Diesel hp rating not always what's advertised!

[Chuck Bates]

An interesting thread on how some Marine Diesel manufacturers alter the conditions to make their hp figures inflated:

www.boatdiesel.com
then: forums
then under Volvo Penta: Volvo General
then: Volvo IPS and something entirely different

Buyer Beware!!

Looks like another person has found out that diesel PR people rate their engine by a combination of hours and horsepower. 1 minute at 1,000 hp or 250 hp at 2,500 hours. Same engine can do both.--------------I see nothing wrong with it, as they are giving YOU the option of blowing the engine.

[gonzo]

The HP is correctly advertized at 25C, that is the standard. They may offer performance at other temperatures also. It is up to the buyer to educate himself and read the specifications.

[ABoatGuy]

Also make sure what HP you are looking at (metric, or BHP). Almost all use metric now because the numbers are a little higher. Most companys do base there ratings on some standard (DIN 6271 / ISO 3046) and most state on there brochures what the conditions are. Pay attention and you should be OK.

[Karl2]

25C is not the standard. It is an option that some manufacters, obviously, is taking advantage of. This enables them to post 2-3% higher hp numbers.
25C is an unrealistic fuel temp and will never occur in a boat while running unless an efficient fuel cooler is used.
Compare to a car manufacturer advertising fuel consumption going downhill only.

Karl2

[gonzo]

A car going downhill? Lets not exagerate. Any standard is arbitrary. As long as they publish it, the data is significant.

[Karl2]

Significant...Hmmmm. If you publish data derived under conditions that the consumer will never experience and then leave it to the consumer to read the fine print and figure this out I'm not sure I agree that there is any value to the data. I mentioned 25C fuel temp - Unrealistic but doable if you employ fuel cooler(s) - The manufacturers using 25C does not supply a fuel cooler with their engines.

Worse is the specific gravity of the fuel - .84 (give or take some on the second decimal) is what most manufacturers use. .86 is used by one manufacturer, which nets another 3% gain in publishable hp. .86 fuel is not available to the general public.

Karl2

I had to check, GM owns SAAB, FORD owns VOLVO.OK. The new rating system is being done by the same PR group that told us BAD tires made Ford suv's roll over like broken eggs.

[Chuck Bates]

Richard,
I think you're missing the point. Check out the website described in my initial thread then check out boatdiesel.com and see what Karl is trying to say. It is Yanmar that's fudging the hp figures, not Volvo.

P.S. Volvo AB sold Volvo car to Ford 6-7 years ago. Ford has NOTHING to do with Volvo Penta.

[gonzo]

Karl2: please do your homework before making claims. Name one large diesel engine without factory installed fuel cooler.

[FAST FRED]

Detroit Diesel 2-71, 3-71,4-71 6-71 8V71 12V71, 16V71 for a start.

FAST FRED

[Karl2]

In the the 10 - 800 hp bracket: CAT, Cummins, Volvo, Yanmar, Perkins, Scania to start with. Some of these manufacturers have fuel coolers on some models. For example: Common rail engines (Volvo D4/D6, Cummins QSB/QSC)
may require fuel coolers by the nature of the system - Not to preserve output but to prevent injectors from seizing.

My point was that the manufacturer(s) that are advertising output @ 25C does not supply a fuel cooler with the engine package.

I'm expressing an opinion: I do not belive that the engine buying public can keep this straight nor do I belive that it is fair to expect that the public should be able to do so. Is it your opinion that this is OK and the buyer needs to figure this out with the help of the fine print ?

If am looking for a diesel engine in the 300 - 325 hp range I would probarbly be looking at The Yanmar 6LPA-STP, Volvo D6-310 and Cummins 330B (Just three examples - there may be several others that belong on the list). Marketing has "established" that the Yanmar is 315 hp, the Volvo 310 hp and the Cummins 330 hp. I'm submitting that 99 out of 100 educated buyers would quote those hp figures if asked.
What is the "real" hp if you employ the same rating conditions for the three ?

Karl

[woodboat]

This is an interesting post from the thread:

I was involved in a recent discussion with another fellow that has the exact same year and model boat as I do. Mine is powered with twin 200 HP Volvo's and his with twin 220 HP Cummins (you may have seen the posts below). I like my Volvo's but to be honest, I would likely have gone with Cummins if I could have... (so I'm not pro or against any brand per se). Our boats appear comparable in weight (without actually measuring) yet his boats performance is off by about 4 knots at both cruise and WOT (about 20%) despite having more rated power ... I'm wondering if this might in part be explained by the same phenominon?

http://boatdiesel.com/BDR/Forums/Thr...archKey=&mc=34

I think Karl2 has a legal beef, if I am reading him right. The test is with a fuel cooler not normally as standard equipment on most Diesel engines. He would be able to say the same with gas Mercruisers. They are not normally standard, but are a option.

[Karl2]

I don't belive there is a legal issue here nor do I belive there is merit(s) for a legal case - The conditions for the ratings are disclosed in the fine print.

I see it more as a ethical issue.

Karl