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

[SamCF]

Finally made it up today (Sunday). Ended up at Rockport (6038’ ASL) So not apples to apples. But overall, I’m quite happy with the Impros elevation adjusted impeller. I’ll give a more comprehensive response later. But, all in all, happy with the investment. Haven’t run all of my assessments yet, as I’ve been behind the bot all morning, but I saw north of 7200 RPM and the bot definitely is pulling stronger. Super happy.

Good work sticking with it. Sounds like that impeller is perfect. You still have some head room before the rev limiter for lower elevation.

 

[ScottS]

I think I see a lonely, red Yamaha in the slip at Rockport that could use some attention.

 

[Calphor]

@ScottS, glad to hear that the impeller brought the performance back. Don’t let the upgrade bug get you. The first successful one brings the need for more.

 

[ScottS]

I think I saw you out there, but I was up on a friend's boat learning to surf while our was anchored onshore.

@Calphor, I think I already have it, haha.

 

[ScottS]

Finally made it up today (Sunday). Ended up at Rockport (6038’ ASL) So not apples to apples. But overall, I’m quite happy with the Impros elevation adjusted impeller. I’ll give a more comprehensive response later. But, all in all, happy with the investment. Haven’t run all of my assessments yet, as I’ve been behind the boat all morning, but I saw north of 7200 RPM and the bot definitely is pulling stronger. Super happy.

Just as a follow up, as the heat set in during the day, my peak RPM’s dropped to around 6600-6700. I’m still quite happy with the performance gains. If I were to recommend one upgrade to improve performance at elevation, the correct impeller is one hundred percent my recommendation. No cavitation today that I noticed, so the Lucky 13 is working as desired. Choppy water today, so no speed test. But it pulled strong to the high 30’s and seemed happy to keep going. Definitely a breath of life back into our boat.

Next upgrade will likely be the ribbon delete and the appropriate air filter. Snag some more of those top end RPM’s. But that is an upgrade for another day.

 

[Tyguy]

Thanks for continuing to update this thread with results, ScottS. What Impros part number did you order? I'm at roughly the same elevation and may do the same thing. My dealer said the impeller was repitched for local elevation prior to deliver, but I can't get those kind of numbers after the simple fixes and checks (oil/filter, spark plugs, tunnel sealed, no impeller or ring damage).

 

[2kwik4u]

@ScottS Glad to hear the new impeller really helped.

Did you ever upgrade the intercooler? I know some years of 192's had heat soak issues that sound like what you are describing. I thought the 195's didn't have that issue though. I can't remember to be honest, but the "heat soak" you are describing is a symptom of a poorly performing intercooler. Either need more water flow, to be cleaned out, or just upgraded in general.

 

[ScottS]

Thanks for continuing to update this thread with results, ScottS. What Impros part number did you order? I'm at roughly the same elevation and may do the same thing. My dealer said the impeller was repitched for local elevation prior to delivery, but I can't get those kinds of numbers after the simple fixes and checks (oil/filter, spark plugs, tunnel sealed, no impeller or ring damage).

Short answer: Solas Yamaha YV-CD 13/20 impeller - but I would give Glen a call and describe your situation to him and he will help get you setup correctly.

Long Answer:

So your dealer may have sent the stock impeller into Yamaha to have it repitched - which I have heard was something that Yamaha used to do. However, you would likely have to pull your impeller to verify and see if there is evidence of the impeller pitch having been adjusted.

If you choose to go through impros.com, you can either send in your current impeller to have it repitched and have any reconditioning that may be needed or you can go the route I did. I didn't want to lose a weekend or two on the water so I opted to keep my stock as a spare and have impros pitch a Solas impeller to 5500' ASL (*I'll detail below some confusion on this point). I called impros and spoke with Glen and he just took my information and told me what I needed and provided me a quote/charge on the phone. However, in reviewing my invoice I saw that he accidentally sent me the wrong impeller and so it pays to know what you need in advance. The correct Solas impeller for the AR195 (model year doesn't impact this to my knowledge) is the Solas Yamaha YV-CD 13/20 impeller. He also charged me to pitch the impeller - in the original invoice it was stated as pitched to 5500' ASL, but in the corrected invoice where he sent me out the correct impeller it states that he pitched it to 5000' ASL. Which I ended up with is anybody's guess. I'm going with the assumption that the second invoice was correct and he adjusted it to 5000' based on the conversation we had while I was informing him that he had sent out the incorrect impeller.

 

[ScottS]

@ScottS Glad to hear the new impeller really helped.

Did you ever upgrade the intercooler? I know some years of 192's had heat soak issues that sound like what you are describing. I thought the 195's didn't have that issue though. I can't remember to be honest, but the "heat soak" you are describing is a symptom of a poorly performing intercooler. Either need more water flow, to be cleaned out, or just upgraded in general.

@2kwik4u I haven't done any changes to the cooling system. I haven't even done any troubleshooting of the intercooler. Prior to my purchasing the boat it had sat on the side of the PO's house for maybe two years. I don't know if it is possible for the intercooler to have been clogged by insects or something without there being massive issues with the air filter, ribbon filter, supercharger, etc. I reviewed the intake diagrams (see below), but I admit to being ignorant as to the flow of air vs lake water through the cooling systems.

Intake 1: 2017 Yamaha AR195 (RP1800AS) Intake 1 | Babbitts Yamaha Partshouse
Intake 2: 2017 Yamaha AR195 (RP1800AS) Intake 2 | Babbitts Yamaha Partshouse
Intake 3: 2017 Yamaha AR195 (RP1800AS) Intake 3 | Babbitts Yamaha Partshouse

To my knowledge, there aren't any easy swaps for the intercooler - I think RIVA may have an upgrade kit? Most of the information on the forum relates to naturally aspirated engines upgrading to the supercharged engine's intercooler. Any advice or pointers are appreciated.

 

[Tyguy]

Thank you, ScottS. Great info.

 

[ScottS]

@Tyguy I hope it helps!

 

[FSH 210 Sport]

@Tyguy I hope it helps!

Hey Scott,

It’s been 5 months since your impeller upgrade. I’d be interested to know your thoughts on that upgrade now..

Thanks!

 

[ScottS]

Hey Scott,

It’s been 5 months since your impeller upgrade. I’d be interested to know your thoughts on that upgrade now..

Thanks!

Overall, I’m very happy with the upgrade. However, I think I’m going to have to send it back to impros and have the elevation retuned. I believe he ended up tweaking it for 5500’ and I’m having some issues with cavitation. I think I’m going to bring it down to 4500’ elevation. Where before the upgrade the boat lacked the torque to get me up on my ski in hot weather, now the boat has too much torque. Especially on those cold early morning rides in pursuit of glass on which to practice my awful waterskiing skills.
If you have any pointed questions, feel free to shoot em’ off and I’ll do my best to reply.

 

[FSH 210 Sport]

Overall, I’m very happy with the upgrade. However, I think I’m going to have to send it back to impros and have the elevation retuned. I believe he ended up tweaking it for 5500’ and I’m having some issues with cavitation. I think I’m going to bring it down to 4500’ elevation. Where before the upgrade the boat lacked the torque to get me up on my ski in hot weather, now the boat has too much torque. Especially on those cold early morning rides in pursuit of glass on which to practice my awful waterskiing skills.
If you have any pointed questions, feel free to shoot em’ off and I’ll do my best to reply.

Thank you Scott! I appreciate your candor and the quick response!

I’m about the same elevation as you with my 210 FSH. While it is lethargic compared to 700’ it still gets the job done but I’m not trying to pull a single ski skier either.. towables and perhaps wake board is on the docket for this summer, when I get closer to pulling the trigger on this mod in a couple of months, Impros is out of impellers at the moment, I may hit you up for some more details.

Thanks again for writing a great post with lots of details!

 

[FSH 210 Sport]

Overall, I’m very happy with the upgrade. However, I think I’m going to have to send it back to impros and have the elevation retuned. I believe he ended up tweaking it for 5500’ and I’m having some issues with cavitation. I think I’m going to bring it down to 4500’ elevation. Where before the upgrade the boat lacked the torque to get me up on my ski in hot weather, now the boat has too much torque. Especially on those cold early morning rides in pursuit of glass on which to practice my awful waterskiing skills.
If you have any pointed questions, feel free to shoot em’ off and I’ll do my best to reply.

Just re read this thread.. did you do the ribbon delete and replace the air filter? If so, any gains?

 

[ScottS]

Just re read this thread.. did you do the ribbon delete and replace the air filter? If so, any gains?

I did not do the ribbon delete and I am still using the stock airbox. If I did either of these I would have more problems with cavitation as I am already putting too much power to the impeller with its current pitch.
Prior to returning the OME impeller to Impros for detuning, I am going to reseal all of the seams in the pump intake area and see if that helps address my cavitation enough that I don’t want to detune. I really wish I had done this prior to the hot weather going away. The boat pushes noticeably better at 60 than at 90 degrees ambient air temps.

EDIT: Above I accidentally left a portion of an auto-correct of impeller (OME) in my write-up above. I do not want this to cause confusion. I didn't send my OEM impeller to impros, as stated in the above posts I have a SOLAS YV-CD 13/20 impeller.

 

[FSH 210 Sport]

I did not do the ribbon delete and I am still using the stock air box.If I did either of these I would have more problems with cavitation as I am already putting too much power to the impeller with its current pitch.
Prior to returning the OME impeller to Impros for detuning, I am going to reseal all of the seams in the pump intake area and see if that helps address my cavitation enough that I don’t want to detune. I really wish I had done this prior to the hot weather going away. The boat pushes noticeably better at 60 than at 90 degrees ambient air temps.

Right on....

I posted in another thread about density altitude and its affect on horsepower. The rule of thumb for elevation gain and subsequent horsepower/torque loss is a 3% loss per 1000’ of elevation gain. However, the hp loss is usually more than that due to atmospheric conditions, temperature and humidity play a big part in how much hp is lost for a given altitude. There is an easy online calculator that can be used to determine density altitude and the associated hp loss.

density altitude calculator

density altitude calculator for pilots

www.pilotfriend.com

Here are a couple of screen shots of the altitudes and temps you mentioned that illustrates the affect temp and humidity has on horsepower. I’ve always used the relative density percentage as an expression of the hp lost, IE 75% relative density = 25% hp loss.







I had talked to a friend of mine who has been in the marine industry a while back about the subject of hp loss and he was telling me about the curve of power available and prop / impeller hp required for a given pitch. I found this page with the math and illustrations. Classic Whaler: Boston Whaler: Reference: Performance: Propeller Power Curve

Here is a screen shot of one of the graphs showing hp / power required to turn larger props and engine speed.



The green trace can be said to be an expression of reserve hp above the prop power demand. The prop power demand remains constant, but available horsepower changes based on the relative air density. There comes a point below red line / rev limiter cut off at which engine speed will not increase because there is not enough power to turn the prop any faster.

If it is kept in mind that the peak horsepower is not achieved until say 7000 rpm, and the prop pitch is such that the engine is kept at 6000 rpm, there is not enough power to get to peak hp rpm’s. The amount of boost the centrifugal super charger on your engine is directly related to rpm’s as it is gear driven. Speaking of your supercharger, there is a water over air inter cooler / charge air cooler (cac) on your boat, the amount of cooling that the cac provides to the heated compressed air or delta V is also much greater with the cooler water temps which makes the engine produce even more power.

So, at this point as the weather has cooled off, your engine is producing more hp and you are experiencing some cavitation issues. To me, and I’m new to this, that means you have more reserve power, and in this case enough reserve power to cause some cavitation. I would ask myself whether or not that reserve power will diminish to the point that there is no cavitation when the density altitude is higher like during the prime boating season, and can I deal with some cavitation by not using that excess preserve power when the weather is cooler. It certainly sounds like you do not need to do the ribbon delete.

A simpler way to put it would be, I want to be able to turn rated rpm’s at any time during the boating season, what pitch impeller will allow that.

My apologies if I prattled on too much or repeated what has already been said with this post, I suppose its my mind working out the best compromise of what pitch impellers to put into my boat.

Hope this helps!

 

[jdkaeser]

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.

 

[ScottS]

@FSH 210 Sport & @jdkaeser

Both of your numbers match up with some of the calculations I have done after a day of boating using similar online calculators for engine performance variance. In essence, using them to compare issues with cavitation and power loss/performance relative to air temp changes throughout the day. However, I can state unequivocally that I gained several hundred RPM when switching to a higher elevation pitch on the impeller - which means I am getting further into the powerband of the motor. The motor provides plenty of power for our activities. Performing a dead water start for a slalom skiing run highlights my issue with launch cavitation - an issue of too much power for ambient conditions and my boats impeller/cone setup. Towing a 3-person tube during the hottest part of the day being when the boat struggles the most for at speed performance - when I lack power.

It is a balance that I am trying to find - my current impeller is better for towing the tube, but cavitation makes my dead water slalom starts more difficult. It is for this reason I am hesitant to tune the impeller for a lower elevation. Once I am above about 17 MPH, I cannot create cavitation while towing for any watersport.

Maybe it is easier to describe a typical summer day on the lake at high elevation and the issues experienced during each activity:

6:00 AM - On the water for slalom skiing - air temp in the low-60's and water temps in the low-70's. Cavitation likely if too much throttle applied during my launch. Once up and on plane - no issues and I can ski up to about 35 MPH (which is too fast for my ski level and ski setup)
* I wish my setup was able to put available power down better so that I could have a better launch experience. Things are great once I get the ski up on a plane.

7:00 AM - Wake Boarders go out and air temps around 70. Wakeboards launch great (more surface area on wakeboards results in much less human anchor from me on my ski). However, I can still cavitate if I don't apply gradual throttle input.
* I am happy with the performance of the boat during these conditions.

8:00 AM - Air temps in the mid-70's - if conditions permit, I will try to water ski again. Cavitation slightly less of an issue as available engine power drops, but still likely with aggressive throttle input.
* Functionally no change from my morning set other than a slightly lower probability of cavitation from throttle input - chalk this up to slightly degraded power.

Noon-5:00 PM - depending on water surface conditions and passenger inclination, we may tube. At this point, air temps are in the 90+/- range. Water temps near the surface tend to be a little higher here (maybe mid to high 70's) and I think I start to have issues with heat sinking also limiting performance. The boat really just cannot throw a tube around and drops in speed on turns and speed recovery coming out of turns is just too poor to have a really aggressive tubing experience. Some of this is due to performance related to air/water temps, but it is also largely due to pump efficiency in sharp turns and drag from the tube with hundreds of pounds of people on it.
If water conditions permit, and I try to ski during peak heat my issues change. If I have more than about 600 lbs of people in the boat and try to do a deep water slalom ski start I have been dragged as long as a full minute before the ski comes up on plane - I can tell you my forearms looks like they are stuffed with cube steak after one or two launches - basically, if I fall, I am lucky if my arms have the strength for one more launch.
*This is where I wish I could adjust my setup the most - gaining some low-end torque to get me out of the water during high temp days.

So there is the conundrum - I cannot raise low-end torque for hot weather launches OR improve mid-day tube towing without exacerbating the cavitation during low-temp morning launches. Too much power for the impeller setup in the morning and too little power to overcome mid-day heat.

I *THINK* if I go to a lower elevation impeller pitch it will improve both of these issues - to a degree.

Reasoning: Tuning the impeller for a lower elevation, in my understanding, brings the leading edge of the impeller closer to the edge of the pump housing - increasing pump efficiency and lowering the probability of cavitation. The lower-elevation pitch also acts similar to a taller gear - I lose some low-end grunt but I gain top-end. This improves my early morning starts when excess power is available and I don't need the extra low-end grunt of the higher-elevation current tune on the impeller. The improvement of pump efficiency from the lower elevation tune will also improve the delivery of power during hot temps, but I think this will be offset by the loss of low-end grunt. Maybe this is where the ribbon delete and air-filter come into play - pitch for a lower elevation and improve available HP? Or am I really just spinning my wheels - changing things just to end up functionally right where I already am?

I haven't thought about this much since my boating season ended in early October, so I am a little rusty and I welcome any more knowledgable people to cut me to pieces.

For everyone following along and providing insight, thanks for all your help over the past year. Merry Christmas!

 

[FSH 210 Sport]

Great post! Your attention to detail in impressive!

It’s always about compromise when chasing a set up... just like dirt bike suspension..you want a set up that works good everywhere.

The first thing that comes to mind is that cone modification that you made to try and get more ummmph out of your boat. What about removing that cone mod and re testing? Perhaps Glen at Impros can shed some light on that?

The other thing that I think is self evident here is the raw power requirements. Have you thought about another Yamaha boat with twin engines? I usually refrain from making suggestions like that, however in this case it appears that may be the solution for you to realize the best compromise, and really at that point there isn’t much of a compromise from a power / thrust perspective. You’d probably still want the high altitude impellers, I think you may have already considered this as a solution. Not trying to spend your money here, just looking at it from what you require to do the things you want to do. This solution allows you to have your cake and eat it too.

I appreciate you sharing all of your research with all of us! You’ve done a great job on this topic!!!