The Twingle Split Single Engine used for 70 years 🤯

[@repairman22]

Touch CC on the screen to turn off the subtitles. I also animate 3D real stories on my second channel: @Trueeventsin3D

[@TrueEventsin3D]

Hi

[@aceecaa]

If possible, can you introduce this two-stroke engine? Thank you. forum.jorsindo.com/data/attachment/forum/201303/31/232919b8g83fupmr9mrmg7.gif i.ntdtv.com/assets/uploads/2013/03/p3318701a990706700.jpg

[@bustjanzupan1074]

Thank you :-) I am telling to people, that Puch was one of the best constructionist at that time 🙂 Pwy 🙂

[@Eduardo_Espinoza]

​@@TrueEventsin3Dhi

[@mkuehn5450]

small detail 1:14 'intake and exhaust occur at the same time' research "blowdown" or the time (in crank degrees) the exhaust is open before the transfer port is opened. reducing cylinder pressure to prevent reversion into the tansfers. you're also wrong in your understanding of "torque" which is strictly a function of the power stroke, the piston area, rod length, and crank pin offset. excellent description of the expansion chamber function.

[@Alan_Hans__]

I had never seen a twin single engine explained before. Nice.

[@robertwest3093]

I didn’t even know that they existed until now!

[@Alan_Hans__]

@@robertwest3093 . I learned they existed 2 weeks ago.

[@megapangolin1093]

Amazing, been driving for 50 years, love cars, lived in the town where Bubble cars were made, but never even heard of this engine type. Thank you I enjoyed every minute.

[@repairman22]

Thanks for sharing

[@TobyLawnjockey]

New to me too, looks efficient, expansion chamber on the triumph? (The cornet, @ 3:56)

[@paulcressman2344]

I bought a used Sears Puck 250 in 1975. Interesting engine, lots of low end torque. Wished I still had it.

[@proadymx1]

Yes, I remember the Allstate 175 made by 'Puch' and sold by Sears.

[@paulreed6089]

250 puch 2 stroke sold by sears was my first motorcycle given to me by my step brother in 1973. Before even starting it someone passing by on the road offered to trade his 1973 DKW Sachs 125 dirt bike for it. So I owned a puch 250 for only 5 minutes.

[@phillipzx3754]

Puch engines were also used in the 100 and 125 Penton. The 175 Penton came with a KTM engine.

[@leopoldpoppenberger8692]

yes I had a 175 PUCH made by Styria Austria 2 pistons one head .

[@theknifedude1881]

I had heard of Twingles but had no clue why they were a good idea. Thanks for the explanation.

[@JC-gw3yo]

I have been a piston head for years, and this is all new to me.. Thanks

[@stevenmitchell6347]

I can see this as practical for modern 2stroke applications i.e. large chainsaws, outboard motors, etc.

[@IainDavies-z2l]

The Twingle or Twin Angle engine is based on a very crude machine built be Canadian lodgers in the 18th century, it's principle was you hade two vertical pipes positioned together with wooden pistons (made from tree trunks) which would be driven up and down the pipes by a steam pump engine at the top. This was used for making waves on the river used to float the cut logs to their destination for processing. This principle was only used in a small area of Canada where the natural river water flow was not strong enough to float the logs at a reasonable speed.

[@JoeGator23]

Modern engineering doesn't even think outside the box compared to these marvels from well over 100 years ago. Impressive, especially considering this was done before the age of computers. If anything, we have gone backwards in some respects. Thanks for the cool video!

[@AlexofZippo]

As complexity increases, so too does the minimum level of genius required to realize the best solutions.

[@electricpaisy6045]

Whenever there is a modern outside the box technology is explained on KZbin, people collectively complain about to much complexity and failure points eventhough modem engines fail much less than old one. The hipocracy is through the roof.

[@OldSchoolZ-wy2yx]

@@electricpaisy6045 Just try to get an OBD2 car to drive a 100km at highway speeds with clogged injectors, multiple vacuum leaks, exhaust manifold and crossover leaks, at least one collapsed lifter, severe detonation, a dead cylinder, very sooty spark plugs, all that and much more on a half and half mix of very old gas and new. A very neglected 93 Cavalier with a 3.1L I saved from a scrapyard did, last year. Modern cars have thousands more failure points than 80's-90's ones, doesn't matter if materials science has come a very long way since then; remake my Cavalier's exactly as is but with modern materials and techniques and they'll outlast everything made today. The simpler, the better.

[@electricpaisy6045]

@@OldSchoolZ-wy2yx OK but my obd2 car never had any of those problems in the first place and even if it did, the obd would tell me and I'd just fix it. Your car might be able to last forever but if it takes 2 times as much fuel at half the HP and less good cornering it's just not worth it to avoid one problem every ten years.

[@electricpaisy6045]

@@OldSchoolZ-wy2yx and just look at the video. Double the friction points and more parts compared to a normal two stroke in the name of efficiency. Why don't you complain about that? It fullfills every of your points but somehow it's old enough for you to accept?

[@derelictarchive]

I love learning about the innovations of many past engines.

[@carlnapp4412]

The Twingle Triumph BD 250 was widely used by the Wehrmacht. She was produced in Nuremberg from '39 until '44.

[@realdbcooper3423]

I LOVE THESE VIDEOS, Cause this is the place to go where you wanna go when you think you know all about engines, but theres more to see, and its type of content know one else gives, showing deisgns and internals and explaining in depth from historical point of view to advantage and disadvantages, to all the components, That is next tier level yt creator. Twingle diesel 2 stroke, and mazda patent mixed with twingle? could be cool. LOVE THIS CHANNEL!

[@sharpbends]

Glad you mentioned the DKW

[@williamjmansfield8768]

Yes, At 80 plus I knew of the Puch/Allstate 2550 twingle engine. Like to have one even today.

[@dougschneider5948]

Do the spark plugs fire at different times with different ignition systems?

[@andrewgent5887]

The stepped piston two stroke engine fitted to the Wolf motorcycle on display at the British National Motorcycle Museum is another version of two stroke technology.

[@rtzlwitz]

Very good video - very good explained. Thanks for that! I learned riding motorbike in the late 70th on an old, 1954 build, Puch SVS 175ccm with a twingle 2-stroke. The Puch twingle engines ("Doppelkolbenmotoren") were famous for being very elastic with a lot of torque from the bottom. The Austrian "Puch" was sold to USA under the brand "Sears Allstate". Didn't know this since I seen the "SR250" in your video. Once more: Thanks for that!

[@theinspector1023]

Enjoyed the video. Thanks. In England they're called split singles. A wonderful example of the opposed piston two-stroke is the Napier Deltic diesel with three crankshafts. Now that's an engine!

[@peterofenback9263]

Thank you for the easy-to-understand explanation of an unusual engine principle.

[@Max-pi7ri]

Great video, Please cover more of 2 stroke engine designs because very few channel have such detailed explanation about them

[@niljulia1380]

excellent video, i have an Iso trycicle called "Isocarro", it was very popular in Spain and Italy in the 50' and 60' as a light van for freight. Once i opened the engine to restore it, i was shocked to find out this system, excellent explication!

[@terryhetherington3364]

Never heard of the twingle. Interesting!

[@donfly-z3u]

Thanks. This is a great video, very well explained. Puch engines are still running today. But they have a thermal problem. When driving quickly on the highway or under high loads at a consistently high speed, the rear piston tends to block.

[@metricstormtrooper]

I thought this would be rubbish from the narration, but its been brilliant, really well explained, so well that I subscribed.

[@MadScientist267]

It's funny, I figured out that the pistons needed to be slightly out of phase with each other to optimize this... and then you mention it. My vision was the second one, 2 independent rods on one journal. I first clicked on this thinking "Why? More friction?" 🤣 -- but it soon made sense.

[@pepelimantour3757]

Many years ago in Mexico has a puch 250 gs with one carb on the side of the cylinder. There was also a model shell with two carbs one on each side of the cylinder. Wonderful bike very fast reliable and even had auto oil injection and enclosed drive chain. Would love to have one today here in South Africa.

[@oldschool2546]

NICE. Wish I'd had this video when I had to choose between 2- and 4-stroke mopeds back in 1985

[@noahwail2444]

The Danish police used the Puch 250 in conjunktion with the Ariel Square Four. The Puch in towns, and the Ariel on the open road. So whereever they showed up, the bad guys had a hard time. ;o)

[@qoph1988]

The Danish police must have loved the back of their engine overheating

[@captinfubuki9728]

i only know about these engines because we have a really old lathe that uses one sadly no longer runs as the crank broke but it worked well until then besides a rare backfire like thing that it did where it would spray flaming fuel out the exhaust so we started keeping a big metal drum under it

[@atburke6258]

In 1964 a friend bought a used Puch 250 SGS that would only go 20 mph. The motorcycle shops could not fix it. I did and got to know the Twingle system. In 1968 I bought one new from Sears as an Allstate. It would not run from new. I told Sears what was wrong and they would not believe a stupid customer knew anything, so they had to refund my money. Too bad, it was a nice bike for its size back then.

[@tauncfester3022]

If it didn't run and your friend's bike only did 20 mph, how did you come to the conclusion that they were "nice bikes"? They sound like they were, in your experience, pretty crappy. I own a Ducati 250 I've owned for 45 years and it does 65~70 mph easily.

[@atburke6258]

@@tauncfester3022 I said in the third sentence that I fixed it. It ran fine after that. It did more than 70mph, easy. That is why I bought a new one years later from Sears. It was DOA because the local Sears "adjusted" a running bike pre delivery and made it quit working. I offered them the fix instructions and even said I would do it myself right then and it would take less than 5 minutes. They were not about to listen to a dumb customer so I told them to stick it and got my money back. I'm still here and Sears is mostly gone.

[@TobyLawnjockey]

Pity, nice looking bikes..(ah, good ol' sears..might order a resonator guitar, and a morphia/heroin/coca/syringe kit, while I'm at it?)...my how things have changed?...

[@paulnicholson1906]

I have one. It runs great. Starts on the first kick and has plenty of low end torque with good speed although being 70 years old I treat it nicely....

[@stephenmathewes5159]

​@@tauncfester3022OP FIXED the first one. Some of us can do that and end up with nice bikes. Some of us can also read. M_r_n.

[@RH-xr8ms]

I had one of the Sears 250's for about 5 years in the 5o's !

[@jobamer7684]

I would have never imagined the Puch 250 to be sold in the USA. As you indirectly mentioned the technology for this kind of engine was already ancient and outdated by the time they were first produced. And I think they were made until mid 70s! Oh and nice video.

[@russbilzing5348]

They also made them in 175, 350 and 500cc versions. My dad had a '64 250 and I had a '67 250 I thought his was the nicer looking, but I kept mine for 20 years longer. I rode it from St. Louis to Alamosa, Colorado and all around Colorado Springs. It would only do about 60 mph and I had to draft trucks on the freeway, but it never, ever failed me.

[@PRH123]

I had a Puch 50 cc moped, it was pretty bulletproof, and got around 125 mpg…

[@andyb.1026]

I had an SGS 250 in '65 (a '60 model) Bombproof and it could keep up with Honda cb72.

[@zogzoogler]

Brilliant video, nice explanation of expansion chambers as a bonus. 👍🏻

[@NC-xk1eg]

I remember the old Sears Allstate 250 motorcycle had this. In those days they were fast! 😄

[@maximumengineering5419]

At close to 350 lbs with only 15 HP I wouldn’t say it was particularly fast. Mine topped out at around 65 MPH.

[@NC-xk1eg]

"IN THOSE DAYS" that was fast. It was the fastest thing that Sears sold. The little Sears Compact was actually a close second. The 2 speed Allstate MoPeds were a hoot & used on many, many paper routes. The gas cap was also an inverted cup for measuring 2-stroke oil at fill ups. (A Yamaha FZ-6 IS fast by today's standards)

[@PHPJN7]

Small correction: 2 stroke engines with valves do exist. Have a look at Detroit 2 stroke diesel engines which utilize an exhaust valve already since 1938. The large container ships of today are also powered by 2 stroke engines utilising exhaust valves.

[@repairman22]

I made a video about 2 stroke diesel. Its in my channel. Thank you.

[@DownhillAllTheWay]

When talking about fuel mixture going straight out of the exhaust port, don't overlook the fact that the fuel mixture is not being pumped into the cylinder continuously, as is hinted by the animation in the video - the engine only has one crank-case full of mixture to supply, so when the crankcase is empty, mixture would tend to stop anyway.

[@marcdheere134]

I used to have a belgium made FN 175cc two stroke with two pistons behind each other. It has only one spark and combustion chamber. The special thing on this type is that there is a main piston rod and the second is not fixed at the bottem of the first. It is made like the connecting rods of a star engine with hinges.

[@confuseatronica]

the diverging part of the exhaust pipe resonator is the part that reflects the wave back up to the exhaust port. The diverging section slows the gas and the gas behind it hits the slow gas and makes the pressure go up. Bernoulli.

[@mkuehn5450]

nope, the divergent part reduces pressure, increasing cylinder scavenging. the convergent part reflects the echo as a physical wave back to the exhaust port preventing fresh charge from escaping by increasing pressure. dwell is the length of the chamber between the two cones, determining the time for the sound wave to return to the exhaust port. effectively tuning the pipe to certain rpm ranges

[@squidcaps4308]

Subscribed simply because you didn't put your face in closeup for minutes on screen but instead opted to stay in the margins and using loads of animations as content. I hate the "big face on a big screen staring at me" style that many channels use.

[@repairman22]

Many channels use that technique to avoid copyright when using images that they did not create.

[@444mopar]

​@@repairman22the bobbing head on the screen infuriates me, especially when the thing they're talking about is sitting right behind them but these guys want to see their face on the screen I guess.

[@user-Dr.]

I remember in the early 60's my dad had a Sears Allstate, the engine in that bike the pistons were front to rear, different than the one you show, during the year or two that he owned it, it burned a hole in the rear piston several times, I was about 5.

[@markrowland1366]

I had a BSA 250 and my friend had a Puch twin. Great fun getting around at fifty with a pip tent. Good god stuf was so expensive in 1966. My parents had a business requiring air freight to be dispatched before school so i got a driving licence at thirteen.

[@ErickC]

An even better solution is to combine uniflow scavenging with, y'know, exhaust valves. It solves a whole lot of problems. ;)

[@ovalwingnut]

I felt a real tingle when I learned about this Twingle... just saying. You R the "Unique Engine Whisperer"

[@kimmer6]

My friend had a Montgomery Ward twingle in 1967. I think Puch made it. The bike had the shifter on the right and the rear brake on the left side, opposite to every bike that I ever rode. It was hard to get used to.

[@rogerlaredo9527]

I had a Puch 250 in early 70s. It had an automatic oiling system, which I thought was rare for something from early sixties.

[@thepubliceye]

Back in the 60's I had a DKW convertible and a Zundab motorcycle, so yes I heard of the twingle.,

[@Triggernlfrl]

Especialy in big diesel engines there are a lot of 2 strokes with (excaust) valves and different ways to get air/excaust gas in and out the cilinder. Especialy in big (old) diesel engines.

[@nathangoshawk]

In the UK there was an odd, but fairly successful, little car called theTrojan. Very plain, simple and economical it was powered by a four cylinder double, split single of 1500cc. Probably the strangest features of this engine were piston rods designed to bend (a little) and a remotely located carburettor some distance from the engine. No passing oddity, Trojan employed this engine from the early 1920's to the early 50's, latterly in (very slow) light vans and also developed a triple, split single.

[@michaelsorrentino-yp7nb]

I recall doing this to Yamaha race bikes in the 70s for racing short tracks !

[@izzatsyahmi5933]

The design is not meaningless actually in 2 stroke era. because you can make the exhaust port bigger by using this design.

[@saylormalan]

Dear, I really liked the video. I didn't know this type of engine. In mechanical books and courses, it is not discussed or shown. I thought this engine was very well thought out.

[@whalesong999]

First motorcycle I ever rode was an Allstate 175cc owned by a friend. I think it was a '54 model, dark red color and a solo seat. That was '57. There were photos of James Dean seated on one just like it.

[@heikojakob6491]

I've got a 1949 Triumph(TWN) BDG 125 with a twin single 2 stroke engine.

[@billylyman2950]

Great work as always

[@repairman22]

Thanks again!

[@maximumengineering5419]

My father bought a new Sears / Puch 250 in 1968 (but it was actually a 1967 model). Looked just like the one in the video. I ‘inherited’ it when I turned 16 (1971). Sold it to a neighbor kid when I got a newer bigger bike. He wrecked it and I talked him into giving it back to me. Frame is long gone but I still have the engine. Great memories! Thanks for sharing this interesting design.

[@adamstobiecki5868]

As a child, i remember hearing my father and his friends talking about a DKW. They seemed to be superior at the time. A lot of good stuff was coming from Germany at that time.

[@robertgreen9614]

The BSA Bantam was a DKW design, part of reparations after WW2. Minsk and Harley also "borrowed" this DKW design.

[@peceed]

I have "reinvented" two camshaft twingle-like H engine as high performance 24-cylinder unit with piston axis angled by 150 and 30 degree (I called it rhomboidal engine).

[@jonwatkins254]

I had a friend bought a Puch 250 in 1964. Riding it home (maybe 15 miles) it stuck 3 times. after cool down ran fine. Wasn't a bad motorcycle until Honda.

[@jimeeeason149]

Hard to believe that design is still around in some form or another like the Sears Allstate Puch 250 my dad had he bought new!!!

[@rdyam]

Thanks for an excellent instructional video. If I can offer a correction, at 5:01 you say that the transfer and exhaust ports open at the same time in a two stroke. The exhaust invariably opens a good deal earlier than the transfer ports and, due to the symmetrical nature of the piston port engine, closes well after the transfers have closed, making the exhaust duration longer than the transfer duration.👍

[@kd350]

Well noted.

[@donaldelrod9172]

many interesting miles on an allstate 175 that wore out 3 times and would still be running today if sears had not quit supporting it with parts.

[@donames6941]

This is the first i have seen this kind of motor

[@Wiencourager]

Do a video,on the amazing rotary radial in the Adams-farwell cars. Some really original thinking.

[@bobese5099]

Thank you for the educational vid. Never heard of this one before

[@wapartist]

I want a Garelli 350! 2 strokes are awesome period

[@furripupau]

The tandem twingle design originates much earlier, in the Trojan utility car. Designed before WWI, but only went into production after the war ended.

[@JohnShuty]

Francis! I really enjoy you animation of the many internal combustion engines! It really makes it easier to understand! Have you considered doing an animation of Bernard Hoopers' 2-stroke stepped piston engine? I believe Norton / Triumph made a prototype called the Wulf. I might be interesting to see!

[@CaseyW491]

This is brand new territory to me. Pretty cool! If I had been considering a design like that, I wouldn't have. It seems unnecessarily over engineered.

[@DianaLatexlover]

I love those animations !!

[@jfu5222]

TWN = Triumph Werke Nurnberg

[@TobyLawnjockey]

A bantam, anyone?..😂

[@terryjacob8169]

My late father had a TWN from 1958 to 1960. He loved it, thought it was brilliant. From memory, it was only three or four months old when he bought it from Pride & Clark, in Stockwell, South London. He used to talk about how good it was for decades after he part-exchanged it for our first family car, a rather troublesome Standard Ensign.

[@putyourideas]

Bad lip-synching with the AI voice. Also, "two stroke engines do not have valves." Two-stroke diesel engines, such as the Detroit Diesel Series 71, have exhaust valves, and two-stroke gasoline engines, such as the Yamaha YZ250, Honda CR259R, and Sea-Doo 947 and 951, use reed valves.

[@anthonymills-nc9qs]

Had a TWN scooter back in the sixties, would beat the pants off Vespa's and Lambreta. Considered a classic now and hard to find in the UK.

[@58singleman]

Dear Repairman 22 you might like to do a show on the "Rotary Radial" aircraft engine which was widely used in WW-1. It's the only engine I know of where the crankshaft was bolted to the firewall and the engine rotated around around the crankshaft. It was a 2 stroke engine with the propeller bolted to the crankcase. Sooooo... the engine spun at the same speed as the prop. The Rotary Radial was used by the French, British, and German air force.

[@tauncfester3022]

Rotary radials are 4 strokes, every one of them. Some of the single valve Gnomes, what were called "Monosuapape' had intake transfer flutes in the cylinders that were uncovered at the bottom of the stroke but they were all 4 strokes, despite the smoke and 2 cycle style of fuel air transfer.

[@maximumengineering5419]

Strangest radial engine was the Fairchild-Caminez. 4 cylinder, 4 stroke that had 4 power strokes per revolution. All done with an ‘8’ shaped cam/ crankshaft and roller followers on the pistons - which were all linked together.

[@MCTeck]

I worked with a guy that had an Allstate motorcycle twingle. It had 2 mufflers and one was missing. It sounded weird.

[@ehsnils]

A dual piston 4-stroke and you'll have the Alvar (from the first name of the inventor) engine which has the ability to do variable compression. The secondary piston don't have to be as large as the main piston.

[@Fuzzybeanerizer]

2:16 The increased ratio of internal surface area to cylinder volume is NOT an advantage for engine cooling or efficiency. Two smaller cylinders will always have more internal surface area than a single, larger-bore cylinder of the same displacement, but the larger surface area needlessly absorbs more of the combustion heat. That reduces thermodynamic efficiency (you want the expanding gases to keep their heat and remain hot) and it creates a larger cooling problem to be addressed by the cooling system. In the case of an air-cooled engine, it would basically necessitate more and/or larger cooling fins on the exterior of the engine.

[@DownhillAllTheWay]

There was another engine - I forget where it was used - that had two pistons, but they had separate big-end bearings on a single crank pin, so that the timing was different between them - One piston led the other by a few degrees, and that was said to improve scavenging. I may be wrong, but I think it was a Puch engine. Aha! I've just discovered that this engine is discussed at 4:44 in the vid.

[@corneliussianturi476]

In my mind when seeing this that singgle connecting rod with mode Y connecting rod, can be usefull for 4 stroke singgle rod with seperating 2 cylinder combustion chamber and share the same cam profile duratin and lift

[@joedufour8188]

Someone looked at a single cylinder 2-stroke engine and thought to themselves "you know what this needs? More friction!"

[@SwagnassJrock]

Anyone else here cause they found a Sears twinkle in FB Marketplace and never heard of a twin piston single ? 😅

[@Yosemite-George-61]

..woeked on one on my first job... woiuld love to have one! There is a DKW (I think) motorcycle with an opposed piston engine... how about doing that? Thanks!

[@ex-engineer6657]

"Fascinating, Jim."

[@robertgift]

Well done! Thank you.

[@paulnicholson1906]

I have a twingle motorcycle. It is a neat piece of machinery. When anybody sees it they are like what the heck is that thing?

[@glasslinger]

These engines are now collectible.

[@Jarda_B]

I have seen one open IN REAL LIFE with my own eyes, I could have even bought it, if I wanted, it was at historical bikes flea market/meet.

[@highpointsights]

I'm guessing that Honda studied this whole engineering milieu!! They have produced all sorts of strange engine configurations!!

[@milankralowetz3391]

hello guys. The Isetta initially had a 250ccm3 4T and later a 300ccm 4T engine..! Not this 2T engine.. Greetings from Germany

[@dougschneider5948]

With the Pistons reaching top dead center at different times, did the engine have an ignition system which fired two spark plugs separately and a different times?

[@repairman22]

No, only one spark. By the time the flame front reaches the 2nd piston, it starts to descend. So there is no problem.

[@GWAYGWAY1]

I thought the Isetta was a BMW250 single engine and similar to the R25 motorbike .

[@Cream_of_sum_yung_gai]

It was after bmw bought the manufacturing rights from iso, who designed the isetta.

[@rt_goblin_hours]

I wonder how effient a fully modernized version with 4 cylinders would be compared to say a 1.2 inline 4

[@stevehageman6785]

Very cool, thanks!

[@paulmryglod4802]

Wow i had no idea these engine designs existed

[@edcew8236]

The Germans had an opposed piston Diesel engine in WWII that flew on a six engine seaplane

[@metehanattilaoguzhanl-yy9qn]

uçağın adı ne

[@dpeter6396]

I thought I'd seen 'em all..... Wow!

[@Bonjour-World]

I remember when sears and reject sold these.

[@HATECELL]

At first I thought this was a 2 cylinder 4 stroke, with the cylinders 360° apart

[@Jarda_B]

I have seen one open IN REAL LIFE with my own eyes, I could have even bought it, if I wanted, it was at historical bikes flea market/meet.

[@zolibartalos]

please make a video about split cycle engines.

[@DiHandley]

Surely a direct injection two stroke would solve all these problems. Were they ever made?

[@repairman22]

Yes. That's another reason why twingles are nonsense today.

[@ErickC]

EMD made millions of them, so, yes. To quote "History and Development of the 567-Series General Motors Locomotive Engine:" "The basic 2 cycle engine design established at this time has been successfully used in the full line of Diesel engines built by General Motors and therefore has been applied to a great many of the Diesel engines in use in the world today. These have all been direct injection, uni-flow engines with air admitted under pressure supplied by the blower to the cylinder through ports in the cylinder liner with the piston acting as the intake valve. The exhaust valves in the cylinder head are open when the intake ports are open, allowing the fresh charge of air to sweep out the combustion products of the previous cycle. Valves and ports are closed at approximately the same time and the fresh air charge is compressed. Slightly before the top of the piston travel, fuel is admitted with very exact control by the unit injector and combustion occurs very near top center to allow full use of the developed power."

[@theharbingerofconflation]

If I turn this into a four cylinder (twin so 8 piston engine) and this is a twingle, because its twin-single, would the new engine be considered a twin-quad aka twad engine?