different impellers on two engine boats
- Thread starter fzandome
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Nozzles....
This is a first time question for this topic...:hurray:
The impeller is the same, the nozzles are different for a simple reason. The Rotax on the twin engine boats are not counter rotating. If both nozzles were the same diameter, the boat would pull hard to the left.
Great question..........:cheers:
This is a first time question for this topic...:hurray:
The impeller is the same, the nozzles are different for a simple reason. The Rotax on the twin engine boats are not counter rotating. If both nozzles were the same diameter, the boat would pull hard to the left.
Great question..........:cheers:
Can we elaborate on this? This is something I would love to know. Why would it pull to the left?
Matt
fzandome
Active Member
On my 95 speedster, there is a right and left impeller 271-000-401 and 271-000-400. The left nozzle is a smaller diameter, which I assume will cause more pressure to keep the boat from going to the left. I have no clue what the different impellers are for, I guess for the same reason. Although the manual indicates they are both 11- 21 pitch.
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Dans97challenger
New Member
You just stated they are both 11/21 so they are the same size they aren't different at all.
fzandome
Active Member
I wondered the same thing and I guess that is what generated my posting.
The manual indicates both are 11-21 progressive pitch, However its' very specific on which impeller goes on which side. The 401 goes on the port side and the 400 on the starboard. In fact the pump bodies even have specific marking to identify the differences.....(Although I don't see any differences in them)
It would seem like a waste of money if the OEM did all this work IDing these different impellers and they were identical.... (drawings, stampings, inventory, etc)
The manual indicates both are 11-21 progressive pitch, However its' very specific on which impeller goes on which side. The 401 goes on the port side and the 400 on the starboard. In fact the pump bodies even have specific marking to identify the differences.....(Although I don't see any differences in them)
It would seem like a waste of money if the OEM did all this work IDing these different impellers and they were identical.... (drawings, stampings, inventory, etc)
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hmmmmmmm....?
So, after reading a bit more, I am having a hard time finding enough information for a conclusive post.
So far, I've read in one manual, that the only thing different between the two pumps is the ride shoe and inlet grate. Then, in another reference, it appears that the nozzle is different. So, now it seems further research is all I can do.
Logically, it seems with twin engines that are not counter-rotating, you'd need some handicap to even the thrust load on each motor. I see in one of the other posts, someone wants to know why. If you picture in your head, the vortex coming from one of the nozzles in a counter rotating pattern, you'll see that the "twist" of that, led by another engine, would cause a pull to the left if they were both of equal power. Like holding on to a battery powered screwdriver when using it. If your putting in a screw, the torque is pulling your hand to the left. If you had to powered screw driver, one putting the screw in, one taking it out, the forces would be equal (though, you'd not meet resistance with the screw coming out).
You'll notice on boats running twin outboards, one motor spins clockwise and the other counter clockwise. This equalizes the centrifugal forces.
I'll have to go through several of the Speedster configurations to figure why it appears some have different size nozzles and others don't and why, if any reason for impellers, to be of different sizes. The progressive pitch impeller can be on both, it's the diameter of the impeller that may change.:cheers:
So, after reading a bit more, I am having a hard time finding enough information for a conclusive post.
So far, I've read in one manual, that the only thing different between the two pumps is the ride shoe and inlet grate. Then, in another reference, it appears that the nozzle is different. So, now it seems further research is all I can do.
Logically, it seems with twin engines that are not counter-rotating, you'd need some handicap to even the thrust load on each motor. I see in one of the other posts, someone wants to know why. If you picture in your head, the vortex coming from one of the nozzles in a counter rotating pattern, you'll see that the "twist" of that, led by another engine, would cause a pull to the left if they were both of equal power. Like holding on to a battery powered screwdriver when using it. If your putting in a screw, the torque is pulling your hand to the left. If you had to powered screw driver, one putting the screw in, one taking it out, the forces would be equal (though, you'd not meet resistance with the screw coming out).
You'll notice on boats running twin outboards, one motor spins clockwise and the other counter clockwise. This equalizes the centrifugal forces.
I'll have to go through several of the Speedster configurations to figure why it appears some have different size nozzles and others don't and why, if any reason for impellers, to be of different sizes. The progressive pitch impeller can be on both, it's the diameter of the impeller that may change.:cheers:
Impellers And Venturis'
The 95 speedster does show different impellers and venturi left and right.
Can't help but wonder why either. I don't think it has to do with pushing the boat left or right cause on 96 and newer speedsters both sides are the same.
I'm gonna call a couple of people and ask "what up?"
DAWG
The 95 speedster does show different impellers and venturi left and right.
Can't help but wonder why either. I don't think it has to do with pushing the boat left or right cause on 96 and newer speedsters both sides are the same.
I'm gonna call a couple of people and ask "what up?"
DAWG
Do that!......
Thanks DAWG.....any inside info on this would be a good thing for the forum. My only thoughts on this is compared to what I see on the older model twin outboards that torque to one side when run at WOT. I know, both Rotax motors are running in counterclockwise directions, but at the nozzle, the stator and diffuser should compensate for most of, if not all of it.:cheers:
Thanks DAWG.....any inside info on this would be a good thing for the forum. My only thoughts on this is compared to what I see on the older model twin outboards that torque to one side when run at WOT. I know, both Rotax motors are running in counterclockwise directions, but at the nozzle, the stator and diffuser should compensate for most of, if not all of it.:cheers:
fzandome
Active Member
I'm having my impellers repaired at SBT and asked about the different impellers. Here is what I was told
" i checked with the tech department as he explained it has something to do with the way the bottom of the boat is built and it is a very slight difference in the pitch, nothing excessive."
That said, the impellers differences have more to do with the boat configuration. As for the nozzle size, that probably has to do with the torque issue, pulling to the left.
" i checked with the tech department as he explained it has something to do with the way the bottom of the boat is built and it is a very slight difference in the pitch, nothing excessive."
That said, the impellers differences have more to do with the boat configuration. As for the nozzle size, that probably has to do with the torque issue, pulling to the left.
Research?.....
I'm just finishing up my research on the "runaway engine" and hope to look into this issue next..............:cheers:
I'm just finishing up my research on the "runaway engine" and hope to look into this issue next..............:cheers:
The Answer
Before you bought your boat, you were sent a form in French from Bombardier which asked you
'Que lard est vous ? Avez-vous un jolie fils' which means 'How fat are you and do you have a girlfriend'
If you answered in English or said 'Tres lard et non jolie fils', your boat came with the mis-matched impellers so that when riding solo, the boat wont pull to the left due to loading on the right. Ever noticed Speedsters lean to the right in the water ?
Simple.
if you believe that, I have a bridge to sell you...
Before you bought your boat, you were sent a form in French from Bombardier which asked you
'Que lard est vous ? Avez-vous un jolie fils' which means 'How fat are you and do you have a girlfriend'
If you answered in English or said 'Tres lard et non jolie fils', your boat came with the mis-matched impellers so that when riding solo, the boat wont pull to the left due to loading on the right. Ever noticed Speedsters lean to the right in the water ?
Simple.
if you believe that, I have a bridge to sell you...
Wow, what a shortcut!......
Thanks UncleJay........now, I ain't got to worry about no research after all!:cheers:
Thanks UncleJay........now, I ain't got to worry about no research after all!:cheers:
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