What Makes The Rotax 915 Aircraft Engine So Special?

[@TravisB2323]

Just got a job working on these in sebring fl these engines are impressive they can go 2000 hrs and still have cross hatch on cylinder walls

[@RR-kl6sl]

Are you going to make one for the 916 also? Should be fairly the same but still nice to have a complete and updated one on that new 916 !

[@cyrooski4]

Great Video but you left out great things about the rotax engine.... About the Rotax engine: The case, barrels, heads and pistons are all of the same aluminum metal which contracts and expands uniformly eliminating the problem of shock cooling. The oil is in a canister and not at the bottom of the engine so it has two traps so that air can never get into the case eliminating condensation and damage from under use. The carburetors never experience ice so there is no carburetor heat in most planes. The heads are liquid cooled so the cylinder head temperature does not rise above 230 eliminating the possibility of softening aluminum and giving hot spots. If cooling fluid is lost due to leakage the engine may still be flown. There is no leaning mixture knob.... it is done automatically. So the pilot cannot damage the engine. Running at higher RPM you can get the same power as a heavier engine by having the cylinders closer to each other reducing the weight of the entire engine so the weight to power ratio is very good allowing 4+ gallons per hour consumption. Lycoming and Continental do not want a gear reduction unit so their engines must turn at the rpm they want the prop to turn. This sacrifice gives us big slow pistons with a lot of bang, not good for longevity. The cylinder attach bolts are computer torqued in the factory in Austria and stabilizing mechanisms are used during the torquing process to ensure balanced forces. All torque values are saved in the engines computer files at the factory. The crankshaft is made of five separate pieces not including four piston rods. If part of the crankshaft is damaged one does not have to buy an entire new one. The prop also has a breakaway clutch from the crankshaft in case of a prop strike to protect the crankshaft. Built with very few seals and gaskets, instead they use a paste, leading to less leakage. No alternator to buy or magnetoes to rebuild. Mogas ready. One dollar less per gallon, so effectively a 16:50 fuel cost ratio compared to to an o-360.

[@MrZrryan2]

funny how a guy that knows so much about Rotax and is obviously a fan, omits to mention the price...

[@turbotimthree]

About 38,000. So…….?

[@mickvonbornemann3824]

Are the heads shrunk screwed or bolted down or both?

[@ronblondeau6631]

The best explaination of how an aircraft engine works I have ever heard Mike. Thank you.

[@FourToedJones]

As a car guy, it's nice to see turbos and computer controls in small aircraft engines. Looking forward to seeing your fuel burn when it's finally flying!

[@nichooo6423]

its around 8 gallon per hour

[@nichooo6423]

The fuel burn*

[@1anre]

I’m happy to hear they don’t have the turbo nightmares Car’s like the 335i BMWs that have turbochargers have

[@goldendemise3165]

You should check out viking aircraft engines

[@louissanderson719]

Nothing new

[@toadman506]

Mike, One Addendum, if you are running 100LL in that aircraft your oil change times will be more like 25 hours, and that will include the oil tank as well, the lead builds up FAST. Rotax Engines have some unique maintenance issues. If you Haven't attended, or haven't planned to, I would seriously suggest you attend one of the Engine courses run by Rotax through affiliates, as you are going to be doing your own work on the plant. The Sling looks Great, Good Luck with it. There's a discussion on oil change times at the link at the end. Remember one thing Oil is Cheap, Engines are not. Engine oil Analysis costs around $25..also a Cheap expense that can tell you about problems LONG before visible metal starts showing up in filters and sumps. www.rotax-owner.com/en/912-914-technical-questions/1437-rotax-recommended-oil-change-interval-100ll#:~:text=Page%2016%20of%20Section%2005,this%20changes%20to%2025%20hours.

[@PlaneMechEsq]

From my google search, it seems the 915 can take E10, so a fill up would take no more than a jerry can and a trip to any gas station; this sound very attractive. But I wonder how reliable the engine is in the long run compare to the legacy engines given that the 915 only came out in 2017.

[@andrewmorris3479]

Chow Yun-Fat Extremely reliable if not more so. The fuel injection system is the exact same as the 912 iS and they already have more than 10,000 hours on test stands with the 915.

[@Kennardy]

Extremely well explained! Great channel. I hope Sling is “sponsoring “ (paying) you as you are making a lot of people desire a Sling!

[@travisbrunner3335]

Agreed! I was always looking at Kitfox but now this is intriguing me. Plus the potential high wing

[@1anre]

@@travisbrunner3335 what did you buy in the end?

[@ndakigeorge8147]

Wow..I am not an engineer but based on your explanation I think I got a pretty good understanding of how this engine works and If i were to choose an engine , I think I'd be able to make an informed decision...Thanks a lot Mike, keep inspiring us. All the way from Tanzania, East Africa.

[@JonMulveyGuitar]

Go MojoSling Go!! Getting close! Can't wait to see it again! Heading down to Sling in two weeks to fly the TSI. Thanks to you! Very informative content here Mike! Great job!

[@OscarDad]

Mojo, Im a newbie just stumbling into the workd of LSA. I live abt 30 min from VANS in Aurora, OR, so spent a lot of time looking at them. Your channel is awesome, thank you, and the SLING is a real eye opener. They look incredible. Thank you again for yr content ! 👍

[@Jimidan1000]

Be like Mike! He knows his stuff. I have been a huge fan of Rotax engines due to them being in my sportbikes. Motorcycle manufacturers using Rotax engines, either Rotax-branded or branded for the OEM, include Aprilia, BMW (F and G series), Buell and KTM. [citation needed] Can-Am resumed motorcycle production with a series of on-road three-wheel motorcycles, starting with the Spyder, using Rotax engines.

[@pierrelaband]

Your best video because each item was explained in understandable detail accompanied by examples in cars, etc.

[@SalveMonesvol]

I've been looking at Rotax engines, and the only thing I'm not sold about is the high rpm. I'd rather have a somewhat larger engine (2.0L) doing max power at 4.000 rpm. That way it could also be connected to the prop without a gearbox. Is there an engine like that?

[@1anre]

Great primer on turbocharged engines, ECU power management & power-to-weight ratio dynamics. Good job Mike

[@jhmcglynn]

I sold my turbo charged Mooney 231 in 2010 after flying it over 2000 hours in the previous 15 years. The Continental TSIO 360 produced 210 up to 15,000’, and gradually less up to its service ceiling of 25,000’. Likewise I’m sure the 915is will produce much more power than a normally aspirated engine up to its service ceiling. I owned a KITFOX SPEEDSTER running a ROTAX 912. It’s a great engine.

[@mcanning51]

Thanks Mike for that great 👍 explanation. Good luck with completion of your Sling LSA.

[@discerningmind]

Very good Mike, thank you. Pump gas is a plus but my thought is to use 93 Octane as I understand the valves run cooler the higher the octane.

[@sm719c]

You should do a fly a fan giveaway once your plane is done!

[@baomao7243]

Give away the Mojo Sling TSI ? 😳 YES, count me in !! 😉

[@ODowney1]

Thought I knew it all, well from you I learned something more regarding turbocharging. Thank you

[@ikay2102]

Mike i can listen to you talk for hours !! Great videos.

[@feinbush]

awesome Vid Mike!! Really a cool modern engine vs the traditional designs that are over 50+ years old! keep up the great work cant wait to see Mojosling fly!

[@richardcollins3825]

Great break down Mike. I am finishing up my 915 install on my Kitfox. Super excited about the new performance I'll be seeing.

[@FarrellMcGovern]

Thank you! That's a great explanation of why the Rotax 915 is such an awesome engine. I've always known they were popular with the experimental crowd, but I never knew why. Now I do. Thanx.

[@andrewmorris3479]

It’s also a certified engine too.

[@pappybo49]

Mike, you did an excellent job on this review. You explained the 915 as well as any Rotax rep ever could. You’ve really learned a lot since starting this plane and I have learned a lot of second hand information from you. Good job 👍 and thanks for sharing. How’s that beautiful baby girl doing?

[@dwayneharris3874]

I am looking forward to seeing your Sling fly and hearing all about what you think of it, once you gain experience with it. It looks like a thoroughly modern aircraft.

[@budrohammbone2806]

Well Done ! An Excellent Overview of the Rotax 915is.

[@peredavi]

Great explanation of Rotax 915 is. I’m planning that engine on a SPORTCOPTER AUTOGYRO. Sling is nice looking plane. Cheers.

[@miguelwall2128]

The ECU would also monitor density and automatically adjust turbo power output based on throttle position and density altitude. Thats why a turbocharged car for example would perform the same at higher altitude as opposed to sea level level, but a normally aspirated engine would have reduced performance and a carburated engine would need an adjustment the fuel to air ratio (reduce/lean fuel due to less density). In addition to supplying cooler air, the turbo is a compressor, compressing that air before the intercooler to supply both cooler and denser air to the engine. In essence acting as though you're at a higher altitude (requiring leaning/less fuel), but with also the added benefit of more density (even better than at sea level on a standard day), while producing more power. The result is the engine runs more efficiently while using less fuel. That's a wonderful engine! Just wish I could afford a build like this.

[@MusicGodsNFT]

Nice video Mike. Thank you! I am curious what type of fuel burn you are seeing in actual flight on average. Cheers to you.

[@hedonzx822]

Once again Mike a very crisp clear presentation, can’t wait till you get to a million subscribers 😇👍🏻👍🏾 You are a great Ambassador for Aviation.

[@prtcgv5105]

Congrats man, beautiful airplane + most efficient powerplant!

[@endolphin]

Wow this video is so great and super informative!

[@timm1583]

I like that rotax is changing the game a bit for lsa. Would love to see more powersports manufacturers putting out airplane engines. To bad Yamaha, Honda ect. won't put out a product. Yes you can get a 3rd party conversion but the amount of R&D these companies have is more than Lycoming or Continental could ever dream of

[@GeneralSirDouglasMcA]

Oh gosh, Honda would dominate if they produced aircraft engines (other than the Hondajet).

[@timm1583]

@@GeneralSirDouglasMcA Do they even make the jets in it?

[@brknbike]

If Honda produced a dedicated engine it would dominate the market, hands down. imo

[@andrewallen9993]

@@brknbike As you cannot be towed to a maintenance site when the engine fails a Honda engine would be a very bad idea from my experience with Honda cars and motorcycles failing without warning. An obsolete rebuilt VW beetle aircooled engine is a much better idea, there are many valid reasons why they are so popular.

[@neocor2000]

This is the piston engine of choice I have been looking at. Either this or one of those small turbines like in Mikes previous vid. Quick google price is 37k USD around 54k AUD as Jun 21. Look forward to seeing this fly

[@MrZrryan2]

That is the price for the engine, and ONLY for the engine. You need another 15K for an engine mount and all the required accessories. Easy to spend well over 50K USD on a new 915. (which is the ONLY real drawback of this engine, IMO)

[@warrenlovell3919]

Love your channel Mike. Great info.

[@blyz_69]

Outstanding detailed explanation. Thank you!

[@craig2100]

Great job Mike... getting excited to see your sling

[@woodbark1008]

The normally aspirated engine is only capable of "breathing in" an amount of air relative to its capacity and low restrictive flow capabilities of it's intake passages. as well as atmospheric conditions. So in order to coax more power out of an engine - along comes the Air Boost systems to introduce more air into the combustion chambers. "Ram Air" system - "Turbo Charger" or "Super Charger"

[@vincedenimarck6498]

Great info on the rotax, Good job again Mike

[@Amduarteoliveira]

Beautiful engine!

[@BruceDuncan]

Maybe the 915 turbo is different but I believe there is a bit of maintenance required on the 914 wastegate to ensure it stays lubricated. They can stick, so you need to check it and drip some light oil on it every now and then. They are great engines though!

[@SantaZeede]

California must be the only place where car gas is about the same price as avgas :( Great video, Mike! I'd be really excited if Rotax can start making higher horsepower engines to work in legacy four seat airplanes.

[@scottquadrelli6688]

Loving these videos, really helping me with my future sling build. Have you done videos of the engine install ?

[@alexwonner7469]

We keep watching and you... keep working!

[@alexandrenazario7857]

I liked my Rotax engine,,,,god job Mike...

[@TheSchwartzIsWithYouToday]

Great presentation. You're big on Bristells, and I watched a video on their latest B23 Turbo that has this engine in it, along with a vari-pitch prop. I guess other Bristells have fixed-pitch props. Have you done any videos on fixed vs. variable speed engines and the trade-offs?

[@rallwest]

What is the difference between a Full FADEC and a FADEC? "Full Authority Digital Engine Control"? is a Full FADEC a Full Full Authority Digital Engine Control?

[@Mrcaffinebean]

It’s surprising to me that every new plane isn’t running turbos and ECUs. These things have been standard in a lot of cars for well over 30 years.

[@1Echo3]

Nice review great job !!

[@ultralightflyer]

Those Sling are very look like Tecnam.

[@guyshilon2807]

Very well informed, I enjoyed every second

[@imriel33]

your are incorrect in how you are selling the turbo, even a vw gti which is turbo'ed and built for daily driving, the turbo will wear out in time, the life maybe longer than non FADEC but should still be checked for play on every annual/100 hour or how ever often EAA aircraft are done, no disrespect, love the channel, i'm an AMT/A&P

[@RawTopShot]

Also, every turbocharged engine has a wastegate; it's integral to the basic functioning of the turbocharging process.

[@sehliamal9105]

is there a system to control this engine in unmanned aircraft plz ??

[@mwenyadaka3367]

This engine is nice in terms of cooling system, the dual cooling system air and liquid, it's so powerful and also good in terms of fuel economical because it can also use car gas

[@RawTopShot]

I have visions of him rolling up to a regular gas station in the middle of nowhere whilst on a long cross country flight and the gas station attendants naw dropping 😂👍

[@bedhonk]

Hi mike, i have rotax 915, i will plug in with 2 blade wooden propeller, how about the plate on hydraulic governor interface, it must remove or not?

[@tjflynn1014]

Another great video Mike. You mentioned you didn't care for the exhaust note because of the higher rpm, but then you also stated that it was quieter. For clarification, is this engine quieter in the cockpit, in comparison to something like the Lycoming IO-360? Also, do you know of any ADs on the Rotax 915? I know it is fairly new engine, just curious.

[@N741SP]

Well done Mike.

[@guitarsarelikestupid7200]

I wish I knew more about A&P.

[@mrinvader]

i love the way you explain things!! #savethe310

[@aryaeskandari4852]

Thank you, Mike Learned many things I really need to find out one answer. Is it possible to use 915 Rotax in pusher propeller aircraft? The main concerns are breathing and cooling systems.

[@mojogrip]

Yes. This gyroplane does kzbin.info/www/bejne/naiUeImfn9WeZ5I

[@jshbontjer]

Nice overview, great narrative! I’m sure it’s going to be a great plane.

[@Christoph1888]

Is it "direct fuel injection"? Or just fuel injection via the intake manifold?

[@supartianatiana978]

Great use fadec

[@davejohnson8960]

Awesome. So what's the deal with props. How's the pairing of the 915 with a constant speed? And what's the deal with a constant speed being paired with the 915 (I think Bristell is doing it) that is a self regulating constant speed...part of the 915 engine?

[@Arjuna86004]

Great review Mike! Consider distinguishing between the standard legacy engines and the experimental legacy engines. I chose the Lycoming YIO-0233 for the reliability of the legacy design with fuel injection and FADEC. Cheers and good luck with your Sling build. David

[@andrewallen9993]

The Sling. An aircraft designed and manufactured in Africa by Africans for worldwide assembly.

[@c-teamtrading9690]

Excuse me. Not Africans! but South africans. Africa is a big continent

[@jdsstegman]

How long has Rotax had this motor? Last year they finally made a factory turbo'd 2 stroke snowmobile engine!! About time!!

[@garyturner1612]

Mike, I love your videos! Your talks are always very interesting and informative.

[@rizkidwi7504]

What the price engine rotax?

[@c-teamtrading9690]

Reading off a board. Plane built by the Aircraft Factory South Africa , not a kit assembled at home ?

[@spiro5327]

Where is the mixture control ???

[@hectordisla]

NIce video Mike!

[@conservativeokie]

Hey brother…. To escape the unwanted noise, pull your carpet as well as your panel and install a layer of Dyno-mat. It is heavy as shit, but unbelievably effective and somewhat fire resistant. You will either not hear the engine very much at all, or reduce it and other cabin noises to the point of insignificance. Just my 2 cents, which, realistically is probably worth zero, so free, or, maybe I actually owe you money for listening to my advice? Damn Mojo! WTF??? 😂🤣😂

[@LTVoyager]

I am looking at the 915 for my S-21. Do you plan to show more detail on the various engine system installations? Electrical, exhaust, cooling, fuel, etc.?

[@andrewmorris3479]

Do it. 145 mph on 7.3 GPH is too great to pass up! Perfect combination for that airframe.

[@kevinbutler9786]

My understanding is that his version of the 915is is specifically for the Sling TSi. The intercooler, oil cooler and radiator are routed specifically for that cowling layout. Same for the 912 and so on. But we get them crated in that layout already to bolt up. Contact Kodiak engines and they will have the info.

[@mikemyers7317]

Great info, thanks. Is she finished?

[@toddy2519]

Mike, what's the cost of this Rotax?

[@mojogrip]

$37k

[@kurakuson]

Looks like the engine used in the newer high-end German Built Autogyro Cavalon (gyroplane) at 180k.

[@johnbell6114]

Mike said he will use car gasoline? Can it be bought for airplanes without all those road use taxes? It seems avgas 100 low lead would be chesper without road use taxes? I'm just learning, but plan to take lessons, asap. Building a plane is a good idea but don't u have to be an AP certified mechanic? Or just psy one to inspect your work? I have much to learn. Thanks gor excellent video, Mike.

[@nateb19]

John Bell car gas is typically much cheaper than 100LL in the US

[@oisnowy5368]

Great choice for an engine! I presume that due to its efficiency, not only can it maintain power at higher altitudes, it can probably do it at lower fuel consumption. Got any idea about that?

[@mojogrip]

The efficiency is all the way. Although you get more speed out of it at high altitude.

[@deedsmillar6056]

So, are you saying that this engine is just as sophisticated as my '92 Jetta? Does it have an odb2 port to clear the check engine light , or do you have to put tape over it? I dont think this explanation of turbo is very informative. Doesn't a Wastegate bleed exhaust gas and not boost? Maybe that's why it sounds different perhaps.

[@ajman9351]

Interesting info on the 915 Rotax. Question about the Sling TSI. Does it have air conditioning?

[@mojogrip]

You can add one. I'll be featuring one soon on the channel that has air conditioning

[@ajman9351]

Mike, Thank you for your response. I look forward to the video. I'm curious to learn about the Pros and Cons and if you will add one to your plane.

[@dangrass]

Interesting that the Rotax 91x series don't water cool the cylinders, and don't use overhead cams. While aircraft engines don't need to rev much, the use of pushrods creates less than optimal combustion chamber design, more reciprocating mass, and several points of leakage. As for the cooling, if you're going to have a radiator and water pump, then why air-cool the cylinders? Odd design choices, but these engines are certainly an improvement over the ancient Lycoming and Continental engines.

[@fransiscozip1459]

Bravo .goode luck. For 8 k you can find helichopter jet engines..miltary surplus freshly sand blasted slightly used but..im thinking ultra light gyro- chopper...

[@ImNotADeeJay]

it boogles me that you can buy a brand new Camaro for the price of that engine... private aviation is a hobby for the rich it seems

[@jsullivan05]

You can buy a used 912 for 1/10th that price.

[@EJWash57]

Used to be some families would forgo a second car and be able to afford an airplane. Today? Not so much!

[@xpeterson]

Tabris you can buy a used Camero for that price. It’s weird to me when people talk about affordability by comparing used things to new things: “Yachts are expensive. A new yacht costs as much as a large new home” “That one that sunk over there is a handyman’s special, yachts are affordable” “Ok.... but that yacht that sunk costs as much as a condemned property” Compare similar things.

[@Factory400]

Does the Camaro go 165mph continuously for 800 miles......over lakes, rivers, hills.....etc??

[@kevinbutler9786]

You can buy a perfectly good airplane for $30k. That engine he is talking about is literally the most advanced engine you can get for general aviation. You could also buy a brand new camaro for the same price as a Ferrari engine. We can play the what you can buy for game for almost anything.

[@chrissanchez9935]

Has anyone tried to fit the 915 engine in a Cessna 152 airframe?

[@alexlo7708]

Normally plane engine run at constant power so it's turbocharges are less likely wear down as car engine. But diesel engines are more robust such centurion engine.

[@operator0]

I don't know anything about the 915. Does it have two ECUs, like many of the modern electronic fuel injection aircraft motors do? I know Diamond does this with their diesels.

[@tennesseewoodsigns8637]

Great info. Thanks!!!

[@projectcontrols]

Mike, is that a reliable engine? I’m told that the failure rate is higher than a Lycoming. Can you please comment? Thank you.

[@Feedback4Utoday]

that is a misconception... based on Rotax also making 2 stroke motors... & much lower cost $ much lower HP. evidence is this series is very reliable.

[@YourFriendlyGApilot]

Hi Mike, love your channel, I've been following along with your awesome build! I know you love the Pipistrel Panthera, so did you ever ask the folks at Sling if there is any hybrid or electrical engine compatible with the TSI?

[@mojogrip]

We've discussed engine alternatives. No electric or hybrid but I know of a turboprop engine in the works.

[@smoothuncut]

MOJOSLING doing Barrel rolls soon! Hi Mike!

[@mikewatkins1197]

Excellent and interesting video

[@thisismagacountry1318]

It's a cheap throwaway so TBO is not a concern? I'm an aviation noob, but that's what I've read so far. Is that accurate?

[@timduncan8450]

Mojo Always enjoy your enthusiasm! Fuel burn at %’s and altitudes? What is max altitude and best ground speed altitude? Going above FL 150 could be very useful for speed and or weather avoiding.

[@lavina58]

Awesome, thanks 🙌🙌👌👍😊🙏🍀

[@jakaria4466]

Bro how much it cost rotax 915

[@MrZrryan2]

over 50K USD once you get the engine, mount, and all the required accessories

[@starman10548]

GREAT REVIEW.

[@kevinbarry71]

Is the turbo liquid cooled?

[@andrewmorris3479]

Liquid cooled heads and air cooled cylinders.

[@kc9scott]

I think this question is about how the turbo gets cooled, not the engine. On car turbos, prior to the mid-1980s, it was common for the only cooling of the turbo bearings to be via the oil. After that time, water jackets on the bearings were almost always added to car turbos for better cooling. I’ve done a turbo replacement myself on my 1992 DSM. For this Rotax engine, I did a quick look at their manual “Maintenance Manual Heavy” in the section “turbo removal”. I couldn’t really tell from that. It has a single bullet item for “Remove coolant hoses”. However, in the pictures with numbers indicating parts, and the numbered procedure for turbo removal, there is no mention at all of the coolant hoses. So I can’t tell from that whether those coolant hoses have anything to do with the turbo. I would guess not.

[@Asturiano53]

Great stuff!

[@vagabondwheels3002]

Just curious about the engine configuration - how many cylinders, displacement, two or four stroke, etc. Maybe dumb questions but I don't know anything about this engine except I think it is Austrian.

[@MrWATCHthisWAY]

It’s a four stroke with four cylinders.