Why There Aren't More 2-Stroke Cars 

Just a minor detail... in the lower right at 7 seconds in, that's the engine I work on in my shop. The Orenda turbojet was designed and manufactured in Canada. Its American counterpart is the GE J47. Both of these engines were used in the F-86 Sabre jet.

honestly huge HUGE shoutout the the editors/animators y’all are under appreciated goats

I think that it was mainly emissions that killed 2 stroke cars. A buddy of mine brought his Trabant over from EG and drove it on IH-35 regularly. Many microcars also used 2 strokes and these , along with scooters, helped get Europe back on the road post WWII. Almost forgot, but SAAB used a three cylinder 2 stroke inline design for many years in their earlier models-John in Texas

Could totally do this with a rotary. Utilize the first rotor for precompression and the second rotor for combustion. It solves the issue of the rotary's current issue of a hot side and cold side per rotor. Rather than having a hot and cold side, you could have a cold compression rotor and a hot combustion rotor. Basically a high rpm gas turbine engine except with rotors vs fan blades. This makes so much sense for the rotary since it can hit high rpm and recent rotary research encourages high rpm low weight rotaries that use the centrifugal forces to hold apex seals in place. Since the rotaries are stacked too, you can literally just pass the air from one rotor to another rotor all internal to the engine rather than using auxiliary piping. This is big money. Could finally make the rotary what it was meant to be. Very little moving parts, long-lasting, a ton of horsepower in a small package like a gas turbine, while also having the throttle response of a piston engine. Make this happen Mazda! Edit: Researched this design concept more and came out with an even better concept! Rather than even use rotor 2 for combustion, remove combustion from rotor 2 and separate this into a combustion chamber that sits in between rotors 1 & 2. Rotor 1 acts as a compressor, a giant rotor feeding extremely compressed air into the combustion chamber which is a constantly lit flame front. The chamber has a fuel injector and a spark plug and its job is to mix and ignite the fuel. However, once the spark plug lights the first flame, the flame stays on until the engine is turned off. As rotor 1 pumps air into the chamber, the gas/fuel ignites, expands, and enters into rotor 2. Rotor 2 extracts all this expanded gas energy from the combustion and drives rotor 1 via eccentric shaft. Coolant is focused all around the combustion chamber eliminating the water seal that constantly fails in the RX-8. The rotary will compress air and extract exhaust gas energy on both banks of each rotor one after the other which results in compression and power at every 180 degrees of crank rotation. Almost all expansion energy is extracted in rotor 2 because all fuel is completely burnt after the combustion chamber except in rich conditions. Holy crap this would maximize efficiency! 100% fuel burnt after combustion assuming 14.7:1 AFR and then it enters rotor 2. If Rotor 2 is optimized to extract exhaust gas energy then it would be one of the most efficient and compact engines ever. The design would only require 2 rotors/housings, a center section with 2 combustion chambers, 2 fuel injectors, 2 spark plugs, and a single eccentric shaft. All that is left is coolant routing and oil routing! Also since combustion is a constant pulsing flame, wear and tear are greatly reduced, this allows for extremely light rotors for very high rpm and greatly increases engine longevity. Definitely would last over 150k miles or even more! Will also sound like a giant pulsing turbo. Someone needs to make this! If nobody makes this I might go and make it. Comment what you would call it, I'm thinking maybe "Rotorbine" Eh...

Can I just say that it’s amazing you guys pour your hearts into making these hilarious videos EVERY SINGLE DAY? I can’t thank you enough for all the laughs and knowledge I’ve gained from this channel.

This engine even borrows from ship steam engines from the 19th century - the big final cylinder is like a triple expansion! Love it!

Sounds like there could be a lot of parasitic power loss with this engine design. You have 4 cylinders with 4 pistons being moved by the crank shaft, yet only 1.5 of them is actually generating power.

This might not make for a good automotive engine but with its efficiency it could been good as a fuel powered generator.

I think it’s worth noting that some MotoGP engineers and riders have said that were the 2 stroke bikes brought back today, with the advances since they were phased out they believe that the 500cc two strokes may be able to make more power than the 1000cc four strokes. Namely things like DI fuel injection, advances in digital engine control, and the continued development of 2 strokes by some motorcycle companies are believed to be able to make a significant difference in the amount of power the engines are able to make. When the regulations first went to the 4 strokes they were much more powerful than the 2 strokes but there have always been some in the industry that attributed that to lack of development being put into the 2 strokes since they were exclusively used in motor sports and power sports. I would sure love to see what a modern day 500cc 2 stroke 4 cylinder MotoGP engine would look like when you let it off the leash.

My father told me stories of my grandfather meticulously revving the 2stroke engine of his Trabant before longer descents to oil up the engine for prolonged engine braking.

You forgot the two stroke Detroit diesels. They were in production for awhile until they couldn’t meet emission requirements. There super cool and would make a great episode on their own

That "getting you pumped about engineering" bit absolutely hooked me into hitting Subscribe. Not just your enthusiasm, but all the supercool info. As I understand it, the EI engine makes power from the large exhaust cylinder as the small combustion cylinder is on the return stroke. Letting the engine scavenge otherwise wasted power, and in my opinion, making it a ONE-STROKE engine. :-)

This sounds incredibly unreliable. As a rotary owner, having one area of the engine that is way hotter than the rest is a recipe for disaster

First piston induces more air into 2nd piston, 4th piston generates a little extra power from the waste exhaust gasses, sounds like a turbo to me, replace piston 1 and 4 with a turbo, oh we made a turbo 2 stroke

12:20 Germany is absolutely dominating this video

I like how they used the sound of a 4 stroke at 2:47

It seems like the concept is “make more use of the fuel we have” instead of “use less fuel”. Which is an interesting take on efficiency. However, it’s hard to imagine how efficient 1-2 cylinders doing the work of 4 actually would be.

If you find a way to spin a turbine (turbo) between the compression cylinder and the last (expansion) cylinder, it might work. You could (in theory) get this thing to make the same power as an old (medium-sized) pushrod V8. If you could maximize the torque potential, I think it would work. In that case, it could potentially work for a utility vehicle.

once again thanks to Donut Media ive learned more than in any classroom. keep up the excellent work guys, Much love from South Africa CPT

Being a car guy at heart,but never having had the opportunities growing up to learn about what makes a car do car things, you guys learn me something new everyday. Thanks for that. 👌🏻

On the topic of how many cylinders it would take to make an equivalent to a regular 4 stroke, I think the most logical solution would be to use the W design like Bugatti uses, since that wouldn’t be too hard to fit in, even if you’ve got a W16 that’s equal to an inline 4, just seems like the most efficient way to fit into a car

“When most people think of two strokes they think of dirt bikes” -Inserts four stroke sound 😂😂

The efficiency returns of Mazda's Skyactive X was far less than the tech seemed to imply, but at it's heart, it's still a standard engine. This all new technology seems too complex for it's own good.

2:45 That's a 4 stoke motorcycle sound clip you played... 🤣

If it turns out to be efficient, it would make for a great hybrid setup. Electric car, but with dedicated onboard generator.

2:46 That's a 4 stroke dirt bike sound lol.

at around 3:09 you guys used a 4 stroke dirt bike sound clip lol. i bet i'm real fun at parties

You should do more Saab and Saab 2 stroke content. Some of the best sounding 4 bangers ever

Some aspects of this engine design remind me of the old triple-expansion steam engine. Three cylinders were used of different sizes to extract more of the thermal energy from the steam before exhausting to the atmosphere.

the irony of using a 4 stroke dirtbike sound when talking about iconic 2 stroke engines

my favorite thing about jer-bear is he goes from dropping some serious knowledge, showing just how educated he is, to doing a weird voice and saying or doing something absurd. you are hilarious. never change

that valve between c2 and c4 to me is probably one of the huge issue you didnt highlight, creating a valve that can open an close that quickly enough and at those temp , speeds and pressure

This engine actually makes me think of a triple expansion steam engine based on its rudimentary design :D

If they keep talking about 2 stroke engines like this, I wouldn't be surprised if they tried to do a motorcycle engine swap on a car

"Will 2strokes engines save us from EVs?" *John Connor tryin to escape the Terminator on his dirt bike. YES!

That comment about Blockbuster able to buy Netflix for $50million, was Savage and so very true. But in way, glad that blockbuster didn't buy Netflix, it probably wouldn't be as good.

My Subaru converted it’s self into a two stroke

With all the fun and jokes, everything sinks in. You guys have helped me with engine swaps, turbo upgrades, etc... love you guys and thank you. PLEEEEEAAAAASE DO A SAAB 95 AERO episode!!!!!

@3:20 It wasn't the Saab Sonic, it is the Sonett, that specific one is the Sonett 2. The Saab Sonett 1 was a super sport prototype that looks amazing even to this day.

3:20 *Saab Sonett As a swede I am greatly offended

This idea blows my mind as much as when I learned about the rotary engine and the Atkinson cycle

Most drivers can’t figure out how to use their indicator lights … and you expect them to do the math on 50:1 per litre or gallon

You guys need to do a dedicated video on the two-stroke Detroit Diesels that were made from 1940 to 1995 and were put in literally anything from generators, trucks, heavy equipment, tractors, and even boats. The sound these engines make is legendary and practically helped to built America in the mid to late 1900s

Rob Dyrdek & Daniel Tosh had a son and he’s in this video.

He’s much more cool calm and confident than his first videos. Props to the rest of the group for helping to build him up.

You should do more two strokes video’s!

In separateness lies the world's great misery, in compassion lies the world's true strength.

Based on the fact that it's still making power even during the exhaust stroke would mean a more even power curve, so while it might not make sense for cars, it would make generators a lot better by having a more constant torque curve and smoother input to drive the electrical components, making them less prone to frequency changes and power loss under load unless I'm missing something, and anything to make a more effective generator has a market available

Loving the fact that when he shows the two stroke dirt bike it makes a four stroke sound

A lot of (European) car manufacturers used the two-stroke, though most of them went either defunct or switched to the 4-stroke after WWII. One of them was Aero, a Czechoslovak company who had built the largest two-stroke in serial production (Type 50, 1997 cc 4-cylinder, 51 hp). Apart from emissions, another major problem of the two-stroke is that the piston displacement can't be chosen as freely as in 4-strokes. As a general rule, the maximum displacement should not exceed 350cc per cylinder for the optimal power to weight ratio. Two strokes do achieve a good power output by revving high, but the disadvantage is the limited torque which is only available in a narrow band. This disadvantage could be at least reduced with automatic multigeared transmissions but not completely eliminated. Direct injection was mainly used for small engines. While the emissions from the mixture could be vastly reduced and catalytic converters were easier to adapt, these engines were far more expensive in production and had some issues with the reliability.

Don't forget one of the most produced diesels for decades after WW2 was the Detroit 2-stroke line, making engines on mass from small 4-53s all the way to 8v92s in standard applications

I’m not an engineer, but I feel like this is a cool theory but I think it would be absolutely ridiculous in practice.. I really want to know what it would sound like though

7:00 "massive and efficient, stop it 🥵" 💀💀💀💀

This is probably a good idea for a generator. Set engine speed with a designed max load and increased efficiency, but otherwise most likely 🗑

Jeremiah seems so natural in front of the camera and he makes these videos just as entertaining as James did

Had me to the end, I loved the concept of the engine as much as your excellent ability to present all of the material , regardless of it's developmental stage.

Been loving the 2 stroke content. Their relative simplicity in motorcycle applications has really helped helped me begin to understand engines. Doing my first top end rebuild soon and I’m excited to do it!

For anyone interested, the Saab mentioned at the beginning is the Sonett not the Sonic. Neat car.

As an aviation mechanic, having 4 SEPERATE sizes of piston to have to figure out and replace sounds like a nightmare, imagine accidentally ordering the wrong head gasket

Day 263 of asking Donut to bring old B2B back

Speaking of new engine tech, you guys need to check into the Astron aerospace omega 1 engine. Really cool and really simple!

"when you think of a 2 stroke, you think of lawnmower, chainsaw or dirtbike baby!" *uses 4 stroke dirtbike sound*

Seeing these videos makes me laugh even more thinking of Jerry’s first few videos. That’s on character development💪🏼✅

If they used larger intake cylinders to feed multiple power cylinders at one time, it could in turn lower the weight and make it easier to balance, may even be more efficient.

2 stroke dirtbike driving trough backround with 4 stroke sound xD

The complexity of this arrangement only makes the simplicity of electric motors that more compelling.

These guys really are great I can't thank them enough I'm 22 and my dad passed when I was 17....didn't have anyone to learn off of....my pops was an avid mechanic and welder always out and about working if he wasn't with our family....when he passed from lung cancer I didn't know what to do with myself everything I was learning from my dad ended up stopping and yet I had the urge to continue his legacy....donut media has been my "2nd dad" so far and I can't thank them enough

I'm just glad we got to listen to Jeri's amazing pronunciation of oil again.

Coming from a recent mechanical engineering grad and a car enthusiast, THESE VIDEOS ARE GOLD.

Hey Jear Bear, could you do an episode on how the liquid piston X engine works?

"Engine goes brap brap brap" *Trabant flashbacks*

Jeremiah is awesome and hes easy to listen to cus he teaches us so much he deserves to be on donut just like everyone else

Watching Jer getting hyped about engineering is a great way to wash the sour taste of Monday out of my mouth. Keep up the amazing content!

3:18 Y'all really did the Saab Sonett dirty, not you Jeremiah you nailed it.

I have a 670ho rotax 2 stroke from skidoo in my 85 honda odyssey. Super easy swap thanks to CVT. 130HP in a little over half a liter.

Funnily enough, I pondered the idea of using 2 cylinders of different displacement for a 2-stroke engine as a kid some 20+ years ago, before I had access to the internet or had any idea that it was an actual way of doing things. but as for the cheeseman cycle, given the complexity, mass, and balancing issues it makes absolutely no sense in a motor vehicle, although I'd certainly love to see it built and tested in a stationary generation scenario. Another thing that could further increase efficiency would be to add water injection to the expansion cylinder as I'd imagine it would still contain a lot of heat from combustion which theoretically could be utilised to produce steam. Sure, it still doesn't technically improve efficiency as you're adding another fuel of sorts, but water is a lot cheaper than gasoline, "burns" cleaner, and it can be condensed/reused

Massively increasing the complexity of the engine doesnt seem like much of a way to compete with the incredible simplicity of EVs. The outer 2 cylinders are just doing what a turbo would do on a large 2 stroke, i cant see how it vastly increases efficiency.

"SAAB Sonic" Lol! It's Sonnet silly boy, not Sonic. Oy!

Jeremiah is one of the best additions to the cast. It's natural to him.

I still think 2 strokes would've been amazing if developed as much as 4 stroke

Isn’t that why two strokes have a idle screw so when you let go of the gas it’s still giving it enough to run the engine?

Yo that intro AD had me lmao at the end. “Cause not everyone lives in Southern California” I live in Vermont. The hottest and coldest place on earth

A supercharged, DI 2-stroke is actually a really good option, particularly for a lightweight range extender for an EV

Better develop it in a place with good ventilation! I'd love to see this tried even if it never leaves the prototype phase and fails...

so this engine is basically a 2-stroke that has the top and bottom of the piston split into 2 separate pistons, turboed by another piston, and recycles the compression energy used by the first 2.

For a different type of combustion engine you should definitely check out the INNengine. It was initially designed as a generator for range extended EVs but there's already a swapped Miata. It has elements of a rotary engine and it's a 1 stroke engine.

What the guy needs is a bunch of engineer students with cad. A few clever machinists, some basic metal working equipment to make at least a prototype.

I would like to point out that with this engine type... just for testing the concept... you could actually get away with using a bog standard 4 cylinder engine with custom designed intakes and exhausts... plus a cam for timing all the valves differently. Cylinder one Intake valve is still the intake, exhaust valve is now used for compression exhaust into the second intake valve of the second cylinder... for ease of manufacture, you could actually use the exhaust port of cylinder 2 as its intake. Then use the intake valve as the exhaust port exhausting into the special combustor which seems to not be too dissimilar to a jet engine's combustor. That then enters the intake valve of cylinder 3, burns, and then uses the exhaust valve to enter in through the exhaust valve of cylinder 4, which then finally exhausts out the intake valve of cylinder 4. Unfortunately, you wouldn't get a 2 stage compression (as the cylinders are the same size) and you wouldn't get as efficient exhaust recoup... but if its gonna run... this should at least prove the concept.

I’ll ignore the misspelled “ignition” during the cauldron scene because I love you guys. Don’t let it happen again though.

Im a semi truck mechanic i sadly have to say that i already see a huge number of issues with that design 1. The different piston masses will absolutely murder the crankshaft 2. The temperature differences from cylinder to cylinder will put high stresses on the engine 3. The engine is very complex and will be a huge pain to maintain Theese are just a few things that immedeatly jumped into my mind here as a mechanix

I would like to see this engine work but I have a feeling that the power to weight ratio would be very low. Im not an engineer but thats just my observation.

So it's a 2 stroke, with one combustion chamber (I'm gonna guess the exhaust chamber isn't as powerful as an actuall combustion chamber because lets be honest it isnt) that takes up as much space as 4 or more combustion pistons (as the exhaust and intake compression pistons are larger). While this is great for efficiency, it does not have the main benefit of a 2 stroke, being 2 times the power pulses of a 4 stroke, as you could fit 4 4 stroke pistons in a row, and have 360 degrees of combustion instead of just the 180 this provides (assuming both theoretical engines have 180 degrees of combustion per power pulse). This is great tech, but it isnt really what I'd expect from 2 stroke innovation, actually losing its main draw for a new one.

And it's really funny that at about 2:04 the video is the most replayed part. Because that's where the ad ends.

It would be cool if you did an episode on the M4+2 Mezyk engine. It combines a two stroke piston and a four stroke piston in one cylinder :) Crazy idea and insane efficiency, much better than this engine. And there is a working prototype

My thoughts would be remove cylinder 1, it just sounds like an inefficient turbo. Then solve the nightmare of balancing this engine. Even with just 3 cylinders trying to balance 3 different sizes of piston sounds almost impossible. Honestly the last piston trying to take advantage of exhaust pressure sounds cool but setting it up on a separate closed system that doesn't involve the engine itself sounds like a more practical and reliable solution.

I designed a 2 stroke gas engine 10 years ago. The design applied to new engines, and upgrade to existing engines. Same crank, same pistons, same cylinders, same fuel, different cam, different timing, different heads. In a 360 degree 2 stroke cycle, 2 of the 4 cycles from a 4 cycle are combined or sharing available 360 degrees. 2 power strokes = 2X more power, but there was a loss from incomplete exhaust scavenging. Engine has to run on boost all the time, just like a 2 stroke diesel ship engine. Exhaust scavenging was improved by other means. Because 4 cycles are using only 360 degrees, top RPM is limited. 6,000 RPM in 4 stroke = 12,000 RPM in 2 stroke. There were changes in the heads that allowed variable CC volume, easier than making a variable displacement engine. Engine always runs at peak efficiency; low load, high load, no load. Engine is capable of over 250 hp per liter of displacement. I have another design using opposed pistons, 2 cranks, 1 shared head. It is capable of 500 hp per liter.

If you think about it, the first and last cylinders do the same function of a turbocharger. It be interesting to experiment this cycle but with a turbo in exchange for those cylinders.

Like number 3 baby woo

Hey guys, obligatory SAAB enthusiast here, the car you call a SAAB Sonic is actually called the Sonett. My father owns one of the later ones with the Ford Germany V4

"Yo, what ya got under this hood?" "W32 CHEESY, dude! 63% efficience"