head redesign
- Thread starter roadkill
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CYLINDER HEAD
Cylinder heads can be reshaped to change the power band. Generally speaking, a cylinder head with a small diameter and deep combustion chamber, and a wide squish band (60% of the bore area). Combined with a compression ratio of 9 to 1 is ideally suited for low to mid range power. A cylinder head with a wide shallow chamber and a narrow squish band (35-45% of bore area) and a compression ratio of 8 to 1, is ideally suited for high rpm power.
There are many reasons why a particular head design works for certain types of racing. For example; a head with a wide squish band and a high compression ratio will generate high turbulence in the combustion chamber. This turbulence is termed Maximum Squish Velocity, MSV is rated in meters per second (m/s). A cylinder head designed for supercross should have an MSV rating of 28m/s. Computer design software is used to calculate the MSV for head designs. In the model tuning tips chapters of this book, all the head specs quoted have MSV ratings designed for the intended power band changes.
Cylinder heads can be reshaped to change the power band. Generally speaking, a cylinder head with a small diameter and deep combustion chamber, and a wide squish band (60% of the bore area). Combined with a compression ratio of 9 to 1 is ideally suited for low to mid range power. A cylinder head with a wide shallow chamber and a narrow squish band (35-45% of bore area) and a compression ratio of 8 to 1, is ideally suited for high rpm power.
There are many reasons why a particular head design works for certain types of racing. For example; a head with a wide squish band and a high compression ratio will generate high turbulence in the combustion chamber. This turbulence is termed Maximum Squish Velocity, MSV is rated in meters per second (m/s). A cylinder head designed for supercross should have an MSV rating of 28m/s. Computer design software is used to calculate the MSV for head designs. In the model tuning tips chapters of this book, all the head specs quoted have MSV ratings designed for the intended power band changes.
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^^^^^ wow nice job man, have some rep, and the biggest difference in mine done buy ken is that the head is now flat, or isnt raised where it is mounted, decreasing space, increasing compression, increasing power, in short/
Here is the oversimplified expl.
1st. you want the fuel charge to burn, not explode. the shape of the head controls the spread of the flame front....
2nd. compression: X amount of fuel/air mixture will expand to a certain volume when burned. Hi compression makes more power by compressing the mixture further, it will only expand so much so to get extraenergy you compress it more so the piston see's more expansion.
this has good and bad effects.... it takes energy to compress it more and it puts more stress on the motor to compress it i.e: more work for the motor.
typically high rpm motors have less compression. you relying on more revs to make more power. the motor spins faster because it doesnt have to work as hard to squish the mixture. (less resistance to upstroke)
A low rpm motor has more cmpression, because it makes power by squishing the charge further (more resistance to upstroke...)
again this is oversimplified
1st. you want the fuel charge to burn, not explode. the shape of the head controls the spread of the flame front....
2nd. compression: X amount of fuel/air mixture will expand to a certain volume when burned. Hi compression makes more power by compressing the mixture further, it will only expand so much so to get extraenergy you compress it more so the piston see's more expansion.
this has good and bad effects.... it takes energy to compress it more and it puts more stress on the motor to compress it i.e: more work for the motor.
typically high rpm motors have less compression. you relying on more revs to make more power. the motor spins faster because it doesnt have to work as hard to squish the mixture. (less resistance to upstroke)
A low rpm motor has more cmpression, because it makes power by squishing the charge further (more resistance to upstroke...)
again this is oversimplified
