Go Back  The Hull Truth - Boating and Fishing Forum > BOATING FORUMS > The Boating Forum
Reload this Page >

WOT MPH 1979 vs. 2019 per same HP rating?

Notices
Like Tree7Likes
  • 1 Post By Jeepman
  • 4 Post By 71Outrage
  • 1 Post By seahorse
  • 1 Post By VTXrider

WOT MPH 1979 vs. 2019 per same HP rating?

Old 03-14-2019, 02:54 PM
  #1  
Admirals Club Admiral's Club Member
Thread Starter
 
Join Date: Oct 2014
Posts: 5,585
Default WOT MPH 1979 vs. 2019 per same HP rating?

I see people asking for numbers on specific HP outboards, short of fuel burn being far better today, are top end speed numbers any better per same HP on same hull?

I'd think 200 HP is 200HP should be the same top speed give or take a MPH or so, no?
YFMF is offline  
Old 03-14-2019, 02:57 PM
  #2  
Admirals Club Admiral's Club Member
 
Join Date: Dec 2008
Location: Texas
Posts: 5,235
Default

No, HP is a measurement of how fast the work can be done. So 200hp is 200 hp no matter what year it is built. How fast it can make that 200hp, or how fast it can make max torque can change by large sums, but at the end of the RPM range they are going to be close to 200hp.
tunnles likes this.
Jeepman is offline  
Old 03-14-2019, 03:05 PM
  #3  
Admirals Club Admiral's Club Member
 
Join Date: Apr 2013
Location: Hingham, MA
Posts: 540
Default

200hpdi seems faster than a 200 4 stroke
njk4o5 is offline  
Old 03-14-2019, 07:51 PM
  #4  
Senior Member
 
Join Date: Sep 2005
Location:
Posts: 619
Default

In the 1960ís and 1970ís, outboard horsepower was rated at the powerhead. Today they are rated at the prop. So a 200hp outboard long ago made less hp than a new 200hp. I donít know what year manufacturers began using prop hp.

Beyond the above, 200hp outboard can be within 10% of the rating...some 200hp motors are putting out more than their stated hp.
71Outrage is offline  
Old 03-14-2019, 11:07 PM
  #5  
Admirals Club Admiral's Club Member
 
Join Date: Aug 2014
Location: Coastal GA
Posts: 1,869
Default

Originally Posted by 71Outrage View Post
In the 1960ís and 1970ís, outboard horsepower was rated at the powerhead. Today they are rated at the prop. So a 200hp outboard long ago made less hp than a new 200hp. I donít know what year manufacturers began using prop hp.

Beyond the above, 200hp outboard can be within 10% of the rating...some 200hp motors are putting out more than their stated hp.
Outboard manufacturers were rating propshaft horsepower for many years prior to stern drives. But I don't know the exact years. I believe stern drives changed from crankshaft hp to propshaft hp in the late 1980's; maybe early 1990's.
Ric232 is offline  
Old 03-15-2019, 12:32 AM
  #6  
Senior Member
 
Join Date: Dec 2014
Location: Land down under
Posts: 8,923
Default

Originally Posted by YFMF View Post
I see people asking for numbers on specific HP outboards, short of fuel burn being far better today, are top end speed numbers any better per same HP on same hull?

I'd think 200 HP is 200HP should be the same top speed give or take a MPH or so, no?
Top speed denotes wide open throttle. A 1980 200 HP motor would propel the boat at the same speed as a 2019 200 HP motor. All else being equal.
alloyboy is offline  
Old 03-15-2019, 03:07 AM
  #7  
Senior MemberCaptains Club Member
 
Join Date: Jan 2005
Location: Cape Cod
Posts: 12,667
Default

A 200hp from 1974 was about 400# today it is about 505. FI creates better low end torque numbers all else being equal how ever a carburetor will allow more top end air flow to the engine when properly designed. An EFI can be better economically by alot at idle but not so much if a carbed engine is pulse tuned for a given rpm range. In fact it can slightly favor a carbed engine tuned to the weather. Most of these skills today are being lost to the computer tuned efi products though
ubettcha13 is offline  
Old 03-15-2019, 03:43 AM
  #8  
Senior Member
 
Join Date: Feb 2012
Location: PSL, FL
Posts: 753
Default

The year was 1983, though some manufactures made updates a year earlier or later. See document ICOMIA Standard 28-83 .

For reference a merc 140 inline 6 became a 115 under the new standard.

Other than that, if measured the same, horsepower is horsepower. Fuel injection, and particularly DFI, allow better tuning through the mid-range and across ambient conditions so the acceleration may be better on modern motors.
Matt Gent is offline  
Old 03-15-2019, 06:04 AM
  #9  
Senior Member
 
Join Date: Jan 2002
Posts: 6,832
Default

The ICOMIA 28-83 propshaft HP rating specifications were approved in 1983 by all the outboard manufacturers but it was not required by the industry until 1985 model year motors.
seahorse is offline  
Old 03-15-2019, 06:09 AM
  #10  
Senior Member
 
Join Date: Jan 2002
Posts: 6,832
Default

Originally Posted by YFMF View Post

I'd think 200 HP is 200HP should be the same top speed give or take a MPH or so, no?
Even today's 200 HP motors do not always have the same speed as there are differences in propeller efficiency, the hydrodynamics of the gearcase shape, engine setback, and transom height. Gear ratio and WOT engine may also play a small part in it as prop rpm may require a different blade shape, diameter, pitch, and rake for best results compared to a 200 HP motor with a lower prop rpm.
alloyboy likes this.
seahorse is offline  
Old 03-15-2019, 07:22 AM
  #11  
Senior Member
 
Join Date: Dec 2014
Location: Land down under
Posts: 8,923
Default

Originally Posted by seahorse View Post
Even today's 200 HP motors do not always have the same speed as there are differences in propeller efficiency, the hydrodynamics of the gearcase shape, engine setback, and transom height. Gear ratio and WOT engine may also play a small part in it as prop rpm may require a different blade shape, diameter, pitch, and rake for best results compared to a 200 HP motor with a lower prop rpm.
Correct. Which is why I added the words "All else being equal".
alloyboy is offline  
Old 03-15-2019, 07:48 AM
  #12  
Senior Member
 
Join Date: Apr 2012
Location: Miami, FL
Posts: 1,175
Default

I would add that it is doubtful that a 20-30 year old engine is putting out the same power that it did when it was new/just broken in.
BOSBoatMan likes this.
VTXrider is offline  
Old 03-15-2019, 08:46 AM
  #13  
Senior Member
 
Join Date: Dec 2014
Location: Land down under
Posts: 8,923
Default

Originally Posted by VTXrider View Post
I would add that it is doubtful that a 20-30 year old engine is putting out the same power that it did when it was new/just broken in.
I would agree with that doubt.

Unfortunately that is unrelated to the question. Question as I see it is "would a 30 year old motor producing 200 HP propel a boat to the same WOT speed as a brand new motor that is producing 200 HP?" All else being equal it would.

alloyboy is offline  
Old 03-15-2019, 09:12 PM
  #14  
Admirals Club Admiral's Club Member
 
Join Date: Mar 2017
Location: Tarpon Springs, FL
Posts: 2,324
Default

If you go way back to the 50's there was not really a standard method of advertising horsepower for outboards. Manufacturers used terms like "peak" or "continuous". As a result, Mercury was far underrated compared to the "OMC" brands. A 40 hp Mercury would be more like a 60 Hp Evinrude.,
GaryDoug is offline  
Old 03-15-2019, 10:35 PM
  #15  
Senior Member
 
Join Date: Jan 2007
Location: NSW Australia
Posts: 4,486
Default

Originally Posted by GaryDoug View Post
If you go way back to the 50's there was not really a standard method of advertising horsepower for outboards. Manufacturers used terms like "peak" or "continuous". As a result, Mercury was far underrated compared to the "OMC" brands. A 40 hp Mercury would be more like a 60 Hp Evinrude.,
seems like that bullshit was around even before the internet, and continued to be bullshit now.
noelm is online now  
Old 03-16-2019, 07:45 AM
  #16  
Admirals Club Admiral's Club Member
 
Join Date: Mar 2017
Location: Tarpon Springs, FL
Posts: 2,324
Default

Originally Posted by noelm View Post

seems like that bullshit was around even before the internet, and continued to be bullshit now.
It's not BS you tactless person. Mercury did not rate the HP in the same way as others. That was to give them advantages in competition. The racing organization had to create a special racing class just for the Evinrudes and Johnsons. I owned both the 40 hp Mercury version (1956, called the Mark 55 for obvious reason) and a 40 hp Johnson (1960) and there was absolutely no way the Johnson could keep up. My experience, 40 MPH for the Mercury Mark 55 40 hp versus 32 MPH for the Johnson 40 hp on the same boat. You really have no idea of which you speak, as usual. It was no secret except possibly where you lived.
GaryDoug is offline  

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are On
Refbacks are Off


Thread Tools
Search this Thread