21P Mirage Copy/250 XS Merc
 

After running a worked over 24p Tempest for the last year the 21p Thunderbolt is like adding a 100 shot of nitrous. Out of the hole in a boatlength and screams to the 6000 redline/alarm at 56MPH. Mileage is better too. We went over 70 miles on about 12 gallons of fuel cruising at 3500 to 4000 RPM -- 32 to 38 MPH. I have yet to hook up the Smartcraft gauges.. Time to get to cracking on some projects.. :sly:

I thought you had run a 21 Mirage before?

Oh and when I read the title of the topic, I first thought you had picked up a Lightning hull(Mirage tunnel hull copy) and put your xs on it

What diameter is that prop?

I started with the 21P but never ran it for long on this motor. Because the MPH is down with this prop and the company I have been keeping (trying to follow a Champ boat around so when he flips I can swim him out), along with the fact that it does pull the larger prop to 60 I just ran the bigger one. Even towed another boat on-plane with the bigger prop. I woulda snatched the bow eye off that little boat with this prop. LOL

Yeah, I wish on the Mirage Copy.

Diameter is 14.8" according to the number embossed into the hub.

So is the 21 a little low on pitch? Sounds like you got the pervormance you want. But with the XS relining will you try a 22? What diameter was the 24? I remember you saying Ferm reccommended a smaller prop.
I was on Mercs prop site the other night and I could not believe the different props they have. I assume the Mirage is a good all around prop?

Ferm was perplexed as to why the MPH wasn't higher, he never actually said you need a new prop. The worked on 24p Tempest has a lot of propslip with the motor height and trimmed to the moon and vessel light I can still find the limiter. I have a plethora of props to use and try. The stock 23P Tempest hits the limiter but not as hard as the 21P. I think I will leave the 21 on there for a while. Acceleration is fun..

I'm wondering if you don't have a 2:1 lower unit ratio in it. I know I hit 53 with a 17 pitch MIRAGE copy on my HYDRA-SPORTS which was only about 3-4% prop slip. If your running even a stock 1.86:1 lower unit ratio, then your prop slip even on the 21 at 60 must be around 18% or so which is on the high side(5-8% is just about ideal at WOT, with 12-15% considered ideal in teh cruise range). if you had a 2:1 lower unit, that would explain your high RPM's with a 21 pitch prop. I know my flats boat with stock 1.86:1 lower unit hit 60 with a 21 pitch TROPHY plus, but I had it jacked up high and was still only turning 5600 with it slipping and blowing out all over the place.

:beer:

I know my propslip is still high. Not as bad as the Tempest.. They are 1.86:1 gears. I am not sure 2:1 was even available in the 3.0Liter Torquemaster. Did your Hydrasport have a T-top and a refrigerator of a console?

No t top, but it did have a big console in it not to mention teh hydra sport weighed a good 600 pounds more than a v-20 does(it was one HEAVY built 20 footer with ceramic, kevlar, and heavy wood construction). I'm just surprised your mirage type prop has that much slip. I was running a mirage type and only about 3% at WOT(53 MPH was 5600-5700 RPM's). And I thought some of the sportmasters were made with 2.1:1 for pushing heavy scarabs.