WOT RPM for KAD44's...

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mrgrumpy2

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WOT RPM for KAD44\'s...

What would people expect a pair of KAD44's to rev to at WOT on a Sealine S37. Both the hull and props are clean and currently the port engine revs to 3350/3400 with the starboard reving to 3450/3500. Whilst i realise they are not achieving the same as each other I am also suspecting that the max should be higher.... Thanks in advance for you help
 
Re: WOT RPM for KAD44\'s...

As I recall, it's actually rated for 3800, but +-100 is deemed acceptable by VP.
 
Re: WOT RPM for KAD44\'s...

As jez beat me to it 3900 so your well down on revs, have you trimmed the boat right?, are your filters clean as in both fuel filters and the air filter, you may have an edc component fault that does not show up on the diagnostic keypad , its a boost fuel control sensor. You could also have slipping belts and are actually getting the speed but the correct revs are not being show as the tacos are driven from the alternator via a belt, you could also have a turbo problem, blocked intercooler etc.

Have the engines had a recent service, if you look back at recent post on tappets on kad 44 its very important to keep to the recomended service intervals for this.
 
Re: WOT RPM for KAD44\'s...

The engines and legs were fully serviced about 5 months ago and there were no impending issues raised.... The tappets need doing as the hours are just over the 200 mark. Thanks for confirming my suspicions, it sounds like I am going to have to pay the Volspec guys another considerable amount of cash to investigate and rectify.....Thanks again
 
Re: WOT RPM for KAD44\'s...

Hi are you based near to volspec then? im midlands based but do work on the southcoast too if thats any help to you.
 
Re: WOT RPM for KAD44\'s...

Hold fire a bit before shedding out £££'s

a) does she have the original props? (check with Sealine.... a call should do)
b) check fuel pickup gauze ... if that is clogged, you won't get full fuel flow
c) check fuel pipes ... if they are starting to de-laminate, you won't get full fuel flow
d) presume pre-filters/air filters and all has been changed, so won't go there ... but have you checked if you get any difference when running without air filters or hatches open?
e) Check the RPM true with mechanical or strobe scope (your rev counters could be wrong)

If all these 'self check' items come out as negative, then you may have to spend some ££...

Good luck...
 
Re: WOT RPM for KAD44\'s...

[ QUOTE ]
As jez beat me to it 3900 so your well down on revs

[/ QUOTE ]Being thick as a brick, I gave a look at VP website, and according to the 44 product bulletin, it's rated for 3800.
With an acceptable max range between 3700 and 3900 (=3800 +-100, as I said).
Jez is correct re. the 43 though, which is rated for 3900. But don't ask me why.
Down on revs he still is, anyway.
 
Re: WOT RPM for KAD44\'s...

[ QUOTE ]
"..........Both the hull and props are clean ............" /forums/images/graemlins/smile.gif /forums/images/graemlins/smile.gif

[/ QUOTE ]

Well its only 300-400rpm down, not wishing to cause offence but I've seen a few so called clean hulls, i'd put money on a four new fuel filters and a quick scrub fixing it.
 
Re: WOT RPM for KAD44\'s...

Mr Grumpy is real sensible and has cause to be concerned.

The term 'under revving' does not describe this situation seriously enough. A diesel engine unable to reach rated speed is overloaded, plain and simple.

Volvo require the engine to reach rated rpm 3800 rpm and an extra 100 rpm out on the governor droop as an overloading margin due to bottom fouling. So good so far.

If you are 300/400 rpm down the engine is near to 100% overload. Rememember it is not a percentage of the engine rpm, but by the propeller exponent. Put another way, the fuel pump is set to maximum rpm and the prop is telling the engine I want more! You have the pump delivering maximum fuel in an effort to please the prop. However engine can only make say 3400 rpm therefore you starving the engine of air.

Diesel engines work on excess air, force a diesel to run with insufficient air and exhaust gas temperatures rocket. The engine is designed to cope with max exhaust temperatures of around 450C. The margin of over temperature is small, a 100% overload will easy see exhaust temperatures 100 C higher. Exhaust valves start to feel poorly at 550C. If you are running a boat with pyro's your hair will turn as white as the needles on the guages.

Acceptance 'only 400 down' for inviting head gasket, valve or piston failure at a later date.
 
Re: WOT RPM for KAD44\'s...

[ QUOTE ]
Ive been to conway and Deganway quays, thats it, south wales is too far.

[/ QUOTE ]
Just been in Deganwy Quays Today squirming about a Sealine eng dept!
Your right not to go to South Wales.
They play with funny shaped balls there /forums/images/graemlins/laugh.gif
 
Re: WOT RPM for KAD44\'s...

"300/400 down "
Thats my 2 x 40AQD shagged then,have only ever seen 3300 rpm running down hill with the wind behind them.
Should I expect trouble soon,to date only managed 3000 hours since 1982.
/forums/images/graemlins/smile.gif
 
Re: WOT RPM for KAD44\'s...

"bit less stressed" Grr..... we can put out nearly 120 hp even if a bit wheezy round the edges and desperately in need of a sit down every 1/2 mile or so .:p
 
Re: WOT RPM for KAD44\'s...

120hp from 3.6L ?

/forums/images/graemlins/laugh.gif

Sorry, I had forgotten exactly how relaxed these were.
Pipe, slippers, and cap, please?
 
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