CHECK OUT THE NEED OF MULTIPLE CYLINDERS IN ENGINE INSTEAD OF A SINGLE BIG ONE OF SAME VOLUME !!

Suppose we have a Chevrolet Spark of 1 litre (998 cc to be exact!) displacement. It has a 4 cylinder engine. So let's see what if we replace it with a single cylinder engine.

Let's do some basic calculations to find out the bore and stroke of this hypothetical engine. Assuming square type of engine ( bore equals stroke) we get bore=stroke=10.9 cm as opposed to original stroke of approx 5.8 cm. ( Assuming stroke of 7.7 cm ) So that is quite a big stroke length! So now let's discuss a few things about this-

1. With this big stroke, we need longer crankshaft. Longer is the crankshaft lesser is the maximum RPM achieved by the engine. This hampers the power output of engine. Hence the single cylinder will never be able to produce the same power as that of multi cylinder for the same compression ratio. Although some might argue that this will fetch good low end torque, which is true.
2. Single cylinders are impossible to balance! They will produce vibrations which are difficult to damp. You will definitely not like your car vibrating like a Royal Enfield bullet. Although flywheels and anti vibration mounts will come to the rescue, but mounts ( not flywheels) require periodic maintenance.
3. You will need to redesign the clutch which was designed to handle smaller bursts of power than a huge single one! Hence the clutch needs to be bigger and stiffer to avoid slipping which will increase clutch pedal effort enormously and break drivers legs. ( Assuming rest remind same). Moreover the transmission gears needs to be reinforced to handle rough shifting. This is not at all good for a nice passenger car!!
4. Single cylinder engines are difficult to keep cool, since the coolant jacket is far from the centre of combustion chamber and piston centre, overheating is more probable.
5. You will be burning all the fuel in one cylinder only which was earlier burnt in four chambers. Complete combustion is difficult to achieve. Also higher in-cylinder temperatures will aggravate NOX formation. Your car is less likely to pass pollution checks unless you invest in expensive Cat-cons. Not at all good for a cheap passenger car.
6. With single cylinder engine your car will start sounding like a oversized Bullet with utterly no respect for refined exhaust note. No one will buy such sounding car.
7. If at all you plan to turbocharge your engine, it will not be recommended by turbo manufacturers for turbo and engine safety. Such huge single cylinder's exhaust putts are capable to destroy a turbines of perfectly matched turbo. Singles are definitely not turbo friendly.
8. Now at this point let's assume you successfully replace the engine overcoming all difficulties. Now there will be such engine parts which you have custom made eg- high Flow fuel injectors, fuel pumps, ECU, also including engine Mechanical parts such as big end bearings and small end bearings etc. But these parts are not even remotely available in any spare parts shop if in case you damage any. If Chevrolet makes such engine they will have to face a lot of difficulties in arranging spares for their angry customers.