Philip_Fry
regular
Reged: 01/05/2005
Posts: 79
Loc: South Glos (Northavon) & Dorse...
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Just wondering what the preferred running speed of a D3 should be. Lately we've been running the engine at around three thousand revs, but with the throttle pushed fully forward against the stop, it would give three and a half thousand. This is under load of course. I'm not in favour of running an engine flat out - and especially not doing so continuously.
It is generally reckoned with these motors to ease off ten per cent from 'flat out'. But is this for engines under load, or free running?
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Westline
regular
Reged: 04/04/2005
Posts: 6920
Loc: ality Unknown
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The D3 is rated to 4,000rpm - so if you are only getting 3,500rpm on the stops I would start to question your set up. Is the boat particularly fouled, or has a lot more (heavy) kit on than standard?
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Westline - performance motor boats
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D3B
regular
Reged: 28/11/2004
Posts: 2875
Loc: Ely, Cambs UK
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Jez
My D3-160's used to give 3800 max.
since i had the overheating problem ....now cured i can only get 3650.
clean bum, new A/F.
engines are due a major service so will see if it improves after that.
But i suspect VP have teaked them down a bit....
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I changed it cos it was too long....to drink and in letters :-)
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Westline
regular
Reged: 04/04/2005
Posts: 6920
Loc: ality Unknown
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Fair do's. I have only been on one other d3 powered boat and that made close to the 4000rpm mark.
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Westline - performance motor boats
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Philip_Fry
regular
Reged: 01/05/2005
Posts: 79
Loc: South Glos (Northavon) & Dorse...
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> The D3 is rated to 4,000rpm - so if you are only getting 3,500rpm on the stops I would start to question your set up <
Someone has suggested it - Nimbus 280 'Familia' - is over propped.
May be so, but think I'd prefer that than to have too small a propeller.
Be that as it may, but I don't fancy running the engine at a higher speed than designed.
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Lateboater
regular
Reged: 06/02/2008
Posts: 27
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Phillip,
Whithout wishing to be rude where on earth are you coming from. Listen to Westline.
A diesel engine HAS to make rated rpm plus droop. On an electronic engine droop is only about 50 rpm. Therefore unless you get to rated rpm plus the droop you are overloading your engine.
Bear in mind this is by the exponent of the rpm. Therefore running at WOT and only reaching say 200 rpm less than rated speed can result in an overload of as much as 100%.
Any diesel engine will not be damaged by running on the governor.
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