Thanks Thanks:  0
Likes Likes:  0
Page 7 of 22 FirstFirst 12345678910111213141516171819202122 LastLast
Results 61 to 70 of 218

Thread: My Kilo Motor

  1. #61
    Sam Cullis Mark75H's Avatar
    Join Date
    Nov 2004
    Location
    Annapolis, MD USA
    Posts
    1,795
    Post Thanks / Like

    Default

    I do not know of anyone using 10:1 or 12:1 at this time, so that is moot.



    32:1 is essentially 3% oil ... 25:1 is 4% oil ... 50:1 is 2% oil .... the difference between 4% and 2% is virtually undetectable in both mixture strength for fuel/air and pouring viscosity

    TRY IT and see, DON'T just guess or assume
    Since 1925, about 150 different racing outboards have been made.


  2. #62
    Team Member
    Join Date
    Nov 2004
    Posts
    76
    Post Thanks / Like

    Default

    I do! & have.
    Fully synthetic has sometimes required a smaller jet.

  3. #63
    Team Member
    Join Date
    Sep 2008
    Location
    Singapore/Melbourne/Italy
    Posts
    780
    Post Thanks / Like

    Default

    Ignoring viscosity issues does the following add up?

    lets say you have gone from 50:1 to 25:1, (2% to 4%)
    Therefore you have lost 2% of the fuel as it is now oil.

    Just to compare the difference.
    ( assuming OMC C jet as in twin barrel, so size is number in thou)
    There is a 1.67% area difference between a 060 and a 061 jet all things being equal the change of oil ratio from 2 to 4% has made a bigger change than one jet size to the mixture.

    ( anyone know the theory for flow in a pipe?)

  4. #64
    Team Member
    Join Date
    Nov 2004
    Posts
    76
    Post Thanks / Like

    Default

    Test first the 060 jet with the 25:1 & see if it makes any difference, remember doubling the lube, might colour the plug.
    Freds the man to ask, he seems to have tried every permutation.

  5. #65
    Team Member
    Join Date
    Nov 2008
    Location
    Horseshoe Bend, ID
    Posts
    657
    Post Thanks / Like

    Default How much oil?

    Dyno tests clearly show that more oil makes more horsepower. A good 55H was tested at 50:1 and delivered a respectable 39.9 HP. Doubling the ratio to 25:1 delivered a shocking 43.3 HP. We now understand why - the reasons apply to all two-strokes. Why do you think ratio makes a differece?

    Also, the discussion about jet size -vs- oil ratio is dizzying. Once you settle on a ration and fuel type, the engine will tell you what it likes - provided you don't burn a piston first. Certainly an EGT is a nice tool, but to do it right you'll need one for each cylinder as the OMC triples are actually three one cylinder engines.

    Finally, all my engines run 16:1 with Avgas. Why would I pick such a "risky" fuel? There are two primary reasons. There has been lots of discussion: Don't you know Avgas will burn your engine down because of it's high density. Hmmmmm. What gives?

  6. #66
    Team Member 850cc racer's Avatar
    Join Date
    Sep 2005
    Location
    australia
    Posts
    220
    Post Thanks / Like

    Default

    wowsers so much discussion in my thread all about oil! there has been some good points raised. and some interesting data!

  7. #67
    Team Member
    Join Date
    Nov 2004
    Posts
    76
    Post Thanks / Like

    Default

    Impressive 55H figures Tim, are the test results on the net?

  8. #68
    FFX-61
    Join Date
    Aug 2005
    Location
    Stellwagan Ledges
    Posts
    1,389
    Post Thanks / Like

    Default

    Mod 50 owner manual, first paragraph, inside cover, 50:1 mix uesin 100-130 octane

    Part one of "Secrets of the OMC Mod 50" : http://www.boatracingfacts.com/forums/showthread.php?t=2052

  9. #69
    Team Member
    Join Date
    Aug 2005
    Posts
    67
    Post Thanks / Like

    Default

    So what is the reason more oil makes more hp in the 55h...leaner mix?

  10. #70
    FFX-61
    Join Date
    Aug 2005
    Location
    Stellwagan Ledges
    Posts
    1,389
    Post Thanks / Like

    Default

    compression i would say, lean does not make more power, lean melts pistons.

    Part one of "Secrets of the OMC Mod 50" : http://www.boatracingfacts.com/forums/showthread.php?t=2052

Thread Information

Users Browsing this Thread

There are currently 4 users browsing this thread. (0 members and 4 guests)

Similar Threads

  1. Evinrude Outboard Motors
    By Skoontz in forum Technical Discussion
    Replies: 5
    Last Post: 07-08-2014, 03:55 AM
  2. Evinrude Outboard motors
    By Skoontz in forum Outboard Racing History
    Replies: 2
    Last Post: 10-30-2006, 06:13 AM

Tags for this Thread

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •