Thanks Thanks:  0
Page 4 of 15 FirstFirst 123456789101112131415 LastLast
Results 31 to 40 of 141

Thread: Racing exhaust for laker 49 OMC

  1. #31
    Team Member
    Join Date
    Jun 2005
    Location
    Eastern PA
    Posts
    766
    Post Thanks / Like

    Default

    Correct, Sam. Got the photos mixed up.

    Jeff

    PS: Are you going to the Pottstown AOMC show in February? I plan to be there and would like to meet you at last.

  2. #32
    Sam Cullis Mark75H's Avatar
    Join Date
    Nov 2004
    Location
    Annapolis, MD USA
    Posts
    3,934
    Post Thanks / Like

    Default

    Probably not this year unless there is going to be something there I know about in advance.
    Since 1925, about 150 different racing outboards have been made.


  3. #33
    FFX-61
    Join Date
    Aug 2005
    Location
    Stellwagan Ledges
    Posts
    2,095
    Post Thanks / Like

    Default

    um, i need the first plate different than shown, best to correct #2 port for maximum Bang.

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

  4. #34
    Sam Cullis Mark75H's Avatar
    Join Date
    Nov 2004
    Location
    Annapolis, MD USA
    Posts
    3,934
    Post Thanks / Like

    Default

    I think Fred is correct
    Since 1925, about 150 different racing outboards have been made.


  5. #35
    Team Member
    Join Date
    Nov 2008
    Location
    Horseshoe Bend, ID
    Posts
    755
    Post Thanks / Like

    Default

    Quote Originally Posted by OUTBOARDER View Post
    Out the top is all about the firing order and which cylinder is plugging the outher

    The nydahl log box is all about adding volume where the cross pulsing is going on so
    cylinders arent swaping flames, it lowers temp in box so squeeze wont burn pistons.
    This by no means is the only advantage or reason. Nice thing about chamber is squeeze is moved down stream to tail cone so you can sqeeze more without burning up stuff which means you can go with alot more port timing and reap more power.

    hope it helps some one out there
    Actually, the top outlet pulse order benefit was consequential.

    Fighting elusive tuning issues with early "down" outlet exhaust systems, I decided to change to "up" outlet as an experiment to dump exhaust into clean air. This change also made engine rigging easy because the "up" pipe did not require a special steering bar.

    Initial complaints of burns caused by incidental contact the "up" pipe on restarts, concern about potential contamination by foreign objects, tall & won't fit in the trailer, etc. These issues were quickly forgotten as the top outlet system tuned easily and seemed to run more consistently than the down versions. Note: It's my guess that water vapor ingestion may have caused tuning inconsistencies.

    Anyway, Anthony is correct that an expansion chamber can ultimately produce more power, but this power comes at the expense of weight and complexity. Pound for pound, dollar for dollar, and horsepower for horsepower, there is no better OMC triple exhaust available than my top outlet fabricated steel system. Also to my knowledge not a single megaphone has been dropped in the lake.

    Seeing as they've won numerous national & regional titles and set a competition record, it's become the standard for the SE/850cc class. Good enough there are a few copies built by capable craftsmen. Indeed, imitation is the sincerest form of flattery!

    Tim

  6. #36
    Team Member
    Join Date
    Nov 2008
    Location
    Horseshoe Bend, ID
    Posts
    755
    Post Thanks / Like

    Default Good to go!

    OK 49.9 racers,

    There was enough interest that the project is going forward. The pattern is at the foundry and will be back next week for finer tuning. You'll see an update mid-February.

    Tim

  7. #37
    Team Member
    Join Date
    Nov 2008
    Posts
    174
    Post Thanks / Like

    Default

    haaa tim,,, have to argue with you on your the best exhaust system out there ,, deff prettiest,,,, mine seem to be working pritty good,,,, was 4 mph over the 1 mile record in feh,,, crappy water prevented us raceing,,,,.... just giveiing ya grief,,,,cheyney

  8. #38
    Team Member
    Join Date
    Nov 2008
    Posts
    174
    Post Thanks / Like

    Default

    on going project this season,,, a bounce pipe that actually works on the 49.9er,,,, iam very very close,,, and it works with multiple port designe..... shall see..

  9. #39
    Team Member
    Join Date
    Nov 2008
    Location
    Horseshoe Bend, ID
    Posts
    755
    Post Thanks / Like

    Default Chamber va Pulse tuned?

    Hey Cheney,

    Yeah, yeah; I agree the expansion chamber will make more ultimate power, but at the expense of complexity and weight (especially if triple sliders). Simple and light is good. Would love to see a photo of your record engine up close.........

    Meanwhile, many thanks to Burt Hoefs for the Nydahl loaner! Note the cleaned up duct (boss moved external). A few more hours work to go. Should be ready to take orders early March.

    Tim
    Attached Images Attached Images    

  10. #40
    Team Member
    Join Date
    Jun 2011
    Posts
    48
    Post Thanks / Like

    Default

    does this plate work good? Its a little different from the others I have seen on here. Can it be bolted to a stock block? I bought this a while back but, I haven't had time to mess with it yet it yet.

    Name:  mod50exhaust.jpg
Views: 1178
Size:  237.7 KB
    Name:  mod50.jpg
Views: 1175
Size:  105.2 KB

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Similar Threads

  1. Tunnel boat Series history
    By OPC1 in forum Tunnel Outboards and Tri Hulls
    Replies: 7
    Last Post: 01-09-2010, 03:21 PM
  2. Trivia
    By Mark75H in forum Open Discussion
    Replies: 71
    Last Post: 07-02-2009, 05:21 AM
  3. Class A - OMC Evinrude stock racing outboard
    By John (Taylor) Gabrowski in forum Motors and Powerheads
    Replies: 5
    Last Post: 10-17-2007, 12:51 PM
  4. Old Omc Racing Parts On E-bay
    By mercmack in forum Parts and Accessories
    Replies: 0
    Last Post: 02-04-2007, 09:36 PM
  5. Quincy 6 Pipe/Bell Racing Exhaust For Sale
    By John (Taylor) Gabrowski in forum Parts and Accessories
    Replies: 8
    Last Post: 07-17-2006, 01:18 PM

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
  •