Mirage Plus Hole Shot
 

Can anyone help me here please.

I am running a handed pair of Mirage Plus 25" pitch props on Bravo 1 drive with an "X" -2" at 31" centres.

The engines are new 383ci based on new Dart blocks and heads.

All forged internals, stainless steel marine exhausts, Comp Hydraulic roller cams with a compression of 9.1 :1 plus 750 cfm Holley marine carbs.

Cam peak is 5500 rpm

Here is the issue.

With Spinelli over hub 3 blade 14 x 26" cleavers at 5800 RPM = 71.5 mph and easy out of the hole.

With Mirage plus 25" pitch 5100 RPM 75 MPH but beyond painful to come out of the hole.

Can Mirage Plus props be made to perform out of the hole with a high "X" diamention please and if so how ?

Many thanks

Kalaazar

I would try some 23 Mirage Plus props. They should spin about 400rpms faster to your 5500rpms and come out of the hole better.
Top speed should stay about the same with the 2" pitch decrease and 400 rpm increase.

Appreciated, thanks.

Try what Griff said and also call BBlades for their input.

http://bblades.com/

What's your prop shaft height ?

My Bravo drives are 2.5" up on the X dim.

Many thanks for your input, appreciated.

I'm not up on X dim. but I have done a lot of trial and error the past few months. with prop shaft parallel to bottom of boat, how many inches bellow or above is the prop shaft from bottom of boat. I have learned on 3 blade props they shouldn't pierce the water surface. Are you twin engines with V hull

Hi, I will measure the shaft height from the bottom of the hull this weekend. This is a twin Bravo 1 installation in a Magnum27 Sport.

To date the very best overall propeller performance is with a pair of Spinneli 3 Blade outboard cleavers.

These are very easy to plane out, fair top speed, but have a high slip percentage and a few to many revs. Size 14" x 26" 1.5 : 1. 5850RPM = 71/72 MPH every day.

My propeller shafts are 5" to the centre below the bottom of the hull on the drive fore and aft centre line.

When trying to get on plane are the Mirage + props slipping or lugging. I am guessing lugging. If they are lugging send the props to BBlades and have them labbed and ventilation holes added. It should get you out of the hole much better, better top speed and raise the RPM to where it needs to be at 5500 RPM.

Thanks for your input. With the Mirage Plus propellers trying to come onto the plane the props "let Go" and blow out, no grip.
One encouraged on to the plane by both weight shift and very slow throttle etc. the propellers bite and the acceleration is fantastic all the way up to top speed.
I have sent an email to BBades and are now awaiting their return to work after the holiday weekend.

I would call BBlades and try out a BRAVO 4 blade labbed 24 pitch. should come out of the hole great and get you the top speed like the spineli. That Spineli has a lot of blade surface area.

Many thanks, I am keen to see what BBades come up with.

I tried the Bravo 1 Props. and found that the RPM was exactly correct at 5600 rpm but we lost 3mph. compared to the Spinelli`s turning at 5850 rpm but at 25 % + slip.

Kalaazar

I think you will need to go deeper on prop shaft. mine, 2001 29Scarab, twin MPI 383cid 400hp bravo1's, 25p mirage, 7 3/8 deep, 8-9% slip 72-74mph. I tried -3imco and -2imco which made it 4 3/8 and 5 3/8 deep with many props. ran out of time and available props to try. In short of long story, Nothing but a 5 blade would get it on plain at 4 3/8 deep with very much patience. At 5 3/8 deep a Bravo would get on plain but running with 23-26% slip, 3 blade mirage plus was a struggle to keep from blowing out and the % was extremely high. I learned a lot of little things during all this.

Try a set of rev4's. They have the bow lifting characteristics of the mirage plus props on the top end but act like 4wheel drive when fully submerged during take off.

Thank you everyone for your input, appreciated.
Kalaazar

let us know your results Kalaazar

Thank you and yes I will.

Again many thanks all-round.

Kalaazar

Kalaazar,

Hello, I just saw and read this thread. I'm not sure if we have spoken as to this date.
I looked back in my emails for a note from you and did not find one. However, I'm not sure Kalaazar is the route to find your email. You may have received a email from Brad.
I do have some suggestions and options to help you get to your desired goal. If it is a option for you, please call the office tomorrow and we can discuss the current performance and the options you have.
Sorry for the delay in responding.

Brett