• Welcome to Jetboaters.net!

    We are delighted you have found your way to the best Jet Boaters Forum on the internet! Please consider Signing Up so that you can enjoy all the features and offers on the forum. We have members with boats from all the major manufacturers including Yamaha, Seadoo, Scarab and Chaparral. We don't email you SPAM, and the site is totally non-commercial. So what's to lose? IT IS FREE!

    Membership allows you to ask questions (no matter how mundane), meet up with other jet boaters, see full images (not just thumbnails), browse the member map and qualifies you for members only discounts offered by vendors who run specials for our members only! (It also gets rid of this banner!)

    free hit counter

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

FSH 210 Sport

Jetboaters Admiral
Messages
5,890
Reaction score
6,902
Points
417
Location
Tranquility Base
Boat Make
Yamaha
Year
2020
Boat Model
FSH Sport
Boat Length
21
I don't know how accurate this online calculator is:
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

Jetboaters Lieutenant
Messages
488
Reaction score
547
Points
167
Location
Delaware County, Ohio
Boat Make
Yamaha
Year
2019
Boat Model
SX
Boat Length
19
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

Jetboaters Admiral
Messages
5,890
Reaction score
6,902
Points
417
Location
Tranquility Base
Boat Make
Yamaha
Year
2020
Boat Model
FSH Sport
Boat Length
21
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

Jet Boat Lover
Messages
121
Reaction score
124
Points
82
Location
Salt Lake City, Utah
Boat Make
Yamaha
Year
2017
Boat Model
AR195
Boat Length
19
@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

Jetboaters Admiral
Messages
5,890
Reaction score
6,902
Points
417
Location
Tranquility Base
Boat Make
Yamaha
Year
2020
Boat Model
FSH Sport
Boat Length
21
@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!
 
Top