AR222S/AR222SE/AR222XD Performance on Payette Lake or Lake Cascade in Idaho

[yjb2024]

Wondering if anyone out there is running any of the AR222 models on Payette Lake in Mccall ID or Lake Cascade in Donnelly ID. Curious on the performance of the 1.9's at altitude.

 

[FSH 210 Sport]

Wondering if anyone out there is running any of the AR222 models on Payette Lake in Mccall ID or Lake Cascade in Donnelly ID. Curious on the performance of the 1.9's at altitude.

It would be helpful if you could provide the altitude of Payette lake. Then others who operate at similar altitudes can give you the information you seek.

 

[Exciter 220]

At your elevation, 5000', you will see a noticeable loss in performance compared to sea level performance. Those engines are normally aspirated. A supercharged engine will maintain performance at higher elevations better. On an 80° day, the air density would be about the same or worse as it would be at about 7500 on a standard day (density altitude).

 

[FSH 210 Sport]

At your elevation, 5000', you will see a noticeable loss in performance compared to sea level performance. Those engines are normally aspirated. A supercharged engine will maintain performance at higher elevations better. On an 80° day, the air density would be about the same or worse as it would be at about 7500 on a standard day (density altitude).

Thats true that the engine will loose power at higher altitude, BUT, you left out the main fix for this and it is re pitching your impeller(s). Re pitching, or pitching for altitude is a common practice with all types of boats, from small outboards up to the big sport fishing boats. Super easy to do by sending one’s impeller off to one of the impeller places, Leading Edge or Impros. What you’re after is to get the rated / max rpm out of your engines at any given altitude to get the best performance.

I mainly boat at 5000’ and have the 111 hp TR-1 engines in my boat and was able to get back a large amount of performance by switching to high altitude impellers. Yes my engines are a lot more perky at 600’ than 5000’ feet but my boat still scoots right along.



@yjb2024
Here’s a link so that you can determine the density altitude for any given location.

density altitude calculator

density altitude calculator for pilots

pilotfriend.com

Today’s weather at 34* and a dew point of 34*, the density altitude is actually less than the altitude above msl (mean sea level) 4784’, so you’d be down 13% on hp. On those hot days you’ll be down a little over 20% hp, easily accommodated with an impeller re pitch. There will be plenty of power to get the boat up and moving at a brisk pace. In fact, some of the dealers at higher altitude sell the boats with the high altitude impellers.

So what happened with your boat in the thread below? Did you get the high altitude impellers for it? I read through it and your boat in that thread was down 1200 rpms.

Y

Thread '2024 AR220 Power Issues at 4900' Altitude (TR-1's)'

Jul 22, 2025

Dealer claimed 2024 AR220 would have plenty of power (top end speed) at altitude as is, without high altitude impeller. Does anyone know expected top end speed improvement with high altitude impellers? This seems like a boat that should not be sold into high altitude locations. RPMs maxing out under 7,000, 2 people in boat WOT at 29-30 mph, if you add up to six people max speed at WOT under 25 mph. Expected WOT slightly north of 40 MPH. If you try to pull a tube and turn with 6 people in the boat, boat heavily bogs down to around 15 mph. Any ideas would be helpful. Very frustrating...

• yjb2024
• Replies: 22
• Forum: General Discussion

 

[Exciter 220]

Flattening the pitch of the impellers will give a boost in bottom end acceleration, but your top speed will suffer. It would be like driving your car in low gear.

You need power, which is RPM x torque. Torque equates to manifold pressure, which is lower at higher elevation. Density altitude is only half of the equation, pressure is the other half. Density altitude in Phoenix, 1000' elevation on a 120° day is about 5000', which would be the same as Lake Cascade on a standard day. But the engines will produce more power in Phoenix because the atmospheric pressure (manifold pressure) is higher. The atmospheric pressure in Phoenix would be about 29" Hg, whereas the atmospheric pressure in Idaho would be about 25" Hg.

A supercharged engine can maintain the manifold pressure at higher elevations.

 

[FSH 210 Sport]

Flattening the pitch of the impellers will give a boost in bottom end acceleration, but your top speed will suffer. It would be like driving your car in low gear.
You need power, which is RPM x torque. Torque equates to manifold pressure, which is lower at higher elevation. Density altitude is only half of the equation, pressure is the other half. Density altitude in Phoenix, 1000' elevation on a 120° day is about 5000', which would be the same as Lake Cascade on a standard day. But the engines will produce more power in Phoenix because the atmospheric pressure (manifold pressure) is higher. The atmospheric pressure in Phoenix would be about 29" Hg, whereas the atmospheric pressure in Idaho would be about 25" Hg.

A supercharged engine can maintain the manifold pressure at higher elevations.

That is what density altitude is, an equation that takes all parameters, height above MSL and atmospheric conditions into account so one can accurately discern engine performance at a given density altitude. The pressure is clearly shown in the density altitude calculator I linked above.

Higher density altitude is less pressure, and less O2 ergo less hp.

In terms of engine driven super charged engines such as the SVHO, they are less affected but are still affected because their boost is limited to the engine driven rpm. Turbo charged engines are unaffected once they’ve spooled up, they will just spin faster in the less denser air until they arrive at their boost pressure. To clarify, normally aspirated engines have negative pressure, vacuum, in the intake manifold and super charged engines have positive pressure in the intake manifold, at wide open throttle the vacuum in the intake manifold of the normally aspirated engine decreases.

Taking pitch out of the impellers allows the engines to turn at their rated rpm, that rpm x torque thing you mentioned, which maximizes are flow and therefore the ability to burn more fuel albeit less fuel because the ECU has pulled the fuel back due inputs from the MAP sensor and IAT sensor due to the higher density altitude. Since these boats do not have transmissions, the only way to correct for the resultant too high load for available horsepower on the engine one has to reduce the load aka pitch of the impeller to allow the engine the same mechanical advantage it had at lower density altitude where it made more power. If you do not re pitch and the engine runs at 1200 rpm below rated rpm then it is a big double whammy, less fuel due to the ECU pulling the fuel out and lower than rated / max rpm which is where the peak power is made, less air flow means less fuel can be burned thus less power.

I’ve done a lot of impeller testing here at 5000’ in 90* weather which is similar to what the OP’s lakes are like. The OEM pitch impellers make the performance of my boat anemic in those summer conditions, peak rpms are at 6800 rpm. This yields roughly 29-30 mph tops. With the re pitched impellers I get around 7800-7900 rpm and top speed is roughly 35-36, or a 20% increase in top speed over the OEM pitch impellers at this altitude, but it is the lower end performance where it is really felt the most, the boat gets up on plane smartly. I have a couple of sets of impellers, one set for high altitude and one for lower altitude and swap them accordingly. Just like in your car at high altitude, you use a lower gear to gain performance, and unless the car is turbo charged its top speed will be reduced in high gear. But with these jet boats it is the velocity and volume of the water being pumped that determines the speed of the boat given that boats resistance and weight remain the same.

No matter which Yamaha jet boat you were to run at 5000’ on a hot day with density altitude approaching 8000’ said boat would need a set of re pitched impellers to achieve the best performance possible with that boat, whether it is a SHO or SVHO engine, the same is true with outboard, I/O’s and inboards. 5000’ is where the OP lives and operates his boat, so he needs answers on how to best optimize the performance given the atmospheric conditions, the most logical solution is to get a set of high altitude impellers to attain max / rated rpm on a typical summer boating day. As the weather cools his boat will be slightly under propped but have better performance getting up to maximum speed. It is a compromise.

 

[Exciter 220]

You are correct that, as you've seen in your own boat, a flatter pitch propeller increases low end acceleration. You're getting more horsepower on the low end because you're increasing RPM, while manifold pressure stays the same. Top speed suffers because the engine can't run any faster.

Density altitude is a comparison of specific conditions to the International Standard Atmosphere (ISA). Engine manufacturers rate their engines at specific manifold pressure and RPM.

Boosting an engine will allow it to maintain rated horsepower at higher elevations because manifold pressure can be maintained. No need for an impeller change. This is why I mentioned the idea of a supercharged engine in my first post. Yamaha offers some boats with supercharged engines, but not the one the OP asked about.

I have owned normally aspirated airplanes for the last 50 years. I have flown into Telluride, Colorado, the second highest airport in North America (9078') several times. When you push the throttle in for takeoff and watch the manifold pressure gauge stop at 20" Hg, your butt puckers up. Technically, it wasn't even legal to take my Piper Aztec there because the performance charts only went to 8000'. I was solo and the takeoff was fine, but quite long.

 

[gthorson]

I have the 1.8's at similar altitude The 1.9s will be similar in performance. My dealer put in high altitude impellers and didn't even really act like it was an option to stick with stock. My understanding is stock impellers are not going to work and may not even get you on plane. I lose top speed for sure. I mostly boat at 4000' to 5000' but sometimes up to 7500'. I notice quite the drop in speed when I go higher. Most performance reviews for my boat say mid to high 40s at sea level. I get 42mph tops at 4000' and 37mph at 7500'. Your boat will be faster but with similar drops. I would expect you to be hitting mid 40s. Hole shot power isn't a problem. You will be able to pull, ski, board, and surf and will be amazed at the take off power.

Your biggest problem will be that you would be kind of between elevation uses. You probably wouldn't go much higher than McCall unless you get to east Idaho, but you do have a lot of 3000' lakes that you could go to and maybe even lower. You will need to get impellers pitched for the elevation you will be running. Other than some top speed reduction, it will run fine.

 

[FSH 210 Sport]

You are correct that, as you've seen in your own boat, a flatter pitch propeller increases low end acceleration. You're getting more horsepower on the low end because you're increasing RPM, while manifold pressure stays the same. Top speed suffers because the engine can't run any faster.

Density altitude is a comparison of specific conditions to the International Standard Atmosphere (ISA). Engine manufacturers rate their engines at specific manifold pressure and RPM.

Boosting an engine will allow it to maintain rated horsepower at higher elevations because manifold pressure can be maintained. No need for an impeller change. This is why I mentioned the idea of a supercharged engine in my first post. Yamaha offers some boats with supercharged engines, but not the one the OP asked about.

I have owned normally aspirated airplanes for the last 50 years. I have flown into Telluride, Colorado, the second highest airport in North America (9078') several times. When you push the throttle in for takeoff and watch the manifold pressure gauge stop at 20" Hg, your butt puckers up. Technically, it wasn't even legal to take my Piper Aztec there because the performance charts only went to 8000'. I was solo and the takeoff was fine, but quite long.

Nice to see that you have pilotage and can reference performance charts as well as standard atmospheric conditions. I did my high altitude check out at Big Bear Ca, roughly 7500’ if memory serves, and yes a long take off run due to decreased hp, and much higher ground speed due to the thinner air.

However I respectfully disagree that an engine driven SC will maintain the same manifold pressure / hp at 8000’ density altitude, as the engine driven SC is creating a fixed pressure differential at any given density altitude of X, if the ambient pre boost pressure is lower then the boosted pressure will be lower, the only way an engine driven SC can maintain a given amount of boost is if it has another higher speed, like the aircraft engines of WWII that had two speed engine driven SC’s. A lot of the aircraft used turbo super chargers to maintain manifold pressure at high altitude. In GA aircraft the usual form of forced induction is turbo charging, because the turbo will spin faster due to the lower ambient pressure / thinner air until the pressure comes up to achieve the designed boost pressure, there are limits to this but this is one reason why turbo charging is superior over engine driven super charging, that and turbo charging does not have the parasitic losses that engine driven SC’s have.

And I disagree again on the top speed suffering at high altitude, my top speed increased due to the pitch being correct for that altitude. If I was to use the high altitude impellers at low altitude then the top speed would be lower than with the OEM pitch impellers.

It all comes down to the hp demand of the jet pump at rated rpm and available horsepower. If there is enough power to run the jet pump at rated rpm / output at sea level the boat will go X mph, raise the density alt to 8000’ and the power drops off there is not enough hp to turn the jet pump at rated rpm / output the boat goes slower.

Again, the goal is to get the engine to rated rpm where peak hp is generated. Top speed is basically irrelevant, it is what it is at that point.

I’m at the point now where I run a set of Leading Edge high altitude impellers at 5000’ above msl which gives me roughly 7300 rpm on a hot day. When I drop down to one of the other lakes at 3500’ rpm I get a bit more performance and higher rpm, when I drop down to 1250’ I’m getting very close to 8000 rpm, at 600’ I’m under propped running at 8000 plus or where ever the rev limiter is letting it rev to, and I’m still right at my top speed of 39-40 mph due to the amount of weight I carry on my boat, BUT! I have a ton of reserve power and the boat is an absolute hoot to drive aggressively, it drives through turns and pushes you into the deck. When I run my OEM pitch impellers at 600’ I’m at 8000’ rpm and roughly 40-41. The sacrifice with the high altitude impellers at 600’ is in fuel mileage at best cruise, I lose between .3-.5 mpg because the engine is spinning at 6500 rpm to get the same 24-26 mph best cruise speed as I do with the OEM pitch impellers at 6000 rpm due to the lesser amount of water being pumped with the lower pitch impellers which would be the same with aircraft except its air. And unlike complex high performance aircraft out boats do not have variable pitch propellers to maximize at all conditions.

Great explanation of how turbochargers work from AOPA.

Turbochargers

 

[FSH 210 Sport]

I have the 1.8's at similar altitude The 1.9s will be similar in performance. My dealer put in high altitude impellers and didn't even really act like it was an option to stick with stock. My understanding is stock impellers are not going to work and may not even get you on plane. I lose top speed for sure. I mostly boat at 4000' to 5000' but sometimes up to 7500'. I notice quite the drop in speed when I go higher. Most performance reviews for my boat say mid to high 40s at sea level. I get 42mph tops at 4000' and 37mph at 7500'. Your boat will be faster but with similar drops. I would expect you to be hitting mid 40s. Hole shot power isn't a problem. You will be able to pull, ski, board, and surf and will be amazed at the take off power.

Your biggest problem will be that you would be kind of between elevation uses. You probably wouldn't go much higher than McCall unless you get to east Idaho, but you do have a lot of 3000' lakes that you could go to and maybe even lower. You will need to get impellers pitched for the elevation you will be running. Other than some top speed reduction, it will run fine.

Great post thanks! Nothing like real world experience!

I think the OP will find that impellers pitched for his home lakes at 5000’ will perform just fine at other lakes at 3000’, he will be a little under propped which will give better take off power and mid range performance. Sure top speed will suffer a bit if the impellers were optimized for the 3000’ lakes but then performance will suffer at 5000’.

If it was me and I had a boat with the 1.9L engines or the SC 1.8L engines I’d be going with a twin screw impeller. Although I don’t have much experience with how the four bladed impellers that are coming on the 1.9L boats perform.

 

[Exciter 220]

The amount of boost you get from a supercharger will obviously depend on how it's designed. I'm not familiar with the Yamaha setup, but my supercharged Kawasaki has a blow-off valve to dump excess boost. Where I normally ride it, elevation 2000' and about 100°F (density altitude 5000+'), I still get about 12-13 PSI boost. It still reaches the USCG mandated max speed of 67 MPH easily. I've heard that the new models will let the supercharger pump max pressure for a short period (30 seconds?) to get it moving, then the blow-off valve kicks in to keep the engine from grenading. I don't know what the max sea level boost pressure is for those engines.

I don't have a clue how much pressure the Yamaha SC engines are designed to run at. If they pump excess air, then you could still maintain rated power until you reach critical altitude.

Anyway, interesting discussion. In answer to the OP's question, high elevation will cause performance to suffer. It can be noticeably improved with flatter impellers. Supercharging is another alternative, but that also brings increased cost and maintenance. I suppose it all depends upon what the manufacturer's intent was with supercharging. I would guess they want to create more power at sea level, whereas in an airplane the goal is to maintain sea level performance at high altitude.

 

[FSH 210 Sport]

The amount of boost you get from a supercharger will obviously depend on how it's designed. I'm not familiar with the Yamaha setup, but my supercharged Kawasaki has a blow-off valve to dump excess boost. Where I normally ride it, elevation 2000' and about 100°F (density altitude 5000+'), I still get about 12-13 PSI boost. It still reaches the USCG mandated max speed of 67 MPH easily. I've heard that the new models will let the supercharger pump max pressure for a short period (30 seconds?) to get it moving, then the blow-off valve kicks in to keep the engine from grenading. I don't know what the max sea level boost pressure is for those engines.

I don't have a clue how much pressure the Yamaha SC engines are designed to run at. If they pump excess air, then you could still maintain rated power until you reach critical altitude.

Anyway, interesting discussion. In answer to the OP's question, high elevation will cause performance to suffer. It can be noticeably improved with flatter impellers. Supercharging is another alternative, but that also brings increased cost and maintenance. I suppose it all depends upon what the manufacturer's intent was with supercharging. I would guess they want to create more power at sea level, whereas in an airplane the goal is to maintain sea level performance at high altitude.

The SVHO engines, at least on the boats as far as I know do not have a waste gate or pop off valve on them, but people add them to help protect the SC clutch can fail when the vehicle gets air born then the engine gets loaded suddenly when it lands back in the water. As far as boost pressure, I think the SVHO’s make about 12 psi of boost. It’s a centrifugal design and does employ a CAC / intercooler.