as I was chasing a low voltage / non start due to solenoid not pulling back issue – I rewired all on the hardstand using 70mm2 cables and stripped A LOT of excess cable out – so the engines now see high volts and start very quickly. So when it went back in and the issue wasn’t there I thought it was fixed. Now I guess its not unless i have a sticky fuel shut off?

My other thought is that the refuelling could have stirred up some sediment in the tank and blocked a fuel filter – But i cant work out how the fuel filter could become unblocked while on the hard? I guess the only way of finding that is either replace the filter (I think they are 30mic’s but see you recommend 10?) and see what happens – or start fitting gauges..

Is there anything else that anyone could suggest that could cause this? Stb side engine was happy to keep increasing speed while the port had hit is limit – we had some extra water and 4 extra persons on board (over the test runs previously)- but again it was fine on the way out – so should have been fine on the way back albeit carrying some extra fuel but only a small amount in the great scheme of things..

The other thing to note is that when this first occurred (back at Christmas)- it was running fine one trip – and then not the next – its not like it had degraded along the way..

Any suggestions would be greatly received.. its a bit of a weird one.

After coolers are due to be stripped shortly as well as the HX on each engine.

Steve

[Tony Athens]

Best overall performance will come if you make an accurate “OVER 2900RPM” when the vessel is loaded as you use.. As to all the rest–does not matter other than your props need to be of a very high quality..

Tony

[Stephen Oliver]

We’ll finally got some good weather to test and what a difference when one engine isn’t dragging the other along! Faster and smoother.

Never trusts a tacho eh?

The downside is it looks marginally overpropped. We are heavy with gear but only have 300l of fuel and about 200l of water on board, but then I am also carrying extra batteries that I haven’t taken off yet and also tools.. lots of!

Idle rpm needs upping a bit as they are sitting at 600 ish.. and low oil pressure alarm strikes on the port engine after a fast run.

Top rpm sat at around 2850 and we were doing 25kts which i didn’t think was bad for a 12t boat with 660 horses. I think I need a few more revs at the top end though. It didn’t struggle getting there and no black smoke pouring out. We had 2 people on board, but will be running with 4 or 6 today..

Props are 4 blade Mikado 20×21 so probably need them taking to 20×20, however I want to check boost and egts first to see how worn the turbos are… gauges will be ordered soon

Thoughts on the revs achieved? They look ‘right’ in a purely blinkered sense but I feel that it needs more rpm ..

Steve

[Stephen Oliver]

HI Tony

Sorry

should have read (i cant go back and edit)

Tach Laser Error Tach Laser Error
1000 870 130 1000 960 40
1600 1390 210 1600 1535 65
2000 1740 260 2000 2000 0
2400 2100 300 2400 2340 60

So yes port side is close but due to the dampened motion of the lever and the tacho (and I was doing it single handed from the flybridge) the port side I would consider to be accurate (although sluggish) If i did the revs set and measure several times I would get a good average. The starboard side was way out – but is now correct (ish) after adjustment and the levers pretty much align. Thanks for the tip on the electrical tape!

From what I have read it looks like my tacho’s may be alternator driven – I need to get new Tachs as the hour meter has stopped and was going to go mag pickup type to save this hassle (as I thought it was mag pick up anyway)… so another thing on the list.. oh and the more I look the more I think the harness has been butchered or isnt standard (no Circuit breaker – extra wires all over the place duplicating existing wires. – Looks like i’m going to have to go over each engine – clean the connections and sort any additional wiring out.

I dont suppose the harnesses are available off the shelf?

Rob – Yes the Aetna’s are nice but a bit exxy when I can replace with a VDO digital at at least half the price.. and thats buying it locally – if I go international it gets cheaper, plus the analogue gauge is more suited to the scruffy tub 🙂

Steve

oh forgot to say – yes when I get to take it out in decent weather (Friday looks good here) i’ll be aiming for 2900 – 3050 WOT i’ll be happy with 2900 though as the boat is fairly loaded with tools, batteries cables and other crap so is probably around its normal weight – also as the winds are pretty bad here – we very rarely travel at much more than 16-18knots as the conditions dont allow it – this is usually around 2200rpm

[Tony Athens]

Is that 300 RPM off at 2400 on the one engine? Not sure on the other one (2340 ??) but I guess it’s close?

1000 870 130 —- 1000 960 40

1600 1390 210 —— 1600 1535 65

2000 1740 260 —— 2000 2000 0

2400 2100 300 —— 2400 2400 2340

Either way, you need to get your tachs right and the actual engine RPM at least 100+ over the minimum rated at WOT loaded as you use the vessel.

Photo tach trick– Put BLACK electrical tape on the damper first, then the reflective tape— and no sun light.

Tony

[Rob Schepis]

Good your getting them sorted out but do put the Aetna’s on your wish list…

[Author]

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