Thread: "Green Charge" speed results
07-09-2007, 12:47 PM #1
"Green Charge" speed results
We (my father and I) finally took our RXP’s out after the newly installed Green Charger wheels with 42 lb. injectors last weekend, and thought I would share our results.
First, let me give some spec’s on how both machines were setup along with speed stats before the Supercharger wheel install…
Both RXP’s mod list:
2006 Viper Red RXP’S with 20 hours on them
Water strainer (Jerry’s store)
Catch can (Homemade)
Jerry’s metal clutch washers
Rideplate holes filled
Reverse bucket trimmed
Custom 4” inch air intake with 9” cone filter (homemade)
Riva intake grate (Jerry’s store)
Riva adjustable venture with 83mm ring installed (Jerry’s store)
2 degree Riva pump wedge with VTS rod (Jerry’s store)
Solas 15/20R 4 blade prop (box stock) (Jerry’s store)
Stainless steel wear ring (Jerry’s store)
Piranha parts intercooler kit with silicon hoses (Jerry’s store)
RE blockoffs (Jerry’s store)
No impeller cone
Oil level set between the two bends
The above combination would net speeds in the 75.2 to 75.6 with a full tank and 76.3 to 76.8 with a little under a half tank. These speeds were very consistent with both skies, (I must have raced my GPS what felt like about a hundred times!!!) RPM was 7980 to 8100 depending on the water and air temp (7980 to 8000 in 75 deg water and 80 air and 8100 in 65 deg water and 73 air). So we were both very happy with the result especially considering we hadn’t even touched the supercharger yet!
The next mods were as followed:
Green Charger Supercharger wheel (Jerry’s store)
Rochester 42 lb. injectors (Jerry’s store)
New spring washers (yes they were almost shot with 20 hours on them!!!)
So to the lake we headed. With the above additions we swapped out the 83mm ring for a 80mm and went out riding. The results of both skies were less then exciting… we pulled 7780 rpm and 75mph with a full tank of fuel. Now, also know that the air and water temp was the highest that we ever ran our skies in so far, along with less then optimum water conditions with no less then a foot of chop. So anyhow, back to the dock to swap to a bigger ring. After we gave it some thought… my father changed back to his 83mm ring and I opted to swap to the 82mm ring. So back we headed and started to obtain some better numbers. With my 82mm ring, I was able to hit 8020 to 8040 rpm most of the time, and speed now picked up to 76.2 to 76.4 with a full tank of gas. My fathers ski was hitting a good solid 8120 rpm most of the time and getting 76.5 to 76.7 on a full tank. Later when lower on fuel I ran several 76.3 to 76.7 and a 77.2 and 77.7 mph. I was happy about the 77 mph runs but unhappy that I couldn’t run them consistently. So I can’t really say it’s a 77 mph ski. It was running mid to high 76 mph 80 percent of the time.
In short…we got roughly .5 to 1 mph and 100 rpm increase after the wheel and injector install. These were definitely better number then before the wheel upgrade, but I have to say that we were left feeling a little disappointed with the results. The skies did feel a little faster and the wheel did add a little better pull, but it really wasn’t all that impressive… it wasn’t a night or day difference like when we installed the Piranha intercooler and 15/20R prop. Those two mods made the ski pull like a monster!!! And the funny thing is… I read more post then I care to count that would swear you couldn’t turn a box stock 15/20R prop with just an intercooler, and that the prop is to tall and you would have to take pitch out of it.
So, my questions is… are these the typical results of a drop in wheel (rotax, A-Kit, Green Wheel, ect...) with only a 100 rpm gain and 1 mph??? I am not worried about the speed so much, just more about the RPM increase of only 100 rpm. We looked of over both skies and can’t find anything wrong like signs of boost leaks. Plus, both skies run pretty much the same… so it rules out problems in my book.
So what kind of RPM increase are people seeing with these drop-in wheels???
And to the people that a have stage 2 +++ skies (stock ecm’s)… how are you guys getting 77 to 78 mph??? Are your skies running these speeds consistently? Or do they require ice cold temps, especially the ones claming to have NO pitch taken out of the prop? Also, what RPM’s are you turning? Will running it in the 8160 to 8200 rpm rang net more noticeable results?
I hope no one takes this post like I’m talking bad about the “Green Wheel,” because I’m not. I’m just trying to get an understating on what the realistic RPM’s that one can expect from a drop-in wheel. And share my speed recipe and results so we can all learn from them.
Any input would be appreciated.
07-09-2007, 01:11 PM #2
Wow thats kinda shitty i guess, my green wheel hasnt got shipped yet im wondering if maybe i should have went with RR wheel instead! I have just about the same mods as you minus the intercooler and injectors! and im hitting a consistent 73 and i get the odd 74-75! on a super good day (cold days). And i was wondering you said your spring washers were worn, how do you tell if they are worn, Without taking them out does your machine run any different or do anythign abnormal? And were they hard to change?
Where abouts in Michigan do you guys ride?
07-09-2007, 01:33 PM #3
IMO, I would lop off my left nut for a 100 rpm gain and 1 mph gain. Were you expecting 5 mph? How much boost was the ski putting out. No way you have all that and no boost gauge?
07-09-2007, 01:35 PM #4
Matt, I think most people gain approximately 1 mph and better acceleration from a good drop-in SC impeller, so your results are normal IMO.
Your speeds prior to the SC wheel (and after) are VERY similar to what many of us with Stage 2s have run ... good to hear. I ran 77.3 consistently with a 1/3 tank of gas with pretty much the exact setup you have, but with an 81.5mm ring and the 15/20 pulled back 1.5 mm. These skis seem to like that setup ... 81mm nozzle, slightly pull back the 15/20 trailing edge to get rpms 'right'. Your speeds are good, but you may want to drop to an 81mm ring and pull back 1mm on the trailing edge of the 15/20. My guess is that would give you a consistent 77+ mph ski.
FWIW, I thought I would be joining Dan (RXP'n in MI) and post a 78 mph GPS speed this year by now, but I am chasing a few gremlins this year. I will be installing a Friebe manifold and putting a shim in one or both of my SCs, then hopefully be back at 100%.
07-09-2007, 01:45 PM #5
- Join Date
- Oct 2005
NeverEndn...Jerry's wheel is better than the RR wheel. It's a little different than the RR wheel. You made a good purchase. The only way you would have got more bang is if you opted for the Riva S3 SC.
07-09-2007, 02:35 PM #6
07-09-2007, 02:36 PM #7
- Join Date
- May 2006
What about your low mid range? Did that improve? Weather and water temp has alot to do with speed. IT was 94 degrees this weekend on my lake, and its noticable when its hot out the loss of power.
Just for an FYI I have an 06 with stage one 14/19R RR thru hull and I turn 8120 all day long.
I"m curious about your spring washers I just put jerrys metal washers in my ski with about 24hrs on it, everything looked good.
07-09-2007, 02:42 PM #8
How in the hell were you getting 75 before the green wheel? I'm running a stage 2 with the 15/19 3 blade, I wonder how my acceleration is compared to other skis cause I'm only getting 72 mph in ideal conditions.
You have to remember that you are about the limit with the stock ECU, change it and you will see more gains.
07-09-2007, 02:44 PM #9
must be nice for you guys.... green blade is pointless for older 185hp motors
07-09-2007, 02:48 PM #10
- Join Date
- May 2006
lurker, my ski was running 72-73 last summer on a stage one, with RR thru hull. I only weigh 150lbs though that might help. IT feels stronger this year though, I'm at 34 hrs now. Need to gps again.
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