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cds11

Contributing Member
1987 bayliner 2.3 omc. prop is in poor condition and im looking for a little more speed. it takes off fine and planes out qiukly and has hydrofoils on it. the prop that is on it now is a 13 19. if the 13 is the diameter i dont think there is much room for a larger diameter prop. boat is 17 feet long and weighs about 2,000 lbs. at wot it tops out at 35 mph and only runs 4,000 rpms. the prop that is on it now is aluminum and since im cheap the replacement will also be aluminum.
 
kimcrwbr1 said:
You may do good changing like to like what is the WOT spec for your engine a lower pitch will give you more R`s. It could be just your prop not the size or pitch dragging the r`s down
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so what number/pitch prop would you recommend? i dont know what it came with from the factory and im not sure what the rpm range is for my engine, i have done searches and people say anywhere from 4600 to 5500. your saying lower pitch will get mor rpms but wouldnt i lose more top end also? thanks for your help kim, i do appreciate it.
 
I have a 1989 Sunray with a 2.3l ford. I had a 13 19 on it and it was a pig out of the hole but lots of top end 42 mph@5000 rpm. i canged to a 13 15 and it jumped out or the hole but i lost some on the top end. 35mph@5000rpm. For the boat I think the WOT is 5200-5400 rpm, but I try to keep it at 5000rpm or below. IMO the engine is a little too small for the weight of the boat.
 
thanks for the help guys. i just bought a 13 15 off ebay this morning so hopefully it will help. im with you on the engine being to small robb. im still not sure why i can only get it up to 4000 rpms. robb, when you changed your prop the rpms stayed the same? any ideas why mine are so low? timing?
 
I would not say the rpm's stayed the same, because i could not get the boat up to the speed of the 13/19 prop. If I tried to push the boat to 40mph and beyond, the rpm's were red lining. I feel the motor is undersized and because of that you have to choose your poision, i keep both, one for pulling a skier and tube, and one for crusin. As for the timing, i have no idea, i can only speak of what problems I have had and what I did to rectify it. remember there is two greatest days of a boat owner.............the day you buy it and the day you sell it. Good luck.
 
I just cant understand why people just HAVE to have more speed? When I destroyed the Prop on my Drive, the Repairman re-pitched (he " cupped " it) it to an 18 from a 16. I gained a LITTLE more speed ( 35 MPH - 20 foot 2,750 pound Runabout, 225 V6 1 barrel ) but lost RPM at WOT. It tops out at 4100 RPM, which I like better than seeing it screaming at 4600 RPM.
Not trying to be mean or anything....just sayin'.....
 
Corsair23, i agree with the speed, i much prefer to get up out of the water quicker. but sometimes you may have a way to go, or it may be getting dark and want to be home, and sometimes it is fun to go fast!
 
I also have a 17 foot bayliner with the 2.3 liter engine and I have found that a 13.75 X 15 prop works really well. The max wot rpm for that engine is 5600. on a calm lake with no extra gear or people on board take the boat to full throttle and see what rpm's you are turning. If you do the math a 19 pitch turning 4000 rpm's will move your boat 3167 feet and a 15 degree turning at 5600 rpm's will move your boat 3,500 feet your boat will be going faster with the lower pitch you would also get a better take off plane quicker and there will be less porposeing. All figures were done assumeing zero slippage with both props and that the gear ratio is the two to one gear ratio that the drive is supposed to be. The reason your not getting higher rpm's is that you are pitched to high on your prop the 2.3 cobra is only 128 horse power which is not enough for the pitch you are currently running. Also check your engine compression and vacuum to see what shape your motor is in. any slight engine problems will hurt this engines performance greatly. I hoped this helped you out some.
 
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wmlaks said:
I also have a 17 foot bayliner with the 2.3 liter engine and I have found that a 13.75 X 15 prop works really well. The max wot rpm for that engine is 5600. on a calm lake with no extra gear or people on board take the boat to full throttle and see what rpm's you are turning. If you do the math a 19 pitch turning 4000 rpm's will move your boat 3167 feet and a 15 degree turning at 5600 rpm's will move your boat 3,500 feet your boat will be going faster with the lower pitch you would also get a better take off plane quicker and there will be less porposeing. All figures were done assumeing zero slippage with both props and that the gear ratio is the two to one gear ratio that the drive is supposed to be. The reason your not getting higher rpm's is that you are pitched to high on your prop the 2.3 cobra is only 128 horse power which is not enough for the pitch you are currently running. Also check your engine compression and vacuum to see what shape your motor is in. any slight engine problems will hurt this engines performance greatly. I hoped this helped you out some.
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hi wmlaks, this is exactly what i was looking for! thanks! i got the 13 1/2 15 prop put on the boat this past weekend but i havnt had it out yet. i will let you know the results. thanks again.
 
well i ended up doing two upgrades to the boat so im not sure of the results of each. i put the 13.5 15 prop on and i also put the nauticas smart tabs on and took the hydrofoils off. the boat definately comes out of the hole and gets on plane much quicker while towing a tuber. i did lose some top end while pulling a tuber and passengers, 35mph to 30mph and my wot rpm is still low at 4800 compared to everyones 5200 to 5600 wot rpm.
 
cds11 said:
well i ended up doing two upgrades to the boat so im not sure of the results of each. i put the 13.5 15 prop on and i also put the nauticas smart tabs on and took the hydrofoils off. the boat definately comes out of the hole and gets on plane much quicker while towing a tuber. i did lose some top end while pulling a tuber and passengers, 35mph to 30mph and my wot rpm is still low at 4800 compared to everyones 5200 to 5600 wot rpm.
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Im glad you chose the Smart Tabs, and got rid of that transom-straining hydrofoil !!! I knew it would climb up faster with the Tabs on it.
One question... Did installing the Tabs slow you down at idle while in gear?

Reason: I wanted to know that for Trolling purposes while fishing.
 
corsair23 said:
Im glad you chose the Smart Tabs, and got rid of that transom-straining hydrofoil !!! I knew it would climb up faster with the Tabs on it.
One question... Did installing the Tabs slow you down at idle while in gear?

Reason: I wanted to know that for Trolling purposes while fishing.
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i really didnt pay attention to the idle speed. it seemed about the same when i was coming into the marina i guess.
 
did you see what your wot rpms were with a light load and not pulling anything my 13.75 X 15 will get into the 5200 - 5600 range only when I am on the lake by myself
 
4800 is still about 600 rpm's to low for that engine. have you done any performance tests on the engine (compression test, vacuum test checked to make sure that the weights are fully fuctional in the dist. and have you checked your timing belt) My self and most people I know with this engine have had problems with the belt stretching which robs power from the engine
 
wmlaks said:
4800 is still about 600 rpm's to low for that engine. have you done any performance tests on the engine (compression test, vacuum test checked to make sure that the weights are fully fuctional in the dist. and have you checked your timing belt) My self and most people I know with this engine have had problems with the belt stretching which robs power from the engine
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i havnt had a chance to check any of the vitals yet. i cant even find time to get it out on the water. i have had the boat a couple of monthes now and only been out in it three times.
 
if you do not know when the timing belt was changed last go ahead and change it. the belt is about $20 and I recommend changing it every year if you run your boat reagularly
 
i plan on doing the timing belt and a few other things to it this winter. it has an issue of getting hot while sitting still but as soon as i take off the temp comes right down. im trying to find a 13 pitch prop to see if it will help the rpm. how late in the year do you guys usually keep boating? we just went sunday and the kids froze after getting out of the water. i was fine on the boat tho, i dont tube, just drive.
 
I go up into october but I am in a southern state where the lake stays warmer longer. As for the temp when sitting still idleing have you checked or replaced the impeller in the outdrive. I think OMC recommened changing them every 3rd year they are easy to change and not very expensive. Only tools needed to change them is a 10mm wrench or socket.
 
i already changed the impeller on the outdrive, when i first got the boat this summer the outdrive had a bad pinion bearing so i tore it all apart and replaced all the bearings and seals in it and the impeller had one flap missing so i replaced it. i didnt replace the impeller housing though.
 
I always change the housing also they are not very expensive and I had one that the steel sleeve spun in the plastic
 
wmlaks said:
I always change the housing also they are not very expensive and I had one that the steel sleeve spun in the plastic
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thats exactly what i should have done! getting ready to go boating this afternoon so i went ahead and pulled the impeller housing off and the housing has a little hole back in one of the craters by the bottom bolt. im pretty sure thats whats causing the over heating at idle. i went ahead and used some jb quick weld on it so i can use the boat today. i will let you know if that fixes it. regauardless a new one is being ordered.
 
well we took the boat out yesterday and i thought the problem was fixed but it wasnt. seemed fine at first but it eventually got warm sitting still. that wasnt a big deal tho, was cruising along 25 to 30 mph and hit an unseen rock. destroyed the prop and it was only a few weeks old. now that i have to get another prop, would you recommend a 13 pitch?
 
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