MFG's don't just state their max, their diesels are goverened to it. Only way to go over is if you have an oil runaway.I was unaware of the WOT "test". It hardly seems like a "little stress".... but I don't know much about engines. I do know that my MD17D which is quite old has a recommended OEM "RPM operating range.". As I noted in an earlier post that I never have had a need to even run at the high end of this range because I can achieve hull speed as lower RPMs.
Perhaps there are times when a burst of full throttle may be called for. I'd like to hear of some examples. But surely not for 15 minutes WOT.
My naive sense of this matter.... is that if the mfg gives a recommend max operating RPM, the user should observe it.
WOT seems to be excessive stress. Who knows, it may cause some damage.
Running the engine to the max rpm to which the engine is governed by the mfg.Thanks for the comments.... they are somewhat helpful.
I don't know what WOT is on my engine. I do know that 2100 RPM is what is needed to reach hull speed. I have pushed the RPMs to high 2000s at times for very brief periods... perhaps needing to give a burst of speed for some reason. The engine did not suffer. Actually I am not sure that the throttle can add more fuel... it seems to be limited by the morse cable installation travel. As I said mine may be limited to the high 2000's RPM.
What is WOT technically?
I suppose #3 is to determine if the engine is properly governed.As mentioned by someone earlier, running loaded at WOT can also show engine mount issues and cooling system leaks, among other things.
#3 isn't really a thing, since governed WOT is known for most engines.
I have a 2012 Volvo D2-40. I pulled the following text from the manual.Our past 2 Volvo's state within 500rpm of WOT.
The engines sections lists engine RPMs at 2800-3200 for D1-13, Dq-20, D1-30, and D2-40 engines. I typically cruise at 2200 rpm which puts me around 6.5kts in chop for a boat that has a theoretical hull speed of 7.6. I believe I have gotten a little over 7 kts at around 2500.Avoid operations at full throttle for best fuel economy. We recommend a cruising speed that is around 500-1000 rpm below the maximum rpm at top speed (full throttle).
Depending on the type of hull, choice of propeller, load and sea state etc., maximum revolutions at top speed may very, but should be within the full throttle range; refer to the Engines section.
The Volvo-Penta MD17D model was made from 1981 to 1984 and had a slight increase in performance. This motor achieves 36 horsepower at 3,000rpm and is capable of 3,350rpm. MD17D has a compression ratio of 17.5-to-1 and features a displacement of 102.51 cubic inches. The heavy duty MD17D heavy duty has a max of 2,900rpm.WOT is whatever the engine is governed to. On the MD17D, it is 3000rpm.
Yeah, I got the 500 delta number from our previous MD2030, which I remembered off hand. Your D2-40 is 400, and our current D2-55 is 300. I think the difference is the difference in governed rpm - 3600 for the MD2030, 3200 for the D2-40, and 3000 for the D2-55.I have a 2012 Volvo D2-40. I pulled the following text from the manual.
The engines sections lists engine RPMs at 2800-3200 for D1-13, Dq-20, D1-30, and D2-40 engines. I typically cruise at 2200 rpm which puts me around 6.5kts in chop for a boat that has a theoretical hull speed of 7.6. I believe I have gotten a little over 7 kts at around 2500.