bronze vs plastic pump

[jammin777]

I began pulling my 99 seadoo gsx rfi apart today and noticed that the pump is plastic rather than bronze that my 97 gsx had. i tried to Google it and only found that on the rfi the plastic pump produces more low end torque and considered the poor mans skat trac. is this true? so which is really better and why. are they interchangeable? thanks.

 

[LouDoo]

I believe your 99GSX RFI uses the larger pump, 155mm, so it's not interchangeable with your 97GSX (140mm pump).

Lou

 

[jammin777]

thanks for the quick reply LouDoo, the specs say 140mm and also measured @ 140mm.

 

[LouDoo]

Well, then they should be interchangeable, I prefer the bronze pump, they're bullet proof.

Lou

 

[jammin777]

yes that was my thinking exactly. when i first googled bronze vs plastic, in another forum someone said that the rfi plastic pump produced more torque but not sure if that is true or not. anyhow, i pulled my pump apart getting ready to pull the engine, inspecting the pump i noticed one of the stator veins has a small 3/16 to 1/4" curve like maybe broken closest to the impeller. could that cause issues?

the impeller has a few small gouges but not too bad and the wear ring looks great! no scouring and the gaps looks very good 14 thousands to be exact. may still replace the impeller not sure maybe sbt or concord.

i need to buy an impeller tool so when i get the impeller out i will take pics and post what i'm talking about on
bad stater vain.

 

[jammin777]

looking at the stater vein it look like its the way it is made more like a 1/4 to 3/8" curved. can anyone confirm this?

 

[Sportster-2001-951C-Stock]

I'd expect the plastic pump probably does outperform the bronze pump, but there are disadvantages as well, the plastic pump is more fragile, I wouls expect, it can warp and crack easier. The bronze pump weoghs more and the castings probably have more flash, I would guess the stator veins are somewhat thicker, as well.

So, I'd bet the plastic pump is slightly more efficient and probably yields a better top speed, it should pump more water. It's just not as forgiving if rocks, gravel and sand are sucked up?

My bronze pump has a bent stator fin I'm going to try to straighten or file/grind a bit, I bet a plastic pump would've been smashed all to heck?

 

[Sportster-2001-951C-Stock]

yes that was my thinking exactly. when i first googled bronze vs plastic, in another forum someone said that the rfi plastic pump produced more torque but not sure if that is true or not. anyhow, i pulled my pump apart getting ready to pull the engine, inspecting the pump i noticed one of the stator veins has a small 3/16 to 1/4" curve like maybe broken closest to the impeller. could that cause issues?

the impeller has a few small gouges but not too bad and the wear ring looks great! no scouring and the gaps looks very good 14 thousands to be exact. may still replace the impeller not sure maybe sbt or concord.

i need to buy an impeller tool so when i get the impeller out i will take pics and post what i'm talking about on
bad stater vain.

I think if one of the stator veins is missing a piece larger than the diameter of a dime, it will begin to have a negative impact.

 

[jammin777]

ok so i dug deeper on the older gsx bronze pump vs 99 -2000 plastic. the rfi plastic pump has a larger diameter hub and cone than the early bronze.
in a nut shell more low and mid thrust. also the rfi uses a different impeller with a larger diameter hub for the same reason. used to modify the water flow with less cavitation - better hookup. the larger hub impeller with shorter blades = less flex. the more the blades flex the more wear ring gap which causes cavitation.
it was also said that a secret behind the 96 xp used for racing was a 140 mm large hub and cone pump.
i thought id share the info to those that don't know that would want the benefit. so as it sounds the bronze and rfi plastic is interchangeable.
i would liked to have posted the url to what Ive read but wasn't sure how folks would feel about me posting info from another forum.

heres a photo of the 2 pumps

 

[LouDoo]

Thanks for posting. I did a little checking and it appears that the other 99GSX's used the 155mm pump, while the 99GSX RFI used the 140mm pump. I don't have a clue as to why but your explanation sounds as good as any.

Lou

 

[Sportster-2001-951C-Stock]

I can believe the plastic pump has a larger bearing hub, that makes perfect sense to me.

 

[jammin777]

yep the 98-99 gsx limited uses the 155mm pump for the 951 but you probably knew that. lol. it's too bad that they didn't make the larger hub pump for the rfi out of bronze as you said bullet proof. as long as i continue to not beach my craft and anchor it, the plastic one should be fine.