The Single Cylinder Engine (again)

"Moose Kitty" (moosekitty)
05/14/2014 at 15:43 • Filed to: None

Yesterday I made a post on the single cylinder engine I would want to make. There was some confusion on feasibility with the concept that I'll clear up in this post. Plus some advantages and disadvantages with the engine.

The main gain a single cylinder engine has on something like a I3 or V12 is simplicity. There's only one of everything and so long as it's a two stroke they don't have a valve train. As our V Twin lover friends (should) know that most two stroke engines use carbs. Most single cylinders are the same way, but have a gain in lightness, torque, and simplicity. In most applications the vibrations of a single cylinder is manageable, and others intolerable. They also need more flywheel effect, and need strong components to keep the engine from shaking itself to death, thus more weight. An obvious drawback is the lack of hp. The highest recorded so far has been 70 hp from the KTM 650 Duke R. Though it doesn't sound like a lot it pushes the bike well past 150 mph (2014 model).

To start off the single cylinder engine I came up with is based off a 8-bit hillclimb micro car with a 1197 hp 1cyl engine. My concept doesn't make nearly the same horsepower, but well over 70hp. To lead into the build, the engine would be two-stroke (compared to the earlier four stroke from my last post). It would be air cooled to keep it light and simple. To increase horsepower, torque, lightness, and fuel economy it would be direct injected. The block would be aluminum lined with steel. The same would go for the crankshaft though more steel than aluminum would be used. The headers would be magnesium. The piston would be aluminum. There would be three spark plugs to increase power, have a cleaner burn, and if one goes out the engine can continue to run.There would also be a nicely sized fan to help keep the engine on the cool side.

Now onto the big guns...the ELECTRIC SUPERCHARGER...the main power house to our est. 100+ horsepower single cylinder. The very large compressor would be made of CF and be lined inside with aluminum to keep any air from leaking from the the walls and be pushing around 70-90psi. There would be no lag and be light weight since there isn't an exhaust turbine to restrict building materials. The supercharger would have a fairly large, rear mounted intercooler. To keep vibrations low while not having to go big with counter balances and flywheel effect, the revs would be under 8000 rpm (can't put all this stuff on and not have super high engine destroying revs). The engine mounts would also have dampers to keep the vibrations minimal. The transmission would be a 5-speed manual or a semi auto cvt to to hopefully lessen the chance of liquification.

With all that I would est. about 150-190 hp in a car smaller than a BAC Mono and lighter than a SMART Roadster + great aero would make a very power full single cylinder car. I'd really only use this engine in short races and hillclimbs instead of something like the LeMans for cooling reasons. You'd look like this guy in the drivers seat pretty much:

What do you guys think? Better? More confusing?

*Disclaimer: THIS IS A JOKE. I KNOW THIS IS A RETARDED ENGINE I MADE IT THAT WAY. I WAS BORED DURING LUNCH AND THOUGHT TO FUCK AROUND A BIT JEEZ.*

DISCUSSION (33)

nevergonnahaveapermanentaccount > Moose Kitty
05/14/2014 at 15:50

My 705cc Kawasaki single makes 47 whp and 42 tq. (chain drive motorcycle) Its a fully built, but stock compression (9.5:1) 4-stroke. I thought I was at the upper realm of mechanical ability until I started reading into 250cc Honda and KTM screamers that make upwards of 40hp.

I like this topic.

Opposite Locksmith > Moose Kitty
05/14/2014 at 15:50

Wat

CRider > Moose Kitty
05/14/2014 at 15:50

You want a turbocharged, single cylinder two-stroke car? You're insane. Just get a motorcycle.

Mr. Ontop, No Strokes, No Smokes...Goes Fast. > Moose Kitty
05/14/2014 at 15:54

It would be a hell of a fun go-cart, but that's just not enough for a full on car.

RamblinRover Luxury-Yacht > Moose Kitty
05/14/2014 at 15:55

I'm unsure why you spec a steel piston. There's almost no reason ever to use one.

I should also point out you'll have a hell of a time making a steel liner behave - plenty of air-cooled engines get away with aluminum block+ steel liner, but mid-high RPM supercharged two-stroke seems likely to try to dump so unimaginably much heat you may have liner retention issues. Bad ones.

Also, I think your supercharger will likely melt the shit out of the resin in its carbon fiber. More realistic to just economize on the aluminum, that way the compression heat won't set the bike on fire the first time it starts.

Also also, you're throwing away a bit of an opportunity to have power pulse damping in the supercharger drive, unless you're counting on driving it from an armature specifically designed to be an ungodly heavy flywheel as well.

You might still be best off with a torque converter manual or other shenanigans to keep from pulsing the drivetrain to death.

Moose Kitty > Mr. Ontop, No Strokes, No Smokes...Goes Fast.
05/14/2014 at 15:56

It would be like a wider Caterham 7 with a single seat. That's along the lines of what i was thinking. It would also be strictly a track car.

Moose Kitty > CRider
05/14/2014 at 15:58

Ahh, but that's the thing it would be a track car not road car. Plus I'm a worrywart and sold my motorcycle after a friend had a very serious crash.

CRider > Moose Kitty
05/14/2014 at 16:00

For track use only? Ok, get a motorcycle. Stop worrying, wear the proper gear, don't be an idiot and you'll be fine. I wouldn't stop riding due to a crash unless it killed me or made it impossible for me to ride. You can get nice and fucked up in a car crash too.

Moose Kitty > Opposite Locksmith
05/14/2014 at 16:03

Mind blowing am I right.

Kinja'd!!!

Moose Kitty > CRider
05/14/2014 at 16:07

yeah yeah I know, but still if it's your helmet almost kills you and it was a drunk driver in an SUV that was why i started worrying. Especially since there are so many Azteks over here. "what killed you?" "An aztek." "WOW REALLY" "A Pontiac Aztek" *silence*.

JawzX2, Boost Addict. 1.6t, 2.7tt, 4.2t > nevergonnahaveapermanentaccount
05/14/2014 at 16:15

50HP (crank) and 44 lb/ft here: BMW F650 with Rotax Power ;)

Cé hé sin > CRider
05/14/2014 at 16:15

You write of being insane like it's a bad thing?

Moose Kitty > RamblinRover Luxury-Yacht
05/14/2014 at 16:17

I didn't think of a torque converter manual good idea. What was the point you were trying to make with the supercharger got confused with the wording. With the carbon fiber its more weight saving while trying to also keep heat regulated and keep the air from leaking through even a little bit. With the steel pitson that was just a whatever kind of move. I would most likely use an aluminum piston. You make a good point with the lining, and I was trying to think of a heat sink while keeping the engine air-cooled. What do you suggest?

CRider > Moose Kitty
05/14/2014 at 16:38

Luckily, there aren't many drunk Aztec drivers on a racetrack. That's what scares me most about bikes though- getting hit by someone. That's what will kill you. But off road, either in dirt or at a track I think bikes are as safe as the people riding them. Modern riding gear is amazing.

CRider > Cé hé sin
05/14/2014 at 16:38

It's a good insane, but he's describing a go cart.

RamblinRover Luxury-Yacht > Moose Kitty
05/14/2014 at 16:40

A supercharger pushing ~80 psi will produce quite a lot of heat. At a loose estimate, gauge pressure 75psi is roughly a 4x increase in pressure, and that's a constant heat input into the supercharger. It's hard to dump, and might build up enough to cause breakdown of the resin used with the carbon fiber, unless very costly. Since that pressure range isn't prohibitively high, though, you're probably better off using aluminum for the whole thing. Carbon fiber won't add that much strength for a given weight savings to offset cost, I think, because of the combination with other materials.

I don't really have any suggestions on temp control, other than enthusiastic amounts of oil cooling. There are probably tricks that haven't been tried yet where two-strokes and cooled oil are concerned.

Moose Kitty > CRider
05/14/2014 at 16:46

bit bigger than a go kart but pretty much a go kart that resembles a car.

Moose Kitty > CRider
05/14/2014 at 16:48

I see what you did there. And I do agree and i'll probably get another bike (Bandit Streetfighter i'm looking at you), but I cant run risk right now in the family situation i'm in.

CRider > Moose Kitty
05/14/2014 at 16:50

So you want a slower Midget racer?

Moose Kitty > RamblinRover Luxury-Yacht
05/14/2014 at 16:51

hmm...good point on the supercharger. With the temp control, I'm going to run through some ideas and probably make a post on it. Thanks for the input though makes a lot of sense.

Moose Kitty > CRider
05/14/2014 at 17:08

How much hp. I know they have a high power to weight ratio, but with this it would be an attempt to make a very light track car (carbon fiber used in the body), have a pretty good power to wieght ratio, and if i were to cool the engine with cooled oil use it in endurance racing having it mated to a electric motor. I never did specify the displacement of the engine or the weight of the car either so more lenience on the speed of the car.

CRider > Moose Kitty
05/14/2014 at 17:13

They make around 350 horsepower and weigh 900 lbs.

KurtAKX > Moose Kitty
05/14/2014 at 17:14

I hope this story ends with "April Fools", or a trip to an ABET-accredited engineering college.

Starting from the top:
1) A single cylinder engine does not inherently (for a given displacement) make more torque than a multicylinder engine.

2) A magnesium header? Magnesium autoignition temperature is 883 °F. What do you think your exhaust gas temps will be?

3) An aluminum composite crankshaft?
... I actually don't have the patience to go through this whole "thought exercise". The point is, the reason something like this doesn't already exist is not that you are the only person smart enough to think of it.

Moose Kitty > KurtAKX
05/14/2014 at 17:26

Whoa calm the flames im only in highschool for one. The magnessium thing was more of a joke than anything else and im glad you caught that. I never said that a multi-piston engine made less torque than a single cylinder engine I was just pointing out that a single cylinder engine can make a lot of torque with a few other factors mixed in. The crankshaft was more of a "fantasy" part since this engine is pretty crazy and rather dangerous with all the weird stuff i've mashed together.

Moose Kitty > CRider
05/14/2014 at 17:36

Well luckly this is a fantasy engine. Sign me up for a midget racer.

CRider > Moose Kitty
05/14/2014 at 17:38

Oh shit, I made a mistake and signed you up for midget wrestling instead. I hope that's ok?

Moose Kitty > CRider
05/14/2014 at 17:44

6'1 and 180lb i think i'll be fine. :D

tromoly > Moose Kitty
05/14/2014 at 20:53

What cc engine? I'm wondering what your Carnot efficiency would give you, let alone a real-world engine.

Isn't 8k rpm on a turbine a little slow? IIRC most exhaust-driven units hit 100k rpm easily, I'd love to see an 8k turbine hit 70psi compression, and on top of that the heat generated is going to be a little higher than ambient (read: a lot), how does that affect the carbon? What cooling will you have for the turbine?

Why a 2-stroke? How are you going to optimize your tuned pipe? What actual advantage is there? And don't say "lack of valvetrain", that's illogical.

So a larger flywheel is needed with a single, how much torque is eaten to drive that flywheel? Since it's a single, how does the flywheel keep the engine going? Further, since it's a single, how is the torque map affected versus an engine with 2 or 4 cylinders? These are things to think about.

How big of an alternator will the engine have? How much power is required to turn that, and how much of the power generated is going straight for the turbine? Remember, perpetual motion does not exist, the energy for the turbine still has to come from somewhere.

So the crankshaft has both aluminum and steel. Why?

Sport bikes run aluminum blocks with coated cylinders, why do you need a steel sleeve?

Hopefully this gives you some insight as to why your design won't work. It takes a great deal of math and engineering to make things work, it can't be done by just anyone.

Moose Kitty > tromoly
05/14/2014 at 21:42

For one i haven't picked a cc the engine is more of a joke through an engineering and chemist point of view (magnesium headers are a horrid idea). The turbine wasn't what i was reffering to it was the engine. the turbine would probably reach about 140k rpms. The lack of valvetrain is one of those jokes i was talking about. I picked a two stroke mostly for simplicity. A lot of torque would be consumed, but i also said in the article that i would still make it light weight and explained methods of vibration dampening which is why a heavier flywheel needs to be used it's stronger. The fly wheel is weighted as a counter balance which helps calm vibrations. The torque map actually is relatively flat so long as the vibrations are kept in check.

The alternator would have to be at least the same size as one used in a three cylinder engine (the three spark plugs are the main reason). A larger one would be used to be keep the turbine at optimum performance.

The crankshaft is aluminum and steel because hell why not lightweight and strong. It's mostly a bullshit part like the magnesium headers. The steel coating is mostly a heat sink. Is it a good one? No? But another commenter gave me an idea of using cooled oil as a better heat sink than the steel lining.

Lastly IT WAS A JOKE. I'm a car obsessed teen that has rebuilt engines and understands all of this. Fuck no would this work it would be retardedly dangerous and most of it is bullshit with some actual though behind it, but not much other than it has to actually be an engine. Be glad that i didn't decide to make it even more unfeasible (12000000004 HP BITCH HAHAHA). I know not everyone could come up with an engine, but id like to get to that point. Hell I could of said it was fused with a human heart to keep the revs up.

tromoly > Moose Kitty
05/14/2014 at 22:06

The flywheel is not used to dampen vibrations, it's used to keep the engine going for the other 540-degrees of rotation that is not the power stroke. The counter-weights on the crankshaft are what attempt to deal with vibrations, and because it's a piston engine there will always be some form of vibration (unless it's an I3, I6, etc). Torque map and vibrations have absolutely nothing in common.

Steel as a heat sink in an aluminum block? Learn heat transfer and then say that again. And if you're using cooling oil, why not actually make it water cooled?

You clearly do not understand everything that goes into an engine, take basic level Thermodynamic, Heat Transfer, and Kinematic classes and you'll learn far more than you already know.

Moose Kitty > tromoly
05/14/2014 at 23:13

Mother of GOD...okay i'll put this out simply for you. 1) I off set the weight of the flywheel to help balance the engine since there is only one piston. 2) If the engine destroys its transmission then no torque then huh...3) yes the steel was a heat sink or better yet a heat shield to keep the aluminum from warping. 4) using oil is to keep weight low since it would be the same oil running through the engine (yes it will make oil changes more frequent and it's a work in progress). 5) You have no clue what level in any of these areas.

Can't even make a joke without internet engineering expertrolls coming for my engine badge and hobby license.

tromoly > Moose Kitty
05/14/2014 at 23:43

It's obvious you are trolling when you talk about doing oil changes on a 2-stroke. I'm not even going to touch everything else.

And as for your final comment, I'm getting my BS in Mechanical Engineering on Saturday and have been involved with FSAE for two years, FYVM.

KurtAKX > Moose Kitty
05/15/2014 at 08:47

I hope you do choose engineering when the time comes.