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Ric232

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Reply with quote  #16 
Huey,

I found this, which states "propshaft" hp.  I guess "CBHP" means Competitive BHP.  Makes a lot of since.  Also shows why I was disappointed in the top end on my Yamaha F115LB.  Good graphic. Found it here:  https://www.wavetowave.com/home/2019/6/13/evinrude-adds-new-midrange-models-the-new-three-cylinder-g2

Evinrude+G2+dyno+115+HO.png

GEB

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Reply with quote  #17 
Hi Ric232,
That graph is a good illustration of the “Competitive” performance differences but I find the terminology used a bit confusing. No reflection on you who only posted the graph.
The graph Tile “Competitive Propshaft Horsepower Curve’ (CBHP.) is wrong and misleading.
By definition “Propshaft Horsepower” is just that, Horsepower (HP)
I understand CBHP to mean Crankshaft Brake Horse Power which is just BHP.

IMHO the use of the term Crankshaft as in CBHP is redundant “artistic license” meant to convey / reinforce the fact thar BHP (Brake horsepower) is the power measured at the crankshaft just outside the engine, before the losses of power caused by the gearbox and drive train efficiency. ... Brake refers to the device which was used to load an engine and hold it at a desired rotational speed.
I’m not being critical but I think it important, especially when looking at comparative (power) curves that the same unit of measurement is being used throughout eg BHP with BHP and HP with HP.


To Summarise
1. HP is the output horsepower rating of an engine, while BHP is the input brake horsepower of an engine.

2. BHP is the measurement of an engine’s power without any power losses, while HP is BHP less the power losses.

3. HP is measured by hooking up the engine to a dynamometer, while BHP is measured in a controlled environment without anything attached to the engine.

Cheers
GEB



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seahorse

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Reply with quote  #18 
I believe it means "Corrected Brake Horsepower"
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GEB

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Reply with quote  #19 
Hi Seahorse,
Further to your correction (thank you) I have edited my original post accordingly and reposted here. Should it need further correction please do.

Hi Ric232,
That graph is a good illustration of the “Competitive” performance differences but I find the terminology used a bit confusing. No reflection on you who only posted the graph.
The think the Tile “Competitive Propshaft Horsepower Curve’ (CBHP.) is wrong and misleading because in the graph’s Title the term “Propshaft Horsepower” (HP) is used but the unit of measurement is (Corrected) Brake Horsepower. (CBHP)
I now understand, refer Seahorse’s correction, CBHP to mean Corrected Brake Horse Power which is (still) just BHP.
By definition “Propshaft Horsepower” is just that, Horsepower (HP) and
BHP (Brake horsepower) is the power measured at the crankshaft just outside the engine, before the losses of power caused by the gearbox and drive train efficiency. ... Brake refers to the device which was used to load an engine and hold it at a desired rotational speed.
I’m not being critical but I think it is important, especially when looking at comparative (power) curves that the same unit of comparison/ measurement is being used throughout eg BHP with BHP and HP with HP.
To Summarise
1. HP is the output horsepower rating of an engine, while BHP is the input brake horsepower of an engine.

2. BHP is the measurement of an engine’s power without any power losses, while HP is BHP less the power losses.

3. HP is measured by hooking up the engine to a dynamometer, while BHP is measured in a controlled environment without anything attached to the engine.

Cheers
GEB


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ElderSparky

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Reply with quote  #20 
My suggestion of CBHP is that it means corrected brake horsepower. Corrected means air temp, barometric pressure, and relative humidity are measured and used to provide a correction factor to standardized atmospheric conditions.
Without the correction factor, observed horsepower will vary depending upon the conditions.
Ric232

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Reply with quote  #21 
Hey, I learned something from this.  Cool.  But a question:  Doesn't BRP (and others) use a "brake" as part of their dyno which measures horsepower at the propshaft?  Just curious.  Even if so, I now realize it is not accepted nor conventional to use the term "bhp" in this scenario.  I still like the graph, except the CBHP part.
GEB

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Reply with quote  #22 
Hi Ric232,
Sorry I can’t answer your dynamometer question but I did want to add that the horse power output numbers, usually expressed as BHP , published by all the different outboard manufacturers can at least be replied upon to be accurate as there is an industry standard which they all must comply with.
It’s interesting that on the CARB emissions certificate of the new G2 150 the “rated power”, is listed as 110.32 kW @ 5500 rpm which is 147.94 HP. While on the graph posted by Muskimouth the power of the E-TEC G2 150 is about 152 CBHP @ 5500 rpm.
I think from this you could safely say that the power at the propshaft for the 150 is 147.94 HP which lines up with what you said earlier in this discussion about “transmission” losses.

FYI There is no difference between US HP and Imperial HP, they are both “mechanical horsepower.
Cheers
GEB





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seahorse

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Reply with quote  #23 



Yes, the proper nomenclature is CORRECTED BRAKE HORSEPOWER, not certified brake horsepower as I mistakenly mentioned earlier and which I have edited in my first post. 

Brake horsepower is what is measured directly (in this case) from the propshaft, and it is corrected by using factoring for humidity, barometric pressure, and air temperature experienced during the dynamometer run, all of which affect total power output of an internal combustion engine.

There are a number of standards on how to determine horsepower for an engine.  The International Council of Marine Industry Associations (ICOMIA) 28-83 is referenced by all engine manufacturers in the outboard motor industry in addition to the International Organization of Standards testing procedures.


ICOMIA Standard No. 28-83
Power measurements and declarations for
marine propulsion engines and propulsion systems


ISO – International Organization of Standards


• ISO 3046/1 -- Reciprocating Internal Combustion Engines:
o Performance--Part 1: Standard Reference Conditions and Declarations of Power, Fuel Consumption 


• ISO 3046/2 -- Reciprocating Internal Combustion Engines:
o Performance--Part 2: Test Methods


• ISO 3046/3 -- Reciprocating Internal Combustion Engines:
o Performance--Part 3: Test Measurements


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Ric232

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Reply with quote  #24 
Quote:
Originally Posted by GEB
Hi Ric232,
Sorry I can’t answer your dynamometer question but I did want to add that the horse power output numbers, usually expressed as BHP , published by all the different outboard manufacturers can at least be replied upon to be accurate as there is an industry standard which they all must comply with.
It’s interesting that on the CARB emissions certificate of the new G2 150 the “rated power”, is listed as 110.32 kW @ 5500 rpm which is 147.94 HP. While on the graph posted by Muskimouth the power of the E-TEC G2 150 is about 152 CBHP @ 5500 rpm.
I think from this you could safely say that the power at the propshaft for the 150 is 147.94 HP which lines up with what you said earlier in this discussion about “transmission” losses.

FYI There is no difference between US HP and Imperial HP, they are both “mechanical horsepower.
Cheers
GEB



I wouldn't place too much credence in the 110.32kW CARB rating for the new 150 as the 2.7L G2 150 is listed as having the exact same output of 110.32kW.  Not likely.  Also, the new 1.9L 115HO shows up as 84.60kW (exact same as the V4 115 and 115HO) or 114.45hp, when the new 115HO is supposed to be rated at 125-126hp.  I've noticed that BRP never seems to be very honest with their CARB ratings.  Yamaha's and Merc's CARB ratings mostly makes sense.  Hard to say about Suzuki.
seahorse

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Reply with quote  #25 


Notice it is rated horsepower which is the same as advertised horsepower, and keeping within ICOMIA 28-83 guidelines which are used by EPA. CARB, and all the marine engine manufacturers, there is a plus or minus 10% allowance for propshaft HP.

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casaleenie

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Reply with quote  #26 
I'm a little confused with this whole subject...
but what I do know is that my 2008 115hp Evinrude pushes my 20ft boat at 22mph at 3100 RPM's and I get between 5 and 6 MPG and flat out it runs close to 40 mph.   and that works for me
and when all the technical sword fighting is done... would someone be concise and post the results?
Ric232

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Reply with quote  #27 
Quote:
Originally Posted by casaleenie
I'm a little confused with this whole subject...
but what I do know is that my 2008 115hp Evinrude pushes my 20ft boat at 22mph at 3100 RPM's and I get between 5 and 6 MPG and flat out it runs close to 40 mph.   and that works for me
and when all the technical sword fighting is done... would someone be concise and post the results?


I haven't see a test on the new 115HO yet (on a boat that tops out ~ 40mph).  There will be one shortly, I'm sure.
jimh

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Reply with quote  #28 
Quote:
Originally Posted by seahorse
...there is a plus or minus 10% allowance for propshaft HP.


Not quite—there is a manufacturing allowance for individual units to deviate from the rated power by plus or minus ten percent.

There is a different tolerance for the rated horsepower and the peak horsepower: six percent.

I published an actual text copy of ICOMIA 28-83 many years ago in November 2003 when I found it was not available on-line:

http://continuouswave.com/whaler/reference/ICOMIA28-83.html

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GEB

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Reply with quote  #29 
Hi jimh,
Thank you and (for me), as said in the Commentary “For outboard motor enthusiasts, this standard clarifies several frequent questions. ”
Cheers
GEB

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The learner will not shear the rams.

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