Anyone know how to convert 9.9 to 15 hp?

[Stream_fisherKY]

I have a 1976 model evinrude 9.9 that I am interested in converting to a 15 hp engine before I place it on another boat. I need to know what parts are required for this switch, if anyone knows please inform me. Thanks all. <br /><br />Streamfisher

 

[DJ]

Re: Anyone know how to convert 9.9 to 15 hp?

Stream,<br /><br />Fuggedaboutit. The question has been asked before and the differences are VERY deep. Block, carbs., reeds, and more.

 

[FlyBoyMark]

Re: Anyone know how to convert 9.9 to 15 hp?

Not always djohns..certain john-rudes 9.9 to 15 but not all models its the carb only, late ('89 to present) model Merc 20's to 25, carb only, Merc 3 cylinder 40 to 50 bigger carbs & throw away the reed stop(60 HP attenuator gets another 100 RPM too), Force or Sears 9.9 to 15 carb only.......There may be others but these are the only ones that I know of that don't require a new block or other major modifications. I'm not sure about the year of your outboard though if it can be done.

 

[Boatist]

Re: Anyone know how to convert 9.9 to 15 hp?

The carb is only difference or a 1976 but you have to change the whole carb not just the jets. The 15 carb has a bigger bore and bigger jets. It will use more fuel and make more power at top end. After 1989 when they tunned the Exhaust to get 15HP at the Prop Shaft instead of at the powerhead there may be more changes.

 

[wildgans]

Re: Anyone know how to convert 9.9 to 15 hp?

Well, just to add to the confusion, is there anything I can do to my 91 15 hp Rude to make it a 20 or 25 hp?<br /><br />Just curious.<br /><br />Thanks,<br />David

 

[FlyBoyMark]

Re: Anyone know how to convert 9.9 to 15 hp?

Nope...totaly different engines. BUT you could dump a ton of bucks into machine work, after market tuned exhaust, carbs, alcohole fuel, balancing the crank, high compression custom pistons if ya got money to burn as a hobby jus for your own pleasure. Ya might even git 50 -60 hp out of that little block if ya can git it to stay together @ 10 to 12,000 RPM <br /><br />Or for the less money jus' buy a new 25 or 30 HP.

 

[FlyBoyMark]

Re: Anyone know how to convert 9.9 to 15 hp?

Forgot one other engine I know of: Suzuki early 90's 3 cylinder 25 HP to 30 HP. Remove the FACTORY restrictor plate from behind the carb.

 

[smalloutboardsarecool]

Re: Anyone know how to convert 9.9 to 15 hp?

is there any way I can pull some more horse power out of my 1997 evinrude 6hp two cycle two cylinder 100/1 oil mixture? is there any thing I can do>?

 

[The_FoX]

Re: Anyone know how to convert 9.9 to 15 hp?

You could always say to hell with premix and run it on 100% 93 octane gas. You will get the performance that you need but I have to warn you that your engine wont live long.

 

[JB]

Re: Anyone know how to convert 9.9 to 15 hp?

Jees!, FOX!! What the hell are you doing??? Somebody's gonna believe you!!<br /><br />SailBoaty.<br /><br />1. Forget the 100:1 mix. OMC rescinded that almost immediately. Use 50:1 with 87 octane regular unleaded.<br /><br />2. To get more power reliably, get a bigger engine.<br /><br />Good luck.

 

[JB]

Re: Anyone know how to convert 9.9 to 15 hp?

Flyboymark.<br /><br />You are hereby nominated to answer every post by someone who wants to hop up and destroy an outboard.<br /><br />We will now get an even bigger flood of 'em.

 

[FlyBoyMark]

Re: Anyone know how to convert 9.9 to 15 hp?

He-He-Ha-Ha-He-He Boy am i gonna have fun with this!!!!!!!!!!!!!!!!!!!!!!!!!!!!

 

[FlyBoyMark]

Re: Anyone know how to convert 9.9 to 15 hp?

Anybody wanna try model airplane glow fuel...will double the power AND FUEL consumption, but ya gotta order a spark plug converter bushings from Tower Hobbies to screw in a glow plug. Then ya gotta start the engine with 1.5 volts to each glowpug then remove once all jugs are fireing. Good HIGH power premix of 10% oil, 5-10% nitro methane(for reliable idle to keep glow plugs hot), balance of mix methonol alcohol. OH! almost forgot, you MUST increase jet size but I don't know the formula for that. Engine WILL run cooler but I dunno if it will take all the extra power?????????? Anybody wanna try it on an old eggbeater? Oh, toss the spark advance....

 

[FlyBoyMark]

Re: Anyone know how to convert 9.9 to 15 hp?

More oil in the fuel makes the engine run leaner and warmer(less power, causes detonation, overheating), less oil than recomended makes the engine run rich and fowls plugs(less power too), makes carbon deposits but friction increases so more heat is made. If you really want more power add nitro methane to fuel at your own risk or run alcohol fuel Which requires rejetting(much bigger) and new fuel system to keep from being melted by the alcohol (silicone hoses and alc. proof carb floats, fuel pump with parts for alcohol).<br /><br />0.

 

[Franki]

Re: Anyone know how to convert 9.9 to 15 hp?

To He!! with all that..<br /><br />Get a B&M underbonnet blower, take off the pulley, and put a spline gear on it so it will work of the flywheel.. stick it between the carbs and the block.. dial up 10 pounds of presure.. increase your jet size to accomodate..<br /><br />Then go cruzing.. with this setup a 15hp will probably get up to 50-70HP, but you need lots of mates waiting around the motor to catch the bits when it detonates. also, fuel econnomy will suffer, as will emisions. but on the upside, a scavanging exhaust is no longer necessary as the 10 psi will basically force a huge shot of intake charge all the way through and probably most of the way out the exhaust as well..<br /><br />expensive, but sounds like fun huh???<br /><br />I might try it if I had a 15hp made entirely from titanium... internally balanced to perfection with heavy duty everything, including drive shaft and gear case.. corse that would be about 10 times the cost of a new 70HP.... <br /><br />all in jest...<br /><br />rgds<br /><br />Frank

 

[FlyBoyMark]

Re: Anyone know how to convert 9.9 to 15 hp?

I got this little 200 lb. 2.8 all aluminum v-6 chevy block punched out to 3.4 and good to 8 grand for 350 HP........thinks' wee' cud' find an adapter plate for that 15 HP leg?

 

[Rex]

Re: Anyone know how to convert 9.9 to 15 hp?

Red sky it all about volume and the B.T.U. of <br />the fuel that you well be burning.<br />1 ex.) let say #1 cy. should have 120 psi<br />but all it has is 60. Would you put a larger jet in<br />or a smaller. Just like you said it time to have some fun.<br />Well if it was me i would say larger Why<br />you only have half the compress right.<br />So that means the fuel is only pressed half as much and that means that you would be running on the lean side.<br />I try to tell people this little simply way to look at fuel and they just do not get it.<br />P.S. if you had the head milled or had some tuned exhast. What way would you go.<br />1/2 the compression does not mean 2times the size of the jet.<br />but some people could put in lets just say a jet<br />3sizes up and make the top two cyl. run better.<br />Now red sky what do you think of that little <br />thing.<br />This is not aimed at you RED SKY but everybody.<br /> <br /> Has anybody thought about why car run alot<br />better and longer. forget about the great oil they have now days.<br /> The o2 senor know when the engine startes to run lean so WHAT does it do, puts more fuel in it.<br />THANK YOU <br />REX A. HUBBLE

 

[FlyBoyMark]

Re: Anyone know how to convert 9.9 to 15 hp?

Tuned exhaust has a very interesting effect on 2 cycle. Will increase power up to 20%, scavenges the cylinder for all old exhaust + pulls extra fuel air like supercharging, then pulses back into combustion chamber jus' before port closes. Jets must be enlarged. Downside is very narrow power band unless the tuned pipe "slides", also VERY noisy.

 

[vucelick]

Re: Anyone know how to convert 9.9 to 15 hp?

Honda 9.9 and the 15 four stroke are IDENTICAL save for a bit of adjustment to the throttle shaft/linkage. Look very carefully at the carb when you open the throttle and you will see what I am talking aobut....

 

[Rex]

Re: Anyone know how to convert 9.9 to 15 hp?

Just put bigger reeds and a bigger carbs. and you<br />off and running.<br />REX