lab props
 

i have a 26 foot ChrisCraft Scorpion with twin stock 260's and alphas. this winter i am putting on carbs/intakes/cams/exhaust. mild stuff probably bring em up to about 325's or so. i am currently running 23 inch quicksilver mirages. last year i knew they were to big for the boat as the best i could spin them to was about 4200rpm. i am hoping to be able to spin them with the mods i am doing. my question to you . . .the all knowing OSO tech squad ;) . . . .will i be able to benifit from labbing the props with this mild combo? i am planing to have the props re-con'd but dont know if spending the extra $$$ for labbing would be worth it.

best bet would be to GPS the boat now, then do your engine mods , break out the gps again and see what speed and rpm increase you picked up, you can call a good prop shop then and they can help you on your slip ratio and what a lab job would do for you, if you are after that last couple mph, then a lab job would help.

thanks H2X. i am seeing 55/56mph at 4200rpm WOT. that is with the stock 260 hp mercs. like i said i know i am over propped so i am hoping that by adding 50 or so HP per side i can spin them up to about 4600 or 4700. not really looking to squeeze the last mph out of it but if labbing would be worth it in a modest performance like my boat. a friend of mine picked up like 3 or 4 mph by labbing the props on his 38ZX. i know thats a whole diff ball game but if i thought i could pick up a few mph i would consider it. i guess I'm just wondering if the gains can only be utilized at the higher end of the scale. thanks again

Dave, I have a set of 21's you can try if the 23's dont work out. Oh, are yours counter-rotating?

Dave, if you can get on plane ok with those mirages, then your x-dim is too low. You'll find a couple mph in going higher. The question is how to do that with alphas.

formula- thanks for the offer. i was thinking of trying 21's. they are both right handers though. what kind of props are they?

cord- actually that thought crossed my mind. being a glass guy it is somthing i can handle. only problem i have now is i only see myself in this boat for about one more season, not sure how badly i want those last few mph :D. you mentioned geting on plane with the mirages. are you saying these props are happier closer to the surface? right now the x dim is very low. is there a better prop for my application? thanks

GLASSDAVE GO ACCLERATOR
 

DAVE,you can stay with the 23 pitch props and have them re designed to the ACCLERATOR PROP,This prop design allows you to plane quick,with no or very little cavation and midrange is awesome,and the props that we have done our customers are getting a solid 2.5 to 3 mph on top end .give me a call or p.m. me and I will hook up you up as far as the price and in the water:D .here is a picture of a mirage converted to what we call the ACCLERATOR.

ACCLERATOR DELIVERS AT BOTH ENDS OF THE SCALE.
 

here is a right hand ACCLERATOR,Also if any pitch changes where needed in the future we will do it at no charge,but in the ACCLERATOR THE 23 PITCH WILL WORK AND RUN THE QUICKEST.If you have any questions p.m. me and I will gladly call you,Thanks Darin

Glassdave,

There are a few things to keep in mind. The new cam shaft will pretty much dictate at what rpm you will have to run the motor to obtain max HP. The other improvements you mentioned will all improve HP at higher rpm. Your 260 HP motor should be between 4400-4800@WOT. With the work you have done to the motors you may need to run above 5000@WOT to obtain the best top end speed. Since you don't have dyno numbers on the motors the best way to find out what rpm to run is to put different pitch props on and see which rpm gives you the best top end speed.

With the work you have done to the motors I think you may see an increase of rpm of about 300-400 rpm. You may see very little rpm increase, however. It all depends on the camshaft. I doubt the 23's will work for you. You probably have to be in 21 Mirage's (not Mirage Plus') to get the rpm up around 5000..

With the standard Mirage it's really not worth lab finishing them. I suggest having them checked to see if they are true. If they are have them cleaned up and they will run great. There really isn't a lot to gain with the old style Mirage through a lab finish, if they are true.

The best thing to do is the run the props you have now and go from there. If you have any questions feel free to call.

Matt
877 842 6855 toll free

Dave, well mine are left and right so I can only help you with one but there should be plenty of 21 Mirages around