# Excellent video on making reliable power in a Mazda Rotary engine

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#### jedi

##### Well-Known Member
Was anyone really confused? C'mon.

We could instead say : "Thank you, Billski, for taking the time to write a substantive post that addressed the issues in the video I posted."

While doing a "quick read" I for one did not pick up on this error and appreciated the Paraplane comment and Billski's detailed reply.

I am so pleased to see this resolved in a civilized manner.

No Zone!

#### paraplane

##### Well-Known Member
It would be nice if people would consider that there is a real person at the other end of these comments and consider that maybe just maybe that this persons life maybe unlike yours and that being anything other than tactful and considerate could justify that person making retaliatory comments.

#### rv7charlie

##### Well-Known Member
Supporting Member
Well, jedi was obviously, and sadly, mistaken. I'm sure that most of us have said things on line that we regret; I know I have.

Here's a 3rd party opinion; use it as you wish.

Somebody made a functionally accurate post, that happened to contain a couple of unfortunate typos. Someone else decided to take the facts and the typos as a personal attack, and promptly responded with multiple profane posts directly attacking the other party. Several people, including the person attacked, have tried to tactfully steer the conversation back to civil discourse, but that doesn't seem to be working. If the behavior continues in the same vein, the attacker might not get banned, but it will likely stimulate the use of 'ignore' buttons on a bunch of computers, and those computers will no longer show his posts, rendering any communication with, or assistance from those users, impossible.

#### Dana

##### Super Moderator
Staff member
Moderator note: I just removed 15 posts from this thread. Please keep it on topic. This is the Homebuilt Airplanes forum, not the grammar forum, the self help forum, the mommy forum, or the interpersonal relationships forum. Some of the posts removed were themselves fine, but part of the pattern we've seen before of a thread going ugly.

#### wsimpso1

##### Super Moderator
Staff member
It would be nice if people would consider that there is a real person at the other end of these comments and consider that maybe just maybe that this persons life maybe unlike yours and that being anything other than tactful and considerate could justify that person making retaliatory comments.
Moderator Mode ON:

This is a technical forum and we are expected to stay more or less on technical topics. It is OK to take on the topics. While some sensitivity might be nice, it is not required. Please read the Code of Conduct and understand that it is the basis for our moderating efforts.

Moderator actions are taken when the CoC is violated on an individual post basis or when a series of posts is strongly trending into CoC violation territory.

I strongly urge our members to not debate folks who you feel are being inappropriate, but instead ask that you click on the report button, and describe what you see as violations of our CoC. The three volunteer moderators will get to the subject posts much sooner than if we all just wait for the moderators to discover the posts.

Billski

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#### RVC

##### Member
The point I want to add here is that you cannot give YT all your trust. A good friend is a first rate fabricator and he has informed me he saw people posting videos regarding sizing piston rod ends measurements with inappropriate measurment tools such as interior calipers and snap gauges. YT can have wonderful offerings; just confirm what you see and like before 'going all in.'

#### dwalker

##### Well-Known Member
Supporting Member
I fully intended to watch it; just hadn't had time to watch it when I wrote the post. Just watched it this morning, and all the mods he mentions are common knowledge for rotary 'tuners'. But as expected, they're all focused on making insane levels of power from the engine. Running any 'conversion' (auto) engine in an a/c at higher than its original stock HP is rarely, if ever, a good idea. So all those mods that prevent the engine from doing the 'banana' thing just aren't needed in an engine that survives at 'stock' HP levels, and trying to do the mods when you're not experienced in working on the engine greatly increases the risk of doing more harm than good. The only *internal* mod that I've seen the a/c guys do that might be justified is typically done on the older 13B engines. That's to remove the tension bolts one at a time & coat them with a spiral of silicone & replace/torque them. There have been a few cases of a tension bolt breaking, attributed to the bolt being excited at its resonant frequency & failing due to fatigue. I don't recall it being an issue with the Renesis, but I could be wrong. All the other mods he discusses fix issues that basically don't exist until you're pushing the engine way beyond what you'd ever do in a 'daily driver' aircraft.

AFAIK, everyone flying the engine uses either 2stroke premix (as he described in the vid), or uses Richard Sohn's adapter for the oil injection metering pump and runs an external 2stroke oil tank. But that's not a mod to the engine core.

Bottom line, for me, is that if you're not dwalker (I most certainly am not), leave the core alone except for the thermal pellet mod and focus on cooling. Then try to get the intake (& exhaust, if you're running a 13B) right to get stock power levels back after removing the originals.

I have been super busy- which is odd for a retired guy- and missed this thread. I agree with pretty much everything you have said. I constantly warn "car people" that messing with the rotary is risky and can lead to very expensive problems.

#### dwalker

##### Well-Known Member
Supporting Member
The point I want to add here is that you cannot give YT all your trust. A good friend is a first rate fabricator and he has informed me he saw people posting videos regarding sizing piston rod ends measurements with inappropriate measurment tools such as interior calipers and snap gauges. YT can have wonderful offerings; just confirm what you see and like before 'going all in.'

While I do agree about YT for the most part, Rob is extremely accurate and has real world experience behind what he is saying.
I run E85 in rotaries a lot. In fact, I ran a car at the Pikes Peak International Hillclimb a decade or so ago running on E85 and it worked great. Excellent power, engine ran cooler, far less carbon, only downside was fuel usage, which was partially due to me incorrectly scaling the baro fuel correction table for the altitude. E85 is about the perfect fuel for the rotary, with of course the downsides of availability of course. The neat thing is that with a fairly inexpensive alcohol "flex fuel" sensor and some straightforward engine mapping you can run regular unleaded or even leaded avgas added into the E85 rather seamlessly.

I agree about using the studs/enhanced bolts in a rotary and IMHO it is near mandatory for flight engines. The stresses on the engine in a flight engine are different than when bolted to a car. Keeping in mind that rotary engines really do not care about RPM in the way piston engines do, the fact remains the entire engine is a bolted together stack, and that stack is known to fret at high loads. I should think a propellor hanging off the end would meet the "high load" criteria. Now we know that there have been tension bolt failures in the past- Tracy Crook had one himself at a fly-in that was documented in an article of IIRC, Kitplanes magazine. At that time it was concluded that the harmonics of the rotary running at a constant RPM was causing the tension bolts to fracture, and the recommended remedy, carried over fro racing rotary engines, was to use globs of RTV/silicone on the tension bolts where they passed through the rotor housings to act as dampers. This does work, for sure. However, as more and more power has been applied to the rotary and a couple of decades of failed engines analyzed, it is now "common knowledge" that using studs or larger bolts along with solid dowel pins results in a far less failure prone engine.
The take-away there is that the stud or bolt kits are easy to install and readily available.

#### wsimpso1

##### Super Moderator
Staff member
Team Aviation F/X and Russ and Eric McFarland bring you the World Recordfor time to climb to 10.000' in 1'40" from brakes release.
The aircraft is a modified Harmon Rocket powered by a massive Wankel rotary engine boosted to 650hp.
The McFarlands are expert promoters of the Wankel rotary engines

Now that engine could probably have used (and maybe did use) upsized case bolts/pins and ethanol/ oil premix fuels. But us running at production power levels?

#### rv7charlie

##### Well-Known Member
Supporting Member
Now that engine could probably have used (and maybe did use) upsized case bolts/pins and ethanol/ oil premix fuels. But us running at production power levels?
They were actually running Methanol, and met the typical pitfalls of those unfamiliar with the differences between M vs E. They had to rebuild the fuel system before the record flight. Which goes to the point of my earlier post about leaving the core alone. Most of us don't have the engine building knowledge/experience of dwalker, so 'statistically', homebuilders doing the case bolt mod in their garages are much more likely to cause an unreliable engine than fix a relatively rare (at our power levels) issue. I'm pretty sure that Tracy's failure was back when he was running a 13B. I can't recall any accounts of a Renesis breaking a through-bolt while running in an a/c.

#### PMD

##### Well-Known Member
Just to pick up on a few points raised in this thread:

E85 really is a nice thing for racing fuels. We used to race Speedway and ran both E100 and M100. Inside of engines - absolutely clean. You could come in off a hard race (all are 4 laps with 4 riders) and grab the exhaust pipe right near the cylinder head with your bare hand. Cooling was a breeze (sorry for that bad pun).

Rotaries really don't want to be air cooled at higher power levels - as the exhaust events all happen in the same part of the engine without an intake event to quench the area, so a real bear to cool. You will note the stainless/fancy alloy insert on the exhaust ports to keep them from melting....yeah, THAT hot.

When talking about the tie bolts and shear loads, one must consider that a rotary in car use reacts the driveline torque out between the bellhousing and the mounts - and THAT can be a fair bit on a highly boosted 2 rotor, lesser tuned 3 rotor or pretty much ANY 4 rotor. BUT: in aircraft use the gearbox turns the prop and something between 3 or more to 1 and unless torque is reacted out on a mount on the front housing (and I seem to recall seeing some that were not) you could be reacting not only 3x the engine torque through those dowels and ears but also subjecting them to the torsional assault of resonance from the prop and its drive.

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#### TFF

##### Well-Known Member
There is no E85 around here without trucking it in or starting up grandpa’s still. You will definitely need flex fuel capability for the day you find some. E10 and some low octane straight is what’s around here. About a 600 mile radius.
Case bolts sound more like damned if you do damned if you don’t problem.

#### dwalker

##### Well-Known Member
Supporting Member
Just to pick up on a few points raised in this thread:

E85 really is a nice thing for racing fuels. We used to race Speedway and ran both E100 and M100. Inside of engines - absolutely clean. You could come in off a hard race (all are 4 laps with 4 riders) and grab the exhaust pipe right near the cylinder head with your bare hand. Cooling was a breeze (sorry for that bad pun).

Yeah, E85 even for street cars makes a lot of sense.

Rotaries really don't want to be air cooled at higher power levels - as the exhaust events all happen in the same part of the engine without an intake event to quench the area, so a real bear to cool. You will note the stainless/fancy allow insert on the exhaust ports to keep them from melting....yeah, THAT hot.

That insert is inconel.
When talking about the tie bolts and shear loads, one must consider that a rotary in car use reacts the driveline torque out between the bellhousing and the mounts - and THAT can be a fair bit on a highly boosted 2 rotor, lesser tuned 3 rotor or pretty much ANY 4 rotor. BUT: in aircraft use the gearbox turns the prop and something between 3 or more to 1 and unless torque is reacted out on a mount on the front housing (and I seem to recall seeing some that were not) you could be reacting not only 3x the engine torque through those dowels and ears but also subjecting them to the torsional assault of resonance from the prop and its drive.

That's probably accurate

#### EzyBuildWing

##### Well-Known Member
Bill Joengbloed built a turbo'd 13B with a gear reduction, a few years ago....a big article appeared in Sport Aviation....
The turbo helps quieten the exhaust-note.....
How many HP are you looking for?
The following might be of interest:

With roots in the world of auto racing, a new gear reduction unit has been mated to the Mazda 13B by Bill Jongbloed, Jongbloed Aviation Box 40, Chino Airport Chino, CA 91710

A Mazda set up such as ours will produce 170 BH at 5000 rpm and 200 BMP at 6500 rpm. Remember that there is no magic, so cast a wary eye towards those claims of 300 BMP and 250 pounds. To reach those HP levels you must spin 9000 to 9500 rpm and that only happens on racing tracks in racing cars. My engine consultant is Clayton Cunningham of CCR racing whose motors are about the best in the business and he says 6500 rpm.

As far as 250 pounds goes, it's true but that's a race engine without an aircraft gear reduction. What dwells under our turbocharger is a basically stock 13B motor with a mild port job, plus one mandatory modification. There are some planetary gears inside the motor which must be exchanged for their hardened counterpart. These gears are available from a variety of sources but they are a must.

Carburetion is at this time experimental, however, an automotive Holley 2 barrel seems just fine unless aerobatics are your desire with negative GS.

Continuing on the subject of weight, let's now look at powerplant weights. According to Jane's, a Lycoming 0-360 weighs 268 pounds and produces 180 BHP. That's fine but put that engine on a scale with oil, exhaust and acessories and it will read 325 pounds.

Besides, once you are up to 10,000 feet, your available power is 125 BHP, giving a powerplant power-to-weight ratio of 2.6 lb. per hp. Now, by installing our Mazda conversion, your engine-gear reduction weight, including oil, water, turbo system and accessories, will be 330 pounds forward of the firewall and 50 pounds aft in the cooling pod.

You will have turbine smoothness, better aerodynamics up front where it counts and 200 BMP at 10,000 feet. Total package weight is 380 pounds, giving a power to weight ratio of 1.9 lb. per hp. Remember, too, that the cooling pod will be virtually drag free due to thrust recovery. Mounting of any powerplant requires a proper motor mount and cowling.

#### dwalker

##### Well-Known Member
Supporting Member
Bill Joengbloed built a turbo'd 13B with a gear reduction, a few years ago....a big article appeared in Sport Aviation....
The turbo helps quieten the exhaust-note.....
How many HP are you looking for?
The following might be of interest:

With roots in the world of auto racing, a new gear reduction unit has been mated to the Mazda 13B by Bill Jongbloed, Jongbloed Aviation Box 40, Chino Airport Chino, CA 91710

A Mazda set up such as ours will produce 170 BH at 5000 rpm and 200 BMP at 6500 rpm. Remember that there is no magic, so cast a wary eye towards those claims of 300 BMP and 250 pounds. To reach those HP levels you must spin 9000 to 9500 rpm and that only happens on racing tracks in racing cars. My engine consultant is Clayton Cunningham of CCR racing whose motors are about the best in the business and he says 6500 rpm.

As far as 250 pounds goes, it's true but that's a race engine without an aircraft gear reduction. What dwells under our turbocharger is a basically stock 13B motor with a mild port job, plus one mandatory modification. There are some planetary gears inside the motor which must be exchanged for their hardened counterpart. These gears are available from a variety of sources but they are a must.

Carburetion is at this time experimental, however, an automotive Holley 2 barrel seems just fine unless aerobatics are your desire with negative GS.

Continuing on the subject of weight, let's now look at powerplant weights. According to Jane's, a Lycoming 0-360 weighs 268 pounds and produces 180 BHP. That's fine but put that engine on a scale with oil, exhaust and acessories and it will read 325 pounds.

Besides, once you are up to 10,000 feet, your available power is 125 BHP, giving a powerplant power-to-weight ratio of 2.6 lb. per hp. Now, by installing our Mazda conversion, your engine-gear reduction weight, including oil, water, turbo system and accessories, will be 330 pounds forward of the firewall and 50 pounds aft in the cooling pod.

You will have turbine smoothness, better aerodynamics up front where it counts and 200 BMP at 10,000 feet. Total package weight is 380 pounds, giving a power to weight ratio of 1.9 lb. per hp. Remember, too, that the cooling pod will be virtually drag free due to thrust recovery. Mounting of any powerplant requires a proper motor mount and cowling.

While not inaccurate. It is decades out of date.

#### rv7charlie

##### Well-Known Member
Supporting Member
Well, that 268 lb number for a Lyc O-360 ain't exactly accurate, even bare.

#### Regdor

##### Active Member
Leaded fuel is what is at all airports. Swift fuel takes some planning for trips, but it is unleaded 94 octane.

Why not build an engine able to withstand higher HP? You can and it most likely does not hurt anything at power and rpm levels we use in airplanes. I suspect that it also does not hurt anything to NOT do it at our power and rpm levels. Here is why: The bolts and the like are sized for normally aspirated or mildly boosted power of the RX7 and RX8. Quite a few folks running 150-200 hp with essentially stock innards and decently long lived engines. The stock bolts are supposedly plenty strong enough and plenty stiff enough to keep the stack of housings clamped and not shifting relative to each other at these combustion chamber pressures. Go from 200 hp to 500 hp and more, you have to raise the boost and combustion chamber peak pressures to 250% of stock, which means the engine is also trying 250% harder than stock to separate the housings and twist the housings relative to each other. This is fastener theory basics - the fasteners must keep housings clamped sufficient to prevent opening the joints and relative movement between housings. So, you make the bolts thicker and/or tightly pin the parts against relative rotation.

So, if the power is low, and the joints neither shift nor open in use, adding more bolt/pin stiffness adds no advantage to the engine.

As to building your own new Wankel with aircooling, knock yourself out and keep us informed as to how it works out. I suspect that it will result in substantially higher temperatures and thus thermal distortion in the housings on the power and exhaust parts of the housings, which could seriously increase problems with housings, gaskets, and seals. Liquid cooling is great for managing temperatures in the hot areas of all engines, keeping the seals and gaskets alive, keeping the oil from getting cooked, etc.

Billski
The big culprit with an air cooled Wankel may become tip seal chatter....Thermal distortion changes the dynamics with the seal housing interface....The Wankel engine has a hot side and a cold side,
the water flow greatly equillibrates the whole...

#### Regdor

##### Active Member
The Wankel engine: design, development, applications, Hardcover - January 1, 1972 by Jan P. Norbye (Author) 11 ratings See all formats and editions Hardcover $29.99 8 Used from$23.00 1 Collectible from \$39.99 Language English Publisher Chilton Book Company Philadelphia, PA Publication date January 1, 1972 ISBN-10 0561001375 ISBN-13 978-0561001371