Yamaha RX1 Engines

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Posted

You can pick what ever pitch you want. Simply pick the gear ratio you want out of the 4 ratio's offered for the c-gearbox. They are 2.62, 3 , 3.47 and 4:1. Most are using the 3:1 but Steve Henry used the 3.47 for a bit. He said he got the best STOL performance with it. He said it felt like the same power as his big bore 912 when he injected the nitrous. As far as longevity of these higher RPM engines that is a yet to be determined. I dont think there is enough flying hours on them to giess at a TBO #. 

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Posted (edited)

And experts help my thinking here, but the 6 deg willis was shooting for was on the warp protractor...  near the tip right?  So i think that doesn't quite equate to say a hartzell pitch at what is it like 70% of prop length.

Point being that maybe 6 deg is not so flat as it sounds?

 

Edited by MN Kitfox 2

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Posted

And experts help my thinking here, but the 6 deg willis was shootimg for was on the warp protractor...  near the tip right?  So i think that doesn't quite equate to say a hartzell pitch at what is it like 70% of prop length.

 

Well,  the 11 or 12 degree pitch that the Soob pulls is on the same Warp prop and protractor as his 6 degrees, so I think that is apples to apples.   EDMO

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Posted (edited)

I agree that the soob must have more torque,the gear ratio was 2.53/1  and the yamaha is roughly 3.5/1 with the built in reduction, the soob swung the prop at 11 degrees 4800 rpm and the yamaha is now at 8 degrees(at the prop tip) and were getting 9000 rpm wot, we are still messing with the main jets to make it happy, its a bit of a pain to get main jets for the mikuni carbs  , I guess everything is going fuel injected these days. My cruise is 6500 rpm and think it was around the 80 mph in the RX1

Edited by marshawk
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Posted (edited)

I agree that the soob must have more torque,the gear ratio was 2.53/1  and the yamaha is roughly 3.5/1 with the built in reduction, the soob swung the prop at 11 degrees 4800 rpm and the yamaha is now at 8 degrees(at the prop tip) and were getting 9000 rpm wot, we are still messing with the main jets to make it happy, its a bit of a pain to get main jets for the mikuni carbs  , I guess everything is going fuel injected these days. My cruise is 6500 rpm and think it was around the 80 mph in the RX1

My Soob is 1.84:1 reduction, and Suberavid has either a 2:1, or 2.2:1 and both will pull a 3-blade 72" WD at 11 degrees static.   Actually, I have to go to 12 degrees to get closer to same prop rpm at slower static.  EDMO

Edited by EDMO

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Posted

Attached an engine today.

20170412_165116.jpg

But back to topic:  Congrats!  Can't wait till I can take a pic like that!  Those headers look like a work of art.  Did you make them?

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Posted

Looks good and I agree on the nice work on the headers

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Posted

I have to thank Steve Henry for the headers and motor mount.

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Posted

I agree that the soob must have more torque,the gear ratio was 2.53/1  and the yamaha is roughly 3.5/1 with the built in reduction, the soob swung the prop at 11 degrees 4800 rpm and the yamaha is now at 8 degrees(at the prop tip) and were getting 9000 rpm wot, we are still messing with the main jets to make it happy, its a bit of a pain to get main jets for the mikuni carbs  , I guess everything is going fuel injected these days. My cruise is 6500 rpm and think it was around the 80 mph in the RX1

Anxiously awaiting your final results once you get the Yamaha tuned and dialed in!

An avid going from a Suby to a Yammy with the same prop...  the best "apples to apples" data that can be had!

Taking a wild guess here, but once you get tuned, and set up for a  prop pitch that puts you somewhere in the middle of the power prop / cruise prop compromise, I bet you will be back close to 11 deg.

And 2 cents worth of ideas on tuning:  my float level was off and my rx1 was running so rich that it was only putting out power equal to another sled I own that is 90 hp.  Slight float adjustment and the rx1 was faster than my 135 hp ski doo 1200.  Point here being that the float level plays a major role in mixture.  Also, I  sure like the O2 sensor (fuel to air ratio) guage that teal uses.  That is the way a lot of turbo snowmo users guage their tuning and I kinda think it gives better data even than egt does.

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Posted

I just got a gauge for balancing the carbs and still waiting for 148 main jets to arrive to try them in the next round

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Posted

image.thumb.jpeg.a7325f4d86cbf3da9eafeb9image.thumb.jpeg.6cad95a280de047a33c7583Yamaha just released the 2017 factory TURBO version of the 3 cylinder motor. I hope you can get a mount together that is as nice as the one you have for the Yamaha 4 cylinder RX1.  It will take 1-2 years before the prices come around on one of these wrecked or salvaged snowmobiles  

 

180hp may be out of the Rotax C gear box range.

 

https://m.youtube.com/watch?v=Wxy-j4rZdMk

Been a long time since posted, but still a current issue.  Also, now I'm looking for a power plant.

180 hp too much for a Rotax gearbox, but in an airplane at constant power output, limiting the RPM to protect the gearbox, also extends expected engine TBO. I wonder how long one of these engines would last at the reduced RPM at say 120 HP ?  Seems like a good deal.


4-stroke, 120 HP continuous for let's say 1500 hours (Toilet Paper Guess), turbo to have same power regardless of altitude

Depending upon weight, would love to have 120 HP in an Avid/Kitfox

As for ignition and needed reliability, that's a tough one.  I'm guessing the ignition is synchronized with the turbo operations.

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Posted (edited)

I managed to get a hour flight in this morning in the avid with the Rx1 engine,It ran nice and smooth and climbed at 800 ft/min at 7500 rpm without trying, I could easily cruise 6500 rpm @80-85 mph and stall without and flaps was around 50mph , was awhile coming but it seems worth it :BC:

rx1avid.JPG

Very nice looking plane.

When you get around to it, would like to see your collective performance statistics.
A set of Airspeeds at different RPM vs gallons per hour. each at different density altitudes
Empty weight of aircraft
Installed propeller static thrust at different RPM
any other specs you would not mind sharing

Very interesting adaptation !!!

 

Edited by JimD
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Posted

 

Depending upon weight, would love to have 120 HP in an Avid/Kitfox

As for ignition and needed reliability, that's a tough one.  I'm guessing the ignition is synchronized with the turbo operations.

It sure would be great to see the sidewinder adapted!  So far it appears no one has approached it though.

It would really open up a huge market in the EAB community (far beyond the rotax niche) since some simple tweaks can put the motor up to 250 HP

http://mcxpressturbos.com/turbo-kits/snowmobile/yamaha/sidewinder/

But if  about 120 HP is what you want, then I think the RX1 motor seems like the way to go.  Simple, proven (to at least some degree), cheaper, and with conversions available.

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Posted

RX1 / Apex engine mount for Avid:

(For anyone who may of missed it in the general hangar)

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Posted

Progress

20170424_121939.jpg

20170424_123357.jpg

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Posted

Nice !!!! How is weight distribution? The angle is not so unusual, just wondering how balanced it turned out.

 

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Posted

Got some more work to do before I break out the scales.

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Posted

Here is a picture of the  engine mount glen (flyingwrench) makes and has for sale.

20170426_194001.jpg

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Posted (edited)

Since the RX1 is a 4 stroke, is it quiet in the cockpit? As compared to a 2 stroke.

Can you post a YouTube with your engine running?

 

 

Edited by JimD

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Posted

Since the RX1 is a 4 stroke, is it quiet in the cockpit? As compared to a 2 stroke.

Can you post a YouTube with your engine running?

 

 

The RX-1 turns upwards of 10,000 rpm on takeoff. Steve Henry had to do a lot of trial and error with exhaust systems. He said on his first version it was so loud that it was absolutely deafening in the cockpit.

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Posted

Since the RX1 is a 4 stroke, is it quiet in the cockpit? As compared to a 2 stroke.

Can you post a YouTube with your engine running?

 

 

The RX-1 turns upwards of 10,000 rpm on takeoff. Steve Henry had to do a lot of trial and error with exhaust systems. He said on his first version it was so loud that it was absolutely deafening in the cockpit.

Might be a good reason to start making the Swiss Mufflers?  EDMO

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Posted

Anyone have a recommendation for a analog tachometer preferably a 2 inch version?

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Posted

Anyone have a recommendation for a analog tachometer preferably a 2 inch version?

I got a 3" analog tack at O'Reilly Auto Parts - They may have a 2" version?  EDMO

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Posted

Anyone have a recommendation for a analog tachometer preferably a 2 inch version?

Recommendation:  Don't buy one. 

This forum is littered with stories of inaccurate and failed analog tachometers.  A digital tach  is far more accurate and reliable. 

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Posted

Any of the digital tachometers that I have looked at only go to 9999 rpm and it would be nice to have a steam styled gauge to match the rest. I am told that I need one to count 6 pulses pre revolution. Any suggestions where I might find such an animal in a 2 inch?

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