Wear Ring

[gejettest]

Hello,
I would like to know the disadvantages with the stainless steel wear ring. In my opinion if the pump is going to suck FOD (foreign object debris) the impeller is going to get the hit on the leading and trailing edges. Why sacrifice a soft outer diameter shroud, basically that is what the wear ring is, made to maintain tip clearance of the impeller.
Thanks,
Henry

 

[DCKD]

The wear ring is called a "wear" ring for a reason. It is meant to wear....and prevent damamge to more expensive parts such as the impeller or drive shaft (not sure if this is what it is called).

Imagine a rock/peice of wood being sucked up into your intake, it can't fit throught the gap between your impeller and wear ring so it damages the wear ring on the way out with minimal damage to the impeller.
Now imagine you have a metal wear ring the peice of wood/rock is unable to fit through cause there is no give with the metal ring. This will either cause damamge to your impeller or drive shaft because the rock/peice of wood is going to have to get out somehow. If it can't get through....it could jam the impeller and cause damamge to the drive shaft.

Bombardier has obviously had their engineers look entensively into this and has decided that a wear ring that wears is better than one that doesn't.

In the end it is your decision....

Hope that makes it more clear.

Matt

 

[gejettest]

Matt,
Thank you for the explanation, I work on jet engines for a living, so I'd like to believe I am familiar with how a jet pump works. I believe that when the impeller contacts FOD, the leading edge will take the brunt of the damage, normally the material will eject back out the exhaust. Maybe on watercraft impellers, the object is more likely to be expelled outward. Jet engines have shrouds, much like the wear rings. Likewise they are made of softer material than the blades. This is so when the blade tips make contact, which they shouldn't provided the initial clearances are set up right, the softer material will wear, rather than the blade tip wiping out. Not so much as to eject the FOD between the blade and shroud. I understand what you are saying, maybe jet pumps push the flow outward more than jet engine theory.

As far as the engineers at Bombadier goes, I'm sure they built it like that for a reason, but sometimes building obsolesence into machines for future spare parts sales is in their agenda also.

Question this, why does this machine come with an aluminum impeller and not a stainless one? I believe the 2008 255 hp. model has a stainless one?
I've heard stainless is better, can be repaired, pitch changed/corrected, welded and reworked.

Has anyone who used a stainless wear ring experienced any problems with them, if so what are they?

Thanks,
Henry

 

[DCKD]

Jet engines have shrouds, much like the wear rings. Likewise they are made of softer material than the blades. This is so when the blade tips make contact, which they shouldn't provided the initial clearances are set up right, the softer material will wear, rather than the blade tip wiping out.

You are right on with that one...I have seen a few wear rings with groves from the impellers....i think it can be cause by bad bearings or improper alignment. As for foreign object...you are right...larger ones will just get pushed back and sit inside the intake area and they definately do dammage to the impellers...I was talking about smaller peices that do get pushed through....i am not positive...but I would think having a softer wear ring would minimize the dammage.

Matt

 

[seadoosnipe]

Correct DCKD....

As a jet mechanic, your already familar with the way a compressor works. The only difference is the jet aircraft compressor uses a less dense material, air. The compressor of our jet pumps, uses a single stage axial flow pump and nozzle (with one stator vane) instead of a compressor of several stages of rotating and stationary vanes. With the density of the water, it acts as a carrier for the smallest in particles to impact the outer casing of the pump housing.

The reason they made the wearing ring of hard rubber, is because those particles (normally sand) will impact and bounce off (imagine being hit with a sand blast nozzle, that's what the pump goes through) rather than impact and scratch (with scratching comes metal removal), therefore, lasting a lot longer than a metal one. Yeah, I've seen all the high performance mods. You could probably buy one of titanium if there was a demand for it.

Redundancy in parts.......I'm happy for that. You may find the same axial flow pump and wearing ring through 10 years of production. But I don't think it's related to greed, since Rotax was first established in 1920, in Germany, they have made tremendous advances in technology. Then, they built the first Bombardier engine in 1962 for the Ski-Doo snowmobile. IN 1970, Bombardier and Rotax integrated. Their first marine engine was designed in 1988 and the first Rotax 4-TEC engine was built in 2001. So, with that kind of history, I don't think their design is about the money, I believe it's about technological advances.

In the new 4-TEC super charged engines, the horsepower created by the super charger is so great, that the benefits of a stainless impeller verses an aluminum one far outweigh the disadvantages. In my opinion, all the parts of such a high performance engine have a lot shorter life span than those of a naturally aspirated, lower horsepower engine. The top speed of the PWC's is around 70 mph and that's with a 947 RFI 2 cycle engine. Why all the extra horsepower and engine wear if your only benefit is to get a good jump out of the hole. I have nothing against the new 4-TEC engines, except that I can't work on one yet. I'll eventually adapt and buy all the necessary computer equipment to communicate with the onboard electronics. But till then, I"ll continue to repair the 2 strokers.......

Right now, we are at a bottle neck on engines. You'll have to admit, 255 ponies in a PWC!....What will be next? I did a post last year on the new 2012 models as a joke, saying it was going to have an after burning, gas turbine engine and automatic hydrofoils that deployed at 70 mph to hold you on the water till you top out at 110 mph....:rofl:.......
:cheers:

 

[SeaFury]

Hello,

I work for a company who makes high performance elastomiric bearings, the wear ring Sea Doo uses is a very cheap Nylon material. Product it worth less than a dollar to Sea Doo. My company has quoted the replacement of the current and ring and be pushed out due to price.

Ryan

 

[sporsterjoel]

Matt,
Thank you for the explanation, I work on jet engines for a living, so I'd like to believe I am familiar with how a jet pump works. I believe that when the impeller contacts FOD, the leading edge will take the brunt of the damage, normally the material will eject back out the exhaust. Maybe on watercraft impellers, the object is more likely to be expelled outward. Jet engines have shrouds, much like the wear rings. Likewise they are made of softer material than the blades. This is so when the blade tips make contact, which they shouldn't provided the initial clearances are set up right, the softer material will wear, rather than the blade tip wiping out. Not so much as to eject the FOD between the blade and shroud. I understand what you are saying, maybe jet pumps push the flow outward more than jet engine theory.

As far as the engineers at Bombadier goes, I'm sure they built it like that for a reason, but sometimes building obsolesence into machines for future spare parts sales is in their agenda also.

Question this, why does this machine come with an aluminum impeller and not a stainless one? I believe the 2008 255 hp. model has a stainless one?
I've heard stainless is better, can be repaired, pitch changed/corrected, welded and reworked.

Has anyone who used a stainless wear ring experienced any problems with them, if so what are they?

Thanks,
Henry

you answer your own question.... wear ring is there for a reason like everyone has said its there to protect the motor, drive shaft and pump. I talked to people who have fully modded ski's with the riva stage 3 who have installed an SS wearring, and said there no point in it cause it doenst increase the performance and they actually wish they didnt in stall it. One big down fall of a SS wearring is that it can still be pron to damage BUT good luck trying to get it out, lot easyer and quicker and less money to replace a plastic one then it is a SS one.

 

[sporsterjoel]

Hello,

I work for a company who makes high performance elastomiric bearings, the wear ring Sea Doo uses is a very cheap Nylon material. Product it worth less than a dollar to Sea Doo. My company has quoted the replacement of the current and ring and be pushed out due to price.

Ryan

Ya every thing has mark up. How much do u think they spend on gel glass and resin to make these boats bet its under 1500 bucks. Also u guys up there in Burlington get any snow.... we got tons in london.

 

[SeaFury]

No snow here, saw a few cars driving around with a bunch on the roof. Was cold enough though.

 

[Mirage]

I have only had to replace one, and that was on my GTX that the wife was riding, trust me when I say "it takes ALOT to tear one up"...

"Oh honey that's ok , that rock bank just jumped right out in front of you", but i was really thinking " WOMEN DRIVERS"!!!