PDA

View Full Version : 22 ZX (Non-Stepped) Prop?



Top-Gun
08-02-2010, 05:43 PM
Hello,

I've got a 97 22 ZX (non-stepped) running a 454 Mag with Stainless Marine manifolds. The boat currently runs 5100 RPM and about 70 MPH on the speedo (never GPS'd it though). Its got the stock 23P Mirage 3 blade prop on it.

I'd like to bring the revs down a bit as I'm a little concerned that I'm spinning the motor too high. I don't particulalry want to lose any top speed and if possible I'd like to squeeze a tad more out of it. Looking for some input as to what may be a good prop to try. I was thinking a 24P Bravo prop may be an option but I've read that the non-stepped 22's don't like 4 blades.

Any assistance is appreciated.

Last Tango
08-04-2010, 12:30 PM
Well, it would seem that some "prop testing" is due. I went from a 24P to a 24 3/8"P (I had my local prop shop do it from a brand new stock 24P 4bld). You can either try a 25P 3bld or maybe just have a prop shop curve your current prop up a bit like I did.
I curved my prop for exactly the same reason as you. I was right at redline at WOT and felt I didn't really want to do that. The extra curving also gave a little better hole shot and a little more midrange torque. And it did drop the WOT revs a couple hundred RPM's without any apparent loss of top end speed.

Dr. David Fleming
08-04-2010, 12:38 PM
Top Gun - I have the stepped 22ZX with 502 similar to yours. You are right about the rpm because there is about 30 more horsepower at 4800rpm. If you run at this speed you will probably pull more mph because you are using that horsepower. I got two more mph propping for less rpm but I got less acceleration. In my boat I run 85mph on the speedo which is 79mph GPS on a Bravo I - 30p lab finish prop. My 28p prop runs less speed but can carry more passergers faster so it also depends on your load weather conditions and what you are doing. Donzi used the Bravo I on the step hulls. I do have some performance head work on my engine - port and polish and large valves with Crane valve gear. Also CMI e-top headers but the difference between them and the stock manifolds is small.

I would say going up in pitch to the next prop - the three blade Mirage because this is what Donzi used on the non step hull would give you more speed depending on the passenger load. Also, the speedo's - Gaffrig or Livorsi usually read about 4 to 6 mph fast - on this site get and use a hand held GPS because no one takes speedo readings seriously. Your tachometer is best judge of what is going on.

When my 502 was on the dyno it pulled 445hp at 4800rpm and 418hp at 5000. Your engine has to be in good shape to pull the speed numbers.

The 310hp 22ZX runs about 58mph GPS - 62 to 64mph on the speedo. The stock 502MAG MPI ran 72mph GPS - 76-78 on speedo. The 454 MAG MPI runs about 65-68mph GPS and 70-72 on the speedo. This is all aproximate and differs slightly from boat to boat.

seascarab
08-05-2010, 11:58 AM
I have also a 97 22zx non-stepped with non-Magnum 454 wit CMI Headers. I went from a Mirage 3-Blade 21 or 23 ( I donīt know anymore)to a 24īBravo I Lab-finished.
I lost almost know top-end ( 1 MPH), but have much better holeshot. Turning 4900 rpm with an empty boat.