what do i need to get more speed

[614-bass]

Hey guys ive got a 16 lowe bass striker with a johnson 9.9 with a 15hp carb. The motor has manual tilt and trim and the anti-cav plate sits just under the bottom of my boat about a inch and a half. I am pretty sure it is the stock prop. At WOT im getting about 15mph at just under 4500 RPM if i remember right. I want to get the most speed out of it as i can so ive been looking into some different things. Would i benefit from having hydraulic tilt n trim or a hydraulic jack plate both are really pricey. also i could go with just a mini jacker the fixed one that sells for around 100 or a manual jack plate for around 170. Also would i benefit from a aftermarket prop and how do i tell what one is right for me.
Thanks
614-bass

 

[bcbouy]

it sounds like you have wrung all you can out of a 9.9. maybe its time to sell and buy a bigger hp motor.thats a lot of boat for that motor. just my 2 cents.

 

[user 6672]

it sounds like you have wrung all you can out of a 9.9. maybe its time to sell and buy a bigger hp motor.thats a lot of boat for that motor. just my 2 cents.

+1

 

[Pappy]

First off what year is your engine? Later engines (around 1982 or so) of your HP had an exhaust tuner in addition to your carb change. This is worth a little more horsepower.
Second. Yes, you will benefit from jacking the engine up on the transom. Go adjustable if you can. There are a couple good threads on here addressing that subject. With your rig you may be able to go up around 2.5" or so from where you are currently at and still run the same prop. That engine likes to turn over 6,000RPM and the additional height may get you there or a little closer. How did you check RPM?

 

[614-bass]

Thanks i have a rpm gauge on the console and its a 2000 i read some of the other threads but was still confused on which was better for my case. But it looks like im going to go with a jackplate. And the reason for the 9.9 is i fish alot of 10hp lakes only a handful of unlimited lakes and when i fish those its as a partner or co angler in someone else's boat. Not to mention im high school senior so money is pretty tight for me. anyway thanks guys.

 

[chrispy186]

If you are mechanically inclined, you could port and polish the intake/exhaust. My cousin has a 15hp evinrude, which he ported and polished the intake/exhaust, and changed the prop pitch. On his 14ft lowe jon with plywood decking, he gets 27mph on the gps. Then again he also burns at least half a tank of gas every time out.

 

[nomowork]

IMO you need more cubic inches.

A hydraulic trim wouldn't hurt either if you can swing it. It really helps in my fiberglass boat but then I'm not in a real great rush in either boat. :mrgreen:

 

[Jay D]

you got what your gonna get. I have a 25 evinrude on my 1648 lowe big jon and it gets at best 18-20mph on my gps. Can I get more? yeah probably, if I want to put another couple hundred into it, and my bucks are not going into the boat right now. Fish, dont drive the boat. :wink:

 

[turbotodd]

As said, if it's a '82 or later, the exhaust tuner between the 9.9 and 15 is different. The carb is different too but a 9.9 with a 15 carb and no other mods is only about 11 hp. The tuner is worth some power...and RPM....and obviously speed.

The stock prop doesn't like to be run shallow, so lifting the engine on the transom much more than about 3/4" above the bottom isn't going to play well with the stock prop. At least thats the way mine is. I switched to a Solas 4 blade 9x10 aluminum. Much smoother and stays on plane at a lower RPM/speed which is more important than fastest top speed.

I wouldn't mess with a hydraulic trim if it were mine. You start adding weight. Might as well get another 9.9 and run dual engines...LOL. The 9.9/15 are really lightweight and I suggest using that to your advantage. You can play with the trim pin and get it real close to what your needs are.

Jackplate not really needed on a little 15 HP. IF your transom will allow it, a transom lift adapter can be made cheaply which will raise the engine however much you want it to be. I used a wooden 2x2 under the motor, clamped it, tried it out and it seems to be just about right. Then I bolted the motor to the transom. It is solid. Cheaper than buying a mini-jacker. also lighter weight. My 1432 is a heavy boat (plywood decking on front and all plywood floors) and runs around 21 mph @ 5800 GPS and a tinytach. Could stand a bit less pitch (9 vs the current 10) but it works for what I do with it. The 15 likes lots of RPM BUT you don't have a 15...you have a 9.9 with a "little" more extra power. The tuner will help a bunch and then you can turn the RPM up to about 6200 or thereabouts and still make power where the 9.9 with 15 carb signs off at about 5800-ish.

 

[614-bass]

thanks for all the input guys im going to look into some of the stuff u guys suggested

 

[gotmuddy]

I have a manual jackplate that would definetly come in handy for you. You could build one yourself for about $25. It has helped me on the rivers I run with my 9.9 mariner and now helps with my 25 merc.

you cant see it good in these pics but if you want to build one I can take more detailed pics.

To put the exaust tuner on you will have to remove the powerhead...I dont know if that is worth the effort.

 

[614-bass]

How do you adjust that jackplate you built and could you send me some more pics of it when you get time and the materials i would need. Thanks id appreciate it.

 

[G Lap]

If your anti-cavitation plate is currently sitting 1 1/2" below the bottom of the hull, I think you would benefit from blocking up the motor . . . as TurboTodd mentioned. I have a 1648 welded boat with an older 25 HP Evinrude, and I blocked up the motor with square aluminum tubing to bring the anti-cavitation plate up and even with the bottom of the hull. According to the GPS from my truck, I am getting 30 mph. When your motor sits low like that, it is just adding extra drag. This is an easy and cheap step to take to see if raising the motor helps you out. If your clamps get close to the top of transom, be careful and bolt the motor down as soon as you are happy with how it runs.

 

[Cartman]

I am fairly new to the outboard world, but on one of our jet-skies we milled the head down. This will give you higher compression and more power (will most likely have to run 93 octane). A good machine shop should be able to give you a good price and advice. Has anyone else done this before on outboards?

 

[bcbouy]

thats a lot of money to spend on a maxed out 9.9 on a boat that big.

 

[Lil' Blue Rude]

I am fairly new to the outboard world, but on one of our jet-skies we milled the head down. This will give you higher compression and more power (will most likely have to run 93 octane). A good machine shop should be able to give you a good price and advice. Has anyone else done this before on outboards?

Alot of people have it done. One of the best bang for your buck things to do and it's easy.

 

[earl60446]

NITROUS! or a SUPERCHARGER! is the way to go.

I agree with the others that say you are getting about all you are gonna get. You are already going faster than me and my buddy in my 14ft lund / 15hp mariner. Of course, we are "king size"