Hey Skools

[willy]

Lord Skools info please, just reading the manual on the boat I just brought home. Remember when we talked about the 1999 115 Johnson Ocean Pro , on this boat and all the rpm I got was just under 5000. Well the manual says that it is a looper engine and that the max rpm is between 4500 and 5500 depending on prop used and load. Does that sound right to you and if correct that means I'm turning the right Rpm right?. And that means the highest mph I'm going to get will be about 30 mph like it gets now right? Someone I forget who was getting much faster mph on this site soI don't understand ???

[Skools Out]

that extra 500 rpms would give you more speed what prop are you running? and SS or Alum.?

[willy]

Aluminum but i can't see what it is now will have to look tommorow

[willy]

does that sound right to you, I was surprised at the manual but it is very clear, it is a looper engine and the max rpm is 4500 to 5500 depending on prop, when I took it out on sea trial with Fillet1 it maxed out at just a hair under 5000. I could of sworn someone said 1999 would not be a loop charged unit and they were getting 5600 rpm from their 115 hp, not sure what year theirs was

[willy]

Bump ;D

[Skools Out]

Here's your specs. That was the first yr as i can find of the 115 hp Looper V-4's.

Johnson V-4 115 hp
Year: 1999
Engine: 60º V
Horse Power: 115
Displacement: 105 cu. in.
Bore/Stroke: 3.60" x 2.59"
Cylinders: 4
Fuel Induction: Carburetor
RPM: 4500-5500
Weight: 319 lbs.
Gear Ratio: 2.0:1
Shaft: 20 in.
Gears: F N R

Systems:
Alternator: 5/20 Amp.
Cooling: Temperature & Pressure
Ingition:
Starting:
Exaust:

Other:
Scavenging: Loop
Steering: Remote Thru Tilt Tube

[willy]

Got it Skools that is what javascript:huh()
javascript:huh()the manual says too. So my 5000 rpm's should be right in the ball park depending on the prop I guess. Just surprised at the speed some guys said they got out of that engine on a v20 when mine is maxed and getting 28-30. Unless that enclosure drops it a lot

[Skools Out]

oh yeah that will so will the center of the windshield closed too. see which prop you have let us know and were you testing in Salt or Fresh water?

Salt water is faster always than fresh water.

[Skools Out]

Which have you tested it in? you need to make sure of your Max RPM in both waters if you are going to use it in both it will be slightly different. the slight difference could be enough to hurt the motor if you were to change the prop.

[willy]

Skools the prop on the boat has no markings whatsoever, the spare prop which looks exactly the same has just a serial # on it 011007 thats it no brand no other numbers. went over it real good

[willy]

Skools does that number mean anything to ya, I looked again and there is no other markings at all :-/

[Skools Out]

no if it's a OMC prop it should have numbers at the prop nut may have to take it off to find the markings.

[willy]

Ok that must be it because all other props I've seen have some info on main body somewhere these have none.

[Skools Out]

found ya prop i think
http://www.shipstore.com/ss/html/MWC/MWC011007.html

http://www.overtons.com/cgi-bin/overtons/detail/pdetail2.cgi?r=detail_view&item_num=31558

see if that is it if so you have a 15x17 prop i'd go to a cupped stainless 15x15, 16, *or 17 prop they made some 16's by OMC in SS if you look on ebay they are great props.

[Skools Out]

http://www.boat-props.com/match/match_omc_props.html

[willy]

Checked out those site Lord Skools thanks, that looks like the prop. Can you tell me why it would be better to have the other size props you mention

[Skools Out]

http://www.boat-props.com/prop_info_2.cgi?page=rpm

http://www.gulffishing.com/choosingaprop.html


For some boaters, choosing the right propeller can be difficult. However, choosing the correct propeller for a particular boat and motor is actually a fairly simple task once you understand what a propeller really is.

First, think of a propeller as a gear, similar to one on a car or a bicycle. A lower gear offers a faster hole shot and more power, but the revolutions are much faster, so at a point you can only turn that gear so fast until you over rev the engine. Now, think of a car stuck in 5th gear. It's very slow out of the hole with little torque, but eventually it reaches a good cruising speed.

The same basic concept applies to propellers, except with a prop you are committed to only one gear. You need to find the prop size that gives the best overall performance.

Your engine has a recommended wide-open throttle rpm range. For example, an 18' boat with a 125 hp engine has a range of 4,500-5,500 rpm. In many cases, you purchase a boat with some sort of propeller on it. Let's say this motor has a 21 pitch prop and at wide-open throttle, under a normal boatload, the engine turns 4,900 rpm. It's in the range so it's the correct prop, right? Yes and no. For the health and longevity of the engine it's okay, but for overall performance, you want to run a propeller near the top of the range.

To get there, remember this rule: for every 2" of propeller pitch, rpm will change approximately 400 rpm. As you drop in pitch, rpm increase, and as you go up in pitch, rpm decrease. If you want to raise rpm you should choose a lower pitch prop. Following the rule, going down to a 19 pitch should raise rpm to about 5,300. That would help the hole shot and also gain more speed.

This is not an ironclad rule, however. Sometimes varying 2" of pitch will only change rpm by 200. Switching propeller brands or manufacturer can also sometimes alter the rule.

The most important concept to understand is that less pitch equals more rpm and more pitch equals less rpm. For a boat to perform at its peak, you need to run at the upper end of the engine's recommended rpm range. If you still want more speed, handling or lift, that's when a propeller's brand can make a difference.

Here's a simple adjustment you can make to improve performance under varying boatloads. If you normally run with one other person on board, use that boatload as a measurement to determine your wide-open throttle rpm. But if you load the boat with more people or try to pull a water skier or tuber, use a prop that is 2" lower in pitch than your normal prop. It will compensate for added weight and drag and greatly improve on performance in these circumstances. Remember to keep an eye on your rpm when running a lower pitch for these circumstances so you don't over rev the engine.

Most props have the size marked on the barrel, blades or front or back of the propeller. Use the pitch that you're currently running as your starting point. If it's already running correctly then that is your pitch. Contact Turning Point Propellers Inc., 896 Cambridge Drive, Elk Grove Village, IL 60007; Phone: 847-437-6800. www.turningpointpropellers.com;

Editors note: Adam Kendall aids in the testing of Turning Point's propellers and also serves as the company's Marketing Director. Contact Turning Point Propellers at 847-437-6800 or www.turningpointpropellers.com.

[willy]

Thanks Lord Skools ;)

[reelapeelin]

Good stuff, Skools... ;D...as always... ;)...

[mirage2521]

That was a really clear and concise easy to understand explanation