question about camshafts
01-06-2006, 12:57 AM
#1
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question about camshafts
people are confusing me when there saying 2 cams on a head
from what I understand the cams are rods that help open the valves.. if I have a SOHC engine that means its 2 valves right? and there is 2 camshaft rods or am I wrong?
and what about the DOHC that means there is 4 camshafts? someone please clarify
from what I understand the cams are rods that help open the valves.. if I have a SOHC engine that means its 2 valves right? and there is 2 camshaft rods or am I wrong?
and what about the DOHC that means there is 4 camshafts? someone please clarify
01-06-2006, 04:48 AM
#3
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RE: question about camshafts
96-04 GT's were SOHC 2V
96-04 Cobra's were DOHC 4V
05-06 GT's are SOHC 3V
The DOHC Cobra's have 2 cams on each head(4 cams total) and the SOHC GT's have just one cam on each head(2 cams total).
96-04 Cobra's were DOHC 4V
05-06 GT's are SOHC 3V
The DOHC Cobra's have 2 cams on each head(4 cams total) and the SOHC GT's have just one cam on each head(2 cams total).
01-06-2006, 08:54 AM
#4
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RE: question about camshafts
Whelp no one has really answered/point it out your statement flaw.
Cams are not rods (in terms of push rods) Cams are shafts with eccentric style circles with varying diameters to allow for a rotational movement to be changed into a liner movement.
On an push rod V8 this cam is located in the center of the block and is driven off the crankshaft. But because of the cams loaction you cannont have it direcly actuate the valves in the heads. So you use push rods to transfer the cam's rotaional movement into a liner movement that then acts upon a rocker arm which acts as a mulitplyer of the liner movement which then acts upon the valve.
Got all that[8D]
Basically the cam has 1" of lift (max diameter of th eccentric cam) that 1" of travel gets transmitted up to the rocker arm. The rocker arm acts as a multiplyer of the travel. So say the rocker arm as a ratio of 1.6. That means for every 1" of movment applied to the short side of the rocker will result in 1" plus 600ths of lift. The rocker elminates the need for extremely large cams to give the same amount of lift.
On our cars (2V 4.6), the cam is acutally in the head. The cam is still driven off the crank but the eccentric circles apply the rotaional motion to the valves directly ( there is a small connection kinda like a rod but not really).
In both cases the cam has an exhaust cam profile and intake cam profile. But the advantages of the cam located at the head boils down to higher achiveable RPM. Because you are reducing the amount of rotationg mass the OHC set up can rev higher with out rotationl distortion.
There are are things that are importent when it comes to RPM that does not just include cams. Things like the valve springs and rocker arms play a part.
So to answer you other question. A SOHC car has one cam in EACH head. A DOHC car has 2 cams in each head. A SHOC motor has 1 intake valve and 1 exhaust valve. A DHOC motor has 4 valves. Some will run 3 intake and 1 exhaust others will run 2 and 2, and others will split the two valve types across the cams. It comes down to manufacture set-up. But the cams are in the heads regardless of the set-up.
Cams are not rods (in terms of push rods) Cams are shafts with eccentric style circles with varying diameters to allow for a rotational movement to be changed into a liner movement.
On an push rod V8 this cam is located in the center of the block and is driven off the crankshaft. But because of the cams loaction you cannont have it direcly actuate the valves in the heads. So you use push rods to transfer the cam's rotaional movement into a liner movement that then acts upon a rocker arm which acts as a mulitplyer of the liner movement which then acts upon the valve.
Got all that[8D]
Basically the cam has 1" of lift (max diameter of th eccentric cam) that 1" of travel gets transmitted up to the rocker arm. The rocker arm acts as a multiplyer of the travel. So say the rocker arm as a ratio of 1.6. That means for every 1" of movment applied to the short side of the rocker will result in 1" plus 600ths of lift. The rocker elminates the need for extremely large cams to give the same amount of lift.
On our cars (2V 4.6), the cam is acutally in the head. The cam is still driven off the crank but the eccentric circles apply the rotaional motion to the valves directly ( there is a small connection kinda like a rod but not really).
In both cases the cam has an exhaust cam profile and intake cam profile. But the advantages of the cam located at the head boils down to higher achiveable RPM. Because you are reducing the amount of rotationg mass the OHC set up can rev higher with out rotationl distortion.
There are are things that are importent when it comes to RPM that does not just include cams. Things like the valve springs and rocker arms play a part.
So to answer you other question. A SOHC car has one cam in EACH head. A DOHC car has 2 cams in each head. A SHOC motor has 1 intake valve and 1 exhaust valve. A DHOC motor has 4 valves. Some will run 3 intake and 1 exhaust others will run 2 and 2, and others will split the two valve types across the cams. It comes down to manufacture set-up. But the cams are in the heads regardless of the set-up.
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