2017 Yamaha AR195 - Working through issues at elevation & addressing performance

[FSH 210 Sport]

I don't know how accurate this online calculator is:

Wallace Racing - Braking HP Loss at Altitude Calculator

At 6200' it has a loss of 46.5 HP. That is almost a 25% decrease in power as mentioned above which I would guess gives you a top speed of around 40 - 41 or so. Impeller may help a little but my guess is you'd have to throw a tune and maybe a higher compression impeller in the supercharger to get back to 49 or 50.

I have used the Wallace racing calculator as well it is a good tool. However that too uses just the standard 3% per 1000’ of elevation gain 46.5hp/250hp=15%. The Wallace racing calculator assumes standard atmospheric conditions.

If you were to put in the density altitude at 6200’ on a 90* day, in stead of just ASL altitude of 6200’ the density altitude then is 10,800’ that comes out to a loss of 81hp/250=32.4% loss of hp.

The problem with increasing super charger speeds is that if you were to go to a lower elevation there would be excessive boost pressure which leads to a whole plethora of tuning and other issues that would have to be dealt with. Aka a PITA.

 

[mwalker4]

It seems like in much cooler weather or lower altitude you can't use full throttle when using a high altitude impeller. The most horsepower you can use effectively is the horsepower of the engine at the altitude and temperature you optimize it for. Is that a correct way of saying it?

 

[FSH 210 Sport]

It seems like in much cooler weather or lower altitude you can't use full throttle when using a high altitude impeller. The most horsepower you can use effectively is the horsepower of the engine at the altitude and temperature you optimize it for. Is that a correct way of saying it?

Yes it is.

It seems to me changing impellers is by far the easiest of solutions to this issue.

 

[ScottS]

@FSH 210 Sport Great info and feedback. Thanks. For now I will likely keep my current setup and depending on when the season starts. If it starts early and will be a long and cool spring I may put the stock impeller on and switch back to the high altitude impeller when the summer sets in.
In response to a twin engine solution, we are actually keeping an eye out for a new boat. It is funny, I was ADAMANTLY against our getting a boat... now that we have one, I love it and can’t imagine a summer without one.
We are exploring a v-drive crossover boat (Mastercraft XT series, Nautique GS series, Centurion VI series, and Malibu VTX) for a more versatile water sport experience. We aren’t set on the transition, because I love the benefits of the jet drive. But we are keeping an eye on this crazy market, which is definitely a sellers market as I think we are all mostly aware of.

 

[FSH 210 Sport]

@FSH 210 Sport Great info and feedback. Thanks. For now I will likely keep my current setup and depending on when the season starts. If it starts early and will be a long and cool spring I may put the stock impeller on and switch back to the high altitude impeller when the summer sets in.
In response to a twin engine solution, we are actually keeping an eye out for a new boat. It is funny, I was ADAMANTLY against our getting a boat... now that we have one, I love it and can’t imagine a summer without one.
We are exploring a v-drive crossover boat (Mastercraft XT series, Nautique GS series, Centurion VI series, and Malibu VTX) for a more versatile water sport experience. We aren’t set on the transition, because I love the benefits of the jet drive. But we are keeping an eye on this crazy market, which is definitely a sellers market as I think we are all mostly aware of.

Right on Scott!

What a great adventure this is! So much fun and a great group here on JB forum!