The main types of engine found, minus the fancy names.


Jun 18, 2001


The Bottom Line OHC, DOHC, V8, straight 4, Compresssion, what do all these fancy names mean in basic terms?

What are the engine types? the list is endless. You have Straight 4's straight 6's, V6, V8, V10, V12, OHC, DOHC, OHV, Compression, SIE, 8Valve, 16Valve, 12Valve, 24Valve, the list just goes on and on, but what are they all? Would you know a straight 6 from a V6? Say straight 6 to some people and they think it is a manual 6 speed gearbox! Manufacutrers use these fancy names and abbreviations to make it sound good, if it has a fancy abbreviation then it sounds better than them saying it is a 4 cylinder engine. So here, i will run through a few of the most common engine types, and give a brief explanation of what it means in reality. Just for information and i am not saying any is better than the other, as this all depends on what you want.

Straight 4:
This is a 4 cylinder engine, where the cylinder are positioned horizontally in a line. Running from left to right. This is the common type of standard petrol engine for cars (in the UK and Japan at least) People often think a 4 cylinder is an under powered car, but this is by no means the case, i know for a fact my 4cylinder gives out a better 0-60 time than a V6 2.8 and mine is only a 2 litre. Here size does not matter, Its not what you got, its what you do with it that counts (sound like an agony aunt dont i? ) So dont be taken in by the rubbish that 4 is small, you look at things like the nissan skylines etc, alot of them are straight 4 engines.
Straight 6:
Obvious what this is now. It is the same as a straight 4, but has 6 cylinders in a line instead. Not as common in most cars due to the large amount of space it needs, but often used in your sports cars like Porsche, and farrari as it tends to be a better balanced engine and power wise is very good. You can also get straight 8's but these are very rare now. Sometimes found in large trucks but not often.

V6 and V8 and so on:
This is where the cylinders are mounted in a V form. A V6 for instance will have 2 rows of 3 cylinders, mounted in a V form. They are all connected to one crankshaft. This type of engine is popular in the bigger engine capacities due to the fact you can have more cylinders, thus more capacity with alot less space needed comapared to a straight engine. Generally they are big heavy lumps, due to the fact alot of the mechanics need to be doubled, things like needing twice as many cam shafts etc, and although pump out more power, usually need a larger capacity to obtain it. However they tend to be alot more torque from them.

OHC:
This stands for Over Head Cam. This is where the valves are operated via a camshaft which lifts and drops the valves via a set up of springs and hydrolic lifters (in most cases) These give more power due to less moving parts needed and are fairly new to the scene, although have been around for a long time and cars like Vauxhalls, and racing cars. The cam shaft is controlled via a toothed belt, known as a timming belt, or timming chain, usually rubber, although some did use chains, which is connected to the crank shaft and the 2 halves of the engine are synchronised and kept in time via this belt. However this does mean the whole engine relies on a single rubber band, to put it basically, and if this belt breaks, it can lead to all sorts of problems such as bent valves etc, although i know for a fact in vauxhall (GM) engines this wont happen, but as far as other engines go, i dont know. Ford i know dont like broken belts!


DOHC:
This stands for Double Over Head Cam. Not satisfied with just one cam shaft, alot of manufacturers have opted for 2. It means that the exhaust valves and the inlet valves have their own cam shaft operating them, this gives better performance, and, apparently, longer engine life. Not sure about that myself though. Not as common as the single cam and is mainly used on sports coupes etc. Only really found on straight 4's and 6's. But i am sure V engines will adopt it soon enough.

OHV:
Not used much now. it stands for Over Head Valve. This engine does not have a cam shaft, instead the valves are operated via a system of 'push rods' which are connected to the crank shaft. These are still used on small engines, for instance 1litre engines, or 1 or 2 cylinder engines, but even they are opting for the OHC now. Alot of old cars may use this system still. The main thing about them was they were more complicated and less efficient than OHC.

Compression engines:
In common terms, a diesel. It gets its name because the fuel is ignited by compressing it to a high pressure, this makes it very hot and eventually combusts. This engine does not need spark plugs for instance, as a spark is not required for ignition, however they do have 'glow plugs' which are mainly only used for starting and initial running, until the engine reaches operating temperature. Also they are always injection engines. As the fuel needs to be atomised to work. Not wanting to go into the mechanics of the engine for fear of losing people. And as you will probably find reading around the epinions on here, they have their advantaged and disadvantages. But they produce a high torque, but lack in Brake Horse Power (BHP)

SIE:
Spark Ignition Engine. Put in that term it makes more sense. It is a petrol engine, or gasoline depending on where you are. It uses a spark plug to generate a spark which ignites the fuel mixture. These can be injection or carburettor. Most these days or injection, as they are more economical and can be controlled via computer systems which allows for better engine management. However i prefer a carb to injection personally, as you tend to get a better response. But i have had to call it a day and follow the crowd into the injection scene now.

8valve:
Well it explains itself really. It is an engine with 8 valves. Only found on 4 cylinder engines, it basically equates to 4 inlet valves and 4 exhaust valves. Only use single OHC (SOHC) usually, although i think the odd DOHC is used for 8valve engines.

16valve:
means it has 20 valves! ok ok, it doesnt. Obviously it has 16 valves. Again used on 4 cylinder engines or on V8's. on the 4 cylinder it means there is 8 inlet and 8 exhaust. DOHC is used for this and makes for better performance as 1 fuel can get in quicker, and 2 exhaust can escape quicker, with less back pressure. on a V8 it obviously only means it has 1 exhaust and 1 inlet per cylinder.
The number of valves goes up depending on the number of cylinders.

Turbo charged:
This is an engine that has a forced induction system on it, known as a turbo. A turbo basically drives air into the cylinder and forces the cylinder. It is driven via the exhaust leaving the cylinder. These mean the engine is alot more powerful, without having to increase the capacity. However they do put alot more pressure on the engine. They are good fun though. Common on diesel engines to give them the extra push they need to keep up with a petrol engine. Most engines can be fitted out with a turbo at a cost, and smaller engines are often turbo'd to give them approx 30% extra power.
The alternative is a 'supercharger'.

There, thats basically the main types of engine you will find sitting in the front of your car. All are different and its funny when you think a 2litre straight4 turbo'd Nova can beat a farrari F40 of the lights!!! Amazing what you can do to engines. But anyway, hope that has shed some light on the subject for those of you who didnt know, if you did, then well, it probably bored you.

Read all comments (5)

About the Author


Reviews written: 31
View all reviews by uncle_bob