lots of 19 pitch props, but what radius is correct.

[MAW31]

posted here a while back sizing up prop pitch to my boat, power, usage.

summation was that a 19 Pitch would fit my usage best.

stats restated: 18ft center console, fishing, with '86 110HP johnson.
with a 15 pitch WOT = 5200 RPM, 3 peeps, fishing gear.

looking for 19 Pitch props, 3 blade, Stainless, 13 Spline for a V4.

I"m running into alot of 19 pitch, 13 inch props, and i'm wondering if those are more like 60HP props with a 19pitch, and then jumps to 14.5 radius, 19 pitch (for 150HP plus)

what diameter should I be settling on?

thanks

 

[Dhadley]

Re: lots of 19 pitch props, but what radius is correct.

Don't be so concerned about diameter. Concentrate on what your boat needs from a prop. The correct series prop will fit a 4 1/4" gearcase, 13 spline shaft like your V4 OMC. Your prop will probably be in the 13 to 13 1/2" diameter range, maybe 13 3/4" but let's look at what you need from a prop. Are you looking for strictly top end? Do you need help with bow lift? Or stern lift? Towing water toys (skiing etc)?

 

[reelnative]

Re: lots of 19 pitch props, but what radius is correct.

posted here a while back sizing up prop pitch to my boat, power, usage.

summation was that a 19 Pitch would fit my usage best.

stats restated: 18ft center console, fishing, with '86 110HP johnson.
with a 15 pitch WOT = 5200 RPM, 3 peeps, fishing gear.

looking for 19 Pitch props, 3 blade, Stainless, 13 Spline for a V4.

I"m running into alot of 19 pitch, 13 inch props, and i'm wondering if those are more like 60HP props with a 19pitch, and then jumps to 14.5 radius, 19 pitch (for 150HP plus)

what diameter should I be settling on?

thanks

if your running a 15p prop now and are getting 5200 WOT your in the range were you need to be rpm wise, your motor casing will only let you run to a 13.75 maby a 14 dia max if you were running a 14dia 15 pich prop that would be a pusher prop made for somthing like a pontoon boat application if your running a 13.5 or 13.25 -15 that would be more of a normal type prop for your boat but if you went to a 19pich prop with the same rake and cupping and dia, you would loose about 800rmp and would put you in the 4400rpm WOT range and that would be over propping your boat, your setup sounds like its about the best for you, normal prop sizes for a boat of your size and motor is a 13.25 to 13.5 by 15p or 17p and that would be for salt water use

 

[hwsiii]

Re: lots of 19 pitch props, but what radius is correct.

MAW, I show you have a 2:1 gear ratio and should be running about 5600 RPM, with a normal load, with that motor to stop it from coking up. You show 5,200 RPM with a 15" pitch and if you change to a 19" you will reduce your RPM somewhere about 400 to 800 RPM depending on which prop you use.

YOU should be going DOWN in pitch not UP.

Dale is there someting I don't know from a previous discussion y'all had.


H

 

[reelnative]

Re: lots of 19 pitch props, but what radius is correct.

MAW, I show you have a 2:1 gear ratio and should be running about 5600 RPM, with a normal load, with that motor to stop it from coking up. You show 5,200 RPM with a 15" pitch and if you change to a 19" you will reduce your RPM somewhere about 400 to 800 RPM depending on which prop you use.

YOU should be going DOWN in pitch not UP.

Dale is there someting I don't know from a previous discussion y'all had.


H

that motor has a WOT range of 5000 to 5500 him running at 5200 is about perfect 5600 would be over reving it

 

[Dhadley]

Re: lots of 19 pitch props, but what radius is correct.

Nope H, 5200 is lugging the motor pretty bad on todays fuel. We need to get the r's up not down - you are correct. The set up seems to be off pretty far so I was trying to get an idea of what the intended use is.

 

[Dhadley]

Re: lots of 19 pitch props, but what radius is correct.

that motor has a WOT range of 5000 to 5500 him running at 5200 is about perfect 5600 would be over reving it

5600 is still border line lugging. There really isn't such a thing as "over reving" a motor like yours as long as it has a load on it. We look at combustion temps and how those temps affect engine life. Your motor propped out at 5200 will not live as long as your motor propped out at 5800.

 

[reelnative]

Re: lots of 19 pitch props, but what radius is correct.

5600 is still border line lugging. There really isn't such a thing as "over reving" a motor like yours as long as it has a load on it. We look at combustion temps and how those temps affect engine life. Your motor propped out at 5200 will not live as long as your motor propped out at 5800.

dude you have lost your mind or just drink way too much, that motor has a WOT OF 5500 rpm ive spent the better part of my life as an omc mecanic and ill tell you or anyone elese that what you are spewing out is crap, that motor is designed to operate right at were he has it 5200 rpm thats right in the middle of its WOT range, you run that 24yr old motor all day at 5800+ rpm and you wont be looking at combustion temps you will be looking at needle berrings in the crank case or a nice hunk out of the side of the motor

 

[walleyehed]

Re: lots of 19 pitch props, but what radius is correct.

dude you have lost your mind or just drink way too much, that motor has a WOT OF 5500 rpm ive spent the better part of my life as an omc mecanic and ill tell you or anyone elese that what you are spewing out is crap, that motor is designed to operate right at were he has it 5200 rpm thats right in the middle of its WOT range, you run that 24yr old motor all day at 5800+ rpm and you wont be looking at combustion temps you will be looking at needle berrings in the crank case or a nice hunk out of the side of the motor

Tell ya what there, RN... the dude you think drinks too much is a proffessional consultant for one of the Hottest Prop designs in the world. He has accumilated more time in just Boat drag racing than most of us will aquire in a lifetime of pleasure boating. AND, to top that off, He's spent many, many years helping Engineer Outboard components and testing them to the full limits.
I've spent 20+ years as an OMC tech as well...if you missed the bullitens and recommendations, take a look at my combustion temps on my prop tests above when getting down below 5500rpm. I've measured them, as has Dhadley.
Another note, as an "OMC" tech, you would know Needle bearings and the advantage they offer because there is nothing to come apart at high RPM and they have no clue how fast they are rolling...the engine is an "airpump".
NOW, we will respect each other and keep it clean, or I have other tricks I can pull if needed.

 

[Dhadley]

Re: lots of 19 pitch props, but what radius is correct.

If you say so but that's not what I've found in the testing we've done in the last 35 + years. Or with the race boats. We'll go with your wisdom, after all we're pretty new to this stuff.

 

[reelnative]

Re: lots of 19 pitch props, but what radius is correct.

hahahaha ok ive had enought hows this I give up your right

 

[coolguy147]

Re: lots of 19 pitch props, but what radius is correct.

but dhadley has more posts

motor sounds cool at 5800rpm lol scream! wait my bad....those are mercurys

 

[walleyehed]

Re: lots of 19 pitch props, but what radius is correct.

Another thought there, RN...I turn my 28yr old at a MINIMUM of 6000 and have ran continuously at 7300-7500....for about the last 5 yrs. Everything is great, turn the key and go...No carbon, no Coking, just zero problems. It's not something we have proven on 1-2 engines, it's more like many 100's...
There are some VERY knowledgable folks here...hang around and you'll learn who they are.

Edit: For a Crossflow, 5800 is not screaming..it's the minimum RPM for Longevity...If it's a looper, better make it 6K.

 

[Dhadley]

Re: lots of 19 pitch props, but what radius is correct.

Yep, a V4 crossflow sounds good at 5800 but you should hear one at 7400. Or a modified one at 8000+. REALLY cool!

 

[Dhadley]

Re: lots of 19 pitch props, but what radius is correct.

RN, since you live here, just a thought - we may be looking for a tech at the marina in Punta Gorda. Shoot me a PM if you are interested.

 

[hwsiii]

Re: lots of 19 pitch props, but what radius is correct.

Seems like I missed a rambunctious conversation, but it appears Kenny got his two cents in.

There are some people here that know ALL about outboards and props, and I can promise you Kenny and Dale are at the TOP of that LIST.

Reel, we try to be nice to each other here, BUT I will have to say I have had to make a public apology on here myself.

I will also have to say I am NEVER wrong, UNLESS I am breathing.



H

 

[torbjorn]

Re: lots of 19 pitch props, but what radius is correct.

posted here a while back sizing up prop pitch to my boat, power, usage.

summation was that a 19 Pitch would fit my usage best.

stats restated: 18ft center console, fishing, with '86 110HP johnson.
with a 15 pitch WOT = 5200 RPM, 3 peeps, fishing gear.

looking for 19 Pitch props, 3 blade, Stainless, 13 Spline for a V4.

I"m running into alot of 19 pitch, 13 inch props, and i'm wondering if those are more like 60HP props with a 19pitch, and then jumps to 14.5 radius, 19 pitch (for 150HP plus)

what diameter should I be settling on?

thanks

OMC made a 13x19 and a 13 3/4x15. You don't want more diameter than they started with. 5200 RPM is too low, there's no way you can run a 19. They had a 13" pitch, you can try that or else have your 15 depitched. Motor should turn 5500 - 6000 RPM.