jsteacy

Hi guys, I have been playing with a couple of props last season, best one so far is a mirage+ 25" that i had labbed by merc racing. With that setup I got 66mph on gps and turned 4850rpm

My other prop is a Mirage 25" not lab finished, getting 65mph with it turning 5000rpm, I get better holeshot with the mirage and it seems to hook up better. I should add that Merc racing added a bit of cupping to this prop while it was getting repaired for a couple of nicks.

This season I have added EMI mainfolds and risers, from what i have read i should get 10-15hp increase and with the added weight removed hoping to gain 1mph or so.

Question I have is there any recommendations on what i can do to maybe gain another couple of mph playing with any different props? or do you think i'm maxed out?

thanks

bbladesprops

jsteacy,

Ok, things seem to be a little out of place. The original Mercury Racing Lab Finished 25 M+ is only at 4850 rpm (13.77% slip).

The "non" Lab Finished 25M+ with additional cup is running 5000 rpm and (17.63% slip). These rpm levels do not make sense.

So, the propellers are undefined in my opinion and you can not make decisions per this information. We would need to see these propellers together, or separate to determine what they actualy are. Have the props been touched by ANYBODY since Merc Racing?

Ultimately, your top speed is most likely the best it will be with the power you have. However, getting the propellers correct can reap some definite rewards.

Brett

dbkski

iTrader: (1)

Brett I believe you misread part of the post.

jsteacy has two 25P props. One Mirage Plus and one Mirage.
The Mirage Plus is labbed and the Mirage got "tuned up" for
nicks and had some cupping added at the time of repair. I
have done the exact same thing and have similar results
except my speeds are higher since my boat is lighter. If your
speeds are GPS and your RPM's are accurate (I have a digital
tach) then you are doing pretty darn good. Remember your
engine is not putting out the HP it did in 1997 and your Baja,
I'm sure, has gained a bit of weight from it's 4100 lb. "dry"
specification. Yes the EMI's should help but I can not quantify
how much. As they say, "Every little bit helps". I will review
some of the things I have done and see if they can help you.
I will post again later.

bbladesprops

I meant to say Mirage on the second prop.

There are technicalities of Labbing a Mirage Plus in standard template at Merc Racing that are known by us as well as the differences you have in a Mirage with cup added. There are differences in the casting thicknesses and their respective cup heights and locations as well. Theoretically these props should run quite similar. However, they are off by 150 rpm and 4% slip. This is not a huge difference but I am surprised at the 4% slip difference.
If I was to offer a opinion, I'd concider tweaking the M+ to gain a touch of rpm while trying to avoid additional slip. This could be worth another mph or 23

Brett

dbkski

iTrader: (1)

I found my notes.

From my testing sessions:

Mirage Plus 25P - 70.70 MPH at 4925 RPM's labbed from TU.
Mirage 25P - 70.40 MPH at 5030 RPM's - local shop's recipe
that was a "tune-up" with added cupping.

The local prop Dude told me I could expect higher revs, a bit
more slip, but the same speed. He lied.

I have made a few changes since this time and am a bit faster
today. I'll continue to re-read my notes to find those changes.

jsteacy

Brett,

I have since spun the hub in my mirage prop, and have aquired another Mirage Plus 25P that as far as i know has not been touched.

I have two questions, what does it cost to have the mirage re-hubbed? and what would it cost for you to "tune" the mirage plus for my boat.

I was running 4600-4700 rpm at 65mph with the untouched mirage plus.

Since adding the EMI exhaust I am running 67.3 on GPS turning 4800-4900RPM Is this acceptable?

Thanks,

bbladesprops

jsteacy,

You can turn your engine to 5100 rpm.
Lab Finishing the propeller is a $392 option that will bring you to the 5100 rpm mark and increase your speed by approx.. 2-3.5 mph.
The rehubbing process is just under $100 with the hub cost and the $49 labor charge.

If you decide to send the prop, I'll contact you when we receive and inspect it.

Brett

jsteacy

Brett,

Thanks for the info, I will send you both props, one to be rehubbed and one to be lab finished.

Is there any other info you need for me to include with the props other than the obvious.

Thanks again

bbladesprops

jsteacy,

If you would copy and print this OSO correspondence and include it in the box, that would be great.
We will contact you with any other questions prior to beginning the work.

Thank you,
Brett

jsteacy

Brett, I will be sending the Mirage prop needing to be re-hubbed and also the mirage + that has not been touched, I will include this correspondence in the box. Hoping to get them packed up and shipped by the end of this week.

Thanks,
Jason