prop pitch
 

I run Mirage 23's and get 64 mph at 4600 rpm. twin 7.4 mpi Merc I/O's Also lab finished Bravo 1 4 blades, 62 mph at 4600 rpm.
QUESTION: If I were to have the 4 blade pitch changed to 25 would I pick any speed or just have an rpm decrease?
Any feedback is welcome, Thank You.

bvs629,

Your recommended WOT range is 4200-4600. You are running on the top of that range and it is hard to say if you have a "Sweet spot" in there and where it is. I would look at your current props and try to determine if there is any adjustments that can be performed to possibly increase your speed. Re-Pitching to a 25 will decrease your RPM. Feel free to call me if I can be of assistance.

Thank you,
Julie

Re: prop pitch
 

pitch the 23 up to a 24 pitch add cupping and lab the prop this will run the fastest/also the labbed 4 bld possibly can be thinned out more and add 1" of pitch to achieve a tad more speed but always the mirage will be the fastest as you know/Darin/Houston Propeller SERVICE;)

Thanks for the information. I think I will try to pitch the 4's to 25.
There is a service here local that can do it for a good price.
Pitching the Mirage's up to 24 an labbing them is a little more expensive but a good option, besides they have the Baja logo on them when I bought the boat.
Thanks again!!

As long as the rev limiter does not become an issue, I would repitch the 23 mirages to a 22 pitch taking the rpm to 4800. In my opinion, 4800 is a good max wot rpm for your engines. Let'em sing :)

Good luck,

BT :cool:

BVS629 Glad to be able to give my 2 cents /will be glad to work with you if needed/Darin

Thanks to all My rev limiters are are 4700. Thanks again.
Darin If I do anything I'll let you know how it turns out
BVS

Then I would change my ignition to one with a 5050rpm rev limiter and still repitch to 22.

BT :cool:

What would be the effect if I were to d this and run my present
labbed 4 blades, 24' pitch.
I know pitching to 22 would let my rpms come up. but how would that increase the speed with less pitch. Curious reverse logic.

Thanks awaiting your reponse,

BVS:puppy:

Changing the ignition to one with a higher rev limiter will not affect your achievable rpm. Changing the ignition and keeping the same prop won't change anything. You need to repitch the mirage. Mirages seem to give the best top end (depending on boat) . Bravo1s give the best cruising range, but generally you will loose a little on the top. Your engine should like 4800 as well.

Just my opinion... I am sure the businesses that posted before me could give you better advise :) Good luck,

BT :cool:

thinning the blades will increase rpm and pitching up will increase forward travel and a little extra cupping to pull the rpm down right where it needs to be/ equals greater speeds.Darin

If thats a 29 outlaw I would leave it like it is, that is the best setup for 7.4's

# 12
You are right about the winter, the rain has been just as bad.

BVS

I WOULD TRY SWAPPING THE DRIVES AND SPIN THE PROPS IN INSTEAD OF OUT. IT WILL GIVE YOU MORE BOW LIFT AND LESS WETTED SURFACE= MORE SPEED.IT WORKED WONDERS ON MY PANTERA.

Z ZUPERBOAT
 

how did your boat handle after switching to turning in. i have a fountain w/o step hull ran with it turning in handle great ran good. everyone said they were faster on a fountain turning out well B.S. it slowed down 4mph. im fixing to switch the cables and leave in turning in .

swapping drives
 

thats a great idea/;)

HoustonProp,
Would you be willing to quote me a price for 2- Mirage plus 23's,
twisted to 24, with cupping and labbed by you?

BVS629

I think you should give Rev 23's a try, they will pull 300 RPM less than a 23 Mirage plus, and is faster on many boats, and on a 29' they will be faster than a Bravo 1. Labbed Rev's would probably be the best of all.

rev four too much blade area
 

I just finished two rev fours again 23 pitch,I have been shaping the blades like a bravo one which, I have found that the rev four is running400 to 500 rpms lower than a 23 mirage also thinning them out and doing a nice balance job on the prop seems to be the ticket ./Darin/Houston Propeller:eek:

Re: rev four too much blade area
 

Again Darin,

Your recommendation for the labbed 23's sound to be the best way to go. I think the higher the RPM the better for the motor.
Would not it be best to stay closer to the top end of my range, even if the range is increased.
And a price. Revolution 3 blades or Mirage Plus 3 blades.
I think I would prefer Mirage Plus 23's twisted to 24, and have the lab finish and extra cup as you discussed early.

V/r,
BVS

BVS You have mail/Darin

Does adding more cup to the blades make for more bow lift/less wetted surface as well?

I have a twin screw application with Bravo One drives on extension boxes with Bravo One 4-bladed props.

Kaama,Yes adding cup will create more bow lift./Darin

I will check when I get home.
Thanks!