prop help

[bigmanr6]

I have a 95 scarab 454 330 hp with a bravo 1 1.50 gear running a 23p stilleto steal prop I get about 54 gps at 4000rpm with three people and a half tank of gas I think my prop slip is 7% but I could have figured it wrong. I was wondering if anyone had any suggestions about changing props I would like to get more top end. thanks

[bbladesprops]

Your right on with the slip #. Getting more rpms with a 23 pitch in 3 blades is the best method. Unfourtunately the Stilleto props don't repond well to Labbing. I would test with a 23 Mirage Plus and then use that baseline to create the best Lab recipe for you hull.

Let us know if you would like to test a propeller.

Brett

[bigmanr6]

Hmm...so stepping up to like a 25p or 26p wouldn't be the way to go?

[BDM]

Wouldn't stepping up to a steeper prop drop the engine RPM because of the prop grabbing more water, hence needing more power to turn the prop?

Maybe I'm way off base here... but that's what I would think... is that right or wrong? I'm still learning too!!.... :oops:

[bigmanr6]

I don't know I think I got it about props then im completly wrong:shock:

I cant get the motor to turn more than about 4200rpm but I dont know what it should redline at either

[BDM]

I would guess from other posts that you would want it around 5100 or so RPM, but i'm not sure about that and it's pure speculation on my part.

I do know that there SHOULD be a label on the top of the engine with the "recommended" redline posted on it. If it's an older boat, maybe on top of the air cleaner... but on the Cobalt that my father in law has, it's on the plastic on the top of the engine...

[bigmanr6]

it should but its not the stock engine so im on the hunt for a tag on it somewere I figured at least 4500 or so

[Griff]

You want to spin a 454/330 to about 4800 for max power. You may actually want to try a 21 Mirage plus to get the rpms up. Right now you are lugging the engine and it is harder on the engine than spinning it faster.

[bigmanr6]

thats what I was thinking just didn't want to turn it to tight without knowing for sure

[Revd Up]

I used to have a 22 scarab with a 454 MPI Ran a labbed 25 Mirage Plus at 4600 rpm. Ran 68-70 GPS. Then put a 502 MPI in . Ran the same prop now at 5250. 73-74 GPS. Fun Boat.

[bigmanr6]

yep I enjoy the boat![smilie=trink39]

[bbladesprops]

21 pitch will get the R's up. My suggestion was to Lab a 23 M+ to get the R's and the best top speed. However, a test first would make the most sense. Labbing a 21 into a 22 may also be a good alternative.

Brett