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Not getting the speed I should!
Have a Baja 252 islander that I had a custom motor built. It had a 6.2 in it before this one. Brovo 1 drive with 1.50 gears.
Conditions where about 97 degrees and light chop. Today I ran a 23P M/P 3 blade on it and was spinning the prop at 5400 RPM's and was only getting 63 MPH!!!!!!!! Prop has never been reworked Ran a Mach sterndriver prop 4 blade and at 5100 RPM's and was running 66MPH. This prop has never been reworked. Ran a 25P Mirage 3 blade at 5100 RPMs and was running 65 MPH. This prop had something done to it but don't know what. Why am I not seeing more speed? I do have a drive shower on it. Could that cause any problems. Is the X dimention different for Baja's when they install the 6.2 in the boat? Mesured from the bottom of the V to the bottom of the outdrive and was 5 1/2 in. Should I have the hook taken out of the hull? There is a slight hook 16th to 1/4 in on both sides. What would be a better prop to try. The slip I'm getting is way to much for the 3 blades. I think I need a prop that can get the hull farther out of the water. Bravo 1? |
Re: Not getting the speed I should!
Try a Rev 4 23" pitch, worked wonders on my 24 Outlaw, will lift the the hull up & out more than the 3 blades. Call Throttle up & ask Julie whats she thinks. The have prop trest program. Have fun
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Re: Not getting the speed I should!
Not getting the speed you think you should?
You must be new here, we all have that problem. |
Re: Not getting the speed I should!
No not new just added new power to a boat that had a 6.2 in it. Wondering if they change the x dimention between there big blocks and small blocks. If the x dimention is diff can I compinsate some by using a different prop. The Mach prop was the fastest. But is there a better prop out there than this. I don't think the 3 blade is going to work for me.
Russ |
Re: Not getting the speed I should!
Are you still running the same size motor? Your question is vague,and last----HAVE YOU EVER HEARD OF SUPERCHARGING?
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Re: Not getting the speed I should!
No I'm not running the same power. Added in a big block 502 that has been modified. Dont think a 6.2 could spin a 23P M/P at 5400 RPM's.
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Re: Not getting the speed I should!
Seriously Russ,I know supercharging isn't the answer to everything but give us a little more info on your new motor. Iv'e had the best luck with 4 blade props on my 272 baja. Where is the power band supposed to be on your new motor?Iv'e noticed on my 272 it goe's the fastest trimmed to max (but i'm sure you've realized this already)Smitty
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Re: Not getting the speed I should!
Peak HP is at 5100 RPM's. It is a carbed motor and the builder said shouldn't have a proplem running up to 5400 RPM's. The motor is putting out around 470 HP. The boat weight is around 4700 loaded. gas gear and people.
What 4 blades have you tried? Do you know if the x dimention is different when they add small block or big block? I'm thinking I need alot more stern lift. Russ |
Re: Not getting the speed I should!
What pitch is your Mach Sterndriver? It seems to be putting you at the right rpm's. You could have it reworked to get you some more speed. I use a Mach Sterndriver on my boat and it worked better for me than the Rev 4. I am able to run 1" more pitch with 100-200 more rpm's. The Rev 4 did give me more lift but the extra diameter took more HP to spin it. I am running the 496 Mag.
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Re: Not getting the speed I should!
Russ,i would try a bravo 4 blade 24 pitch,see what it rpm's.If it can't turn it at least 5000 rpm's then try a hydromotive 3 blade 23 pitch,when my 272 was stock and had 450hp/415pshp it went 62mph fully loaded at 4900 (23 pitch mirage),64 mph at 5050 light load,66 mph w hydromotive 23/3 blade 5200 rpm's. As far as your x-dimension,mine is also 5 1/2 inches (2000 272 boss,originally had 502 mpi). My 502 stock couldn't turn a 4 blade 24 pitch much past 4600 rpm's(weight sounds about identical).How much total timing are you running,are they stock rectangle port heads/stock exhaust?
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Re: Not getting the speed I should!
The Mach prop is a 24P.
The motor with good exhaust would be putting out 490HP. I still have the stock exhaust on it no muffs. The stock heads were reworked to flow better. Russ |
Re: Not getting the speed I should!
Sounds like you are turning the RPM's but no power/torque.
What cam did the engine builder install on the 502. Nonmarine too radical for the application? Are your speeds by speedo or GPS? My .02 worth |
Re: Not getting the speed I should!
How can a motor spin a 24P 4blade prop at 5100 rpms and not be making power/torque? And the speeds are GPS.
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Re: Not getting the speed I should!
Russ how much power did the 6.2 have? How fast was she then?
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Re: Not getting the speed I should!
The 6.2 was 320 hp. would run about 57 mph with a 19p prop at 4900 rpm's. The boat doesn't seem to come out of the water at higher speeds. You just don't seem to feel the boat lift up out of the water. Seems to ride flat. I will gain speed when I trim up but you don't feel the boat lift!
Might look into takeing the hook that's in the hull out. And finding some bravo 1 prop's. Russ |
Re: Not getting the speed I should!
Russ Your 6.2 was 320 at the prop your new engine is 470 at the crank. You have a 100 to 120 hp gain. this is good for a 7-9 mph gain. You seam to be in the ballpark...
Your hull may have some hook in it, causing the "wet" hull feel. |
Re: Not getting the speed I should!
This is the engine build up. But I had it changed to a carbed setup instead of fuel injected. Edlebrock performer air gap intake and Holley 800 cfm carb. The heads where worked on more than what they did in the artical and I still have stock exhaust. Changing that out next year. They made 490 hp with the setup in the artical.
http://www.hotboat.net/members/artic.../BOLT-ON_s.htm |
Re: Not getting the speed I should!
is it possible that the islander model is just not that fast of a hull regardless of hp??
not trying to be sarcastic, just askin |
Re: Not getting the speed I should!
Hey I am with you I am running 393 Stroker in a 205 Four Winns Sundowner and can only get my RPM's up to 4000 Red line is 4800.
I can tell you I went to a MEr Rev4 21Pitch on a King Cobra Drive adn I am turning in 72MPH with mine. Hey can any one tell my if thru-hull exhaust will get me more RPMS I do not want to drop pitch? |
Re: Not getting the speed I should!
Terrible Spelling to night sorry
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Re: Not getting the speed I should!
Double check your tach.20% slipage on a mirage plus seems high for your boat.I have a 257 mirage wich weighs 5000#s loaded up and has a 24 deg deadrise and I hit 69 mph at 5350 rpm with a 23 mirage plus prop.My slipage is 12%.I had a inacurate tach reading that progresivly got worse as rpm increased.At full throttle I was out 300 RPM.I don't think your slipage should be any worse than mine.What is the dead rise of that boat?I noticed with my boat that the slipage is lower with higher horsepower engines.
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Re: Not getting the speed I should!
Originally Posted by Russ
The boat weight is around 4700 loaded. gas gear and people.
??? D. Ocean Pompano Beach, FLA |
Re: Not getting the speed I should!
Just go buy a cat and be done with it :) Seriously though, if you added 120 pshp and added 200 lbs to the transom at the same time, a 9 mph gain is pretty decent.
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Re: Not getting the speed I should!
That weight was with less than a 1/4 tank of gas and 2 people. There could be something wrong with the 23P prop I was trying I'm taking it back today. We checked the RPM's and it is a 100 off from what the tach say's and I'm taking that into consideration when posting RPM's.
With talking to other 252 owners in Texas and other places and reading alot the speed just seems low for that hull. Every one I've talked to that owns a 252 says they don't have the hook in there hull (but maybe they just don't know it?) And I'm wondering if that might be part of the problem. Going to call Throttle up to see if I can demo a prop. Russ |
Re: Not getting the speed I should!
Did you check your tach at idle or full throttle.I would say the props are pretty good because the slippage is about the same on 23 versus the 25.
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Re: Not getting the speed I should!
Talked with Throttle Up and bought a Bravo 1 24P 4 blade. The tach was checked at idle, at 3000 and at 5000. But I might change it out just to check.
For some reason I'm just getting alot of slip with the 3 blades. Might just be the prop's I tried. But really can't try my freinds 23p and 25p props because they don't have solid hubs. And I blew out the brand new hub on the 23 I had. Russ |
Re: Not getting the speed I should!
Russ,if your friends are running merc props just buy 1 solid hub kit,you can knock the hub out in 2 seconds,substitute yours in and try it. I own 5 diff props but only 2 hub kits,it's a waste of money to buy a hub for each one (but all my current props are merc). You start getting into 500 hp and 24 pitch props you'll need solid hubs anyways.
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Re: Not getting the speed I should!
I'm getting a solid hub kit with the prop from Throttle Up. I just hope the bravo 1 24P prop works better than the others I've tried. The boat just doesn't seem to get out of the water very well. I have the boat trimmed to to almost half way on the indicator and just don't feel the lift and don't even see a rooster tail trimmed that high.
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Re: Not getting the speed I should!
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Well I ran the prop today 24p Bravo 1. 97 degrees today very calm.
3000 rpm's was 36MPH 3500 rpm's was 43MPH 4000 rpm's was 50MPH 4800 rpm's was 61MPH 5000 rpm's was 63MPH 5200 rpm's was 66MPH No diff than the Mach prop 24P Pics are at WOT full trim. Does it look like I'm getting enough bow lift? Does anyone have a clue on what I would need |
Re: Not getting the speed I should!
just so you know, bravo 1's are actualy about 1.5 -2 deg pitch less then stamped when comp. to any other prop.
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Re: Not getting the speed I should!
Yes I do know that.
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Re: Not getting the speed I should!
Russ,
I too am experiencing something similar. My 272 used to get really loose when I trimmed all the way up...the bow used to come way up and I used to get alot of air under the boat....much higher speedo speeds too. I did have some issues with the VST tank and I changed the ignition wires and plugs. I also hit something totally destroying my 24 bravo 1. I had it rebuilt and then the boat was 3-4 mph slower.....feels like the boat was "plowing" through the water. I have since purchased a brand new 24 bravo 1 thinking that this was my problem.....boat only 1 mph faster....still cant get the nose out of the water??? I did install a "skeg guard" on the skeg because when I hit ground I took a chunk out of the back side close to the prop. My RPM's are the same but the speed is not...so I too am confused about the Plowing. I was chaulking it up that my engine is getting tired (700hrs) and just doesn't have the torque anymore eventhough I can achieve 4900 rpm with the 24 bravo. I also have a labbed 23 but the engine runs too fast for that prop. I am starting to lean toward the skeg guard???? Or possibly the alignment of the Drive and the engine (from my impact) Other than that everything else is the same unless the engine is just tired?????? Let me know what you figure out. |
Re: Not getting the speed I should!
Speedo's are 9 times out of 10 wrong. Mine is about 7 miles an hour off. Did you have the drive taken off? Maybe they fixed the pilot tube for the speedo and now is more accurate? Did you ever GPS it before the accident?
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Re: Not getting the speed I should!
no, never used GPS....but I know how the boat feels. It used to get very lite and squirrly when I trimmed up....lots of air even on smooth water...now it feels like it is plowing....nose is much lower.
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Re: Not getting the speed I should!
You might try taking off the skeg gaurd to see what happens. Was your original 24p prop labbed? Did you ever have the drive taken off to have it checked after you hit something? Do you have any WOT pics of your boat running before this happend? And maybe some pics after it happend?
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Re: Not getting the speed I should!
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Russ those #'s seem about right and not too bad. Looks like you could carry the bow a little higher, How are you trimmed? This pic is at only about 45mph running a 24"bravo1.That prop likes alot of trim and carries the bow very high if you want it to, at least on my particular boat.
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Re: Not getting the speed I should!
Almost to half way on the trim indicator. Going up any more doesn't help. The slip on the Bravo 1 24p is 16%. I've did other calculations on other baja's 232,252,272's. Most are running 3 blades some 4 blades with less slip than that. But I don't know which ones where labbed or not.
One example is 252 Baja with 23P M/P 5050rpms 415HP = 68 GPS thats 7% slip. Don't know if his prop was labbed or not or if he was telling the truth! I ran a 23P M/P 5400 RPM's to 63 MPH and I'm making more power than a stock 502! But it could of been the prop I tried I don't know. |
Re: Not getting the speed I should!
Only reason I asked is my 3 blade would slip if overtrimmed, but the bravo1 on my boat will take so much trim its scary before slipping, and thats where I pick up alot of speed. It will actually make a roostertail with a trs drive when trimmed out.
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Re: Not getting the speed I should!
I don't know about the rest of the Baja's but mine's out of the water alot more than yours. I gain speed and lift all the way past half trim. I assume as long as you don't blow the prop out and you're gaining speed keep trimming.
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Re: Not getting the speed I should!
Kennyo
What engine, RPM's, GPS Speed and prop are you running on your 272? Got any pic's of your boat running at WOT? Do you have any hook on your strakes? Whats your x dimention? |
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