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camshaft durations

  #1  
Old 08-05-2007, 12:46 PM
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Default camshaft durations

im getting a f20b engine. whats the max duration that the pistons can hanlde in that engine?
 
  #2  
Old 08-05-2007, 03:17 PM
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Default RE: camshaft durations

Has nothing to do w/ the pistons, more like the valve springs.
 
  #3  
Old 08-05-2007, 11:05 PM
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Default RE: camshaft durations

yes it does have to do with the pistons. if the cam duration is too high, the valve will go through the piston aka ptv (piston to valve) contact. the valve springs are related to the lift of the cam NOT the duration.
 
  #4  
Old 08-05-2007, 11:44 PM
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Default RE: camshaft durations

welp ur sorta right... the duration is more of the stroke, compression ratio, cam advance, and yes also how much is cut out of the piston for the valve to clear... realy theres alot of factors that affect how duration works... the ramp speed and the lift are the 2 major factors in determining how much duration you can have... if u shorten ur lift and raise ur duration it could clear the piston better than a short duration high lift... and give the same result personaly i would stick with the premade aftermarket cams made for a stock engine...
 
  #5  
Old 08-06-2007, 12:13 AM
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Default RE: camshaft durations

alright so does any one know the max duration that the f20b can handle?
 
  #6  
Old 08-06-2007, 10:10 AM
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Default RE: camshaft durations

ORIGINAL: phibbs87

yes it does have to do with the pistons. if the cam duration is too high, the valve will go through the piston aka ptv (piston to valve) contact. the valve springs are related to the lift of the cam NOT the duration.
Doesn't matter how long the valve is open, if its not opening far enough to touch a piston or let enough air in/exhaust out. The point I was trying to make is that you need to take more than just duration into account when selecting a valvetrain. All the aspects are important, not just one.

Also - if you're gonna have a cam w/ long duration, the stock valve springs aren't going to hold to that kind of abuse for long b/c they weren't designed to handle it. This is why people upgrade the entire valvetrain (cams, springs, retainers, etc) at once.

And honestly there seems to only be about a handful of people on here that know this kind of stuff. You'd probably have better luck on honda-tech.com
 
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