Mazda Rotary Engine

[Armilite]

With even mild peripheral porting and boost, turbo 13Bs in aircraft have no trouble exceeding 200hp at 5500 rpm, and they'll happily turn faster than that and make more power.

================

True, you can push any Engine to make more hp, but there is a Point in Continuous use for Hours like on a Plane where you can go too far! You can do the Porting, you can use the High Temp O-rings, the Ceramic Apex Seals, and today you do have better Synthetic Oils to use. Just as every Plane has a limit on Prop Size it can use! You can use the Light Weight Housings to Save on Weight. How much Boost is too Much for Aircraft use? Finding a Reliable Reduction Drive was the biggest problem for many Years. For Endurance, a Long Service Life your probably looking at Max 6500rpm! 6500/2750rpm = 2.363 Ratio. As I said, the output of late 13B-T was 185 hp (138 kW) at 6500rpm! To make 200hp and using a lower Max rpm, means more Boost!

4500rpm/2750rpm= 1.636 Ratio!

5000rpm/2750rpm= 1.818 Ratio!

Is there even a Redrive in them (2) Ratio's to meet his Mission?

Wouldn't a 20B 2.0-liters be a better option? The 20B-REW in the Eunos Cosmo is referred to as the production 20B. In this guise, it’s remarkably powerful, putting out 300 horsepower and 403 Nm of torque thanks to the combination of 2.0-litres and sequential turbocharging at just 0.7 bar of boost = 10.15264 psi. I didn't see at what rpm it was rated. It would be better to Detune a 20B to his desired 200hp.

5500rpm/2750rpm= 2.0 Ratio!

6000rpm/2750rpm= 2.181 Ratio!

6500rpm/2750rpm= 2.363 Ratio!

 

[dwalker]

================

True, you can push any Engine to make more hp, but there is a Point in Continuous use for Hours like on a Plane where you can go too far! You can do the Porting, you can use the High Temp O-rings, the Ceramic Apex Seals, and today you do have better Synthetic Oils to use. Just as every Plane has a limit on Prop Size it can use! You can use the Light Weight Housings to Save on Weight. How much Boost is too Much for Aircraft use? Finding a Reliable Reduction Drive was the biggest problem for many Years. For Endurance, a Long Service Life your probably looking at Max 6500rpm! 6500/2750rpm = 2.363 Ratio. As I said, the output of late 13B-T was 185 hp (138 kW) at 6500rpm! To make 200hp and using a lower Max rpm, means more Boost!

4500rpm/2750rpm= 1.636 Ratio!

5000rpm/2750rpm= 1.818 Ratio!

Is there even a Redrive in them (2) Ratio's to meet his Mission?

Wouldn't a 20B 2.0-liters be a better option? The 20B-REW in the Eunos Cosmo is referred to as the production 20B. In this guise, it’s remarkably powerful, putting out 300 horsepower and 403 Nm of torque thanks to the combination of 2.0-litres and sequential turbocharging at just 0.7 bar of boost = 10.15264 psi. I didn't see at what rpm it was rated. It would be better to Detune a 20B to his desired 200hp.

5500rpm/2750rpm= 2.0 Ratio!

6000rpm/2750rpm= 2.181 Ratio!

6500rpm/2750rpm= 2.363 Ratio!

The problem is your information is 30 years out of date.

 

[Lendo]

rv7charlie. Well JC's program (that Jan Carlsson - now dec'd), is pretty good, it depends on 'data-in' like Hp for Cruise and Max, it also allows flexibility (within reason) for Prop Diameter. I started a week ago to reverse engineer the Math and only today worked-out the last input, it's not hard but can be a very tricky to follow. I' haven't worked through all his math but have now discovered all the Prop Pitch along the blade percentages, with corresponding Angles. That understanding is a big step for me. It's one thing to see a program work and another to understand how it works.

You may wonder why I went to the bother of doing this, well one it is the understanding, and two I had copies on two computers and one corrupted and I figured I would have ended up with nothing if the other one crashed and I didn't understand the Math.
George

 

[Cardmarc]

I believe Mistral went to the 3 rotor for a good reason, their G300 is conservatively rated at 300HP. That package can easily push them into the PT6 market. The PSRU looks very similar in size to the AirBus AS350 planetary that I have been prototyping with. The most common PT6 power rating is 650HP. PW has been producing many "blocking" patents in the last decade

Any further reports on this planetary?

 

[Urquiola]

With even mild peripheral porting and boost, turbo 13Bs in aircraft have no trouble exceeding 200hp at 5500 rpm, and they'll happily turn faster than that and make more power.

It's not to forget, every one here knows this, Mazda 13B are car engines, where low rpm, low load toque is needed for driveabilty, this is why Mazda choose side intake ports, even if in Japan, sports versions with Peripheral Intake Port where offered.
As discussed, my ideal Wankel would have Renesis RX-8 housings with an added intake PPort, Side Intake ports clogged, and a twin peak Reed-Valve controlling intake. Lots of RV from 2-Strokes are offered in eBay and spare parts sellers.
About placing the new PPort in housings, YouTube videos exist about doing this, the book 'Rotary Engine', by Kenichi Yamamoto, 1981, available for free download in the Web, indicates results when P Intake Port is closed earlier or later in shaft turn.
Mazdatrix once sold shafts for single rotor engine, but it seems are not available now.
Blessings +

 

[dwalker]

Renesis did not make more torque with the side ports, they used higher static compression and intake plenum controls to do that.

 

[Lendo]

Yes! Mistral were conservative and avoided P-ports, their reasons Longevity, however I now believe they didn't want to have to design a PP that didn't leak coolant into the combustion chamber, the biggest problem with the PP and coupled with the poor idle control. I believe Powersport put a butterfly in the PP housing to solve that Idle issue.
Urquiola, I have never heard of a Twin peak read valve being used- any photos?
George

 

[dwalker]

So, to be clear, peripheral INTAKE ports are in general to be avoided in aircraft engines. Mainly because they are meant for high-RPM operation and as importantly they will leak coolant into the intake airstream at some point and may or may not be able to be repaired.

Peripheral EXHAUST ports are KEY to producing power in the rotary and the reason that no matter what you do to it a normally aspirated Renny will NOT make more than about 230HP at the flywheel, and even then at an excessively high RPM. Even if it would make such power the DB level of the exhaust would be very uncomfortable.

For aviation purposes the standard side intake/peripheral exhaust arrangement is likely the best solution. If more torque is needed then the best, and really only ways to achieve this is either with increased compression or boost or a combination of the two.

 

[Lendo]

dwalker, 'Naturally I'm not against your opinion on these things as many engine builders have tried most things here in Australia, down to welding in the PP tube which seemed to work better than most other attempts like high-temp epoxy etc., however it's my belief the PP can be a leak proof design as I'm privy to some design ideas, which I can't discuss and some sort of control of inlet air volume at low RPM, is actually doable as Powersport demonstrated.
I believe it best not to disregard and design possibilities until their proven a failure. Sorry I can't say more.
George

 

[dwalker]

dwalker, 'Naturally I'm not against your opinion on these things as many engine builders have tried most things here in Australia, down to welding in the PP tube which seemed to work better than most other attempts like high-temp epoxy etc., however it's my belief the PP can be a leak proof design as I'm privy to some design ideas, which I can't discuss and some sort of control of inlet air volume at low RPM, is actually doable as Powersport demonstrated.
I believe it best not to disregard and design possibilities until their proven a failure. Sorry I can't say more.
George

Well, as I stated somewhere else, my semi-p-port housings are welded, which I believe are the most reliable, but can still crack and leak.

The pressed in billet sleeves with sealing compound and o-rings have a lot of promise, with the only obvious concern being the life of the O-rings.

My specific concern really is the fact that p-ports on the intake side are meant to make high-rpm power and very often lack powerband.

Also I have no ego about any of this, I just really prefer accurate tech info that will not tend to lead a reader down the wrong path.

Cheers!
Don

 

[Cardmarc]

Lots of info on PP construction on Paul Lamar’s old mail list! Seems it has been long perfected……

 

[dwalker]

Lots of info on PP construction on Paul Lamar’s old mail list! Seems it has been long perfected……

Mmmmm.. seems? No, sorry, P-Ports have not been perfected as far as the sealing goes. At some point they will leak coolant into the intake stream. They are also not in any way optimized for the RPM range used in aircraft. Sure, if you want a high power low time powerplant that is turning 9,000rpm and requires a 3/1 reduction to keep a reasonable prop on the plane, a P-Port might be right for you.

For the rest of us that would like to use the aircraft to go places and see things without rebuilding the engine once a year or living with coolant loss during operation, the P-Port is a serious liability.
Yes, reed valves and variable geometry intakes can help to shift the powerband slightly and provide a reasonable idle, but now we are adding complexity on top of complexity.

So, and I find it VERY ODD I am the voice of reason here, but there is literally ZERO, and I mean ZERO reason to use a P-port or even a semi-p port motor in an aircraft. If you need 300hp thats easily done at a serviceable RPM with the application of boost. If you "only" need 200hp that is less easily done but certainly do-able with less boost. 150HP can be done with low stress with an NA motor using either the Renesis or a4 or 6-port NA 13B. Having a motor that needs to 6000rpm before it makes anywhere near the needed power is a waste of fuel and wear on the engine, and invites issues in the PSRU and pretty much everything bolted to it. The ol' saw "RPM kills engines" is accurate, even in a rotary. Sure it is not going to fly apart, but the wear on all components, especailly springs, seals, and housings, will be greatly exacerbated.

 

[Cardmarc]

Mmmmm.. seems? No, sorry, P-Ports have not been perfected as far as the sealing goes. At some point they will leak coolant into the intake stream. They are also not in any way optimized for the RPM range used in aircraft. Sure, if you want a high power low time powerplant that is turning 9,000rpm and requires a 3/1 reduction to keep a reasonable prop on the plane, a P-Port might be right for you.

For the rest of us that would like to use the aircraft to go places and see things without rebuilding the engine once a year or living with coolant loss during operation, the P-Port is a serious liability.
Yes, reed valves and variable geometry intakes can help to shift the powerband slightly and provide a reasonable idle, but now we are adding complexity on top of complexity.

So, and I find it VERY ODD I am the voice of reason here, but there is literally ZERO, and I mean ZERO reason to use a P-port or even a semi-p port motor in an aircraft. If you need 300hp thats easily done at a serviceable RPM with the application of boost. If you "only" need 200hp that is less easily done but certainly do-able with less boost. 150HP can be done with low stress with an NA motor using either the Renesis or a4 or 6-port NA 13B. Having a motor that needs to 6000rpm before it makes anywhere near the needed power is a waste of fuel and wear on the engine, and invites issues in the PSRU and pretty much everything bolted to it. The ol' saw "RPM kills engines" is accurate, even in a rotary. Sure it is not going to fly apart, but the wear on all components, especailly springs, seals, and housings, will be greatly exacerbated.

Appreciate your POV. I am not an advocate of modifying the ports either in the name of reliability. But a big question is how do you pick a suitable turbo for aircraft use on a 20b or a 13brew. It seems like witches brew to pick one! I have both engines.

 

[rv6ejguy]

But a big question is how do you pick a suitable turbo for aircraft use on a 20b or a 13brew. It seems like witches brew to pick one!

Compressor maps and experience...

 

[dwalker]

Appreciate your POV. I am not an advocate of modifying the ports either in the name of reliability. But a big question is how do you pick a suitable turbo for aircraft use on a 20b or a 13brew. It seems like witches brew to pick one! I have both engines.

Not hard to pick the right turbo.
I am going to be using a Garret based GT3582R with a .70 anti-surge compressor housing and a stainless V-band inlet/outlet turbine housing in the .82 to 1.06 range.
There are other, simpler and cheaper choices. It would be hard to go wrong with a Borg/Warner S366 or similar. These turbos are designed with diesels in mind and so are meant to be "in boost" constantly and live a long long time. The problem a lot of people run in to is trying to adapt a street car turbo to an airplane. Airplane engines live at constant, unchanging power and rpm levels and operate in a wide spectrum of efficiencies. Cars do not. Put a turbo that "is designed to make 300hp on this Audi" on an airplane motor making 200hp and watch it fail in short order. A lot of this is simply long periods of time under boost, but the other common issue is overspeeding at higher altitudes attempting to make boost in thinner air.
For any aircraft turbo I strongly recommend a turbine speed sensor with an alarm to let you know if it is close to or has managed to overspeed the turbo. Once or twice might be ok, but pushing the envelope will lead to the turbo coming apart, usually when you need it most.
Other strategies to help the turbo live is to use an electric water pump along with a timer circuit to circulate coolant after shut down while the turbo is still super hot, use good synthetic oil, and make sure the pressure in and drain out are suitably sized and properly plumbed.

Charge cooling, water/alcohol injection, etc. can go a long way to keeping good power for a long time.

 

[lelievre12]

but the other common issue is overspeeding at higher altitudes attempting to make boost in thinner air.
For any aircraft turbo I strongly recommend a turbine speed sensor with an alarm to let you know if it is close to or has managed to overspeed the turbo. Once or twice might be ok, but pushing the envelope will lead to the turbo coming apart

Turbine Wheel speed on its own is not enough to predict failure from overspeed. Blade creep or failure results from a combination of temperature and RPM. RPM creates the centrifugal blade load and temperature places the metal higher on the yield curve. This is why turbos are TIT limited. In a well designed engine a turbo will reach its TIT limit before it will overspeed.



Its worth noting that TDi turbos usually are not designed for the same TIT limits as gas engines are more thermally efficient. Put simply, less heat goes down the exhaust pipe as combustion gases are more fully expanded within the cylinder before they exit. I'd therefore be careful about permissible TIT limits if using a turbo designed for a TDi on an gas engine.

PS> We instrumented a turbo bearing section on a TSIO520 and found the 'cool down' after taxi not required. By the end of descent at lower power on final, the turbo is already cool before the wheels even touch the ground. Simply taxi to your hangar and shut down immediately!

 

[dwalker]

Turbine Wheel speed on its own is not enough to predict failure from overspeed. Blade creep or failure results from a combination of temperature and RPM. RPM creates the centrifugal blade load and temperature places the metal higher on the yield curve. This is why turbos are TIT limited

View attachment 117115

Its worth noting that TDi turbos usually are not designed for the same TIT limits as they are more thermally efficient. Put simply, less heat goes down the exhaust pipe as combustion gases are more fully expanded within the cylinder before they exit and TDi is always LOP. I'd therefore be careful about permissible TIT limits if using a turbo designed for a Tdi on a gas engine.

That is all correct, but I can monitor compressor and turbine shaft RPM accurately, temps not so much.

 

[rv7charlie]

That is all correct, but I can monitor compressor and turbine shaft RPM accurately, temps not so much.

Isn't that a little like, "All I've got is a hammer, so I'll use that to drive screws."?
;-)

 

[dwalker]

Isn't that a little like, "All I've got is a hammer, so I'll use that to drive screws."?
;-)

MMM no?

Overspeeding is the reason most turbos come apart. Shaft RPM is a huge indicator of that and it is not particularly hard to monitor.

Thermal limits are an entirely different matter and get into a realm of rabbit holes I see no need to go down. Yes, we can monitor EGT before and after the turbine, AIT before and after the compressor, and if we have a SBC or data logger set up to do a bunch math you should be able to come up with a set of temperature conditions that will tell you the compressor wheel is about to snap the shaft or the bearings in the CHRA are about to melt down allowing more than acceptable shaft wobble.

Or we can just know that under normal conditions we do not want to see Xthousand shaft rpm, ever, but certainly not more than once.

While we are on the subject of extreme operation conditions for turbochargers, please watch the following video-
Slight warning- if at work the volume might need adjusted for the intro

 

[rv6ejguy]

OTS Garrett turbos and parts have been successfully used in Experimental aircraft for over 20 years and proven very durable if TIT and N1 limits are observed and are fed cool and clean oil. I've been turbocharging cars and planes for over 40 years. Thousands of hours driving, racing and flying them. Never had a turbo failure yet. Use good synthetic oil and I've never had a need for water cooled CHRAs either- just don't shut them off while red hot.

The Reno championship racers I've been involved with run 1800F+ turbine inlet temps and pressure ratios of well over 4 to 1.

Most normal GA applications will come nowhere close to taxing these limits.

I've never used a speed sensor either. The compressor map and calculator will show you if you'll be anywhere near the N1 limit for your mission.

One constant on aircraft turbo matching is using much larger turbine wheels and A/Rs than would be used in automotive applications. Response isn't usually an issue and we want the lowest possible losses across the turbine for best power and fuel economy at the high continuous power settings aircraft engines run at.