Help with prop
08-06-2016, 09:30 AM
#1
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Help with prop
Hello guys,
I need some help on prop size, I have a 1991 Baja 226 Islander it came with a 330 horse 454 and a bravo 1 1:51 drive , I replaced the motor in June of 15 with a Carolina Machine Engine 496 430 horsepower, I'm still running the Q-Jet carb that was on the 330/454 and running the stock thunderbolt ignition as well , the prop on the boat is a stainless steel 3 blade 21 pitch, the old engine ran 60 mph on the speedo at I think 4800 rpm the new motor with the same prop which I know is( under propped for the boat) the motor WOT is 6800 RPM and have no idea how fast we are going the speedo lays over on 60 around 48/5k , I know the bravo probably doesn't like it( and neither does the wife) and I don't bring it there often , we ski,tube, cruise, we haul a lot of weight(3kids with friends) while doing so, I need a good all around prop 3,4,5 blade I doesn't matter to me as long as it performs , I have a 3 blade 29 pitch stainless Mirage but haven't tried it yet. Thanks for taking the time to read sorry it so long about a subject that is probably exhausting . Any help would be great !
I need some help on prop size, I have a 1991 Baja 226 Islander it came with a 330 horse 454 and a bravo 1 1:51 drive , I replaced the motor in June of 15 with a Carolina Machine Engine 496 430 horsepower, I'm still running the Q-Jet carb that was on the 330/454 and running the stock thunderbolt ignition as well , the prop on the boat is a stainless steel 3 blade 21 pitch, the old engine ran 60 mph on the speedo at I think 4800 rpm the new motor with the same prop which I know is( under propped for the boat) the motor WOT is 6800 RPM and have no idea how fast we are going the speedo lays over on 60 around 48/5k , I know the bravo probably doesn't like it( and neither does the wife) and I don't bring it there often , we ski,tube, cruise, we haul a lot of weight(3kids with friends) while doing so, I need a good all around prop 3,4,5 blade I doesn't matter to me as long as it performs , I have a 3 blade 29 pitch stainless Mirage but haven't tried it yet. Thanks for taking the time to read sorry it so long about a subject that is probably exhausting . Any help would be great !
08-06-2016, 12:49 PM
#2
Where does your new motor make peak HP? That is where you should prop the motor.
I believe your 29" prop would be too much. For starters a Mirage Plus 23" or a 4 blade Bravo 1 24" would be good starting points. A Rev 4 prop in 24" pitch would also be another good starting point. I doubt you'd have to change much from any of those props.
The Mirage would likely be your all out fastest prop, with the 4 blades being better out of the hole and more efficient in mid range.
I believe your 29" prop would be too much. For starters a Mirage Plus 23" or a 4 blade Bravo 1 24" would be good starting points. A Rev 4 prop in 24" pitch would also be another good starting point. I doubt you'd have to change much from any of those props.
The Mirage would likely be your all out fastest prop, with the 4 blades being better out of the hole and more efficient in mid range.
08-06-2016, 12:55 PM
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I hope 6800rpm was a typo, I'd worry about your motor way before the drive at those rpms.
08-06-2016, 05:32 PM
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08-06-2016, 05:46 PM
#6
I wonder what prop the boat came from the factory with? Possibly somebody previously propped down to compensate for tired motor. If so it would be much more than + 100 HP maybe +150 or more. How many hrs on original motor and how hard it was used?
08-07-2016, 04:00 AM
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GlENAMY,
I'm at a loss is why i'm here. there was no hour meter on the boat when I got it so I can't even guess, I have a couple big blocks in vehicles and don't like to turn them over 5500, when I got the boat it ran good for what we do, I had to put a new carb on it fresh plugs/wires,oil change and fuel and we where skiing, I had the intake changed from steel to a marine aluminum by some trusted friends due to me being out of the country for long periods of time, the pictures they sent me of the lifter valley and camshaft where unbelievable ,the cam had large rusted pit marks on the lobe surfaces, but I thought it ran well for a stock big block in a boat (never had one before), so I had them clean it and put the intake on ,I came home ran it it ran well and continued to run it when I could for about 6 months that's when the motor decided it no longer liked the #7 rod and thru it out the oil pan , I replaced the motor and all hoses and cooler lines, exhaust(spent my whole vaca doing it) I have no leaks or issues except when just one or 2 people in the boat it spins that high if I wanted to and like I said don't go there often but would be blowing smoke if i told you I hadn't been there, I tried a 17,19,the 21 all 3 blades, a 24 5 blade and there is no happy medium is why I'm here, I have spent a lot of money on my guessing what it might need for a prop they are on my dinning room floor and have been told that if I come home with another ( I think this is the one ) prop I'm sure she'll hit me in the head with one!!
I'm at a loss is why i'm here. there was no hour meter on the boat when I got it so I can't even guess, I have a couple big blocks in vehicles and don't like to turn them over 5500, when I got the boat it ran good for what we do, I had to put a new carb on it fresh plugs/wires,oil change and fuel and we where skiing, I had the intake changed from steel to a marine aluminum by some trusted friends due to me being out of the country for long periods of time, the pictures they sent me of the lifter valley and camshaft where unbelievable ,the cam had large rusted pit marks on the lobe surfaces, but I thought it ran well for a stock big block in a boat (never had one before), so I had them clean it and put the intake on ,I came home ran it it ran well and continued to run it when I could for about 6 months that's when the motor decided it no longer liked the #7 rod and thru it out the oil pan , I replaced the motor and all hoses and cooler lines, exhaust(spent my whole vaca doing it) I have no leaks or issues except when just one or 2 people in the boat it spins that high if I wanted to and like I said don't go there often but would be blowing smoke if i told you I hadn't been there, I tried a 17,19,the 21 all 3 blades, a 24 5 blade and there is no happy medium is why I'm here, I have spent a lot of money on my guessing what it might need for a prop they are on my dinning room floor and have been told that if I come home with another ( I think this is the one ) prop I'm sure she'll hit me in the head with one!!
08-07-2016, 07:02 AM
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ok, at 20 inches pitch, a 2 inch increase is good for 10% reduction in WOT RPM. why you put a 17 inch renken-searay-bayliner prop on there is a mystery to me. that 22 baja is a small boat. that 496 is not a terribly small motor. and I believe your first post is a testimony in favor of Q-jets. and don't waste any time-money thinking about upgrading the thunderbolt ignition. but I digress. first, get a GPS app for your phone. then, see what the boat is doing at 4500, 5k, 5500 with the 21. then put the 29 on since it is already paid for and see if you can even get up on plane and how well. then see what you get for WOT RPM with the 29. next, where are you? there are lots of guys on here with lots of props. there are also lots of props available on the swap shop here and craigslist and ebay. the 23 will drop you from 6800 to around 6k even. a 25 will drop rpms about 500 more to around 5500 or so. I think you will barely hit 4k with the 29 and it won't be a user friendly boat.
08-07-2016, 07:15 AM
#10
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ok, at 20 inches pitch, a 2 inch increase is good for 10% reduction in WOT RPM. why you put a 17 inch renken-searay-bayliner prop on there is a mystery to me. that 22 baja is a small boat. that 496 is not a terribly small motor. and I believe your first post is a testimony in favor of Q-jets. and don't waste any time-money thinking about upgrading the thunderbolt ignition. but I digress. first, get a GPS app for your phone. then, see what the boat is doing at 4500, 5k, 5500 with the 21. then put the 29 on since it is already paid for and see if you can even get up on plane and how well. then see what you get for WOT RPM with the 29. next, where are you? there are lots of guys on here with lots of props. there are also lots of props available on the swap shop here and craigslist and ebay. the 23 will drop you from 6800 to around 6k even. a 25 will drop rpms about 500 more to around 5500 or so. I think you will barely hit 4k with the 29 and it won't be a user friendly boat.
