Time for a bigger prop?

DonMan · Apr 6, 2002

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!

laster · Apr 6, 2002

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.

wild willy · Apr 10, 2002

props

don man yes go to a 25 mirage plus!! i happen to have one that is labbed and will sell it to you! i think laster is right on!!!!!!! BILL

obnoxus · Apr 11, 2002

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.

DonMan · Apr 11, 2002

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!

OldMagicfloat · Apr 12, 2002

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.

FA18Driver · Apr 12, 2002

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

OldMagicfloat · Apr 13, 2002

I think a labbed 23p , is right where you wanna be.

obnoxus · Apr 13, 2002

so,,, you think a labbed 23 huh?

OldMagicfloat · Apr 13, 2002

uh,yea. I think thats what i said

obnoxus · Apr 13, 2002

you and everyone else ,,,, !!!!

( just teasing !! )

OldMagicfloat · Apr 14, 2002

obnoxus you and everyone else ,,,, !!!! ( just teasing !! )

I never would have guessed

:

mondod · Jan 29, 2003

uh i would say a labbed and cupped would be the way try cupping first less $$$.

OldMagicfloat · Jan 29, 2003

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.

mondod · Jan 29, 2003

i agree with griff. you need a 25p cupping would only bring the rpm down about 150 revs, try a 25p, 3 blade.

DonMan · Jan 29, 2003

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.

Time for a bigger prop?

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