Diesel engine max unloaded RPM?

[Farrari 4]

The diesel engine (Volvo Penta 2003) in Farrari has a max. RPM listed in the owners manual of 3200 RPM. I assume the max continuous operating RPM would be approx 80% of that but what should I expect the max RPM be unloaded?

 

I can't seem to find any reference anywhere in any manuals. Should this also be 3200? I am getting close to 4000 RPM and that sounds a little on the high side to me.

 

The reason I ask is that I suspect that either (or both) the max volume screw or max rev screw has been adjusted by an unnamed organisation that have been servicing my motor. Certainly the max rev screw has the factory paint broken. The workshop manual states that these are set by Volvo at factory and must never be changed.

[wheels 543]

Firstly, confirm you RPM with a measuring device. I have one you can borrow if you want. Gauges can be inaccurate and may need calibrating.

It could be that the max RPM is 4000RPM. The 3200 could be your Max intermittient or maybe even max continous RPM and the engine may well be limited to that point. It is rare an engine will be allowed to rev to it's absolute max RPM. Your normal continous operating RPM should be about 75-80% of the 3200. Out of gear you should be able to reach 3200 (or possibly 4000 if that is the max intermitent) and in gear, ruffly 10% of that max means a properly spec'd prop size.

[Farrari 4]

Thanks Wheels.

 

I have had a taco on the motor previously and the gauge appears to be reasonably close.

[tuffyluffy 76]

FWIW, i have a Volvo 2030 on my tub and I think the max revs is 3,600. Whatever it is, I took the boat out, wound her out (under load) to the max revs + 100, and adjusted the screw thingy so that she wouldnt rev any further. I give her full revs occationally for maintanence, or when i accidentally stand on the throttle lever

 

My donk has a sweet spot at 2,600rpm where she sits on 7knts and only guzzles 2 litres an hour. 42fter weighing 5500kgs.