2001 GTX DI - Aftermarket Impeller???

[vargo27rsv]

I'm trying to figure out which impeller to get for my 2001 Seadoo GTX DI. I don't want to sacrifice much top end performance but would like to be able to pull a skier with not much effort. I will have 2-3 riders on it most of the time. Looks like the stock pitch on this ski is 15/21. I was looking at the Solas Concord ST-CD-15/20. Is this a good match or is there something better? Maybe some of you have some reasons why you wouldn't change (????) Not sure if this affects anything, but I am also looking at the Worx Racing Maxiloader Intake Grate WR212. I'd hate to spend all of my $$$$ and end up with something that doesn't perform... Any suggestions are highly appreciated.

 

[Coastiejoe]

With a 15/20 you are stepping down a minimal amount.

Not sure of your knowledge so please this is not meant as an insult.

The 15 is the diameter and the 20 is how far it travels if it were in a solid. For example, on a boat application if the prop was a 17/25, it would be 17 inches in diameter and it would travel 25 inches in one revolution.

This is important when considering a prop/impeller. Your OEM prop will travel 21 (I assume centimeter) in one revolutions and the one you are looking at will travel 20.

To understand the pulling power, think of a prop/impeller as a axle ratio. The lower the number the strong the pull. Which as you noted does come at a sacrifice of losing top end.

One HUGE difference between props and impellers is,,, the wear ring. So diameter is crucial with a ski as the close tolerance is much of makes our skis go. Unlike a boat, you can use whatever diameter you want as long as the prop does not hit anything when spinning.

In a prop world, generally speaking a larger prop is designed for slower boats that have the power to turn the prop and still keep the engine within good running specs.

In the case of the ski, you can only change the pitch...

By dropping only one-step in your pitch I am sure there will be a difference, just a matter of how much? Most times when people re-prop, they change both diameter and pitch. Again, with the skis we can't do that. Someone else will jump in here and offer their thoughts, but I think you will want to go one more step in order for you to FEEL a difference in you hole-shot or pulling force.

One thing to note is, in a marine application (aka boat), when you step one-inch with a prop it generally changes the RPMs by 200. It goes in reverse per-say, decrease pitch and it will increase RPMs.
Though I don't know this for a fact, I would assume this is CLOSE to true for our skis. If anything, I would guess with today's high tech engines it might be closer to a one-to-one ratio. But that just me guessing...
Clear as mud???

 

[lamajama]

Excellent post. Thanks CJ!

 

[Krispy]

With a 15/20 you are stepping down a minimal amount.

Not sure of your knowledge so please this is not meant as an insult.

The 15 is the diameter and the 20 is how far it travels if it were in a solid. For example, on a boat application if the prop was a 17/25, it would be 17 inches in diameter and it would travel 25 inches in one revolution.

This is important when considering a prop/impeller. Your OEM prop will travel 21 (I assume centimeter) in one revolutions and the one you are looking at will travel 20.

To understand the pulling power, think of a prop/impeller as a axle ratio. The lower the number the strong the pull. Which as you noted does come at a sacrifice of losing top end.

One HUGE difference between props and impellers is,,, the wear ring. So diameter is crucial with a ski as the close tolerance is much of makes our skis go. Unlike a boat, you can use whatever diameter you want as long as the prop does not hit anything when spinning.

In a prop world, generally speaking a larger prop is designed for slower boats that have the power to turn the prop and still keep the engine within good running specs.

In the case of the ski, you can only change the pitch...

By dropping only one-step in your pitch I am sure there will be a difference, just a matter of how much? Most times when people re-prop, they change both diameter and pitch. Again, with the skis we can't do that. Someone else will jump in here and offer their thoughts, but I think you will want to go one more step in order for you to FEEL a difference in you hole-shot or pulling force.

One thing to note is, in a marine application (aka boat), when you step one-inch with a prop it generally changes the RPMs by 200. It goes in reverse per-say, decrease pitch and it will increase RPMs.
Though I don't know this for a fact, I would assume this is CLOSE to true for our skis. If anything, I would guess with today's high tech engines it might be closer to a one-to-one ratio. But that just me guessing...
Clear as mud???

Sorry Joe I know you were aiming to help but I think you may be misinformed about impeller pitch.

The numbers 15/20 refer to the leading edge and trailing edge angles, not diameter and pitch.

I understand where you got your info from though, the method you mention of diameter and pitch is the exact way RC props for planes are measured, unfortunately it doesn't carry over here.

To the OP, I suggest reading the link shown below.

http://impros.com/store/index.php/tech-info/about-impellers.html

Don't be afraid to call impros and tell them what you are looking for. They have given me great help in the past.

Let us know what you decide!




Sent from my iPad using Tapatalk

 

[Coastiejoe]

I am man enough to admit error. I did ASSUME that impellers were labeled just like propellers on boats.

Looks like I have some reading and learning to do.

 

[lamajama]

Excellent post. Thanks CJ!

Ok well now excellent post Krispy!

 

[Krispy]

I am man enough to admit error. I did ASSUME that impellers were labeled just like propellers on boats.

Looks like I have some reading and learning to do.

Its all good Joe, I honestly didn't know how boat props were done so I learned a bit as well.

Ok well now excellent post Krispy!

Eh, just trying to help. I still have much to learn.

 

[Coastiejoe]

I am glad you cleare it up to be honest.

I always feel bad to leave or give advice that steers someone in a wrong direction.

 

[SabrToothSqrl]

I was going to also state that the 15 is not the 'size'.

I run a Solas Concord 15/20 in all of my 951 skis. Very nice prop, cheaper than OEM too. You get a hair quicker off the line, and usually 1-2 MPH more top end. It's also very shiny lol.

I'm not sure it will be a night/day difference, but it is a good prop if you've damaged the factory one.

Depending on the exact Concord, you may lose 100-200 RPMs as well, but your MPH will still be on. the composite housing seems to not let the prop spin as fast. I have both housings at my disposal and run the composite one because it weighs SO much less.

the other things to check are making sure you use new plugs, have clean RAVEs, and for skiing, I would turn them all the way in, that way they don't open and jump the RPMs up while trying to tow a skier. Unless the DI uses the non adjustable ones. I usually work on the carb skis.

 

[vargo27rsv]

Thank you for the replies. That helps me a lot. Joe, greatly appreciate the boat prop info. Now I am able to further understand impeller pitch as it compares to boat prop pitch, which I have more familiarity with.

@ Krispy: Have't called impros yet. The information that is on their website helped tremendously.

But, I have called Skat-Trak and they said something that I found quite odd. The guy told me that I need to get a pump housing from an earlier year model because they have copper vanes instead of plastic vanes. He also said that the appropriate impeller for that ski is a 13/19, which goes against EVERYTHING that I have read about, confirmed by SBT, and the confirmed use of the 15/20 that SabrToothSqrl uses (??) He laughed at me when I tried to suggest that the stock impeller pitch is a 15/21.

Little confused by that... Has anyone ever put the older pump on this ski? Is it even possible to do so? I'm not sure if it is a smaller pump or if it is the same 155 as the stock pump...

 

[mikidymac]

The "Guy" at Skat-Trak was incorrect if he told you that the pump is copper. Seadoo made plastic pumps and bronze pumps. All of the newer ones are plastic and work fine unless you get some rocks through them. I have always used Solas impellers and never used Skat-Trak, they always seemed to be behind solas in my opinion. Coke and Pepsi thing if you ask me. The first thing you should do is pull your pump and impeller and see if the pump, impeller and wear ring are in perfect condition. If they are not, this could bring back the performance you want. If they are fine call Impros, they ca fix and repitch your prop for less than a new one. They did great work on mine.

 

[SabrToothSqrl]

The bronze/plastic pump debate is almost as bad as the oil debate. I've run both on OEM and concord props. I can't verify any difference in MPH or acceleration from either. The plastic pump does however weigh a LOT less. On my XP less weight, the better.

The bronze pump is also no longer made.