I have a set of 23 mirage, non plus props not labbed. I would like to step up to 25 labbed. Would it be possible to re pitch my 23's to 25 or would I be better of to buy new and sell mine? How much can the pitch be changed on a mirage? Thanks

We can make the props "act" like 25's. They will never be the same as actual 25P Mirages. To actually acomplish this you would need to remove the blades at their roots and reattach them at the correct angle of attack. No matter what people tell you, you are never duplicating the 25P by hammering them to a pitch block.

We can however pull rpm out of them by other methods. To gain the most out of Lab Finishing, it is best to start with the correct pitch in order to reap all the rewards Labbing has to offer.

It's common to change the pitch of props an inch up or down, depending on the application. Especially those props that are only available in every other inch of pitch.

It's possible to change the pitch of a prop greater than an inch but we don't do it. The geometry of the blade is changed and the results are usually not good.

In your case it depends on your current rpm, increasing the pitch an inch may be all you need.

Matt

Unless you have a 24 pitch Mirage Plus pitch block (of which there are none) you can not make a true 24 pitch Mirage Plus. Even then, the root attachment wouldn't be correct. You can however use a standard 24 pitch block that more than likely has a different progression than the Mirage family. This indeed will change the overall pitch everywhere except the blade root and a small amount of the radius. In other words you are changing the geometry from the rest of the family. Rpm can be changed within the desired amount between pitch models with other methods. We prefer to use these, or recommend different pitch sizes.

Either way can get you to the rpm you need.

When changing pitch we use a computer to measure the pitch of the prop. This also allows us to adjust the pitch and pitch progression to suit the needs of the customer.

Most shops use cup and call it a pitch change. This is a common practice by Mercury and many other shops. It's a lot easier to put some cup in the prop than it is to change the pitch. The customer needs to understand that changing the cup and calling it a higher pitch prop is not the same thing as actually bending the blades to change the pitch.

There are advantages in up-pitching and down-pitching. As a matter of fact there are times when we will use a prop with a higher or lower pitch than desired and up-pitch or down-pitch it to accomplish the goals we are looking for. Not only can the pitch be changed but it's also important where on the blade the pitch is changed. Again, this is determined by the application and the needs of the customer.

The bottom line is props can be changed significantly from their original design to suit a particular application. There are times when a customer does not want to spend the money for a new prop and changing the pitch will give the customer the desired results at a reasonable cost.
Matt

We sure don't want to get into a argument over changing pitch.

We also repitch propellers in various ways. We will depitch the leading third to help a customer accelerate. The point is, there are no pitch blocks for Mirage Plus propellers. To match the progression for a 24P isn't a feasibly method when you can change rpm with a "exact" trailing edge adjustment. And anybody who reads propeller blades know that changing the angle of attack anywhere along the cord length of the blade, including the trailing edge, changes the overall pitch! Adding and subtracting cup does change the pitch! Yes this is easier, cheaper, and as effective. Why bend the blades for 200rpm? Unless you are bending the blade to change the overall characteristics and performance of the propeller, keep the original geometry the same.

If the propeller characteristics don't suit the application we will suggest other styles propellers or work within the boundaries we feel the prop can sustain. This "may" mean bending it.

Again, if we only need to bump up or down 200rpm, why bend it?

I believe we are all in this to do the same thing......

To get the most out of you rig!

I appreciate the input from both of you. I was just trying to find a cheap solution for this season. I plan on upgrading the power this winter and don't really want to spend the money for some new wheels that will be too small next season anyway. The boat is turning just under 5300 wot with the 23's which seems hih to me for stock 454 mags. Would it be possible to turn labbed 27's at least for this year so I would be a little closer for next year?
Thanks again

Theoredically a 27 Lab Finished Mirage Plus will run the same RPM as a box stock 25pitch Mirage plus.

The 25 pitch Mirage Plus will bring the RPM down about 300 from where you are now. If you're OK with 4900-5000rpm, you should be fine.

You're hole shot will suffer some and your mid range will improve.

To clarify, when I say hole shot I mean ability to get on plane, not slamming the throttle to jump the boat up.

ive got a set of 25's im thinking of selling. shoot me a pm if interested.

The new prop thing has just put on hold for a little while. I smoked the upper gear set in one of my drives this weekend. I borrowed a set of labbed 25's from a friend to try out and didn't even get them on.