Page 1 of 6 123456 LastLast
Results 1 to 10 of 53

Thread: Performance Improvements possible with newer 4 stroke outboards

  1. #1
    Team Member
    Join Date
    Dec 2004
    Location
    Toronto, Canada
    Posts
    248
    Post Thanks / Like

    Question Performance Improvements possible with newer 4 stroke outboards

    Up here the new generation of racers are not interested it the old school 2 stroke motors. They would like to use their lap top and reprogram their motor same as they do with their cars. They don't mine throwing lots on money into their modifications. There is a very good supply of rebuildable 4 stroke outboards on the market for them to work with. The problem is there is limited information on what can be done to improve the performance or any OEM or aftermarket parts. Maybe there is not enough market for companies to spend the R&D money necessary to develop the products. Years ago the same could be said about the small Honda cars.
    To-day that is a BIG business.
    We need find ways to get these new people racing. Are you seeing the same thing in your area?
    Any suggestions?
    Thanks Ron Hill thanked for this post
    Likes Ron Hill liked this post

  2. #2
    Administrator Ron Hill's Avatar
    Join Date
    Nov 2004
    Location
    Tustin, California
    Posts
    8,339
    Post Thanks / Like

    Default Hounddog, You And I Are A Lot A Like

    I spent Saturday going over spec sheets "PAWING OVER" A Mercury four stroke head. Simon Motor Sports in San Diego has figured out how to, I think the word is "Flash" the computer, so they can disconnect the revlimiter.

    But the motors will still only turn 6,500 RPM's.

    My "PROJECT" is "Top Secret" right now, but I will tell you there are many areas that the Mercury 40-60 four stroke can be improved.

    I will be "Up Front" with you. The head looks like the flow may well be restricted on purpose. (Need to sell better running motors in the future, you know built in obsolescence).

    The value springs may be too weak, and allow the values to "FLOAT".

    The exhaust area of the exhaust ports appears to be "Squeezed" down, this me be for pollution reasons, or just planned horse power control.

    "My People" are going to run the numbers, and figure out what the cam is and what they think the cam should be.

    At this time, I have no plans to market anything for these motors. I am working as a "MIDDLE MAN" with some people than want improved performance and they have the financial backing needed for some development work.

    I just wish for you guys in Canada, would look at Texas, Tri Hull's roll cages. Or go to 660 drags. Todd Bucknell's accident, last summer, was not got for boat racing!

    I have no "FACTS" other than hear say, but It appears the NEW Tohatsu four stroke has some real power. I have 18 pitch props running on 30 HP Tohatsu four strokes and hitting the rev limiter.
    Last edited by Ron Hill; 05-20-2019 at 08:37 PM.

  3. #3
    Team Member
    Join Date
    Dec 2004
    Location
    Toronto, Canada
    Posts
    248
    Post Thanks / Like

    Default

    Thanks Ron, yes we are alike! We both want to promote our sport. Our Drag group here is finalizing 2 additional 660 Drag races this summer and T Class is included. Any accident where someone is hurt is not good for our sport. There were a number factors in Todd's accident. The weather was one of them. It was BAD! The T racers wanted to race even though the other classes could not. There were a lot of fans at that race and the racers did not want the cancel Sunday's complete race day. I am not sure if a cage would have helped in this accident because the impact was thru the bottom of the hull and not the side.
    For the last couple of years I have been working on a Critchfield rework. I have the strong box going all the way to the nose. The boat is carbon fiber construction and now after Todd's accident I am adding another layer to the front section. Two of my other T boats already have cells.

  4. #4
    Team Member
    Join Date
    Aug 2014
    Location
    Naples Florida
    Posts
    84
    Post Thanks / Like

    Default

    Quote Originally Posted by Ron Hill View Post
    I spent Saturday going over spec sheets "PAWING OVER" A mercury four stroke head. Simon Motor Sports in San Diego has figured out how to, I think the word is "Flash" the computer, so they can disconnect the revlimiter.

    But the motors will still only turn 6,500 RPM's.

    My "PROJECT" is "Top Secret" right now, but I will tell you there are many areas that the Mercury 40-60 four stroke can be improved.

    I will be "Up Front" with you. The head looks like the flow may well be restricted on purpose. (Need to sell better running motors in the future, you know built in obsolescents).

    The value springs may be too weak, and allow the values to "FLOAT".

    The exhaust area of the exhaust ports appears to be "Squeezed" down, this me be for pollution reasons, or just planned horse power control.

    "My People" are going to run the numbers, and figure out what the cam is and what they think the cam should be.

    At this time, I have no plans to market anything for these motors. I am working as a "MIDDLE MAN" with some people than want improved performance and they have the financial backing needed for some development work.

    I just wish for you guys in Canada, would look at Texas, Tri Hull's roll cages. Or go to 660 drags. Todd Bucknell's accident, last summer, was not got for boat racing!

    I have no "FACTS" other than hear say, but It appears the NEW Tohatsu four stroke has some real power. I have 18 pitch props running on 30 HP Tohatsu four strokes and hitting the rev limiter.
    I was researching the merc inline 3 cylinders and found info suggesting they have valve float beyond the factory recommended rpm's.
    Thanks Ron Hill thanked for this post
    Likes Ron Hill liked this post

  5. #5
    2010 SRG 3 CYL CHAMPION 88workcar's Avatar
    Join Date
    Jun 2009
    Location
    Pierre Part, La.
    Posts
    455
    Post Thanks / Like

    Default

    I have ported several Yamaha and Merc 4 stroke heads, we have had decent success so far. The valve springs are weak, the ECU mod would be awesome
    Helping folks out around the globe.

  6. #6
    Administrator Ron Hill's Avatar
    Join Date
    Nov 2004
    Location
    Tustin, California
    Posts
    8,339
    Post Thanks / Like

    Default Simon Motorsports of San Diego, California

    I have heard, that Simon Motor Sports can "FLASH" the ECU on Mercury 40-60 HP. http://www.simonmotorsports.com/ I'll admit, I don't know what an ECU is. I do know what a rev limiter is.

    I've talked to them on the phone, super polite and helpful, though I didn't have very clear questions.

  7. #7
    Team Member
    Join Date
    Jun 2005
    Location
    Eastern PA
    Posts
    745
    Post Thanks / Like

    Default

    Typically, valve springs are always an issue in running 4 strokes at high rpm. To hot rod one of these 4 stroke OBs, you'd need to install a higher performance cam, stiffer springs, and possibly lighter valve rain components. I suppose some cam manufacturer out there would develop and sell high performance cams for these things IF the demand was there.

    Jeff

    PS: Getting on plane with a 'hot cam' could be a problem here. It is for Go Fast boats with high speed propping.
    "We live at the bottom of an ocean of air." - General Marvage Slatington

  8. #8
    Team Member
    Join Date
    Mar 2018
    Posts
    14
    Post Thanks / Like

    Default

    Hate to revive an old thread, but anyone have any more info as far as performance is concerned on these 4 strokes? I have a merc formula race 60 15" and like to get it tuned by simon, Ron hill have you heard of anyone running one by now? what was the increase? Car worker how has the head work done for performance?

  9. #9
    Team Member
    Join Date
    Aug 2014
    Location
    Naples Florida
    Posts
    84
    Post Thanks / Like

    Default

    I read somewhere that those motors can't handle high rpm's because of valve float. Fact or BS?

  10. #10
    Team Member
    Join Date
    Mar 2018
    Posts
    14
    Post Thanks / Like

    Default

    Not sure, I have heard 6500 rpm is safe any higher is asking for trouble with the valves. Ill be happy with 6500, they rev up to 6300 stock thats pretty high for a stock 4 stroke. Im hoping someone with more inside knowledge can chime in, id really like to tune it although they claim only 5-7 hp gain and from what i hear the engine at 6300 rpm pushes about 65-68 hp so that would put it into the 70+ hp range and id be happy with that. Its hard to find a new midrange power plant with a short shaft and good gear ratio anymore without piecing old stuff together. Thats why i bought the merc 4 stroke. theres small rapid crafts running them at 65 mph so its respectable, just turn key and go, great on fuel too. In the uk they race these on boats 16' 1200+ lbs 60+ mph with merc cleavers. some actually run Hills props too.

Thread Information

Users Browsing this Thread

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

Similar Threads

  1. 4 stroke gearcase on a 2 stroke outboard
    By omcstratos in forum Technical Discussion
    Replies: 0
    Last Post: 04-13-2016, 04:31 PM
  2. Want To Buy a newer model Yamaha 50 4-stroke lower unit
    By Mod40yammy in forum Lower Units and Outdrives
    Replies: 0
    Last Post: 07-21-2014, 08:57 AM
  3. The Harrison Racing Outboards - Legendary Birmingham Metal Products Alky Outboards
    By John (Taylor) Gabrowski in forum Outboard Racing History
    Replies: 169
    Last Post: 11-12-2008, 11:34 AM

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
  •