Great news! The new 4 blade impeller for the 2021 RXP-X is now available.

[GTRD]

Those numbers look a little weird, 15/25 at that RPM should be faster and curious as to your setup to be able to spin it that high. Is your GTR a 4Tec or Ace motor?

Everything about a GTR is weird. Very small pump tunnel. Reason its hard to get um fast.300xx charger, stage 3 cam. Valves, springs, retainers. ‘17 1503 Ace motor

[DinoMite]

Everything about a GTR is weird. Very small pump tunnel. Reason its hard to get um fast.300xx charger, stage 3 cam. Valves, springs, retainers. ‘17 1503 Ace motor

My gut is thinking you may be experiencing some cavitation with that RPM/speed combo. Check and see if it's starting to look a little burnt looking on the edges of the blades. Those mods are respectable but wont turn that prop in a 300 ski at that RPM...something else is going on. We are talking about the Riva 15/25r impeller I assume.

[GTRD]

My gut is thinking you may be experiencing some cavitation with that RPM/speed combo. Check and see if it's starting to look a little burnt looking on the edges of the blades. Those mods are respectable but wont turn that prop in a 300 ski at that RPM...something else is going on. We are talking about the Riva 15/25r impeller I assume.

Yep, riva 15/25. Px and Tx skis have way bigger tunnels. I’m fighting to get water in. Its a gti hull.Think of a vacuum cleaner…motor speeds up when your hand is over the nozzle..not fighting air. This hull will never pump stuff. Processes more water then it can get.

[DinoMite]

Yep, riva 15/25. Px and Tx skis have way bigger tunnels. I’m fighting to get water in. Its a gti hull.Think of a vacuum cleaner…motor speeds up when your hand is over the nozzle..not fighting air. This hull will never pump stuff. Processes more water then it can get.

If you're not getting perfect suction then you're cavitating could be various factors, which then causing the higher RPM...what other option is there? You hit the limit of the pump at some RPM and you're just blistering the water. Take a pic of your impeller and see if has what looks like rub marks towards the edges.


Cavitation is a phenomenon in which the static pressure of a liquid reduces to below the liquid's vapour pressure, leading to the formation of small vapor-filled cavities in the liquid. When subjected to higher pressure, these cavities, called "bubbles" or "voids", collapse and can generate shock waves that may damage machinery. These shock waves are strong when they are very close to the imploded bubble, but rapidly weaken as they propagate away from the implosion

[Team Bilford]

Everything about a GTR is weird. Very small pump tunnel. Reason its hard to get um fast.300xx charger, stage 3 cam. Valves, springs, retainers. ‘17 1503 Ace motor

You have heard of "there is no replacement for displacement". The same is true about intake pump volume. Your best solution to the limitations of the GTi hull is to get one of the hulls designed to feed a 300 pump. You simply can't turn your GTR into a RXP when you start with a GTi hull. The sum of the parts is more than just the engine.

[GTRD]

[QUOTE=DinoMite;3155669]If you're not getting perfect suction then you're cavitating could be various factors, which then causing the higher RPM...what other option is there? You hit the limit of the pump at some RPM and you're just blistering the water. Take a pic of your impeller and see if has what looks like rub marks towards the edges.

Looks fine to me. Compare a gtr/gti intake grate to any 300 grate. Huge difference. Didn’t realize how much until we switched out one on a friends ‘20 px. Wish I took a side by side pic.

[GTRD]

You have heard of "there is no replacement for displacement". The same is true about intake pump volume. Your best solution to the limitations of the GTi hull is to get one of the hulls designed to feed a 300 pump. You simply can't turn your GTR into a RXP when you start with a GTi hull. The sum of the parts is more than just the engine.

Not to be a dick but I don’t remember asking for a “solution”. I was asked of results from a certain prop and replied along with a response to why those results are what they are. Would be very easy to buy a 300 and make it faster than others. Buy a pre-made kit. No kits or database for mine. Had to figure stuff out along the way. Way more satisfying to wax 300’s and GP’s with a GTR. Really hurts their feelings.

[DinoMite]

[QUOTE=GTRD;3155718]

If you're not getting perfect suction then you're cavitating could be various factors, which then causing the higher RPM...what other option is there? You hit the limit of the pump at some RPM and you're just blistering the water. Take a pic of your impeller and see if has what looks like rub marks towards the edges.

Looks fine to me. Compare a gtr/gti intake grate to any 300 grate. Huge difference. Didn’t realize how much until we switched out one on a friends ‘20 px. Wish I took a side by side pic.

It's does look really good. Looks a little discolored towards the impeller where it meets the ring, looks a little burnt to me. I suspect if you pull it, you'll have pitting on the edge of the impeller like every impeller I've run with a stainless ring. I don't seem to see that issue with plastic rings. My theory is the water is getting boiled at higher rpm when the impeller stretches and contacts ring edges causing that discoloration. You could just be getting loss of suction. Or maybe everything is fine...the 9100 rpm just doesn't make sense to me unless you have some cool weather or hp more than a stage 4, (big charger/cam) or combination of. Lot of speculation on my part, I just like to try to understand how one person gets more RPM then I did with less mods. I suspect the mystery will stay a mystery. Thanks for posting that pic. What's that green stuff though? You using triple guard grease on your splines? no nose grease boot?..can't really tell.

[ptscon]

Probably just not enough water getting to to the pump making it spin without it translating into speed. My '12 PX did 86 on cluster at 89xx with 15/21 but I dunno these impellers pitches can be read a million ways I swear this "untouched" 15/21 looks like my impros pitched 15/24

[GTRD]

[QUOTE=DinoMite;3155725]

It's does look really good. Looks a little discolored towards the impeller where it meets the ring, looks a little burnt to me. I suspect if you pull it, you'll have pitting on the edge of the impeller like every impeller I've run with a stainless ring. I don't seem to see that issue with plastic rings. My theory is the water is getting boiled at higher rpm when the impeller stretches and contacts ring edges causing that discoloration. You could just be getting loss of suction. Or maybe everything is fine...the 9100 rpm just doesn't make sense to me unless you have some cool weather or hp more than a stage 4, (big charger/cam) or combination of. Lot of speculation on my part, I just like to try to understand how one person gets more RPM then I did with less mods. I suspect the mystery will stay a mystery. Thanks for posting that pic. What's that green stuff though? You using triple guard grease on your splines? no nose grease boot?..can't really tell.

Green is the solas cone. Blue is synthetic grease