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Choose your engine!
The most important thing you will have to think about is what type of engine the vehicle of your choice contains. Whether its a 4 cylinder dual overhead cam or a simple inline 6 from the 70's. The type of engine you have in a vehicle will affect just about every aspect of that vehicle from the acceleration all the way down to the way it handles in a corner. Another thing to think about is the drive train as it is the engines means of putting power down on the road. Some of the things that will be covered in this section are: different types of engines, the difference between fuel types, what turbo and natural aspiration is, and the different layouts of drive trains.
2 cycle vs. 4 cycle
The main difference between 2 cycle and 4 cycle is this. A 2 stroke (or 2 cycle) engine completes the thermodynamic cycle in 2 strokes, putting fuel air mix intake and compression on one stroke, and power and exaust on the other. these are mostly used to run chainsaws, heavy machinery diesel engines, and dirtbikes/atvs. (I know nothing about 2 strokes...) 
A 4 stroke engine uses 4 strokes to complete the cycle, intake, compression, combustion (power), and exhaust. These are most predominately featured in passenger vehicles of major companies, these are what you will find in 99.9% of scavenging scenarios.
Two stroke vs four stroke, an in-depth look.
(need a page written by a more knowledgeable authority link the above text.)
(need a page written by a more knowledgeable authority link the above text.)
How does a diesel work?
All diesels work about the same as a gas engine (to my understanding) with one exception. Ignition comes not from an induced spark to create combustion, but from the compression caused when the piston begins to rise in the cylinder. (some one who actually understands diesel engines needs to write this article + page because my knowledge is lacking.)
(Link here)
What is Forced Induction and how does it affect the engine?
In a nut shell, turbo and super charging a car is using exhaust force or mechanical force (respectively) to induce a scenario where pre-compressed air is being ported into the engine causing the compression in the cylinder to increase, in turn increasing the power of the engine.
Turbochargers- Turbochargers use the force of exhaust gases fleeing the motor to power themselves and compress air. They do this by way of a set of internal fins. The turbo is connected into the exhaust system and as the burnt gases pass through the angled fins, the pressure turns them.
As the fins turn inside the turbo they cycle incoming air. The spinning pulls the air in and compresses it, packing far more air into one space than is normally possible. Once the air is compressed it is forced into the carbereutor or injection system (forced induction) and mixes with the atomized fuel.
This system is the most efficient in that it only uses exhaust gas to power itself. This does create one small problem for the turbocharger. When the engine is at low rpm and isn't producing a lot of exhaust, the turbo doesn't spin very fast. That means that air isn't compressed as well and less power is made.
This is what we call turbo-lag. It is a small gap where the engine isn't producing the majority of its power due to the turbo not compressing air. It happens at low rpms and lasts until enough exhaust gas pressure is created to spin the turbocharger, also known as "spooling up."
Generally, the bigger the turbo used, the more power is produced. It's the same story for turbo lag, the bigger the fins, the harder it is to turn them. One solution, popular in the nineties, was to use a pair of turbochargers, one built for low rpms and quick response, and one built for top end power. This was an easy way to reduce lag and create a smooth power band. Recently, it has fallen out of favor simply as the technology is better. Modern single turbos can add serious horsepower gains and can do so with almost instantaneous response.
Superchargers- The second main forced induction method, a supercharger is virtually the same as a turbocharger save for its power source. Super chargers too compress air and feed it to the engine to produce significant power gains, though they use a different method to spin the air.
While turbos use exhaust gases, superchargers use a belt drive linked to the crankshaft of the motor. This belt spins a pulley on the supercharger which is connected to the fins inside. The upside of the supercharger is that this method ensures that the supercharger is always spinning and thus provides instant power, while a turbo suffers from some sort of lag.
However, the supercharger has its own flaw, namely that it is parasitic in design. While the turbo puts virtually no strain on the motor in powering itself, the superchargers belt drive requires the enigne to turn it. The increased drag on the motor does rob some power, epsecially in larger superchargers. However, the gains provided are still far more than the power lost to spinning it.
Turbochargers- Turbochargers use the force of exhaust gases fleeing the motor to power themselves and compress air. They do this by way of a set of internal fins. The turbo is connected into the exhaust system and as the burnt gases pass through the angled fins, the pressure turns them.
As the fins turn inside the turbo they cycle incoming air. The spinning pulls the air in and compresses it, packing far more air into one space than is normally possible. Once the air is compressed it is forced into the carbereutor or injection system (forced induction) and mixes with the atomized fuel.
This system is the most efficient in that it only uses exhaust gas to power itself. This does create one small problem for the turbocharger. When the engine is at low rpm and isn't producing a lot of exhaust, the turbo doesn't spin very fast. That means that air isn't compressed as well and less power is made.
This is what we call turbo-lag. It is a small gap where the engine isn't producing the majority of its power due to the turbo not compressing air. It happens at low rpms and lasts until enough exhaust gas pressure is created to spin the turbocharger, also known as "spooling up."
Generally, the bigger the turbo used, the more power is produced. It's the same story for turbo lag, the bigger the fins, the harder it is to turn them. One solution, popular in the nineties, was to use a pair of turbochargers, one built for low rpms and quick response, and one built for top end power. This was an easy way to reduce lag and create a smooth power band. Recently, it has fallen out of favor simply as the technology is better. Modern single turbos can add serious horsepower gains and can do so with almost instantaneous response.
Superchargers- The second main forced induction method, a supercharger is virtually the same as a turbocharger save for its power source. Super chargers too compress air and feed it to the engine to produce significant power gains, though they use a different method to spin the air.
While turbos use exhaust gases, superchargers use a belt drive linked to the crankshaft of the motor. This belt spins a pulley on the supercharger which is connected to the fins inside. The upside of the supercharger is that this method ensures that the supercharger is always spinning and thus provides instant power, while a turbo suffers from some sort of lag.
However, the supercharger has its own flaw, namely that it is parasitic in design. While the turbo puts virtually no strain on the motor in powering itself, the superchargers belt drive requires the enigne to turn it. The increased drag on the motor does rob some power, epsecially in larger superchargers. However, the gains provided are still far more than the power lost to spinning it.
(See Wikipedia Article for more in depth description)
Engine Layout
There are many configurations that engine layouts take. Some of them are V, boxer, inline, and rotary. After that there's the way the engine sits in the engine bay which would be referred to as longitudinal mounting or horizontal mounting. Each layout has some benefits such as inline has more torque than the V configuration. The mounting position doesn't have much more to do with the cars handling other than the force that the torque exerts on the chassis, which is minimal compared to the force weight transfer.
Having a V# engine simply says that you have a certain number of cylinders (always even I think) set up in a V connected to the same cam shaft. The power stroke of the pistons on the bank across from one another help balance the force of the other side and allow the V engines the smoothest operation (IMO) out of all set ups, save for the
boxer.
A Boxer engine is set up so that a number of pistons are horizontally opposed to each other (again I believe this is always an even number of pistons), and connected to a single cam shaft. This engine is a favorite of the major manufacturers Porsche and Suburu.An Inline engine is a number of pistons connected to a single crankshaft in a straight line, hence the name, these are known to include any number of pistons desired. (IMO) Inline engines are sometimes very rough and hard to control (being hard on motor mounts). Though I feel it should be noted some of my most favorite engines are small inline fours such as the Suzuki g13 and almost all I4 Toyota engines (it should be noted that I have no experience with boxer or rotary type engines).
A rotary engine is completely different than piston driven engines in that instead of rotateing a set of pistons a block (triangular in the Wankel type engines) rotates inside the engine block using unique geometry to create the thermodynamic cycle and drive the crankshaft thus powering the vehicle. This is my favorite theory of engines, as it would allow for the highest ease of theoretical operation.
Drive train layout.
The drive train layout refers to the total layout of the engine, transmission, and drive wheels. This is usually referred to as: front engine/front wheel drive, front engine/rear wheel drive, mid engine/rear wheel drive, and rear engine/rear wheel drive. Also, an expression that is widely accepted here (dunno about abroad) to describe the number of drive wheels is XxX e.g. 2x4 and 4x4 of course this expression can be used to describe any number of drive and non-drive wheels. Again, like the engine layout, the drive train layout has an impact on the handling characteristics of the car but on a much larger scale, as it affects not only the center of gravity, but the weight distribution of the vehicle and the way the weight transfers as G's are applied during a maneuver.
Indepth look at drive types.
Fuels for the ages
Fuels for the ages
There are lots of different fuels that can be used to power an engine, some examples are ethanol (formally known here as E85), propane or natural gas, hydrogen, or just plain old gas and diesel. Different fuels have different combustion characteristics, and thus will affect the way an engine runs and where it can be applied the most prevalent fuels in the SE United States is gasoline and diesel. Always, Always, Always make sure you are using the proper fuel when refueling your vehicle or it could have disastrous affects for not only the vehicle, but your bodily health as well.
(note from seek: We may need to break this down into its own directories, we don't want to have pages that are to long. let me know what yall think.)
Bobbysepp |
Latest page update: made by Bobbysepp
, Apr 3 2010, 11:53 PM EDT
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| Started By | Thread Subject | Replies | Last Post | ||
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| PapiSantos | Objections for the Choose your engine thread | 1 | Jan 27 2010, 4:47 AM EST by PapiSantos | ||
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Thread started: Jan 27 2010, 4:43 AM EST
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Hi i have been lurking for some time but feel i need to put some objections in the 'choose your engine' .
- Inline engines are not 'rough' in fact they are argueably one of the best engine configurations out there. This is because an inline 4 or 6 are naturally 'balanced' something hotrodders spend heaps of money trying to get their v8 to do. Taxi's in australia for example all run inline 6's, the engines run nearly non stop for the 6 years they are allowed, V6 can't keep up without major repairs. (in fact many taxi into private hands and still keep another round of abuse) The V6 was invented with the purpose of fitting the inline 6 in smaller spaces. Its also hard to compare V and inline engine overall. There are very few engines with matching displacement and engine configuration. (RWD/FWD, singlepoint or multipoint injection, carbs etc etc) Turbochargers have parasitic loss as well... no turbo nut will admit it but they do, the engine hasws to push that gas out and the turbine is a restrictor, another flaw about the turbo is if the turbo seizes. this can happen as soon as the oil stops flowing to it , maybe a blockage or gunked up , there are some aircooled ones but the bearings can seize too! Not something that you want in a zombie survival. At least with a supercharger you can usually cut the belt it runs off (most cases) and it will still run Forced induction can have its benifits.. not raw power but how its used. EG: If you have a 2L forced induction engine that puts out the same power as a 4L naturally aspirated engine. The 2l engine will be a smaller lighter package, so it weighs less and takes up less space. This means less weight in the engine and less weight in the car design to cater for it. Same power + less weight + better fuel economy Although i would be in the Keep It Simple naturally aspirated camp! |
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| cyrano222 | wow | 0 | Jan 24 2010, 8:59 AM EST by cyrano222 | ||
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Thread started: Jan 24 2010, 8:59 AM EST
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you guys put a lot of work into this, thanks a lot. We, or at least I, appreciate the time and effort going into this.
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| Bipp | Engine Page | 6 | Dec 18 2009, 5:39 PM EST by AlexHigginbotham | ||
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Thread started: Nov 19 2009, 1:38 PM EST
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deathseekrakodo - this is a great article, it is vary well laid out and written. I like the animated diagrams.
All around an enjoyable and informative article. Thank you, for a non-mall ninja page. |
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