23p Mirage plus 3 blade to 23 Hydro QIV to ?
 

I found out the hard way that a 23p Mirage Plus is not a true 23p. I went with a 4 blade 23p Hydromotive QIV to replace the Mirage, and it's too big, I lost too many RPMs. Do I go with a 22p or a 21p Hydromotive to replace the 23?

thanx

If the prop design works well for you, then yes. Expect to go up about 200 rpm's for 1" of pitch you go down. Depending on how many rpm's your missing, labbing could be an option.

Bert--I had the same issue! I lost 500+ RPM between a Hydro QIV 23P and a Mirage+ 23P. One of the reasons is that the Mirage+ is a bow lifting prop whereas the QIV is a 4 blade stern lifting prop..Our Legends need a bow lifting prop! If you try the QIV X which is their bow lifting prop you may have more success from what Ive been told.
Personally Im staying with the Mirage+. I run right at 5000 RPM and about 63 MPH with 2 people on board (Im looking for top speed obviously).

I've been told if you have a deep drive, the 3 blade Mirage will be a faster prop. If you raise the drive then you will want a four blade. $$ may be better spent on getting your Mirage labbed to your boat. They can do a lot of things to tweak a prop.

My problem was chine walk above 60, the four blade cured it instantly and I picked up 2mph. I would usually rev limit at 5100-5200, now I'm 4100-4200, so I think I'm going to talk to BBlades and see what they can do, or just sell it and get a 22 or 21p Hydro QIV.

thanx

You picked up 2 mph with a 1000 rpm drop? That doesnt sound right. I know I lost about 7-8 mph with the QIV and 500 rpm's.
Have you tried a Bravo 1 24P? I know thats a bow lifting prop too and the 24P is actually closer to 23P. Since that is a 4 blade it should help with chine walking too. Either that or look for a Hydro QIV X 22P

--Altitude can also play a factor. I know at 2000 ft elevation I was only running 4400 rpm and 55 mph (with the Hydro QIV 23P). I know your in Dallas so thats probably not an issue but thought I would mention it

I believe the reason I pick up the 2mph was the temp of the water and the air. It was perfect conditions, in April, about 1' chop, 72 degrees outside and the water temp was in the sixties. Normal summer conditions here are 101-104 outside temp and 95-98 lake water temperatures.

Later in the summer I didn't look at all the tangibles till after I tore apart my engine and tested every aspect that you can. When I realized my engine was tight, I looked at the prop and borrowed a 23p mirage plus, and boom, it was right back to where it was.

Then I was told about the pitch sizing issue, all of that over just not knowing the sizing problem. I'm very happy with the hydromotive, so I think I'm just going to dropped down to a 22p.

A Q IV is not the right prop for a non stepped 26' PQ. Too much stern lift. A 22" Bravo or Q IV X would be a better choice.

Q4's lift the stern and create more drag from wetted hull area and from the additional blade in the water compared to the 3 blade Mirage. Drag is the biggest deterrent to speed on performance boats.

You can't compare prop to prop just because of pitch. Blade areas, pitch progression cup height, etc. etc. factor in.
Then there is the way certain hulls react to certain geometry's.

Call us, we will help you to understand. We don't charge for the conversation................

Brett

The first rule of thumb is when you go from a 3 blade to a 4 blade you go down one size (2 inches) in pitch.