Thread: Setup for 81mm Nozzle
04-21-2007, 05:17 PM #1
Setup for 81mm Nozzle
I understand that an 81mm nozzle is GH's best friend. My question is this:
I am at 8160 now with the 15/19r could not get a full speed run in due to choppy water. I got 76.5 before it got shaky. Do I need to repitch for the 81mm nozzle? or just pop it on and go faster. I added 2.5 mm to the trailing edge to get the r's down by the way..Any info on how this all works would be just lovely! Thanks dears!
04-21-2007, 07:00 PM #2
Personally, I would save the 81mm ring until you do your winter projects (ECU). I know, Jerry did this with Princess's ski. You have an p.m.
04-21-2007, 09:28 PM #3
From my understanding you need to put the 81mm ring in first ,get your numbers then pitch your prop..How hard is it to take out the 2.5 mm???
04-21-2007, 11:36 PM #4
04-22-2007, 12:10 AM #5
Steve, if you go from stock (83 mm) to 81 mm, you will lose some rpm, but once you re-pitch your prop you will be faster. Ball park estimate, you will lose 150 rpm, so IMO you could pull 1mm back out and test. The RXP seems to like the 81mm nozzle ...
04-22-2007, 12:48 AM #6
- Join Date
- May 2005
Rxp Steve: I'm running higher rpm's with the ecu. I run the 82. The 81 gave a few tenths of a mph more top end but the acelleration suffered. I liked the 82 better. How much time do you spend at top end vs. acellerating anyway?
04-22-2007, 08:37 AM #7
- Join Date
- Jul 2005
- Lake Dunlap, Texas
RXPSteve--Jerry just got through setting up my RXP. Here is what he found to be best on my ski--(yours will depend on your mods). Had a 80mm and went low 80s. (I have sizes from 80mm to 83mm with all half sizes in between.) Ended up with a 801/2 for yesterdays weather in Morgan City and turning 8500 to 8550 rpms. As the weather heats up might have to got to the 81mm. Last year I found this to be an excellent and easy way to give your ski that last little bit of fine tuning without having to repitch the prop. Takes about 10 minutes to change the ring.
My mods are everything that you can bolt on--in cluding a Rude SC. No internal engine mods other than the Riva valve train up grade.
04-22-2007, 06:34 PM #8
Thanks for the advice guys.
Mark, If water conditions permit, I am WOT until out of gas, and go home..
04-22-2007, 06:41 PM #9
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