Any way to 'Soup-up' a '98 Johnson 115?

[redtrout]

Howdy Everyone -<br /><br />Yeah, I know, it sounds crazy; however, I am thinking it may be cheaper to add something high performance or get someone to rebuild her instead of purchasing a new 150 hp. I have a '98 Johnson 115 60 degree V / oil injected outboard that has been absolutely great to me. I need to get somewhere between 20 and 30 more horsepower out of the engine. I am tired of not going fast. Does anyone have any good ideas or know of someone that I should speak with to accomplish this?<br /><br />Thanks in advance and have a great day.

 

[walleyehed]

Re: Any way to 'Soup-up' a '98 Johnson 115?

See what Dhadley has to say, but the 150 is the best choice. You're not going to get what you are looking for out of that 115.<br />Now, with that being said, the performance you have now is directly related to how you are set up...engine height, set-back, type of hull, even prop type and size.<br />What kind of rig do you have and how is it set up now??

 

[moderator1]

Re: Any way to 'Soup-up' a '98 Johnson 115?

Moving this to J/E, as some engine work would be required, and the best aswers will be there for this question...

 

[redtrout]

Re: Any way to 'Soup-up' a '98 Johnson 115?

Walleyehed -<br /><br />I have a 19' Blue Wave. It is a center console, shallow-water boat with a pocket tunnel. Engine is on a hydraulic jackplate which includes about a 5 inch setback. I just recently bought a new prop (Turbo Flats 4 blade stainless, 14.25" with 17 pitch). The prop is awesome. Gained about 5 mph topend (48 mph at 5500 rpm) and midrange is great (41 mph at 4700 rpm). Boat, motor and light load weigh approximately 1700 lbs.<br /><br />Thanks again.<br /><br />T

 

[Dhadley]

Re: Any way to 'Soup-up' a '98 Johnson 115?

OK lets see where youre at. Tell us about your hull (what type) and the set up. Jackplate? Top speed (accurate), rpm, prop (pitch, brand, style), water pressure, motor mods etc.<br /><br />Then tell us where youd like to be and the intended use. Top end only? Skiing? Holeshot?<br /><br />I'm real curious about how you came up with the 20 to 30 hp number.

 

[Dhadley]

Re: Any way to 'Soup-up' a '98 Johnson 115?

I "hunt & peck" too slow.

 

[Dhadley]

Re: Any way to 'Soup-up' a '98 Johnson 115?

I noticed youre using a V6 prop. The slip numbers are coming up a bit strange even if youre using a standard V6 gearcase. They dont make any sense at all for a V4 ratio of either style gearcase.<br /><br />Count your gear ratio and let us know.

 

[redtrout]

Re: Any way to 'Soup-up' a '98 Johnson 115?

Dhadley<br /><br />Howdy. Above, I provide most of the information about the boat - as you asked for. Additionally, the beam of the boat is 8'; V-hull on front 1/3, transitioning to basically a flat bottom with a small (2" semi-circular) pocket tunnel with a small, stepped transom. Water Pressure is upper 20s at WOT with jack plate down. Water pressure at 20 flat with jack plate raised a couple inches and engine trimmed to attain maximum speed of 48 mph. Water Pressure between 10 and 15 when I have jack plate all the way up, WOT and need to get through some very skinny water. Luckily, the engine has the SLOW protection system because I have overheated while running in skinny water without enough water pressure. <br /><br />Mainly, I want to still have a good hole shot for shallow water get-on-plane while also having a top end around 60 mph. I figured 20 to 30 more HP would provide that if I got the appropriate prop. I mainly use the boat for fishing, however; during the summer, we ski and wake board behing it. Sometimes I travel 80 to 100 miles during a day of coastal bay fishing. Another 15 mph would give me more fishing and less boating time. Additionally, pulling up a large person on a slalom ski has been a chore in the past. <br /><br />Thanks again, <br /><br />T

 

[redtrout]

Re: Any way to 'Soup-up' a '98 Johnson 115?

Everyone -<br /><br />I made a mistake above, the prop is a Turbo Flats IV with 13.25 NOT 14.25 diameter and 17 pitch. The gearcase is regularly called intermediate, whatever that means. I will do some research and find out what the ratio is.<br /><br />Thanks,<br /><br />T

 

[Dhadley]

Re: Any way to 'Soup-up' a '98 Johnson 115?

That inded is a "V4" style or intermediate style prop. A standard V4 gearcase is 2:1. At this point we need to verify the speed and top rpm. I would have thought you'd be running a 19 on that boat and turning more than 5500.<br /><br />A 17" prop on a 2:1 case with the motor turning 5500 equates to a theoritical speed (no slip) of about 45 mph.