Welcome Guest - Sign Up today
Welcome Guest - Sign Up today
Store Links Mobile - Shop Now



Help Tip: If you have a question that has not been answered to your satisfaction in the archives, it is always best to start a new thread of your own. By starting your own thread, you will receive the maximum number of views by forum members.

Below are some additional forum policies in hopes of all iboats members will follow, Thank you.

1. Please do not reply to old topics or hijack existing topics. Old topics of a technical nature are like a library book, Please do not write in them.

2. Old topics should be considered archives and used for reference only. Please do not reply to them.

3. Do not take over someone elseís topic (aka hijack) with your own question, even if it is similar. If you have a question that has not been covered to your satisfaction in the archives, it is always best to start a new topic of your own.

4. If you have a question for the original poster (OP) and the topic is over 30 days old, send the OP a PM, he may not even visit the forums any longer, or may not notice your question in the old topic.

5. By starting your own topic, you will receive the maximum number of views by forum helpers that may not even notice your question when itís posted at the end of someone elseís topic. And those answers will be specific to your particular issue.

6. Please do not post to topics that have been inactive for more than 3 months unless you are the original poster. We have very active forums and any topic that remains inactive for that long should be considered "dead". It is especially confusing when there is an entirely new question posted to an old topic.

7. Posting at the end of any topic is considered to be hijacking the original posters topic which in turn subjects the topic to be closed if it continues to happen thus not making it fair to the original poster in the future had for some reason he/she needed to return for additional information or provide an update of the problem solved which is always welcomed within a reasonable amount of time frame.

8. Please note that you should see a red banner pop up near the bottom of each inactive topic asking you not to reply to old topics. The Red banner will read: Please note this topic has been inactive for 90 days. For the best results, please start a new topic.

Thank you all in advance for doing your part in helping iboats run a smooth ship.

Additional forum rules linked below.
See more
See less

1989 88 SPL Conversion to 115???

  • Filter
  • Time
  • Show
Clear All
new posts

  • 1989 88 SPL Conversion to 115???

    I have a Evinrude 1989 88 SPL, I have been researching the motor and carb part numbers and have found the only difference in the horse power of these V4 motors are the carburetor orifices (Jets). According to my research it appears I can convert the 1989 88 SPL, to a 115hp (1990 Model carb parts) by changing the high speed and intermediate carb jets. Can anyone confirm this before I buy the jets. Is it possible to convert the 90 hp to 115 this way.

    Thanks inadvance for your help.
    1989 Sprint 265, 88SPL
    1991 Sea Nymph TX 175, 70 hp
    1983 Ranger 350V, Merc 115
    1977 Fabuglass, 85 Hp Merc

  • #2
    Re: 1989 88 SPL Conversion to 115???

    I am pretty sure they have different exhaust ports/manifold (bubble back) and intake ports...Mostly speaking if you want a 115 sell your 88 and go buy a 115. These motors have a very specific balance and you have to really know your stuff to convert one that will run right. I have 2 115s a 25" shaft and a 20" shaft. the long shaft motor is a 1995 and the short shaft one is a 1997 OIS 60 degree motor...both are in excellent running condition and I would sell you one if you want to drive down here to Savannah. but you could probably find one there in the Atlanta area.
    Free ignition troubleshooting guide http://www.cdielectronics.com/techni...ort-documents/
    You will need a DVA adapter http://www.usatoolwarehouse.com/usat...e/ESI-640.html First test compression, Second test spark with a spark gap tester set a 7/16 gap, Third check timing, next CLEAN your carbs properly,


    • #3
      Re: 1989 88 SPL Conversion to 115???

      That is correct. The 115 blocks have different porting and a tuned exhaust manifold (bubble back) that helps with scavenging exhaust. Also, the carbs aren't just jetted differently, they're different carbs. The 115 has larger bore carburetors. Turning your 88SPL into a 115 would involve a great deal of machining and finding of parts. As noted above, if you want more horsepower, get a bigger motor...
      Share A Project Page for 1971 GW Invader Banchie 13
      Share A Project Page for 1976 American 18
      Share A Project Page for 1974 American 15


      • #4
        Re: 1989 88 SPL Conversion to 115???

        I am in the middle of changing my 90 hp to a 115...while it is a looper not a crossflow, what i ahve found , PROBABLY applies to your motors as well.

        first off just because you look up a part number and it says it fits both the 90 hp and the 115 hp...does NOT mean they are the same.. the heads interchange from a 115 and a 90./..BUT they are different..the depth of the combustion chamber is about .090" deeper on the 90 hp!!!

        second, like someone said the BORES on the 90 and 115 carbs are way different...thus the volume of air going through is different...youd need the 115 carbs .

        thirdly, while almost every rebuilder will tell you they sell a 90-115 hp block...they cant!! the ports in the sleeves are very different!

        the 115 hp ports are larger and closer to the edge than the 90 hp ports. I took a foredom tool and ground the ports on my 90 hp to match those of my 115 hp( luckily i have a 115 already to measure from) as best i can tell all other parts are the same..

        I would guess that it is at least as difficult to convert your 88 to a 115 as it was for me to convert my 90 to a 115...maybe even more...since i havent seen the exhaust housing on your motor...

        on this picture the port on the right is the original shape for a 60 degree looper 90 hps, the port on the right is about the shape for the same style 115 hp!!

        good luck



        • #5
          Re: 1989 88 SPL Conversion to 115???

          For what it's worth (not much probably), my mechanic told me he could turn my '81 90 into an honest 115 with a carb swap. This issue arose because he was troubleshooting my motor and found that some dopey previous owner had slapped 140 carbs on it. He said there would be extensive other modifications required to make it a 140. Despite my carbs being too large, he was able to get them jetted to the point where my motor runs well. He advised me to look for 115 carbs for it. I haven't though, because it runs awesome as-is and I figure why mess with it.
          2002 20' Hydra-Sports 202DC 200HP Yamaha HPDI
          1976 18' Starcraft SuperSport 90HP Evinrude
          Restoration thread http://forums.iboats.com/showthread.php?t=357767


          • #6
            Sign up today
            Re: 1989 88 SPL Conversion to 115???

            the problem really is that old wives tales have been passed around about making an X hp motor into an X+ hp motor by just switching carbs..or heads....and when the job is done and the motor runs good...the owner THINKS he has more hp, when in fact he probably cant tell the difference....

            a guy would have to GPS his boat, then make the switch and then re gps the boat and verify the boat is actually going faster at the same rpm!!