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Thoughts on RX8 Engine…

Beejer

Member
So I couldn’t sleep… not strange. So my mind wandered onto my o320 in the RV6A and drifted to the “strange that the engine is such an old design, wish it would just start and lean itself out, fuel injection would be nice, electronic ignition” debate started in my head. So I started tooling around and found RX8 Wankel engines. Less weight (talked to an importer, about 320lb without gearbox but still including heavy intake and exhaust and all car accessories that could be adjusted for flying or removed) , more power (again, he estimates 211HP), fuel injected, less vibration, electronic ignition that should self regulate and it burns regular fuel so it should be future proof against whatever they decide to do about leaded AVGAS.

I know it would mean a new cowling, figuring out how to get air through the radiator, and a new engine mount (and 1000 little things I’m not thinking of). Just kinda wanted to see if anyone had looked into it before and why you did or did not go through with it. I really see good potential on these engines and have seen the video of the guy who did the climb record to 10,000 in his Wankel RV8. What are people’s thoughts?
 
The Wankel used to be pretty popular, but they have faded off a lot.

PSRU needs are a biggie, also exhaust on these engines is a LOT hotter than typical Lyclone.

Several folks have been flying behind them for a while, hopefully some will chime in and tell their stories.
 
Turbo help with exhaust temp?

My other dream is to add a turbocharger to the engine to get me up above the clouds (and breathing that pure oxygen, can’t really justify the cost when I’m on the ground… hehehe). :D

Would that help with the exhaust gas temp (eating up energy into motion) or would it just keep it in the compartment longer making it hotter?

Also read that the ceiling on my RV6A is 25,000? Not sure that my engine can even make it past 10,000 right now. Felt like it was losing power at 8,000 when I flew it up to NY (just bought it and then began upgrades so my data points are low. It was a hot, humid day too so not sure how that effects the power) and I’d like that extra power high up.

Thoughts on turbocharger?
 
I haven't followed the rotary world in a long time, but did Mazda ever fix the issues that were causing the RX8 motors to blow up with like 30k on them? My friend had one when it first came out and had a motor replaced at 25k under recall. I've got nothing against the idea, just maybe some concerns over that particular motor.
 
I had a Renesis engine built by Bruce Turrentine may years ago to put in my Cozy MKIV. Shortly there after, Real World Solutions closed up shop and no more support for their PSRU’s or engine control module. I sold it at a steep loss.
 
So I couldn’t sleep… not strange. So my mind wandered onto my o320 in the RV6A and drifted to the “strange that the engine is such an old design, wish it would just start and lean itself out, fuel injection would be nice, electronic ignition” debate started in my head.

I think you could get most of those things at far less time, effort, and expense by installing one of the various EFI packages on your O-320. There'd still be some work to do but you won't need to come up with an engine mount, gearbox, cooling solution, and more.
 
I think you could get most of those things at far less time, effort, and expense by installing one of the various EFI packages on your O-320. There'd still be some work to do but you won't need to come up with an engine mount, gearbox, cooling solution, and more.

Agreed. Even though a bada$$ turbocharged Wankel would be really cool, modernizing your lycoming with electronic ignitions and electronic fuel injection would be much much easier. SDS and EFII sell kits that are easy to install and really do modernize these old technology air-cooled engines.
 
915iS

Your requirements sound super close to a Rotax 915iS. Check out those numbers. It will give you electronic everything, Turbo charging…
 
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For what it's worth - I'm flying behind a Subaru on my Jodel and truly love it. To the point where I am swapping the engine on my RV3 to a Subaru as well.

HOWEVER....

It has taken me three tries with three different engines, gearboxes, propellers and ECUs, at least 1500 hours of modifications, several years of spending online researching, talking to hundreds of people, filtering out the golden nuggets from the opinions, several steaming landings and enough money to buy myself two brand new O-320s to get to where I am now.

If you just want to fly, don't go here. Just don't. Really.

Me, I am too stubborn to quit anything, and so I persevered. And I would do it again (AM doing it again, actually), but that's just me. If you are up for one heck of a learning curve and want to see this through, then by all means forge ahead. This path is paved with failed projects though.

jodel_subaru.jpeg
 
Good food for thought

I like redundancy and I guess the one engine I have along with a chute will do the trick to ease my anxiety. I know the stats say I shouldn’t worry but that’s the thing with anxiety. It’s irrational.

Still not gonna completely forget about this especially with an importer so close to home but I think this has helped me move on in my mind to better projects.

Thanks all. Great discussion.
 
Tried and True

BZ, back in the Jurassic age my buddy Tracy Crook and I built our RV4s, sharing tips and ideas on DRs Yahoo group that predated this site. Tracy however being the over achiever he is, engineered a Mazda 13B rotary power plant installation when the rest of us were trying to figure out how to back rivet!

His tireless efforts, engineering prowess and perseverance created a small following and megabytes of data as well as his own fuel injection and planetary reduction. He’s since retired and still flies his now Renesis powered RV4 and 20-B powered RV8.
He once jokingly told me and several others gathered around his RV4 at a Waco TX flyin (sponsored by DR)

Guys, you want to fly with no issues, install a Lycoming, if you like to tinker and don’t mind an occasional forced landing, install a Rotary!”


https://youtu.be/GlR4j0FTcNM

V/R
Smokey

https://www.rotaryaviation.com/aviation-history.html
 
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Tracy Crook (Rotaries in RV's)

BZ, back in the Jurassic age my buddy Tracy Crook and I built our RV4s...being the over achiever he engineered a Mazda 13B rotary power plant installation...
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V/R
Smokey
*********************************
Smokey: I started following Tracy in about '96, and started building an RV-9A w/ Mazda 13B in '99. Finally retired from ACC and will now be able to finally get back to working on it and get it done; and hope for a first flight next Summer. :)

Doug

RV-3A renovated/flown for 50 hrs. and sold
RV-9A Mazda 13B / FWF (@400 hrs. to finish)
 
IMO, unless you are one of the most skilled titanium/vibranium exhaust welders in the world, only fly over Kansas. A builder I know who worked in the milspec world tried, and tried and tried. Last I heard, he flies behind a Lyc.
 
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