New top speed recorded

[Pat McPherson]

I finally fixed my speedo and broke out the GPS to compare.
Running solo with less than 1/2 tank she hit 73.6 on the GPS and showed about 72 on the speedo at 4800rpm. This was running up river with the wind in a light chop; the tide was slack.
I made a second pass running down river and saw 71.8 GPS and 71 on the speedo at the same 4800. My previous top speed recorded was just shy of 72 with 2 people on board and low on fuel.
My speedo reacts slowly so there may still be a small blockage in the drive/pito.
The boat is vary sensitive to trim with the 3 blade Mirage non-plus. Too much and she slows down; not enough and she feels like she's dragging. I plan to buy a Merc Rev 4 at some point knowing the whole boat lifts much more and performs better at all speeds except WOT.
I also plan to pull the mufflers soon now that summer is just about over. I believe there is another 100rpm to be had.

[Greg Guimond]

Are you going to run the Rev4 this year? Should be interesting.

[Conquistador_del_mar]

I will also be watching to see how the Rev 4 performs. I would be trying one on my Warlock, but the Rev 4 does not come in any pitch above 25. I will be trying a Turbo Fusion 4 27P on the Warlock and I will report how it performs.

[Carl C]

Shouldn't the RPMs be over 5,000?

[Pat McPherson]

Friday Rip in the Donzi.jpg

Shouldn't the RPMs be over 5,000?

The previous owner, Dave at MDG Performance said my tach is about 200rpm off; I think 4800 is truly about 5000.
My engine is a stock 502 with 750 carb; 5000 is about max HP. I think a 25p prop is the correct size. When I tested a rev 4 earlier in the season it was about 1.5mph slower at WOT but 5mph faster between 2200 and 4000rpm...

[Pat McPherson]

Are you going to run the Rev4 this year? Should be interesting.

The wife has me going by a rule of not buying more stuff unless I sell something off. We don't have a garage and our basement is full of boating and skiing stuff. As soon as I sell either my spare dive parts or extra heads, I'll buy another prop to play with...

[joseph m. hahnl]

Shouldn't the RPMs be over 5,000?

Is that your 525 HP recommended WOT ? You usually set WOT to up to 750 Rpm lower than the torque to HP transition of 5250 Rpm.

I like the slip I get out of the Mirage 21 and I like the way it carries the hull. The Phenix 400 is at 5400 I want to pull down with a 25P . I would like to stick with The Mirage. I,m curious though, how the ventilated Plus props work and would work. Couldn't any Mirage become a plus by adding the side holes

[Pismo]

MPlus has more cup.

[Pat McPherson]

I like the slip I get out of the Mirage 21 and I like the way it carries the hull. The Phenix 400 is at 5400 I want to pull down with a 25P . I would like to stick with The Mirage. I,m curious though, how the ventilated Plus props work and would work. Couldn't any Mirage become a plus by adding the side holes

I owned an 87 20' Minx years ago. I recall she topped out at about 60 loaded up and 63 running light powered by the original 270HP 350mag spinning up to 4600rpm. The prop that was on the boat was a 23p Mirage and it worked well.
I swapped out the cam for a 300HP tempest and gained about 200rpm good for another 2-3mph. I had also installed nose cone on the Alpha drive so that probably helped too.
I think a Mirage plus has more cupping than the non plus...
I think those 502cube 525EFI engines can spin near 5400; rev limit 5350?

[Carl C]

[QUOTE=joseph m. hahnl;643796]Is that your 525 HP recommended WOT ? You usually set WOT to up to 750 Rpm lower than the torque to HP transition of 5250 Rpm.

I like the slip I get out of the Mirage 21 and I like the way it carries the hull. The Phenix 400 is at 5400 I want to pull down with a 25P . I would like to stick with The Mirage. I,m curious though, how the ventilated Plus props work and would work. Couldn't any Mirage become a plus by adding the side holes[/QUOTE/]

Recommended top RPM is 5,250 but the limiter doesn't come in til 5,400. I was told to run it close to 5,400 because that is where peak power comes in so I have it set up to bump the rev limiter when running in perfect conditions. The original 496 was supposed to run just over 5g and I'd think the 502 should also but the lazy tach explains it!

[Pat McPherson]

I will also be watching to see how the Rev 4 performs. I would be trying one on my Warlock, but the Rev 4 does not come in any pitch above 25. I will be trying a Turbo Fusion 4 27P on the Warlock and I will report how it performs.

Did you test any props?

I've got a 25p Rev 4 and 25p Fusion 4 headed my direction. I'll be testing next week and the prop that performs better will likely be staying on the boat for the remainder of the year...

[Greg Guimond]

That will be a VERY interesting side by side comparison. I'm looking forward to some details from you when it happens. Let us know..........

[Conquistador_del_mar]

Did you test any props?

I've got a 25p Rev 4 and 25p Fusion 4 headed my direction. I'll be testing next week and the prop that performs better will likely be staying on the boat for the remainder of the year...

I haven't had a chance to try the other props yet, but I will report how they do after I run them. I will also be watching to see your results with the Rev 4 vs the Fusion 4.

[Pat McPherson]

3 people, 1/4 tank, small cooler, extra prop on board, mid 60s, just a ripple on the CT river...

25P Turbo Fusion 4:

27.9mph @ 2100rpm
47.8mph @ 3200rpm
56.4mph @ 3700rpm
67.9mph @ WOT-4500rpm

25P Merc Revolution 4:

28.3mph @ 2200rpm
45.3mph @ 3200rpm
55.7mph @ 3700rpm
71.4mph @ WOT-4800rpm

The boat was vary loose with trim running the F4; did not go much past 1/2 way to the max.

The boat had lots of lift, ran rock solid, and you could trim to the moon running the Rev 4. I will buy this prop.

[Greg Guimond]

Great data and a very interesting conclusion. PM me if you are looking to sell the F4. Hard to argue with the Rev 4.