ALREADY PATENTED!!! - 2 Stroke Engine with Advanced Valve System From Mazda 

60 years ago I worked on the Foden 6 cylinder 2 stroke marine diesel engine. It was very similar to this concept, using a supercharger and exhaust valve. No reed valve needed. The exhaust valve operated on the kadenacy system which allowed the valve to stay fully open longer for better scavenging. The high profile cam gave the valve a snap shut operation. It was the smoothest running engine I ever experienced.

I like that Mazda is willing to walk a different path to other companies.

Love how Mazda is involved in so many diverse technologies and are trying to reinvent the 2 stroke!

Back in the 1980s, Orbital made a 2-stroke engine with a supercharger. The exhaust port was valve-less, on the side of the engine. The intake had a reed valve; as the pressure in the cylinder dropped ('cuz exhaust gasses escaping out the side), the supercharged intake air pressure overcame the in-cylinder pressure and pushed the valve open, admitting fresh air / fuel into the cylinder. Fresh air / fuel in through the top, exhaust gasses out through the lower side. When the cylinder rose enough to cover the exhaust port, the pressure in the cylinder rose and the reed valve closed. It was pointedly setup such that about 2/3 of the (upward) cylinder stroke was compression, about 2/3 of the (downward) stroke was power and the remaining 1/3 of each (near BDC) was overlapped exhaust / intake. Emissions were relatively clean, because there was no oil being burned. Given this was developed back in the 1980s, and Mazda is just adding cam-driven intake and exhaust valves (old news) and direct injection (old news), I'm surprised this was considered sufficiently novel that it would qualify for a patent.

Supercharged 2 stroke diesel. I designed one as part of my dissertation in 2003. However, I withdrew it because I didn't want the university to own the idea. I then spent 20 years bankrupt and floundering whilst I try to develop the idea on my own. Now optimise the torque curve to a hyper efficient narrow band, and use it to charge full electric transmission. Similar to an old Kawasaki train, except with battery storage.

At 7:30 time mark the video states that in a normal 4 stroke engine the camshaft rotates 360 degrees for every 1/2 rotation of the crankshaft. This is exactly the opposite of what happens. The camshaft in a traditional 4 stroke rotates at 50 percent of crankshaft speed. Using the same poorly described action as the video, the correct description would be, the crankshaft rotates 360 degrees for every 1/2 rotation of the camshaft.

The longest production engine ever was a two stroke diesel with a crankcase and an oil pan(crazy, right?) It is the 71 series detroit, made between 1932 and 1994. Because a blower was mandatory for the engine to run, the standard engine-with-blower configuration was considered naturally aspirated, with forced-induction classification only given to engines equipped with the blower AND 1 or 2 turbos. The series classification indicates the displacement of each cylinder in cubic inches(ei 53 series, 71 series, 95 series, etc) meaning that to find the displacement you multiply the number of cylinders by the series classification (8v71 -> 8*71=568in^3) truly the greatest engine of its time, it’s fully mechanical, and can be gravity fed if necessary, with no true requirement for pumps(high or low pressure). They didn’t make very much power, they weren’t very fuel-efficient, they leaked plenty of oil, and they were extremely loud earning them the nickname “screamin jimmy”, but dammit they were probably the most reliable engine of the century, alongside the 6BT.

Truly amazing how well these new engines work in CAD.

I've known how a 2 stroke engine works for 30+ years without actually knowing how it works. That is the best description I've ever seen/heard. Thanks.

I had the idea when I was fifteen. I then discarded it and replaced it with a more suitable DC principle. Inlets at the bottom like on a conventional two-stroke engine and electrically controlled exhaust valves at the top, resulting in a wide usable speed range. This also makes it possible to work with boost pressure. The exhaust gas is used to generate electricity via a turbine with a generator. Although this increases the exhaust back pressure, it hardly slows down the piston as the connecting rod is almost vertical during exhaust (no leverage). Ceramic pistons and cylinders eliminate the need for lubrication. In sliding mode, the engine can act as a compressor to drive the turbine due to the electrically controlled exhaust valves.

It's amazing that Mazda created a backwards spinning supercharger!

Nothing new here, it’s been know for a century that adding a supercharger means crankcase scavenging isn’t required, while poppet valves have also been used on certain 2 strokes for a century too. Look at 2 stroke aero engines for some examples

1n 1978 me and some friends put a Shorrock blower on a Kawasaki KZ900 engine. it had too high of a compression ratio to really use much boost effectively. So we changed sprockets and made it's dual overhead cams turn 1-1 with the crankshaft. Started right up using a Weber carb in draw-through mode. Didn't like to idle down or run slow. Made great drag strip power but longer runs made it overheat. Fuel consumption was ridiculous but we didn't try to measure it.

the simplicity of a 2-stroke engine and the fact that you can rebuild a top end sub 1 hour is what makes them incredible, not sure how I feel about complicating the design further.

Somewhat simple, yet totally brilliant design. I love engineers that come up with great stuff like this, and love the companies that support them.

An interesting phenomena to observe, the way gas engines keep edging ever closer to basically being diesel engines but with a different refinement of crude.

Despite popular belief two strokes don't rev high, for any given engine size they often rev lower that four strokes. They just sound like it because they fire twice as often as a four stroke.

great video with excellent animations. Electric motors are 90% efficient. Overall system efficiency including battery charge/ discharge and control electronics is 80%. Achieving 50% thermal efficiency in ICE is tremendous. Standard passenger cars are in the 20% range to keep emissions in check. These new 2 stroke engines would best be for a charging system in a hybrid BEV. By adding additional cylinders (total of 3) would theoretically balance out the vibration along with some fine balance tuning.

Detrit diesel has been using this concept for decades! Boats and fire engines use them. Emissions were the only reason they weren't used in road legal vehicles since then.

I designed a 2 stroke gas engine years ago. We use the 360 degrees of crank rotation differently and avoid contamination of un-scavenged exhaust left in cylinder. We used a belt driven compressor setup to suck, not blow. The negative pressure in exhaust manifold pulled out exhaust gasses very quickly. We used a compound forced induction with twin turbos feed into the supercharger. Also, we used short stroke and 6,000 RPM was achievable. On paper that is same as 4 stroke running 12,000 RPM. But 2 stroke is slightly less efficient than 4 stroke due to less time for almost overlapping intake and exhaust cycles. Un-scavenged exhaust led to over heating and less combustion flame propagation. In it's final configuration, we ended up with a radical 12 cylinder flat engine (similar to 2 flat six cylinder engines for perfect primary and secondary balance) with 2 crankshafts on end and opposing pistons sharing 1 common head / combustion chamber in middle, with variable chamber volume. We could increase combustion chamber 1X - 5X.This allowed for high CR (1X) under low / no boost, then low CR (5X) under high boost. We were making 2,500 HP - 5,000 HP. The magic is in the special head and crankshaft. Heads have 4 valves for intake and 4 valves for exhaust. Intake ports are on top of head and exhaust on bottom perpendicular to piston. Crankshafts can more up and down to increase or decrease compression ratios.

10:53 : "given that springs ideally work in revolutions below 8000" Honda: *Nervous laughter*

Both 2 stroke blown motor animations are running in reverse 😂😂😂

I love V6 and V8 two stroke sound. Evinrude handed me my first opportunity to hear a two stroke V8 in 1985. Very fast on the back of a boat.

Amazing video. I'm a mechanical engineer and I wish they had your video 15 years ago to lecture about engine specs when teaching thermodynamics cycles theory

I'd like to see their CFD around their valves and in the cylinders. I would think the cylinders would foul much quicker than current solutions. It would be complicated but it'd almost make more sense to have the intake and exhaust valves be concentric rings with the intake being near the cylinder wall and exhaust being somewhat central. Make them flextures to maintain strength.

At the 7:20 mark you state that in a 4 stroke engine the camshaft rotates 360 degrees in half a crankshaft rotation. That's backwards, that would have the camshaft running twice the crankshaft speed and in fact the camshaft rotates at half the crankshaft speed.

I had that idea over 3 decades ago. but at that time no one was even remotely intersted in two stroke technology. I SERIOUSLY hope that Mazda, and then who knows who else will bring back the two stroke. can you tell that I am a two stroke enthusiast!?

Nice! You should have also mentioned mixture loss during scavenging at 2-stroke engine. Overheating issue can be significant. 4-stroke is good, because oil temperature on the cylinder wall does not exceed 120°C not to burn oil.

Nice video. I was drawing up some ideas about a 2 stroke engine 30+ years ago, but never made a working proto-type. My idea was exactly like this motor! I used the supercharger to force the air into the cylinder otherwise it could run backward and stall. My idea was to convert existing 4 stroke engines into this type of 2 stroke. My idea still might work like i thought; but I am glad someone can make the engine I designed on paper.

Mazda is a rebel car company...rotary engines, 2 stroke supercharged engines. Refreshing to see a major corporation that walks their own line.

This sounds really practical. What's lost in horsepower due to lower RPMs should be easily made up in the torque produced with power on every stroke. That should be very noticeable at low RPMs. One of the features of electric motors is the immediate torque when you step on the accelerator pedal. Having a 15:1 compression ratio that can be maintained at low RPMs should deliver that same kind of oomph.

This idea was proposed a long time ago. An article showed a conventional DOHC engine with different camshaft gearing 1:1. Complained that at 4,000 rpm the valves were operating at the frequency of 8,000, if it were a 4-storke. I immediately thought that if the cam lobes on each cyl were offset 180 degrees, and only 2 valves opened on each stroke, that would solve the problem. Now the flow would be halved, but there is a blower to scavenge.

The start of an exhaust sound in any internal combustion engine starts at the exhaust valve or port. The quick opening square edge exhaust port, in a two stroke, gives them their distinct sound venue, add the expansion chamber with its reverse cone and stinger which add to the high RPM Shriek. A poppet valve, Otis cycle or Miller cycle engine has a slower opening round exhaust area that is shrouded by the center valve. These motors there, pop, pop, pop, noise. Just a few small things that influence exhaust noise.

That's one sexy ICE. I like the ability to blow the chamber squeaky clean without spitting fuel in to the exhaust system. The injection system is also a good idea. With the right pump it would allow to burn just about whatever in the chamber. You can run LPG, CNG, Diesel, Petrol, Alcohol, synthetic fuels, paint thinner, whatever doesn't dissolve the seals. Now let's see if Mazda can make a promising production model.

in the late 1980s, every car manufacturer from fiancé, general motors, Ford, all the way down to Daihatsu had running prototype two stroke cars ready to go into production.. The Toyota design had a wet, crank case, you checked the oil with a dipstick, just like a four stroke. The advantage was, all of the metal needed to create an engine, the weight of which produced twice the horsepower of a four stroke engine of the same weight.. or The two-stroke engine would produce the same amount of horsepower as the four stroke engine with an Engine weighing, only half as much as the four stroke.. All the car companies were just about ready to give this 2 stroke plan the go ahead. All it needed was government approval from the environmental protection agency, EPA.. but The results of long-term testing shot that down. Because….. not one of the companies prototype engines could pass the EPA air quality tests after the engines had the equivalent of 100,000 miles of driving on them.. SAAB had two stroke cars running around in the 60s, there have even been large, two-stroke, dump trucks, trucks for pulling tractor trailers that were two stroke. But the air quality issues/requirements of the future ended the two stroke car before it even got started by all of the car manufacturers in the late 1980s.. I have been a motorcycle mechanic and a motorcycle enthusiast since the 1960s. I am currently on my 107th and 108th motorcycle so far. I roadraced motorcycles, winning six championships, two time national champion, I rode off road, two stroke dirtbike‘s for more than 30 years, motocross, bikes, trials, bikes, I rode two stroke, singles, twins, and triples on the street… I have always done all my own maintenance even on my road racing machines. And there is one thing I do notice about two strokes. they don’t last very long. My road racing machine, factory recommendations, new pistons, every 600 miles, rebuilt, crankshaft or new crankshaft every 1200 miles… The engine trouble I’ve had racing or dirtbike, riding or trials, bike riding, or even street bike riding, have pretty much all been the two strokes, piston seizures, that was the biggest fastest wearing parts, the pistons, rings, cylinders.. on street bikes, like my Yamaha RD 350s, 250s, Kawasaki S2 350 2strokes.. my dirt bikes, KDX 175s and 200s with hard plating in the cylinders, pistons were the weak part. And that is due to marginal lubrication of two strokes. They lubricate the engines with already diluted oil, that has been diluted by gasoline, which is a solvent… A film of oil is only so thick, and a diluted film of oil is only marginally sheer resistant.. there is a lot of engineering and tuning and tweaking of fuel injection systems that will have to be sorted to make any two-stroke engine. Be both EPA responsible, and, be reliable at the same time… no engine suffers more from altitude change than a two stroke. They lose 15% of their power just going from sea level up to a city as high as Denver, which is a mile above sea level.. Super chargers and turbo chargers can reduce that power loss somewhat, with a lot of extra systems to compensate.. cooling the engine will be an ordeal itself. Not to mention how do you cool the piston. They are prone to burning holes in 2 stroke pistons because they fire on every stroke. They don’t get that intake stroke to cool down that a four stroke gets… three of my biggest injuries at roadrace tracks have been from two-stroke engine seizures. My last one was my last race, I woke up two days later in plaster in the hospital after that 140 mph seizure on a Yamaha TZ 250 Factory Rd. race machine… of course, that happened during the days when you had to jet your motorcycle according to elevation, barometric pressure, even taken care to consideration the humidity and temperature into your carburetor jetting. I got it wrong that day… but my point is, in my experience, the Pistons of two-stroke engines are the weakest link. I wonder if Mazda can make a two-stroke engine that the piston will still be within spec and pass an EPA sniffer test at the 100,000 mile mark.. I hope they can do it. They are the company that seems to be the ones that are willing to roll the dice, look at the rotary engine that Mazda has been producing. It didn’t pan out when that was first introduced. A friend of mine bought a 1973 Mazda Cosmo rotary engine car right after he got out of the Navy. In 1973 that car was over $7000. he never had a problem with it. Of course he only kept it for about three years… but willingness to take chances the way Mazda does is a risk. Look how long it took mazda to improve the rotary engine seal problem… I really hope that Mazda has some type of a breakthrough with this two-stroke development. Because I have no plans to ever go to an electric vehicle until I absolutely have to. i’ve worked in the electrical generation field for the past 38 years until I retired. And occasionally the subject came up about California’s electric grid, problems, brown outs, rolling, blackouts, and their inability to make a decision about building new power stations. It takes 12 years from idea to going online when it comes to building a power station. and then California would like everyone to drive an EV.. but consider this. If every car in California right now, what is an electric vehicle.. every bit of electrical generation capacity they have whether it is from wind, solar, Hydro, natural gas, coal, nuclear, All of those generation abilities, concentrated on just charging the batteries of EV cars, is not enough, there’s no possible way that California’s electric grid dedicating every volt of generation capacity Simply to charge car batteries could ever meet the demand if every car right now was an EV.. I would like to see more development of the hydrogen engine. I don’t know if the big oil companies and their lobbyists are keeping the government from putting them out of business by going to hydrogen tomorrow, but it seems like that is a more practical solution than electric vehicles. good luck mazda..

The pump in a two stroke diesel is not a supercharger , it is a scavenge pump . It operates at ambient or close to ambient pressure . No supercharging occurs. If supercharging is desired , then turbo-superchargers running off exhaust gases will be added to the engine

Great video thank you. Around the 7 minute mark you state that in a 4 stroke engine the camshaft rotates 360 degrees for every half a rotation of the crankshaft. It's the other way around.

With DI and integrated EGR, it'll be interesting to see how long the valves and seats last before they need decoking. We already see that in contemporary four strokes, and those of us who know about old two strokes know how bad they were for fouling plugs, never mind coking up everything around the combustion chamber. I kinda hope Mazda can pull it off: for one, an unconventional Mazda engine that *doesn't* burn oil; and for another, many companies (Lotus and Ricardo Engineering spring to mind) have failed to get it right. It was assumed then (in the 1990s) that better injection control would be the answer. Maybe this is it...?

Thanks for sharing this information in away that non-engine techies can understand it. I think it's exciting news if we're going to continue to have gasoline engines while others - electric, hydrogen, water (?) are trying to expand their brands to become a viable replacement for the typical 4 stroke gasoline engines.

There is also a small amount of power loss, while the exhaust ports are opening before the detonation can fully push down the piston. Of course this and the overlap between the valve openings are needed for this concept to work. I'm really looking forward to see this in action!

A company called Orbital from Australia spent over a decade trying to make direct-injection 2-stroke engines work in outboards and cars. The final nail in the coffin was that they couldn't meet the emission standards after 100K miles.

@FT - Leave it to Mazda to ride the cutting edges. This is incredible technology. And this would seem to require technicians learn an entire new regime. K, redit - I had to return - (1) Is that a fuel return line? It looks like there's a heat exchanger to keep gas tank temps low(?) (2) With no port injection (and burning diesel?) it's going to be susceptible to carbon buildup on the valves, which would be critical as valve seat design is integral to the flow of intake and exhaust with both valves open. And low RPM, but heavy? Well, trucks and ships would be a good fit, no? As I said, it's interesting technology, and life is about learning; bring it on.

I came up with this idea in 1976 as a teenager and drew it on a piece of notebook paper. I eventually sent a copy of this idea to a company for evaluation.

Long before the internet, I designed a rotary engine. I drove from New York to the patent office in Washington D.C. to see if my design was patentable. I was shocked at how many engines are patented that never found their way under the hood of a car. The fact that this engine is patented means nothing. Many 2-stroke engines use superchargers and valves. An intake port on the side of the cylinder and an exhaust valve up top make the most sense to me. Keep the incoming charge and the outgoing away from each other. Mazda stuck them right next to each other.

Overheating will probably need to be overcome. Also, twice the power (2 stroke) with half the cylinder rotation is countered by the belt driven air compressor. There is no need to fear EVs taking over. The drawbacks are explosive. 🔥

Sounds promising, but we will see if there will be any issues with the engine and if there will be enough momentum to push another ICE revolution. I am all for keeping alive the spirit of ICE and pure mechanical/analog feel of the cars.

Now, how would Mazda get a patent for what Detroit Diesel did 80 years ago? Only difference an intake val

I dont get how they could get a patent on this? Its all stuff thats been thought/designed/used before?

Hi Allan. The Z900 is a Beauty mate. Well done. Cheers from New Zealand 🇳🇿

Having intake valves too is pretty novel. I worked on 2 stroke diesels for a long time which had supercharger and turbo, with exhaust valves. But intake too, and with petrol? Very intrigued.

Your supercharger is running backwards.

Im my opinion, this needs compressed air at start in some container or maybe electric turbo to get boost rightaway in low revs.

A few mistakes in this video. In a 4-stroke, camshafts rotate half as fast as the crankshaft, not twice as fast. 14.7 AFR is the stoichiometric ratio for gasoline, but theyre usually run richer than that (smaller number). For diesel it is 14.5, but they are almost always run much more lean than that, between 18 and 30. Valve springs have no issue operating over 20k rpm. Valve float has been solved. But the higher frequency you need, the more expensive they get. So the practical limit is around 14k rpm, not 8k. Doubling the intake frequency does not increase engine vibration in a way that matters to the user. Perhaps increased camshaft vibration is something the engineers would need to work out. Perhaps higher cost and weight, but not by a meaningful amount when amortized over the cost of a whole car. The supercharger is spinning the wrong way.

I’m kinda surprised it’s actually quite clever. And it looks pretty much worked out

Fajne symulacje. Szkoda tylko, że wirniki sprężarek obracają się w przeciwną stronę niż w rzeczywistości :(

A small engine like this in a EV to extend it's range sounds good.

The benefit of the old two stroke was always more power from a limited space for the motor. That space efficiency was due almost entirely to the lack of a valve train, and no need for external compression, but this engine requires both. What removed two strokes from the streets was the combination of lower fuel efficiency, and added (and more visible) pollution from oil premix/injection, but these have both been alleviated by this design. It seems like it might have a fit in some segment, but I'd like to see a torque curve from a prototype before guessing which segment. I can't wait to hear what these will sound like - hopefully better than Mazda's rotary engines. Hopefully this turns out to be a significant advance - we haven't had major advances in ICE since quad valves, fuel injection, and turbos decades ago, and electric with current battery tech required at least 50 more years of mining and infrastructure to be viable.

Very nice to see old technology revived for a modern world.

I used to be a guy who could get it done with 3 strokes, yet I'm happy someone can do it with just 2

In regard to the fact that the revs would drop to 4.000rpm I guess the resulting sound would not be that high pitch pleasing sound we're used to hear but - provided it would keep the same exhaust and adjacent pipes and etc - it might keep the same tone, just at a lower level. *I raced a lot in kart competitions using 125 cc 2 stroke motors and the sound were gorgeous. People get thrilled with that sound! 😎

Ive been saying for YEARS, we need a pressurized intake 2 stroke that uses a port timing on the intake and a set of exhaust valves that release pressure at timed intervals for maximized fuel efficiency. Less losses of unburned, more power, better cooling. You could hybrid cool the head using air and water jackets.

This is a clear improvement from the regular two stroke engines. A huge step forward! Except, two stroke engines are already not used anywhere pretty much. The question is: is this better than a 4 stroke engine, more specifically, is it better than a 4 stroke engine in motor vehicle use. I highly doubt it... The main issue is in the combined exhaust-intake-compression stroke. You are expelling exhaust gasses, partially by simply pushing them out with compressed air from the intake, meaning some of the fresh air gets pushed out of the exhaust as well and some exhaust gasses will not get pushed out at all. Then there is only a quarter of a stroke or so where only the intake is open, and compressed air is pumped in, this is inefficient because you are pushing in against the motion of the piston. Finally, you only have about half the upward stroke as actual compression with the intake valve closed. This is inefficient because you obviously can't compress as much as on a full stroke and with such a short opening time of the intake valve you also can't push nearly as much air into the cylinder. Everything is just done too short to be efficient, certainly compared to a 4 stroke. The weight savings are not enough to offset this, not on a car at least where weight is not such a big factor.

Oh Mazda you reinvented the wheels again. Mad respect.

Unlike a regular 2 stroke, you can direct inject gas after the exhaust is closed. The problem in 2 stroke is that some fresh gas escapes out the exhaust before the exhaust port is closed by the piston. Also, your animation has the supercharger running when the crank stops and should actually stop when the crank does. I think this could possibly be converted to existing engines with a cam swap and new programming for injectors and adding a supercharger and high pressure fuel system. This video also got me thinking why there is no 2 stroke diesel hybrid system or regular diesel hybrid system. Mazda has always thought outside the box and especially with the Wankle rotary motors. I'm a Toyota guy, but Mazda is to be commended for pushing technology. If you always do what you've always done, you'll always get what you've always gotten.

This tech is nothing short of extraordinary. I'm familiar with the Detroit diesels being turbocharged and supercharged two strokes. I have a 2019 Toyota Yaris/Mazda 2 with a 1.5L DI engine. It's a quasi Atkinson cycle, varying compression from 13:1 down to 9:1 I believe. Gets 45mpg all day long on 87 octane. I have monitored high the high pressure fuel rail on the road, and have seen it go to 3000psi (207bar). Mazda is really stepping up their game with these engines. The only downside is the PCV putting oil vapor back into the intake which cooks on the intake valves. I de-carbon them every 5000mi oil change with PEA turbo and valve cleaner. Sort of a pain, so I hope they resolve that in later designs. If this is a 3 cylinder with 120° firing order, this engine will sound incredible. Also, 120° will give very little vibration. I have a 1974 Suzuki GT750 liquid cooled two stroke road bike, and the sound is amazing, and still like riding on glass. The engine doesn't vibrate either. Relatively slow rpm/ early tech two stroke.

A patent means neither that it's actually good and useful nor that it's guaranteed to be successful.

It's Mazda and every other car maker is eager to find out how new enginws are going to look like. We drove 2 time MX 5 and now for years a CX 5, industrutable and good quality. We'll see this in the future👍

General Motors in WW2 had a Tank engine that was 2 stroke supercharged. Most people think 2 stroke is just add oil to the fuel and no valves in the head, but as this shows you can have a valved 2 stroke. This would burn very cleanly and produce a lot of power.

The basic 2-stroke engine with reed valve crankcase induction is the absolutely simplest engine yet devised, even with spark ignition. Take apart any old chainsaw engine and be amazed; piston, rod, and crankshaft. Holes in the side of the cylinder for exhausting spent gases. Now comes Mazda complicating something already perfect.

Traditional 2-strokes will have, at BDC a slight negative cylinder presssure that helps the rings to lift and lubricate. Mazda's engine will have it's rings fully seated and pressed into the grooves so that makes lubricating it and the walls a little more complex. Ditto for the wrist pins and crank bearings. And it'll probably sound like a four stroke engine.

The sound would still be similar to an engine of the same orientation and number of cylinders that is running at twice the rpm. So if it runs at 4k rpm it could still sound like an engine at 8k rpm if it has the same exhaust system

This is nothing new as far as technology but I appreciate Mazda's boldness to try and bring the 2 stroke back to the market.

Like any engine, heat mitigation is key. It is used here to benefit the process. I hope they move to an in-line configuration. This has some promise. Lighter weight perhaps.

It doesn't surprise me at all. I've had this idea more than 10 years ago and I've always wondered "why don't they make engines like that?". But then I've always known, if I get an apparently brilliant idea, it's certain many other have had it way before me.

I love that Mazda is still putting R&D to work! Another example is the "Wankel" (rotary) engine in the MX30. Unlike other manufacturers Mazda does not focus on the fully electrical movement.

Great video - I've wondered how this could be done, for a long time. Diesel/4-stroke/2-stroke. Great! 🤩

So mazda patented something thats been around for a long time, i have seen a camless engine capable of seamlessly switching between 4 stroke and 2 stroke mode of operation making the best of both worlds, something that should be easy to make today with koenigsegg freevalve system.

Diesels don't have a fixed 15:1 Air Fuel Ratio (8:41). The air fuel ratio varies depending on how much fuel is injected, which is controlled by the rack position. Unlike an Otto cycle gasoline engine, there is no throttle to control intake air flow on a typical diesel. Power output is controlled by varying the amount of diesel injected, resulting in a variable air fuel ratio. This is why diesels had high NOx issues to deal with before the advent of emissions control systems; lot's of nitrogen in the air fuel mixture at high combustion temperatures promotes the production of oxides of nitrogen, which in turn contribute to SMOG when mixing with un-burnt hydrocarbons and reacting with UV from sunlight. This "new" two stroke technology is very similar to the Detroit Diesel Series 71 series engines (6V71, 8V71, etc, 71 cu-in per cylinder), which were first produced in 1938. Production stopped in the mid 1990s because of problems controlling emissions issues with the engines

I love Mazda's ingenuity and passion for thinking outside the box

Mercedes did the same with the 5-Cylinder 300D Motor some decades ago. They took the 5-Cylinder in order to get no simultaniously moving pistons which would have led to parallel ignitions. However, though the twostroker seemed to be easy, the additional components make them more expensive and require more space under the engine hood. The testdrivers were excited about the smooth running and capability to operate at very very low engine speeds but the cost controllers didn´t continue the program. Hoping Mazda will have success. What I didn´t understand in the video: why should a twostroker more vibrations ? It is vice versa: the more working strokes on one revolution the less vibratrions.

I like the AI south Dublin accent 👍 greetings from Ireland 🇮🇪

Who gives a sheet about making noise its a by product of power restiction removal. This is a great piece of work and my guess is its got a place to fill how long ice will be around is an evolution in progress.

Awesome! They invented something already invented.

2 stroke, a power stroke for EACH piston stroke. Would make a great motorcycle engine.

I love Mazda because they are the last Japanese manufacturer to use real transmissions instead of those rotten CVT (constant vibration and trouble) transmissions. We have all bought one because of this.

1. Der Text ist voller Fehler. 2. Meine Vermutung ist: Der Film ist ohne Zustimmung von Mazda. 3. So bezeichnete "Zweitakter" mit Ventil sind keine Mazda-Erfindung. 4. Jeder Motor, welcher nach 360° Kurbelwellendrehung Leistung erbringt ist ein EIN-Takter. 5. Normale Rennmotoren-Zweitakter können über 18000 U/sec leisten. 6. Eine Zulassung in Europa ist nicht möglich, da Abgase mit verbranntem Schmieröl. 7. Hohe Kompressorleistungen zehren die Motorleistung auf. 8. Wo soll das "Patent" gemeldet sein? Unter welcher Bezeichnung?

I think it will sound similar, in a way, to a Detroit Diesel depending upon how high the RPM is allowed to go and how low they idle it. With the two stroke design, a 4 cylinder engine will sound like an 8 for any given RPM assuming the engine will have an even firing order. I ran Detroit 8-71's and 8-92's on electric dynamometers in a building so I really got a chance to hear them under controlled conditions. The sound was very different from any other Diesel due to the 2 cycle operation. During the testing I ran them up to rated speed, which was low at around 2,000 RPM but they sounded like they were going higher, although no where near as high as a V8 gasoline. I have also heard 8-71's and 92's in earthmovers and bull dozers as they carved out an expressway near my house. And lastly, I lived near a truck stop where at any given moment there were 50 trucks idling as the driver's slept inside them. As I drove along the line of parked idling trucks within just a few feet of the front of each it was very obvious which ones were Detroits. The Detroits sounded like they were running twice as fast as the 4 cycle Diesels. So, if the Mazda uses a 4 cylinder, with evenly spaced combustion/ power strokes I will say they will sound like a V-8 4 cycle engine with a higher top rpm sound but a normal idle sound. It will be interesting to hear how it sounds both at redline and at idle with computer controlled fuel injection. Depending upon the RPM Mazda chooses for the rated speed and idle speed, it should sound like it's revving twice as high at speed and about normal for a 4 cycle V-8 at idle, but not an ordinary 4 cycle 4 cylinder engine. One last thing: While I was testing Detroits on dynamometers they made the transition to DDEC and although it made no difference at operating speed, the idle sound became very very precise and may have been set reduced in RPM slightly. I can't remember what the idle speed was anymore as that was probably in the mid 1980's, some 37yrs ago. But I was there and remember the exacting difference DDEC made to the idle sound, it was as steady as a rock. ben/ michigan

I came up with an almost identical system. I was going to start with a McCullough chainsaw motor. Beef up the lower end and weld a pad in the combustion chamber to raise compression. It was going to be a combination of a roots turbocharged induction, fuel injected diesel. I planned to run an alternator at a constant RPM. Charge a bank of lithium batteries, drive an electric motor in an electric scooter. I got COVID, diabetes, CKD, afib, overweight, difficulty walking. I became houseless. Got chewed up and spit out by thieves, tweakers,recyclers and landlords. I guess that you gotta have a big corporation backing you in order to invent.

Wow !! That's the most interesting engine video I've seen. What a very elongated process the 4 stroke engine as we know it, is. Best of luck with its development. Look forward to hearing more about it in the future.

Off setting the crankshaft to the compression side of the cylinder is a common way to almost completely remove oval wear pattern on the piston and cylinder. Additionally important to high compression motors.

Superb video! The graphics have really helped me understand these types of engines a lot better, great commentary too. I have aphantasia (no mental imagery) so the clear graphics were immensely useful. New sub here!

I believe that Toyota took a very similar approach several years ago using the 6 cylinder Supra motor. The rpm issue was there but I don't remember the other hurdles that they felt weren't worth the effort. However, the automotive companies are hooked on electronic fuel injection. The fuel delivery system can be simplified by substituting an fuel vaporizer using a simple FI system downstream from the compressor. Then the system would on pump a homogeneous gas mixture into the engine with a large range for AFR. This eliminates any chance of preignition. My experience on the dyno with a vaporizer system on a NA 4 stroke allowed up to 24:1 AFR without any misfire. This combination would really give this approach some legs and offer greater fuel economy and a simplified FI system with only 1 very large or multiple small injectors at low pressure. This would be similar to Yunick's mixing system but instead of using a turbo to mix and pressurize, the fuel vaporizer would do the mixing and the compressor pushes the mixture into the cylinder. There is very little data on using a homogeneous gas mixtures at elevated AFR's but there are real benefits if the research depts. would just explore the concept.

I imagine that the larger the piston diameter and the shorter the stroke, the more efficient the engine will be, because the gas dynamics will be better directed. Another aspect that should be tested would be the replacement of camshafts with cames with rotary cylindrical valves, which would greatly increase the efficiency of the system.

The valves would need to very big, esp.exhaust ones, hence even more prone to valve float (as cams would run at 1x crank speed). Therefore, only with a Desmo valvetrain would this engine really work well and at the needed RPM for proper efficiency.

The reason why this worked (to some extent) for ships,locomotives,trucks etc, is because of the size of the engines. It will not work for cars. If you're pushing compressed air inside the cylinder while it's going UP, you create an opposing force. To overcome this force you need a HEAVY crankshaft and flywheel. Of course this will further reduce the rotation speed. Even as a generator it will not work because the weight will negate any benefits. In the end, a simple four stroke diesel engine will be more efficient and powerful. And this is why these engines became obsolete in the first place.

I like how Mazda takes everyone else’s technology and puts it together and calls it their own.

The way it is depicted, the supercharger would acutally suck out the air. What a dope!

If freevalve is adopted, it can switch between 4 and 2 strokes. So 2 strokes at lower revs and 4 strokes at higher revs.

Already watch this video a month ago in the original channel but i still ended up watching this video again here 🤦‍♂️

The crankcase does not have to be filled with the intake charge, using a diaphram, the vacuum pulls in the charge, but it is isolated from the crankcast, and thus does not mix with the oil in the crankcase. I have never seen any two stroke done this way. btw, fragile electric components??? wtf the electric components at hoover damn worked for 50 years non-stop everyday without a single issue ever.