What makes the power?
- Thread starter brc80
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my guess would be one needs the other.
more lift results in the valves opening further. more duration results in the valves staying open longer.
theoretically, if the valve opens really high, but doesnt stay open for very long, you'd get the same amount of air/fuel as if it opened not as high, but stayed open longer.
more lift results in the valves opening further. more duration results in the valves staying open longer.
theoretically, if the valve opens really high, but doesnt stay open for very long, you'd get the same amount of air/fuel as if it opened not as high, but stayed open longer.
More lift tends to increase the peak WHP, where duration tends to shift the powerband upwards. (and as you move peak torque higher in the RPM band, it creates more HP due to the age old equation HP = Torque * RPM / 5252).
The reason some cam manufactures choose to have less duration, is because for the most part the average Honda owner is cheap when it comes to their engine build. They have no problem spending the money to do the easy work on the head, but they rarely want to touch the bottom end.
It should be pretty apparent that more duration and lift is the way to make the most power. However the drawback to more duration is the intake valve stays open longer, during the compression stroke. The result is some compression is lost when it is pushed out of the still open intake valve. (dynamic compression)
The way to correct this, is simply run more compression. This leads back to people not wanting to replace pistons. So they are left with nothing but milling and running flat top valves to increase compression which can only do so much.
So these stage 1 / stage 2 cams are often designed with that in mind.
The reason some cam manufactures choose to have less duration, is because for the most part the average Honda owner is cheap when it comes to their engine build. They have no problem spending the money to do the easy work on the head, but they rarely want to touch the bottom end.
It should be pretty apparent that more duration and lift is the way to make the most power. However the drawback to more duration is the intake valve stays open longer, during the compression stroke. The result is some compression is lost when it is pushed out of the still open intake valve. (dynamic compression)
The way to correct this, is simply run more compression. This leads back to people not wanting to replace pistons. So they are left with nothing but milling and running flat top valves to increase compression which can only do so much.
So these stage 1 / stage 2 cams are often designed with that in mind.
A really good explination of camshaft specifications
Duration effects engine idle, a high duration cam will have a very rough idle and low vacuum. Have you ever heard an old muscle car that sounds as if you can hear every cylinder fire that's due to a very larger duration cam.
changing the lift and duration change the area under the curve.
A high lift short duration has a narow band
typical for trying to produce more hp
were a lower lift long duration has a wide band
typically produces more torque
Duration effects engine idle, a high duration cam will have a very rough idle and low vacuum. Have you ever heard an old muscle car that sounds as if you can hear every cylinder fire that's due to a very larger duration cam.
changing the lift and duration change the area under the curve.
A high lift short duration has a narow band
typical for trying to produce more hp
were a lower lift long duration has a wide band
typically produces more torque
Speedracer228
......
thats a good writeup, it explains everything pretty clearly
good find
