High lift, short duration v. shorter lift, long duration
05-30-2006, 07:39 AM
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High lift, short duration v. shorter lift, long duration Ok guys I have read enough about cams to make me 
& 
Here is my question:
What are the difference between "Higher lift with shorter duration" vs "shorter lift with longer durantion" cams??
Interest is for a NA road racing engine, lots of low end torque and high end HP.
TIA
Tom
& Here is my question:
What are the difference between "Higher lift with shorter duration" vs "shorter lift with longer durantion" cams??
Interest is for a NA road racing engine, lots of low end torque and high end HP.
TIA
Tom
05-30-2006, 07:55 AM
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I try to look at it like this. Longer duration is the poor mans way to make more power with less Volumetric Effeciency, which typically I"m power poor so I go with longer duration 
A lot of people talk all day long as they know cams online when they drive a bone stock car and probably have never cracked open a motor in their life. What do you want to do with your car? What do you like about the idea of a cam shaft?
The lope sound is comming from overlap or duration for the most part. You say you want low end torque and high end HP? I'd go with a shorter duration and higher lift cam as I've had plenty of big nasty cams and they do make GOOD power but they smell and the low end throttle response is a little squishey.
A lot of people talk all day long as they know cams online when they drive a bone stock car and probably have never cracked open a motor in their life. What do you want to do with your car? What do you like about the idea of a cam shaft?
The lope sound is comming from overlap or duration for the most part. You say you want low end torque and high end HP? I'd go with a shorter duration and higher lift cam as I've had plenty of big nasty cams and they do make GOOD power but they smell and the low end throttle response is a little squishey.
05-30-2006, 08:36 AM
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Road racing or Road track days.
I have driven some big cam cars from a very popular vender, the cars where dogs out of corners and did not come on strong until above 4000 rpms. Even driving the car in one gear lower to get the rpms, the response was still not as quick as I would like.
More on just leaning about cams and the differnt responses.
When the time comes I will go to a reputable road race motor builder and tell them what I do and what I want the car to do. Then let them do their magic depending on the rules of which class and sanctioning orginzation.
Thanks
I have driven some big cam cars from a very popular vender, the cars where dogs out of corners and did not come on strong until above 4000 rpms. Even driving the car in one gear lower to get the rpms, the response was still not as quick as I would like.
More on just leaning about cams and the differnt responses.
When the time comes I will go to a reputable road race motor builder and tell them what I do and what I want the car to do. Then let them do their magic depending on the rules of which class and sanctioning orginzation.
Thanks
