Yamaha RX1 Engines

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Posted

Very clean install.  What kind of trike is that?  Seems like quite a bit of HP for a trike.

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Posted

Looking great Teal! 

Send some pics of your Avid progress when you can!!

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Posted

Yes looks very cool :BC:

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Posted

Attached an engine today.

20170412_165116.jpg

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Posted

Yes looks very cool :BC:

in thinking about your prop pitch theory, remember.  HP tells you how fast you will hit the wall, TQ tells you how far the wall will move when you hit it.  I would be willing to be that the subie actually has a bit more TQ at a given RPM than the yammy does.  HP is not the end all to making a plane perform, without the TQ to swing the prop with a good amount of pitch you just end up beating the air into submission.  6-8 degrees of pitch is not really that much.  Each turn of the prop is really not pulling you forwards that much.

 

Take a climb prop for a 150 hp lyco for example.  say a cruise prop for it is 76X56 (in inches) the go to climb prop is either an 82X41 or an 80X42.  6° is going to be closer to 10 or so inches of pitch if that (I am just pulling that number out of the air so it is probably brown and stinky).. bottom line is, without the TQ to spin the prop at a higher pitch, what is really being gained.  The videos I have seen of the yamaha conversions so far have not really gotten me too excited about building one for a purely STOL aircraft. 

:BC:

 

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Posted (edited)

I think I have the Torque / HP curves for the EA-81, but don't remember if they show standard curves, or the modified cam curves which brings the peak starting from 4800 rpm down to 3600, or both, I think?  I cant see where turning 10,000 rpm vs 5000 rpm would give you the same engine life.  ??? EDMO

Edited by EDMO

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Posted

I would be more interested in the WEIGHT comparison.   Torque is multiplied in the gearbox.  

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Posted

Maybe someone can explain to me why turning a prop at say 6 degrees pitch is going to fly as fast as a the same prop at 12 degrees without doubling the prop speed, which you cant do without going sonic?  EDMO

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Posted

I can't explain it Ed but I talked to Sterba one time about these mysteries.   One would think that your speed would be equal to the prop pitch multiplied by the RPM but it ain't so.  It goes faster.  Has something to do with what sailors call apparent wind.....or something.  

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Posted (edited)

My reasoning is like Leni's - A flatter pitch climb prop will get you off the ground faster, but then it takes smaller bites out of the air than a cruise prop with more pitch at the same rpms, and don't go as fast.  That is where the IFA really performs!   EDMO

Edited by EDMO

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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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