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Discussion Starter · #1 ·
After installing exhaust manifolds and a K&N arrestor, I am running up on the rev limiter. I have a 7.4 MPI at it is hitting at 4600-4700 rpm. This is with a Mirage Plus 23P. This non-Mag motor is supposed to operate in the 4200-4600 rpm range.
Do I need to go up to a 25P? Or should I have my prop blueprinted with more pitch? Or what...????
I am not hitting the limiter real hard, just kinda creaping up on it.....I want more speed though!
 

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Get a 25 then if the revs are too low have it labbed. Should be good for a couple of MPH over where you are now.
 

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If your just touching the rev limiter I dont think you will be able to pull a 25,, I had the same problem tried a 25 and couldnt pull it. First off though, how is the boat loaded for that test compared to a normal day out? Do you still hit the limiter with a full load of fuel and people on board? If not then I would have your 23 cupped and blueprinted it should put you right where you want to be.
 

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Discussion Starter · #5 ·
I`ve ran it a couple more times. I can get it to just barely touch the rev limiter, this with me, 190 lbs, the wife, 120 lbs, our son, 70 lbs and 3/4 tank of fuel (about 40 gallons). I have spoke more with the prop guy and he was in sync with your thoughts, can`t pull a 25, re-cup my 23. Should gain +2 mph and be running right at 4600 rpm.
Thanks for your input!
 

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I have the same motors, I now have 22's labbed and blueprinted, they are just a little too much on the rpms. Thinking of taking them back, and going to a labbed 23. I had 25's on the boat and could only run about 4100-4200 rpm at WOT. I would say the labbed 23's would be perfect.:D
 

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I am with the Labbed 23's also, I have them on mine and they work well.....good luck and let us know how it goes:D
 

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so,,, you think a labbed 23 huh?
 

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you and everyone else ,,,, !!!! :D :D :D :D ( just teasing !! )
 

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If you lab it you'll gain 200rpms. Extra cupping will subtract most of that, but you will still be close if not hitting the limiter. See if you can borrow/test a 25 Mirage Plus first and see where you're at with it.

Also, your rev limiter should be @ 4700-4750rpms. Get a prop that will run just under it with a light load of people and fuel.
 

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Discussion Starter · #16 ·
I started this post way back in April, 2002.
Last Spring I sent my 23" to be reworked. They cupped the blades and put a satin finish on it. That helped. I am now running right at 4550 to 4600 rpm, wide open. The prop guy said I could send it back anytime for more work. I am thinking of having him lab it for an extra 100-150 rpm. That should put me at or near the limiter and give me maybe 1-2 mph.
 
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