Edge vs Stock Rotax

[iflywhatevr]

So I’m getting ready to order the firewall forward kit for my STI build. Initially I was looking at the 915is although I’m a flat lander I’m looking for exceptional short field performance and I fly turbine powered airplane for a living and personally own a turbo pressurized piston twin for fun now so more power = more better lol. The Edge Performance 915is seems intriguing. About 30k with the performance of a 915 with the weight savings of the 912. Anyone installed one of these? I know it voids the warranty but what is the realistic TBO and performance vs the stock 912 or performance vs the 915.


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[Jcard]

My hangar neighbor has the edge performance rotax 912 with the big bore and fuel injection in a eurofox.
Runs super smooth on the ground and flies circles around my model V with a 912ULS.
Mike at Stolcreek Aviation in Kansas did such nice work on the installation that I ordered a 912STI from him for the model 7.

[Mark123]

David,

I think you may want to talk with Dustin Dickerson. He and his brother just built two STi’s with that engine. Look up the “Dual STi build log”. He has been very thorough with his build information.

Mark

[Shadowrider]

Thomas makes top notch products. The EP912STI pulls hard and performs great. Of course turbos are not for everyone. Edge has made some great improvements and continuing to innovate. Power to weight is very impressive on these engines. If you’re goal is short stol, have you taken a look at the epex 300hp? No one ever said I wish I had less HP.

[aviator79]

I have a 914 that was built by Edge. I added the injection kit after about 100 hours on the carbs. It idles much smoother with the fuel injection, and I'll never sync the carbs or have to weigh my floats, etc. It's a really nice upgrade in that regard. Some thoughts:


Edge has sold a lot of these kits and has a lot of engines out there, but they don't have nearly the operational history of Rotax generally, so I don't think an actual "TBO" number exists that can be compared to a stock Rotax number. To my knowledge Edge does not publish a TBO figure.
I know of a couple failures of Edge engines, but anecdotes are not data. Most of the complete engines sold as "EPXXXXX:" are pretty heavily modified. These aren't just Rotax engines with some bolt-on components, so you can't assume that they have the same reliability characteristics of whatever the donor engine was.
You will not have the same level of documentation as you would for a stock Rotax engine in terms of service, maintenance, repair, and parts. You will have to rely on Edge's support of the many bits that aren't from Rotax. Fortunately, in my experience, the customer service from Thomas in Norway has been excellent. New engines sold in North America are supported by Jason Busat at BadAss PowerSports, and by Mike at StolCreek who I think is some kind of sub-dealer for Jason.
Edge runs their turbo engines hard. I saw a YouTube video of someone with an Edge engine mention that their takeoff was at "ONLY 40" of MAP". That's the absolute max for a 914, and even then there's a 5 minute limitation on anything over 35". For the weight, you can expect outstanding performance vs a stock Rotax because you're running it at substantially higher power, which means a substantially higher Brake Mean Effective cylinder Pressure (BMEP). Generally speaking, BMEP does correlate negatively to engine longevity. Edge believes that their modifications allow their engines to be run this hard without a substantial impact to reliability. But the data are still very sparse compared to Rotax, Lycoming, TCM, etc. The nice thing about their setup is that you don't have to run that hard. You can have them tune your ECU to not flog the engine quite so hard. There's even an option for a cockpit switch that will give you a max performance tune only when you need it. (Which if you're honest, you probably almost never do.)
You do have new and different failure modes. The engine will not run, at all, if you don't have electrical power. This can be mitigated with a second alternator (may be standard on their engines now), or a backup battery. Proper wiring and careful attention to the state of your charging system become more critical. If the ECU or any wiring fails, you're a glider. This should not necessarily be blown out of proportion. All airplanes and engines have several single-point failure modes. But it's a risk that should be identified, considered, and managed.


I continue to trust my Edge engine, although it is not as heavily modified, and I do run it well within 914 performance limitations. Basically, if you want the most redundant, reliable, well-supported, well-documented engine, buy a stock Rotax. If you want a turbo, fuel-injected engine at less weight and expense than a 915, and you're willing to accept that the reliability and longevity are not as established, consider an Edge engine. I know zealous Edge advocates, and I know personally of a catastrophic failure that gives me some pause. I can say that the level of service I've gotten from Edge when I've had hiccups has exceeded every expectation. Maybe that's not the clear thumbs-up or thumbs-down you're looking for, but I hope it's helpful.

[Shadowrider]

Brian makes some great points that I agree with. One thing I like about the Edge engines is the ability to tune the ECU. Rotax does not let you into their ECU, for many good reasons. You can adjust power levels and you can adjust AFR/EGT's on the Edge engines. Of course you better have a good understanding on what your doing or you can get yourself into trouble really quick. Like Brian said, you can tune the engine to run 914 equivalant or less power and you should see reliability that I would argue "could" be better than a stock rotax. If you are considering a 914, I would highly recommend going with what edge calls the 915. (They came out with it before the 915 release I guess) I really like that engine because the power levels are low enough you they don't touch the bottom end. The crank is NOT welded and they have left the bottom end alone. If you are like me, and wanted more I went with the EP912STI. It has been more modified than the 915. I have gone with the higher flow oil pump to help with the oil squitters that are using lower end oil. I have the upgraded to the 35 amp second alternator, and also have the upgraded exhaust. Always happy to talk engines if I can help anymore. Mike at STOL creek is very knowledgeable. I have spoken with him multiply times and he has been a rotax service center for years so he understands these engines. Give him a call!

[iflywhatevr]

David,

I think you may want to talk with Dustin Dickerson. He and his brother just built two STi’s with that engine. Look up the “Dual STi build log”. He has been very thorough with his build information.

Mark

Thanks Mark I will check it out!


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[iflywhatevr]

Thanks Aviator!

I did speak to Mike at StolCreek and he was great although complicated my decision a bit by adding even another option to the mix lol. We talked about reliability and TBO of the engines and how Kitfox says they don’t support Edge engines.

Sounds like the EP914TI might actually be a bit of a better option for me it maintains a 2000 hour TBO has an intercooler option now and basically fits under the standard 914 cowling with only the need to add a NACA scoop for the intercooler.

It’s actually less expensive than the 912STI I think he said $32k versus the 37.5 for the 912STI because it is a 914ULS that has added fuel injection and tuning versus the 912 that’s basically torn completely down and modified with the labor expenses involved there.

The fact the I can use the 914 firewall forward package it sounds like is also a plus. The weight without the intercooler is about 4 pounds less than the standard 914 so I imagine with the intercooler is about the same and puts out 125HP. I would personally not run any turbo without an intercooler. Sounds as though it may be a good compromise between reliability and performance. Need to do a bit more exploring on whether it will in fact bolt on with the 914 firewall forward kit with only the scoop modification.

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[iflywhatevr]

Brian makes some great points that I agree with. One thing I like about the Edge engines is the ability to tune the ECU. Rotax does not let you into their ECU, for many good reasons. You can adjust power levels and you can adjust AFR/EGT's on the Edge engines. Of course you better have a good understanding on what your doing or you can get yourself into trouble really quick. Like Brian said, you can tune the engine to run 914 equivalant or less power and you should see reliability that I would argue "could" be better than a stock rotax. If you are considering a 914, I would highly recommend going with what edge calls the 915. (They came out with it before the 915 release I guess) I really like that engine because the power levels are low enough you they don't touch the bottom end. The crank is NOT welded and they have left the bottom end alone. If you are like me, and wanted more I went with the EP912STI. It has been more modified than the 915. I have gone with the higher flow oil pump to help with the oil squitters that are using lower end oil. I have the upgraded to the 35 amp second alternator, and also have the upgraded exhaust. Always happy to talk engines if I can help anymore. Mike at STOL creek is very knowledgeable. I have spoken with him multiply times and he has been a rotax service center for years so he understands these engines. Give him a call!

Thanks Shadow! I do appreciate the ability to access the ECU. Part of the reason I went with the Yamaha 998 engine on my Sidewinder was the ability to do push button tuning to go from the stock 200HP to as high as 300+ when the fun requires. I’m probably like you more power is always better! Thought about the EPex or similar but think I want to stick with something Rotax for parts and service if needed. Good to know about the second alternator as well any idea if it’s a standard size/weight or reduced as it’s just a backup?


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[aviator79]

Need to do a bit more exploring on whether it will in fact bolt on with the 914 firewall forward kit with only the scoop modification.

Almost exactly what my engine is now. The 914 FWF will work. You'll need intercooler ducting, and if you get the big second alternator, you'll have to cut a bar out of the engine mount.The smaller 15A alternator might fit without modifying the mount.

[Shadowrider]

For the EP912STI I did the 914 FWF kit, and just removed what was not needed. Actually the 912 FWF would work also. (Motor mounts are the same for both I think but make sure to confirm) Fuel lines and intake ducting, naca vents, throttle cable will all need to be sourced, but not hard to do. The EP 35 amp alternator is great. In your pictures you can see it in the top picture. It hooks to the flywheel and the flywheel housing is extended. Not sure the weight probably a few pounds. Like Brian said you need to remove the cross member on the motor mount so the housing will clear. The cross member is there to help support the nose wheel. If you doing tricycle gear I would go with the 15 amp because you want that support for nosegear, but if your going tailwheel I would go 35 amp. The stock one stays inside the flywheel and this attaches aft. I run 35 amp as primary and the 18 amp as a backup. If I go to 18amp backup I will need to load shed some to stay under limits but it will get me back home fine.

[AMK53]

I've looked at their engines a lot because I've wanted to switch the engine on my Kitfox to something more practical (and still remain affordable), but I've always come to the same conclusions as Brian has. They are pushing that 912 really hard and there's just not a lot of hours on those engines to convince me of reliability. I know they say they have a lot of engines flying, but that doesn't really mean much if all those engines have a handful of hours between them. You really need lots of engines flying for lots of hours to get a good sense of whether their design is robust or not.

One thing I would be willing to do is to take a stock Rotax 912is and add their turbocharger to it. Has anyone used their turbocharger and know if it's reliable and easy to add?

[Shadowrider]

To my knowledge they don't do anything with the 912IS. I think its to much brain damage adding a turbo to that and I don't think anyone has "cracked" the rotax ECU.

[aviator79]

To my knowledge they don't do anything with the 912IS. I think its to much brain damage adding a turbo to that and I don't think anyone has "cracked" the rotax ECU.

Definitely true. I'm certain there will never be an aftermarket turbo option for the 912iS. If you want Rotax's fuel injection and a turbo, the 915i$ is your only option. (And a great one if you have the budget!)