An ad in the classifieds says "210 hp at 2,800 rpm, but actually downrated to 150 hp to enhance even further long time reliable service."
Explain, please, the who, how, why.
Thanks.Ask the same of seller. Sometimes it is nothing more than throttle stops other times a bizarre thinking tear out of "bigger" injectors, removal or turbo, bigger prop etc. I'm always leery of these owner induced changes.
Obviously pulling back on the throttles does the same thing.
Ok, so what would an engine surveyor have to say about it?From memory, de rating means changing the physical specs of an engine to lower its HP rating. However people changing these numbers to suit their needs smacks of covering up deficiencies. Buyer beware.
Ok, so what would an engine surveyor have to say about it?
This is what the ad says;
"Single Caterpillar 3160 renamed to 3208 in 1974, w/o any technical changes to 3160. 210 hp at 2800 but actually downrated to 150hp..."
If you look at any marine engine from most of the mainstream marine manufacturers, you'll see different classes of engines, from 24/7 to 200 hours per year of estimated service.
To make a 24/7, they 'derate' or limit the performance in the injection pump or CRD fuel computer controller so it won't output as much as a 4 hours on, 20 hour off engine.
As FF quoted, John Deere has M1-M4 ratings:
M1 <= 65% load factor, unrestricted hours, continuous duty, 154hp output
M2 <=65% load factor, 16 per 24 hour day, 3000-5000 hours annually, 175hp output.
M3 <=50% load factor, 4 hours per 24 hour day, 2000 - 4000 hours annually, 200hp output.
M4 <= 40% load factor, 2 hours per 24 hour day, 1000-3000 hours annually, 225hp output
This is all very interesting.The only difference between a Perkins Sabra 265hp and 300hp was 1/4 turn to a screw on the fuel pump and the stickers on the engine. Yes, I did own one.
This is all very interesting.
So what did that 1/4 turn do to performance?
Perhaps "someone" has been following this and will comment.cappy208 said:I am suspect of 'someone' who says 'they have Derated their engine'. It's not that simple.
Great stuff.View attachment 46448View attachment 46449View attachment 46450
There's some iron ballast.
The turbos are around 3' in diameter. The air boxes are 3' square.
Actually, if de-rated properly it allows you to 'over' prop (more pitch) and aim for a design point lower on the engine's power curve, using more of the available power and torque at lower RPM. This usually puts you in a slightly more efficient operating regime in terms of specific fuel consumption (grams of fuel / hp/ hr) as an added bonus. Nice thing to do if you're not obsessed with top speed, and further points to this being a 'proper trawler'.
Most engines are offered at several ratings, with pleasure boats being allowed to squeeze more power out at higher RPM since they don't do it for as many hours as commercial operators. The downside there is you're 'required' by the mfr to prop the boat for that top RPM, which means less pitch, which means you get less out of the engine at that mid-range RPM you actually prefer to use.
Cool, thanks for showing us your rec room.The shot of the side of the engine? On the aft bulkhead is the 4" and 6" bilge, ballast and fire lines. All painted either white or red.
The insulated lines on the overhead are the potable hot and cold water lines insulated so they don't freeze in the winter when the faucets are shut off.
Currently pushing 100,000 bbls of diesel. 4,200,000 gallons