[DonMan]

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]

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]

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]

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]

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]

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]

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]

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

 

[obnoxus]

so,,, you think a labbed 23 huh?

 

[OldMagicfloat]

uh,yea. I think thats what i said

 

[obnoxus]

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

 

[OldMagicfloat]

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








I never would have guessed:

 

[mondod]

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

 

[OldMagicfloat]

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]

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

 

[DonMan]

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.