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TRU-JACK
08-13-2002, 11:16 AM
I have a 16, with the 4.3 4bbl. and a mirage 23p. and 1.84 drive ratio. I'm able to turn 5100rpm on stock engine with the 23p, and only get about 50mph out of it. I'm looking to move up to a 25p prop, but am having trouble deciding what type to get. I have a ski boat so hole shot isn't too important, and i would love to get 5mph extra and drop my rpm into a safer range. Any or all suggestions would be very helpful. thanks wink

RedDog
08-13-2002, 11:32 AM
Your speed may be better than 50. Usuing a prop calculator I get:

5100 23 1.84 9% slip 54.9
5100 24 1.84 9 57.3

I tried a 24 pitch assuming a 23P Mirage is cupped. Add 1 inch to pitch for cupped prop.

Have you checked with GPS or radar?

Greg K
08-13-2002, 11:40 AM
Theoretically, you should be seeing more speed...60 with no slip...with 10% slip it gets closer 54. At 50 it's with 17% slip.

A new 21 prop should arrive any day here for mine and looking to see about 1.5 - 2 mph increase on top which has a 1.47 ratio with 5.0 engine. I'm looking closer to getting to 58-59.

Got to get that GPS to tell the truth!!

TRU-JACK
08-13-2002, 03:18 PM
Thanks guys, does anyone have the same setup as me and run a 25p prop?

smokediver
08-13-2002, 05:58 PM
I think your tac or speedometer is off. you need to make sure that your tac is correct and take out a gps with you. if you are turning that 23 at 5100 you should be around 53-54. try a 25 laser2 or qss2000. smaller diameter , but that will keep your rpms in the same ballpark but your speed will improve.your slip % will go up with the smaller diameter prop , but if there was no slip there would be no speed. ypu could also try a 24 turbo thats 14.25 in diameter. that might work , or , a labbed 25 mirage plus. happy hunting !!!