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-   -   Roller Cam Upgrade (https://www.offshoreonly.com/forums/general-q/201691-roller-cam-upgrade.html)

jeffswav 05-27-2009 10:52 AM

I just dropped my prop off at Mazco. Five years ago I had the prop balanced and blueprinted the pitch changed to 24 and the amount of cup was doubled which brought it back to a 25. He said the prop was damaged enough to drop 200 RPM's off and a few MPH. He thought with the boat at normal weight I should be at about 5200 RPM. I plan on doing a couple more upgrades this winter that should put me at 5400. I will have the prop back in one week and I will post the new results when I get them.

getrdunn 05-27-2009 07:08 PM

Hey Jeff,
Sounds like your getting close. What RPM did RMBuilder dial your cam in for? (Your max running RPM) Also regarding your dings in your prop. Some may disagree however in the past when wanting to gain 150 ot 200 Rs I would take a file to the cutting edge on the prop. Depending on the severity of your dings this may take them out also.
Don't be affraid to put a relatively sharp edge on it. If this didn't work for me I would never mention it however it has. The only down fall is the prop will nic/ding easier.
Good luck,
John

jeffswav 05-27-2009 07:49 PM


Originally Posted by getrdunn (Post 2874390)
Hey Jeff,
Sounds like your getting close. What RPM did RMBuilder dial your cam in for? (Your max running RPM) Also regarding your dings in your prop. Some may disagree however in the past when wanting to gain 150 ot 200 Rs I would take a file to the cutting edge on the prop. Depending on the severity of your dings this may take them out also.
Don't be affraid to put a relatively sharp edge on it. If this didn't work for me I would never mention it however it has. The only down fall is the prop will nic/ding easier.
Good luck,
John

He said to prop for 5400 RPM. I was hitting 4900 with a heavy load and a dinged up prop. The damage was a little worse than it looked. They are actually going to have to weld a little metal back on the prop and set it back to spec. After blueprinting the props have a sharp edge and a mirror finish. I gained about 1.5 MPH over stock Mirage Plus. He thinks I had at least a 3MPH loss with the damage. Next time I test I will have 2 people and 1/2 tank of gas. That should put me a little closer to 5400.

getrdunn 05-27-2009 10:54 PM

I would guess that would put you near 5100.
Keep us posted.

jeffswav 05-28-2009 09:51 AM


Originally Posted by getrdunn (Post 2874562)
I would guess that would put you near 5100.
Keep us posted.

With a light load I should get about 5200. It is fun to speculate. Testing on the water is better!:evilb:

jeffswav 06-01-2009 09:11 AM

My 25 plus is in the shop and I will not get it back until thrursday. I took the boat out with my spair prop this weekend. The 21 Mirage was so quick out of the hole I was blowing away bass boats out of the hole. I had the rev limiter set at 5600 and ran 66 MPH. It got to top speed in a matter of seconds. Not good for top end but what a rush! I will try the 25 next weekend.

jeffswav 06-08-2009 08:22 AM

I tried the 25 Mirage yesterday and here are the results. I had about 30 gallons of fuel and just the wife and I in the boat. I got 69 MPH GPS at 4900-5000 RPM. I must have had a tail wind or a false reading when I hit 68 with a heavy load and damaged prop. The debate now is should I try a 23 Mirage? The 21 is way too small and the 25 is a little to big.

getrdunn 06-08-2009 10:33 PM

Definately try a 23. Jeff, with a single engine and normal load you will like it much better and put you closer to the RPM meant to be at. It's been a while however back when I ran my 24 Challenger I use to swap between a 23 and 25 Mirage and always like the pull and all around fun with the 23. I can assure you that this will be a good test and well worth the time and or expense. Of course try and borrow or test one first. Given your cam specs I would say you'll pick up 2 MPH / 300 - 400 RPM. Be sure and let us know.
John

jeffswav 06-09-2009 08:52 AM

I have asked around and none of my friends have a spair 23 Mirage. I don't want to ask somone for thier daily use prop. I would like to trade the 21 Mirage for a 23. I have it for sale on craigslist for $200. I was trying to recoupe the money for the repair on the 25. My outdrive is 8" deep, I am thinking about a Imco -2 Shortie for next winters project. Before I spend more money on props does anyone know if the Mirage will still perform well at 6"? I will also be custom fabricating a Ram air kit with (2) 4" inlets. This will also be a winter project.

getrdunn 06-09-2009 12:13 PM


Originally Posted by jeffswav (Post 2884124)
I have asked around and none of my friends have a spair 23 Mirage. I don't want to ask somone for thier daily use prop. I would like to trade the 21 Mirage for a 23. I have it for sale on craigslist for $200. I was trying to recoupe the money for the repair on the 25. My outdrive is 8" deep, I am thinking about a Imco -2 Shortie for next winters project. Before I spend more money on props does anyone know if the Mirage will still perform well at 6"? I will also be custom fabricating a Ram air kit with (2) 4" inlets. This will also be a winter project.

If you can't come up with one locally (23P) be sure and let me know. I'm pretty sure I have one in GR. If you pay the shipping charges from and to I would be more than happy to ship you it. Otherwise I know many people that drive up almost every weekend from your area. Just let me know what you come up with.
John


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