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  1. #1
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    Converting a Johnson 90 to 115HP

    Hi, I know this is a bit low brow for you guys but I have run out of people to ask so here goes.

    I have a 1996 Johnson 90 V4 60 degree model number BJ90SLEDR

    I have been offered the same age 115HP version of this engine for spares model number J115SLEDR

    I have had a look at the BRP parts website and initially it looked as simple as swapping the Carbs and Cylinder Heads (the 115HP is higher compression). Even the exausts appeared to be the same.

    However upon looking more closely at the BRP drawings and part numbers it appears that there are 2 part numbers for what they call "CYLINDER & C'CASE ASSY.," which appears from the drawings to be the two halves of the Crankcase, there is one part number for the 90 and one for the 115.

    I was under the impression that the Blocks for these two engines were the same, is it just that there are differences to the ports in which case am I wasting my time swapping over the other bits?

    Can anyone help me?

    Thanks

    Chris Stevens

  2. #2
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    Well for the Friendrude there is more than Crankcase. If you go beyond the 115 and try to reach 140, the also change the crankase and the exhaust back plate has a bump ( like a pregnant woman) the exhaust tuner is different, heads are also diff. i'm not sure about the gearcase ratio that will be to check.

    Been there done that

    ( i had a 140 ) new and i got a 100 for parts that was the way i figured out the difference in all.
    Glastron GT 150 W OMC 140
    Glastron GT150 w OMC 235
    Hydrostream Vision with 2.0l 135
    Hydrostream HST w 3.0L 225


    I know two things that are infinite, the Universe and Human's Stupidity, although I am not sure about the first one.

  3. #3
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    So are there differences between the 90 and the 115 Crankcase then?

    Chris

  4. #4
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    do a search on 140 crossflow or v4 crossflow, this has been covered so many times
    John E.
    HydroStream Vandal 140 EVINRUDE 69mph GPS
    Black'99 SVT Lightning #1767 of 4000
    If It Ain't Blown It Sucks!


  5. #5
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    Crossflow?????????????

    If those are indeed 60* motors then looking for info on x-flows will do you no good as those are looper engines. The 60* are basically same design as 150/175 just 2 fewer cylinders. I'm not real sure what made the difference between the 90/115 but I believe the 175 v-6 had a .100 higher exhaust port than the 150. So maybe same thing with 90/115. Maybe Racer or one of the other GURUS will chime in and give some advice.

  6. #6
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    They also have a 90 degree 4 in 96 that is a xflow, the blocks are different as are the exhaust and heads.
    Last edited by racer; 05-31-2007 at 02:02 PM.

  7. #7
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    These engines are the 60 degree loopers.

    So what modififaction would I need to make and how easy is it to do?

  8. #8
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    a few a years ago i had a 1998 60 degree 90 rude. i had it on a hydrostream running about 57mph. i changed to the 115 carbs and gained 3mph.

  9. #9
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    sounds like you using all cross flow [small block v4s]. the 115 should have a tuned system between the heads. there's the bubble pack and 4 little wedges that attach at the exhaust post to make the surface flat for the tuned exhaust bubble. note the flange that separates the two exhaust banks. in the 115 there should be a 1" slot cut into the flange at the bottom. you need to cut that slot out. its worth 5 hp.

    the carbs are larger on the 115 as well as the intake to match, they need to be changed. that worth 5 hp. the tuned exhaust is the good for 15hp. the carb change is not really required and will make the motor real fuel hungry. i didnt do the carb. my 16 silveline when from 49 mph to 58 mph on a p tube [not gps but its the net change]

    good luck

  10. #10
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    on the 60 degree engine the carbs,heads and exhaust porting are different on the 90 and 115

  11. #11
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    racer you maybe right on the new stuff [ which he has]. i did mine on the older 1977to 1982 era motors. having said that i cant believe there is that much difference. the big inprovement is the tuned exhaust. when i sold the 1980 moter i kept the tuned exhaust and we installed it on a 1992 motor. we got almost the same results.

  12. #12
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    Bob all the 60 degree engines have a cast in exhaust similar to the xflow bubble

  13. #13
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    thanks that shows how dated i am with omc. my experence is with the older pre prop hp.

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