06-12-2012, 10:34 PM #1
Help Understanding Pitch of Impellers
I am wanting to understand impellers so that I can figure out what impeller would be best for my situation.
The lake I ride at is at 8000' of elevation. I am maxing out at 7600 rpm's @ 63 mph. From what I read, my 2011 RXT-260 should reach 8100 rpm's. Am I correct in thinking that it is like a car's final drive ratio. My Land Rover has a final drive ratio of 3.54, fine stock but after lifting and putting taller tires on, my engine feels gutless. If I were to upgrade the final drive ratio to 4.10, I would gain back some of that power that was lost. Is this similar to how the pitching works? I am assuming so but what do the numbers represent. What is the pitch of my stock impeller and what direction would I need to go to gain those rpm's back? Also, am I correct in thinking that if you went one way, you would increase acceleration but loose top speed, and then go the other way, gain top speed but loose acceleration? Or am I totally off on how impeller pitching works?
If I was to find that perfect impeller, could I get to my 8100 rpm's and gain a few mph from what I am getting now? I am seeing this from a car world. I have too tall of a gear (impeller) and my engine can not utilize it due to not having enough power at this altitude, therefore shorten the gear to maximize the power I do have.
Hopefully you guys can help me out on this.
06-12-2012, 10:53 PM #2
I guess I didn't look hard enough for answers. Found some info on another site. I am basically looking for a smaller # in pitch for my situation, if I am understanding correctly. Skat Trak recommends a 14/19 pitched impeller for my ski stock. If I was to go to a 13/17, recommended for the RXT-215 05'-10', would that help me out???
06-13-2012, 02:47 AM #3
I am no expert, but here is something that might help you out.
Firstly, I would just remove your stock impeller and remove some pitch from the leading edge. Read the thread on impeller pitching, it will help a lot. Removing 2-3mm will get your rpms close to where they should be.
Doing this will increase your acceleration and also your top speed. Remember that your motor is making peak horsepower at around 8000rpms. You will yield the highest speed by having the most amount of pitch your motor can turn to those rpms... Am I making sense?
06-13-2012, 06:44 AM #4
Thanks for the reply manaroman.
I have already sent my impeller to Erik @ SpeedFreeks and said he wouldn't want to re-pitch it any more than he did. He recommended a new impeller and at the time I was broke and forgot what he recommended. I will say this, when I took my ski to Lake Powell, 3600' elevation, my ski ran fricken awesome with what Eric did. I actually hit the speed limiter and felt the pull real good at mid range. Elevation sucks... I couldn't imagine being at sea level
06-14-2012, 07:25 AM #5
The question remains, will the 13/17 Skat Trak be a good option for me at this altitude. I don't want to spend $300 and not have the right impeller... I know that a lot of you aren't even close to running at these altitudes and may not be able to help but am I going in the right direction?
Also, a new question, what are the differences between a 3 blade and a 4 blade impeller?
06-16-2012, 06:33 AM #6
06-16-2012, 07:07 AM #7
Pm Skoepp, he has been our high altitude expert for a long time. Erik is also a genius on these impellers, what ever he told you - I would do it!
06-18-2012, 03:47 PM #8
- Join Date
- Apr 2012
What impeller would you recommend me to use?
I have a european RXT-X 260 RS 2011 model, V-tech 8350 reflash, 4" air intake. home made IC relocation kit.
and a free flow exhaust system.
The boat is going to limit at 8350 with a max speed of 74 mph. What impeller should I use, to keep the acceleration and gain speed ?
06-19-2012, 04:07 AM #9
06-25-2012, 08:30 PM #10
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