Basic engine nomenclature
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==The "strokes" of an internal combustion 4-stroke engine== | ==The "strokes" of an internal combustion 4-stroke engine== | ||
From [http://www.answers.com/topic/internal-combustion-engine#Nomenclature Engine nomenclature]: | From [http://www.answers.com/topic/internal-combustion-engine#Nomenclature Engine nomenclature]: | ||
| − | 1. Intake stroke: The first stroke of the internal combustion engine is also known as the suction stroke because the piston moves to the maximum volume position (downward direction in the cylinder). | + | 1. Intake stroke: The first stroke of the internal combustion engine is also known as the suction stroke because the piston moves to the maximum volume position (downward direction in the cylinder) which pulls the fuel/air mixture into the cylinder. During this stroke the inlet valve is open, and the vaporized fuel mixture enters the combustion chamber. The inlet valve closes at the end of this stroke. |
| − | 2. Compression stroke: In this stroke, both valves are closed and the piston | + | 2. Compression stroke: In this stroke, both valves are closed and the piston moves upward to the minimum volume position in the cylinder compressing the fuel mixture. During the compression process, pressure, temperature and the density of the fuel mixture increases. |
| − | 3. Power stroke: When the piston reaches the minimum volume position | + | 3. Power stroke: When the piston reaches the minimum volume position at the top of it's stroke the spark plug ignites the fuel mixture and burns pushing the piston down. The power is transmitted to the crank shaft mechanism. |
| − | 4. Exhaust stroke: | + | 4. Exhaust stroke: After the power stroke, the exhaust valve opens. During this stroke, the piston starts its movement at the bottom position. As the piston rises the spent exhaust gasses exit through the outlet valve. At the end of this stroke, the exhaust valve closes, the inlet valve opens, and the sequence repeats in the next cycle. Four-stroke engines require two revolutions. |
==Other terms== | ==Other terms== | ||
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That measurement is one of 3 measurements an engine builder must know to add up the STACK of parts to be used in the cylinder block. Pistons come in many different COMPRESSION HEIGHTS to allow their use in different combinations of stacks. | That measurement is one of 3 measurements an engine builder must know to add up the STACK of parts to be used in the cylinder block. Pistons come in many different COMPRESSION HEIGHTS to allow their use in different combinations of stacks. | ||
| − | CONNECTING ROD: Rods come in 3 flavors, cast steel, forged steel and in the case of aluminum racing rods, extruded. 99% of the rods used by us hot rodders will be forged from one steel mix or another, with the formula varying according to how the manufacturer wants the rod to perform in its lifetime. Rods come in many different center-to-center lengths so that we can custom tailor the measurement of the stack of parts we will use in our motor. | + | CONNECTING ROD: Rods come in 3 flavors, cast steel, forged steel and in the case of aluminum racing rods, extruded. 99% of the rods used by us hot rodders will be forged from one steel mix or another, with the formula varying according to how the manufacturer wants the rod to perform in its lifetime. Rods come in many different center-to-center lengths so that we can custom tailor the measurement of the stack of parts we will use in our motor. |
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CRANKSHAFT: Cranks come in 3 different flavors, cast steel, forged steel and billet steel. The vast majority of cranks used in the hot rod hobby will be cast steel. Half the stroke of the crank, or the RADIUS of the crank, will be used to determine your STACK. If a crank stroke is 3.48", then the radius of that crank will be 1.74". In the left part of this diagram, the arrow points to the centerline of the crankshaft main bearing journal. Another arrow points to the crankpin where the big end of the rod bolts on. | CRANKSHAFT: Cranks come in 3 different flavors, cast steel, forged steel and billet steel. The vast majority of cranks used in the hot rod hobby will be cast steel. Half the stroke of the crank, or the RADIUS of the crank, will be used to determine your STACK. If a crank stroke is 3.48", then the radius of that crank will be 1.74". In the left part of this diagram, the arrow points to the centerline of the crankshaft main bearing journal. Another arrow points to the crankpin where the big end of the rod bolts on. | ||
| − | + | The measurement between these two points is the RADIUS of the crankshaft. As stated above, the radius of a 350 crank would be 1.74", or half the 3.48" stroke. A 383 crank, with its 3.75" stroke, would have a RADIUS of 1.875". A 283 crank, with a 3.00" stroke, would have a RADIUS of 1.50". | |
| − | The measurement between these two points is the RADIUS of the crankshaft. As stated above, the radius of a 350 crank would be 1.74", or half the 3.48" stroke. A 383 crank, with its 3.75" stroke, would have a RADIUS of 1.875". A 283 crank, with a 3.00" stroke, would have a RADIUS of 1.50". | + | |
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PISTON DECK HEIGHT: Not to be confused with block deck height, piston deck height is the measurement from the crown of the piston to the block deck where the heads bolt on, with the piston at top dead center. PLEASE PAY ATTENTION. THERE ARE 2 DIFFERENT DECK HEIGHTS. BLOCK DECK HEIGHT AND PISTON DECK HEIGHT. PLEASE BE SPECIFIC WHEN DISCUSSING "DECK HEIGHT". Piston deck height is labeled incorrectly here as simply "deck height". It should be labeled "Piston Deck Height", not to be confused with block deck height. | PISTON DECK HEIGHT: Not to be confused with block deck height, piston deck height is the measurement from the crown of the piston to the block deck where the heads bolt on, with the piston at top dead center. PLEASE PAY ATTENTION. THERE ARE 2 DIFFERENT DECK HEIGHTS. BLOCK DECK HEIGHT AND PISTON DECK HEIGHT. PLEASE BE SPECIFIC WHEN DISCUSSING "DECK HEIGHT". Piston deck height is labeled incorrectly here as simply "deck height". It should be labeled "Piston Deck Height", not to be confused with block deck height. | ||
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SQUISH: The distance from the piston crown to the underside of the cylinder head with the piston at top dead center and with the head gasket in place and its thickness included in the measurement. If the piston crown were down in the bore by 0.010" (ten thousandths of an inch) with the piston at top dead center and you used a 0.028" (twenty eight thousandths of an inch) gasket thickness, adding the two together would yield a 0.038" squish measurement (thirty eight thousandths of an inch). The closer the piston comes to the underside of the head (without crashing into the head), the better the motor will perform. The action is that the piston comes up very close to the underside of the head and squishes out the mixture in that area, jetting it across the chamber toward the spark plug and creating turbulence to help eliminate rich and lean pockets of mixture in the chamber so that the whole mess burns evenly and offers less chance for the mixture to detonate or pre-ignite. | SQUISH: The distance from the piston crown to the underside of the cylinder head with the piston at top dead center and with the head gasket in place and its thickness included in the measurement. If the piston crown were down in the bore by 0.010" (ten thousandths of an inch) with the piston at top dead center and you used a 0.028" (twenty eight thousandths of an inch) gasket thickness, adding the two together would yield a 0.038" squish measurement (thirty eight thousandths of an inch). The closer the piston comes to the underside of the head (without crashing into the head), the better the motor will perform. The action is that the piston comes up very close to the underside of the head and squishes out the mixture in that area, jetting it across the chamber toward the spark plug and creating turbulence to help eliminate rich and lean pockets of mixture in the chamber so that the whole mess burns evenly and offers less chance for the mixture to detonate or pre-ignite. | ||
| − | QUENCH: The terms quench and squish are often used interchangeably, but they actually have different technical meanings. Quench refers to the passing of heat from the combustion chamber into the surrounding metal, some of which finds its way into the cooling system. The more quench that is in effect, the more heat passes into the cooling system and vise versa. On one hand, having a quench-type combustion chamber and piston shape and tight quench distance may be looked at as a detriment to power production (heat IS energy, after all). But in the case of the IC engines we are working with, the loss of heat energy is more than offset by the decrease in the tendency to encounter detonation- which will kill power at a much greater rate and amount than the loss of some combustion chamber heat to the quench effect. | + | QUENCH: The terms quench and squish are often used interchangeably, but they actually have different technical meanings. Quench refers to the passing of heat from the combustion chamber into the surrounding metal, some of which finds its way into the cooling system. The more quench that is in effect, the more heat passes into the cooling system and vise versa. An example would be the close proximity of the piston to the underside of the cylinder head with the piston at top dead center. On one hand, having a quench-type combustion chamber and piston shape and tight quench distance may be looked at as a detriment to power production (heat IS energy, after all). But in the case of the IC engines we are working with, the loss of heat energy is more than offset by the decrease in the tendency to encounter detonation- which will kill power at a much greater rate and amount than the loss of some combustion chamber heat to the quench effect. |
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