Best Cars: engine

Performance Camshafts

<div id="contentText"> The two important aspects of a camshaft, in terms of engine performance, are camshaft duration, or cam duration, and valve lift. Both cam duration and valve lift are determined by the camshaft lobe. Cam duration is the time that at least one valve of a cylinder remains open, i.e., off its valve seat, measured in degrees rotation of the crankshaft, while valve lift is the maximum distance the valve head travels from the valve seat. <h3>VALVE LIFT</h3> Valve lift is somewhat related to intake valve head diameter. An engine with an intake valve head diameter of 1.400in to 1.500in will generally perform best with a valve lift of 0.395in to 0.475in; an engine with a larger intake valve head diameter of 1.750in to 1.875in will generally perform best with a valve lift of 0.425in to 0.550in; and an engine with a large intake valve head diameter of 2.000in to 2.250in will generally perform best with a valve lift of 0.475in to 0.650in. But these are just rough guidelines; ultimately you will need to take some gas flow readings on a flow bench to determine the best valve lift for your particular engine. A number of factors influence valve lift. The most important being the gap between the intake and exhaust valves, the piston to valve clearance and the intake charge pressure. These factors also influence cam duration. Another factor influencing valve lift is valve spring compression. Obviously, once the valve springs are fully compressed, it cannot give any more and the valve cannot be pushed further down into the combustion chamber. <h3>CAM DURATION</h3> As I've mentioned earlier, cam duration is measured in degrees rotation of the crankshaft, rather than the camshaft, and the crankshaft completes two full rotations for every rotation of the camshaft. In other words, with a 310 degree camshaft, the valves are open for only 155 degrees of actual camshaft rotation. A performance camshaft for a naturally aspirated engine will have a duration in the range of 270 degrees to 310 degrees or more, with a 270 degree camshaft described as a 'mild' camshaft and a 310 or more degree camshaft being described as a 'wild' race camshaft. A stock camshaft usually has a duration of around 270 degrees but what differentiates a 270 degree performance camshaft from a stock camshaft is increased valve lift and a much faster rate of valve lift. With a faster valve lift rate, the valve reaches full lift quicker and remains at full lift for longer. This increases Volumetric Efficiency (VE) as more air flow in and out of the engine is possible. A determining factor, when choosing camshaft duration is the purpose of the vehicle. The longer the duration of the camshaft, the further up the rev range the power band shifts, and the rougher the idle. Obviously, as the power band moves higher up the rev range, bottom end power is lost. Also, as cam duration and valve overlap increases, torque is lost. Fuel efficiency also decreases and exhaust emissions increase as valve overlap increases. High performance camshafts start at 280 degrees of duration. These camshafts have increased valve overlap but not too much so emissions and fuel economy are not severely affected. These are generally good camshafts for modified street cars and produce good power from 2,500 RPM up to 7,000 RPM but they do not have a smooth idle because of the increased valve overlap. A 290 degree camshaft requires more cylinder head work in terms of cylinder head porting and gas flowing as they work better when the engine's Volumetric Efficiency (VE) is improved. As you'd expect, these camshafts produce a fairly rough idle. These camshafts are generally good for rally cars and produce power from 3,000 RPM up to 7,500 RPM. A 300 degree camshaft requires even higher levels of VE, reaching the physical gas flowing limitations of a two valve cylinder head with a single camshaft. These camshafts are good for modified race cars and produce good power from 4,000 RPM up to 8,000 RPM. However, they have a very rough idle. A camshaft with a duration of more than 300 degrees is an out and out race camshaft with a power band in the 4,500 RPM to 9,000 RPM rev range. To make effective use of a 300 degree camshaft, you need to ensure that the engine has a very high VE. You also need to ensure that the engine can rev beyond the red line of most stock engines. <h3>VALVE OVERLAP</h3> The limit for opening the exhaust valve is approximately 80° before bottom dead center (BBDC). Opening the exhaust valve any sooner tends not to increase power production but will shift the power band higher up the rev range and will reduce low end torque as downward pressure on the piston during the <a href="http://www.custom-car.us/basics/four-strokes.aspx">power stroke</a> is released. The same applies to closing the intake valve where 80° after bottom dead center (ABDC) is the limit for increased power production. <div class="wideTextAd"> <ins style="display: inline-table; border: medium none; height: 90px; margin: 0pt; padding: 0pt; position: relative; visibility: visible; width: 728px;"><ins id="google_ads_frame3_anchor" style="display: block; border: medium none; height: 90px; margin: 0pt; padding: 0pt; position: relative; visibility: visible; width: 728px;"> </ins></ins> </div> </div>

engine Performance Camshafts

The two important aspects of a camshaft, in terms of engine performance, are camshaft duration , or cam duration , and valve lift ....

Doing The Head

<div id="contentText"> <div class="rightImage"><img alt="A Twin Cam Cylinder Head" src="http://www.custom-car.us/_images/twinCamCylinderHead.jpg" /> A Twin Cam Cylinder Head </div> When it comes to getting the most power out of a naturally aspirated engine the key area that you must focus your attention on is the cylinder head. This is the one area that will potentially give you the greatest increase in engine power. Why? Well, as <a href="http://www.custom-car.us/feedback.aspx?val=langer">Langer</a> explains in <a href="http://www.custom-car.us/basics/default.aspx">engine building</a> and <a href="http://www.custom-car.us/basics/power-basics.aspx">power basics</a>, the key to increasing an engines horse power is to get the engine to ingest more air and be able to expel the resultant increase in exhaust gasses, in other words, getting the engine to pump more air by increasing the air-flow in and out of the engine. On a motor car engine, there are three areas that can affect air-flow and where you can make improvements. These are: <ul><li>The <a href="http://www.custom-car.us/intake/default.aspx">intake system</a>, which includes the <a href="http://www.custom-car.us/intake/air-filter.aspx">air filter</a>, <a href="http://www.custom-car.us/intake/intake-manifold.aspx">plenum</a> and the intake runners.</li><li>The <a href="http://www.custom-car.us/exhaust/default.aspx">exhaust system</a>, which includes the <a href="http://www.custom-car.us/exhaust/header.aspx">exhaust header</a>, catalyst converter and the mufflers.</li><li>The <a href="http://www.custom-car.us/cylinder-head/default.aspx">cylinder head</a>, which includes the cylinder head ports, valve area and the <a href="http://www.custom-car.us/cylinder-head/camshaft.aspx">camshafts</a>. </li></ul> We've discussed the <a href="http://www.custom-car.us/intake/default.aspx">intake system</a> and the <a href="http://www.custom-car.us/exhaust/default.aspx">exhaust system</a> elsewhere on this web site so now it's time for us to turn our attention to modifying the cylinder head. However, in this section we're going to discuss a little bit more than just the cylinder head, we're going to discuss <a href="http://www.custom-car.us/cylinder-head/porting.aspx">cylinder head porting</a>, gas flowing and power tuning the cylinder head, old school style! We'll also be discussing performance camshafts, <a href="http://www.custom-car.us/cylinder-head/cam-timing.aspx">cam timing</a>, valve timing and valve overlap. A word of warning though, cylinder head porting and gas flowing is a rather advanced form of car modification and is not for the novice or for the faint of heart. Cylinder head porting is a skill that must be developed and honed by hours and hours of practice. If you're intent on trying cylinder head porting, the first thing that you need to know is the porting always begins by trial and error so if you're going to do your own cylinder head porting, start on a cylinder head that you can afford to total, in fact, start with a couple that you don't mind loosing. Otherwise you should leave cylinder head porting up to a professional with a flow bench. The other thing to note, is that cylinder head porting requires some rather expensive tools. You'll need a high-speed extended pneumatic die-grinder with carbide and steel grinders, and a high-pressure air compressor (no, we're not talking about turbochargers here) to power the grinder. You could use an electric die-grinder rather than a die-grinder, but electric die-grinders don't operate at a high-speed like pneumatic die-grinders. You could also use an electic drill rather than a die-grinder but you won't get the same results as you would with a longer, more agile and thinner die-grinder. An electric drill also does not operate at the high-speeds that a pneumatic die-grinder does. <div class="rightImage"><img alt="A die-grinder" src="http://www.custom-car.us/_images/dieGrinder.jpg" /> A Pneumatic Die Grinder </div> Right, if you've read all that, bought your air compressor and your die-grinder, and gotten hold of a few spare cylinder heads, despite our warnings, then we can move on and start modifying the cylinder head for extreme power. But remember that we did warn you. Right, we'll begin by looking at the <a href="http://www.custom-car.us/cylinder-head/camshaft.aspx">camshaft</a> before moving on to the <a href="http://www.custom-car.us/cylinder-head/default.aspx">equipment</a> you'll require to port your cylinder head, the <a href="http://www.custom-car.us/cylinder-head/basics.aspx">basics of gas flowing</a> and <a href="http://www.custom-car.us/cylinder-head/porting.aspx">cylinder head porting</a> itself. </div>

engine Doing The Head

A Twin Cam Cylinder Head When it comes to getting the most power out of a naturally aspirated engine ...

The Diesel Engine

The diesel engine was developed by Rudolf Diesel and was patented in 1892. Diesel engines are very similar to petrol or gasoline engines in that both rely on the <a href="http://www.custom-car.us/basics/four-strokes.aspx" style="font-weight: bold;">Otto cycle</a> to convert the chemical energy in fuel into mechanical energy and, in so doing, produce power. The major difference is the way fuel is delivered to the combustion chamber and the way the fuel mixture is ignited. Firstly, in gasoline engines, the fuel is usually fed into the intake manifold or the intake port where it is combined and mixed with the intake air, which is also called the intake charge. In modern diesel engines, the fuel is injected directly into the combustion chamber. This means that only the intake charge is compressed during the compression stroke and the diesel is only introduced once the intake charge has been compressed. Secondly, in gasoline engines, the fuel mixture is ignited by a sparkplug, while in diesel engines the fuel is ignited by the heat from the compressed air in the combustion chamber. However, diesel requires a much higher temperature than petrol before ignition (not spontaneous ignition) can take place. These differences has important consequences for the modification of diesel engines, especially when you consider the differences between diesel fuel and gasoline. <h3>THE DIFFERENCES BETWEEN DIESEL AND GASOLINE</h3> For starters, diesel is a heavier fuel than gasoline. In other words, it contains more carbon atoms in longer chains than gasoline (technically, gasoline is typically C9H20, while diesel fuel is typically C14H30). Because it is heavier, diesel is much more stable that gasoline and vaporizes at a much higher temperature than gasoline. It also vaporizes much slower than gasoline and burns much slower. The result is that diesel requires a much higher temperature to ignite. Gasoline, for example can burn at temperatures of -40° F while diesel requires a temperature of at least 143° F! The main point, however, is that diesel burns slower than petrol. This means that it will produce a steady pressure on the piston for longer. Consequently, diesel can be ignited at a higher temperature, and indeed can be allowed to reach the point at which it will ignite spontaneously. The interesting thing is that diesel needs a temperature of 410° F to ignite spontaneously but will ignite or burn at a much lower temperature of 143° F. Consequently, diesel cannot be introduced into the combustion chamber until the correct temperature is reached, or else it will pre-ignite. Now, to reach the required temperature, air in the combustion chamber must be compressed much more than in a gasoline engine, and because there is not fuel in the combustion chamber, the intake charge can be safely compressed without the danger of pre-ignition. Thus a gasoline engine will typically have the compressions ratio would of somewhere between 1:9 and 1:12 while a diesel engine will typically a compression ratio of around 1:25! And it is this higher compression ratio, as well as its higher vaporization point and slower burning rate and the fact that diesel has about 17% more energy density than gasoline, that makes diesel much more efficient than gasoline. Now you're thinking why not use direct injection in a gasoline engine so we can increase the compress without pre-ignition? Indeed some manufacturers to employ direct injection on gasoline engines, but without the higher compression ratio because gasoline will burn too quickly at higher temperatures, hence the need to keep the temperature of the intake charge down in a gasoline engine. Remember, diesel burns at a slower rate than gasoline and therefore can be ignited at higher temperatures. <h3><a name="Modifications"></a>DIESEL ENGINE MODIFICATIONS</h3> When it comes to modifying a diesel engine, you can apply the same techniques that you would apply to a gasoline engine, except for ignition system obviously as diesel engine has no spark plug. All the basics apply, i.e., increasing the engine displacement, increasing the engine speed, improving and increasing the air intake, and increasing the volumetric efficiency. Nonetheless, there are a number of things to consider before attempting to modify a diesel engine. <ul><li>Firstly, components in the diesel engine are exposed to far higher pressures and temperatures than the components in gasoline engines. Therefore, diesel engines need to be more robust with thicker cylinder walls and stronger pistons. Should you decide to increase the displacement of your diesel engine by boring out the cylinders you should ensure that you improve your cooling system.</li><li>Secondly, diesel burns at a much slower rate than gasoline; therefore a diesel engine will operate at a much lower RPM. This is natural, and getting the diesel engine to operate at higher speed will mean increasing the temperatures in the combustion chamber, which would require thicker cylinder wall and much a better cool system, and improving the cooling system is easier said than done because of diminishing returns!</li><li>Furthermore, increasing the temperatures in the combustion chamber will increase the heat in the intake manifold, and will result in a reduction of air density. Consequently, we're dealing with even more diminishing returns! Still, maximum power will be reached at relatively low RPMs because of the slow rate at which diesel burns and will drop off dramatically at higher RPMs.</li><li>Thirdly, increasing the amount of air ingested by the engine will require a proportionate increase in the amount of fuel injected into the engine. Thus bigger injectors, a higher fuel pressure will be required, or a remapped engine control unit (ECU) would be required. On some turbo-diesel engines, a remapped ECU has led to impressive improvements in power and should be the starting point in your quest to squeeze more power from a diesel engine. </li></ul>

engine The Diesel Engine

The diesel engine was developed by Rudolf Diesel and was patented in 1892 . Diesel engines are very similar to petrol or gasoline engines ...

Engine Building for Power and Reliability

If you're planning to do some serious modifications to a four stroke engine, you'd better do it right if you don't want to end up with an expensive pile of scrap metal. It's easy to slap on a turbo and run mild boost on a stock engine or even fitting a bigger turbo to an OEM turbo engine, but if you're looking for serious power, you have to rebuild the subassembly to ensure that it can handle the additional power without disintegrating. Obviously you need to ensure that your drive train can handle the extra engine power as well, but in this section we'll discuss engine building for maximum power, starting with the subassembly. <h3>THE CYLINDER BLOCK</h3> You've got to start by ensuring that your cylinder block is race grade. Even if you're just building a street race car, engine tuning would be senseless if the block is not up to the job. Start by pressure testing the block. If you have an air compressor you can do this yourself. Strip down the engine but leave the Welch plugs and oil gallery plugs in place. Fit the bare cylinder head to the cylinder block using new head gasket or one that's not too worn. Close all water opening off with steel plates. One of the plates must be fitted with an air line fitting that you can connect your air compressor to. Gradually increase the pressure in the block to 40 psi. Don't increase the pressure too quickly as a loose fitting Welch plug or a weak spot in the block could blow out can cause you serious injury. If everything is still in place, gradually increase the pressure to 50 psi. Now spray the block with a mild water/detergent mixture. Carefully check the block for air bubbles. If you see bubbles, either have it repaired or test another block. If you get no bubbles, release the air pressure and remove the cylinder head. Use a plug tap to clean the head stud and main bearing cap threads and chamfer any stud hole that is not already chamfered. This will prevent the thread from pulling up. Grind away any casting sag, especially around the main bearing webs, the sump pan deck, and the valley area of a Vee engine. This will prevent cracks from developing. Now remove all the Welch plugs and oil gallery plugs and have the block boiled and cleaned in a chemical bath. This will remove all rust and scale in the water channels, and the caked oil in the oil galleries. <h3>THE CRANKSHAFT & CON RODS</h3> <div class="rightImage"><img alt="Chrome-moly forged con rods" src="http://www.custom-car.us/_images/forgedConRod.jpg" /> Chrome-moly forged con rods </div> The stock crankshaft and con rods are usually cast iron items that can be retained if the engine is not required to handle high boost pressures, high horse power, and high revs. Forged crankshafts and con rods are much stronger and are more suitable for high load, high rev engines. In either event, you should have the crankshaft and con rods Magnafluxed to check for cracks. If the crankshaft has no cracks, check it for straightness. A crankshaft that is even 0.002in out of straight will increase bearing load and will be the cause of bearing failure. If your crankshaft is out of straight, you have two options – either have the crankshaft straightened or machine the crankshaft's main journals so that crankshaft rotation is true. However, straightening a crankshaft that is to be used for a high boost, high horse power, and high rev engine is a waste of time and money as the combustion pressure and inertia loads will reverse the straightening process. Machining the crankshaft journals will also weaken the crankshaft. Ultimately, replacing a bent crankshaft is your best option. It goes without saying that all the crankshaft journals should be checked for roundness and size. The same goes for the big end on the con rods. The crankshaft, con rods, and flywheel should then be balanced statically and dynamically to reduce shock loading and vibration. <h3>THE PISTONS</h3> <div class="rightImage"><img alt="Forged pistons" src="http://www.custom-car.us/_images/forgedPiston.jpg" /> High strength forged pistons </div> The next thing you need to consider is the pistons. Most OEM engines are fitted with cast aluminum pistons with a slotted oil groove. High performance OEM engines may be fitted with hypereutectic cast aluminum pistons that have a higher silicon content. The higher silicon content makes the cast material much harder and more wear resistant, which allows these pistons to withstand greater temperature and pressure loads. This makes these pistons ideal for street racers. However, the higher silicon content also makes the pistons more brittle and prone to breaking under detonation. Thus, these pistons are not a good choice for forced induction applications where the possibility of detonation in greatly increased. Forged pistons, on the other hand, have much denser and even harder than hypereutectic cast aluminum pistons but are not as prone to breaking under detonation. Forged pistons also have drilled oil holes round the oil groove rather than a slot in the oil groove. This makes them the best option for high horse power, forced induction engines. Pistons can also be either full skirt pistons or slipper type. The full skirt pistons are heavier but stronger and less prone to wobble. Needless to say, they would be the best option for any engine modification project.

engine Engine Building for Power and Reliability

If you're planning to do some serious modifications to a four stroke engine, you'd better do it right if you don't want to end ...

Maximizing Engine Power

<div class="rightImage"> <img alt="The four stroke engine" src="http://www.custom-car.us/_images/SR20engine.jpg" /> The four stroke engine.</div> <div id="contentText"> Custom-car.us is all about engine tuning and car performance; so if you want to know about car tuning, how to increase engine power and how to modify your car, then you've come to the right place. However, before we can start talking about engine tuning and increasing engine power and torque, we first need to have a basic understanding of how an internal combustion engine produces power. Therefore, over the next few pages of this section, we'll discuss the various basic concepts and principles of the internal combustion engines and the common terms used to discuss engine modifications, such as <a href="http://www.custom-car.us/basics/power-basics.aspx#Volumetric-Efficiency">volumetric efficiency</a>, <a href="http://www.custom-car.us/basics/power-basics.aspx#Engine-Displacement">engine displacement</a> and <a href="http://www.custom-car.us/basics/power-basics.aspx#Air-Density">air density</a> as all of these influence engine power and performance. We also have a <a href="http://www.custom-car.us/glossary.aspx">glossary of car modification terms</a> that you can check for the meaning of some of the terms we use on this site. Once we have a clear understanding of how a four stroke engine produces power, we can move on and start make our P.L.A.N.s to increase engine performance. Although there are two types of internal combustion engines, namely the two stroke engine and the four stroke engine, we're only interested in car performance and since the two-stroke engine is not used on cars, we won't be discussing that engine here. Instead we'll focus out attentions soely on the four-stroke engine because custom-car.us is all about car tuning and because cars use the four-stroke engine and not the two-stoke engine. If you're looking for information about the two-stroke engine, you could try <a href="http://science.howstuffworks.com/two-stroke.htm" rel="nofollow">How Stuff Works</a> or <a href="http://en.wikipedia.org/wiki/two-stroke_cycle" rel="nofollow">Wikipedia</a>. <div class="rightImage"><img alt="The rotary engine" src="http://www.custom-car.us/_images/rotaryEngine.jpg" /> The Wankel rotary engine.</div> There are also numerous derivatives of the four stroke engine – diesel engines, petrol engines, four cylinder engines, straight sixes, boxer engines, rotary or wankel engines, turbocharged engines, supercharged engines, etc. With the marked exception of the rotary engine, all four stroke engines have a common basic design – they all consist of individual cylinders with pistons that are connected to a flywheel by a crankshaft, and they all make use of what is known as the Otto Cycle. This makes it fairly easy to discuss basic engine power concepts as we don't need to concern ourselves with V's and straights, boxers and horizontally opposed engines. Instead our discussion can and will be all about the four stroke internal combustion engine. In addition, the diesel engine has had a resurgence in recent years and has become more of a performance engine, especially the turbo-diesel engine. A lot of what we discuss here can be applied to modern diesel engines but there are some aspects of engine modification that are specific to diesel engines; for this reason we'll discuss <a href="http://www.custom-car.us/basics/diesel-engines.aspx">diesel engines</a> and <a href="http://www.custom-car.us/basics/diesel-engines.aspx#Modifications">diesel engine modifications</a> on their own. So let us begin by looking at the four strokes of the <a href="http://www.custom-car.us/basics/four-strokes.aspx">four stroke internal combustion engine</a> otherwise known as the Otto cycle. You can skip this section if you're already familiar with the Otto cycle and head on over to <a href="http://www.custom-car.us/basics/power-basics.aspx">basic engine power</a> or <a href="http://www.custom-car.us/basics/engine-building.aspx">engine building</a>, but this section does tie into most of what we discuss on Custom-car.us. If you're intereseted in modifying diesel engines, hop on over to our page on <a href="http://www.custom-car.us/basics/diesel-engines.aspx">diesel engines</a> to find out how to apply our discussions to diesel engines. </div>

engine Maximizing Engine Power

The four stroke engine. Custom-car.us is all about engine tuning and car performance ; so if you want to know about car tuning , how ...

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Performance Camshafts

Doing The Head

The Diesel Engine

Engine Building for Power and Reliability

Maximizing Engine Power

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