Elevation and climate and how it affects engine performance and impeller pitch

[jpt7779]

Jim, I am very sure at that RAD you are really down on rpm's. Are you aware that BRP has special impeller pitching for High Altitude users? These high altitude impellers can be ordered right here in the GreenHulk OEM store by entering the part number

[JimPTx]

I didn't realize there were high altitude specs - I appreciate the info! I'm going to look into that.

I'm just out west of you in Lubbock. We're only 3200' elevation but the RAD is high pretty much all the time. Both of my skis were originally sold around Abilene and were at a lake house on PK. They ran much better there!

[Sanfish]

I didn't realize there were high altitude specs
<snip>
We're only 3200' elevation but the RAD is high pretty much all the time.

Since a motor is nothing more then an air pump, less oxygen (rpm loss) requires a different setup than a place at sea-level. Motors run richer the higher the elevation is (if same given setup). Since your 260 has a SC (RPM=boost), you can easily compensate RPM loss with a smaller impeller. If you are running a VTECH tune, you have 4 fuel maps you can adjust (2 normal and 2 high-altitude).

Once you start to think "high altitude" in terms of atmosphere it makes it easier to digest (less oxygen). The advantage of a "power add'er" (SC, turbo, NO2) is it really increases V/E (over 100%) and in simple terms, generates atmosphere.

Each year when the big boys go to Bandimere drag strip (thunder mountain), everyone runs very different setups. For some of the top teams, its a completely different car practically. It's the N/A "pro-stock" guys that have it down to a science (but boring to watch) since they can't generate air

[jpt7779]

Ever notice when flying on a commercial airliner at high altitude such as Denver, Lubbock, Albuquerque, Guatemala, Bogota, etc. the take off roll takes forever to get airborne? The same weather parameters greatly effect performance in a turbo jet also.......BIG TIME!

We crunch the numbers for every single flight for density altitude, pressure, temperature, dew point, humidity, wet, dry, icing conditions and gross weight. The end result is what speed to abort, rotate, and lift off at any given power setting.

The good news is everyone is effected by this equally. The ones that take it into consideration and adapt to the changes are the ones who will out perform.

[Mothman]

Ever notice when flying on a commercial airliner at high altitude such as Denver, Lubbock, Albuquerque, Guatemala, Bogota, etc. the take off roll takes forever to get airborne? The same weather parameters greatly effect performance in a turbo jet also.......BIG TIME!

We crunch the numbers for every single flight for density altitude, pressure, temperature, dew point, humidity, wet, dry, icing conditions and gross weight. The end result is what speed to abort, rotate, and lift off at any given power setting.

The good news is everyone is effected by this equally. The ones that take it into consideration and adapt to the changes are the ones who will out perform.

Power loss accompanied by less air to 'hold up' the plane. The Bernoulli principle, which is why helicopters have a limit as their rotors literally don't have enough air to move through to support lift.
im sitting at the lake house, 2000ft below Lubbock, and even though I'm still 1000ft above sealevel my ride absolutely barks, even with 100% humidity. Makes me giggle. Lol I can't imagine it at sealevel. <whistle>

[RXT-260-DOO]

Thanks for this info! You all need to try riding at 8200' above sea level! 😔 Lake Granby here in CO. I go to Lake Powell every other year, 3000', and that is best I'll ever get to "true performance."

[K447]

... It's an iPhone App.

Link to the app?

App name, publisher?

[viperxxss]

Guys, sorry i'm brand new to the forum and this is my first post so please forgive any ignorance on my part. It's safe to assume that this would apply to the Challenger 215sc boat as well correct? I've read your forum for months now, there are some incredible people posting on here and for that, THANKS! The local lake that i use is at 7000 feet elevation and my boat sucks up here. I've replaced the wear ring, ordered a new impeller, replaced the carbon seals, rebuild the drive shaft, sealed the ride plate and last night removed the supercharger. Is there someone on here the rebuilds them? All that being said, i cant top 22mph for the life of me. I hit 8k rpm's at wot and then it drops to appx 6400. The boat came from So-Cal and i've never seen any real performance out of it. Do i need to re map fuel systems or something? It's really disapointing that i can't pull a tube with my 12 yr old on it faster than 13mph. Any help would be awesome!

Thanks,

[Green Hulk]

Guys, sorry i'm brand new to the forum and this is my first post so please forgive any ignorance on my part. It's safe to assume that this would apply to the Challenger 215sc boat as well correct? I've read your forum for months now, there are some incredible people posting on here and for that, THANKS! The local lake that i use is at 7000 feet elevation and my boat sucks up here. I've replaced the wear ring, ordered a new impeller, replaced the carbon seals, rebuild the drive shaft, sealed the ride plate and last night removed the supercharger. Is there someone on here the rebuilds them? All that being said, i cant top 22mph for the life of me. I hit 8k rpm's at wot and then it drops to appx 6400. The boat came from So-Cal and i've never seen any real performance out of it. Do i need to re map fuel systems or something? It's really disapointing that i can't pull a tube with my 12 yr old on it faster than 13mph. Any help would be awesome!

Thanks,

Welcome aboard! Yes this would apply to your boat also.

Which impeller did you install? You will need a lower pitch impeller at 7000' elevation.

I offer a supercharger rebuild service. More info here

http://www.greenhulk.net/showthread.php?t=146938

[viperxxss]

I installed a Solas 14/19, which if i'm reading right is the wrong one for this elevation.

[Green Hulk]

I installed a Solas 14/19, which if i'm reading right is the wrong one for this elevation.

Yes, that's way too much pitch for that elevation. A 14/19 would be used on a modified stage 1 ski at sea level.

[viperxxss]

A 10/19 then?

[viperxxss]

So this scenario gets worse. I pulled the supercharger tonight. I can't feel it slipping at all but it's an 07 at 76 hours and I don't want to risk the bearing failure. What is this in the output shaft? This is getting pumped into the engine and I don't know what it is, any ideas?

[mrsprinkles]

So this scenario gets worse. I pulled the supercharger tonight. I can't feel it slipping at all but it's an 07 at 76 hours and I don't want to risk the bearing failure. What is this in the output shaft? This is getting pumped into the engine and I don't know what it is, any ideas?

Do you have catch can installed? If not, i would guess its oil 'vapor' returning into the system.

[viperxxss]

I don't. Where would I get those parts?