Cam and compression ratio compatibility

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(Undo revision 3477941 by 164.90.34.153 (talk))
 
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==The following is for fellows who know nothing about engines==
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You do not match characteristics of camshafts.  You design the camshaft to create the performance characteristics you desire from your engine components.  The following are as they describe it, "only rules of thumb", "ballpark figures", "a little more" or "a little less", a "starting point" and "nowhere near scientific or definite in it's scope".  If you are interested in the facts about selecting the proper camshaft, you can receive the facts and mathematics on the internet from Controlled Induction Software.
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==Matching cam to compression ratio==
 
==Matching cam to compression ratio==
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==STOP RIGHT HERE, THIS IS INCORRECT==
 
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What size stroke is in these engines that these figures above are suppose to represent.  You can't believe that an engine with a 3.000" stroke is going to have the same RPM range as an engine with a 4.500" stroke, using the same duration cam?  It won't and all of these generalizations are ridiculous.  The duration of a camshaft is determined by the Mean Port Velocity and the Mean Piston Velocity, which is determined by the Stroke and RPM.  You're trying to fill the cylinder at a given RPM, and in order to due that you need to control the Mean Port Velocity during the induction process.  Controlled Induction!  Compression does not have anything to do with determining the correct cam duration for your engine and desired Peak HP RPM? 
 
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((Mean Piston Velocity FPM / Mean Port Velocity FPM) * PI), and 2 more calculations give you the valve seat duration. You can find it in Controlled Induction.
 
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==Additional reading/engine theory==
 
==Additional reading/engine theory==
 
{{Note1}}  
 
{{Note1}}  
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*[http://www.uempistons.com/calc.php?action=comp2 Dynamic compression calculator] by KB
 
*[http://www.uempistons.com/calc.php?action=comp2 Dynamic compression calculator] by KB
 
*[http://www.wallaceracing.com/dynamic-cr.php Wallace Racing DCR calculator]
 
*[http://www.wallaceracing.com/dynamic-cr.php Wallace Racing DCR calculator]
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{{Note1}} Some dynamic compression ratio calculators (like KBs) ask for an additional 15 degrees of duration be added to the IVC @ 0.050" lift point figure. This works OK on older, slower ramped cam lobes, but the faster lobe profiles may need to have 25 degrees or more added to be accurate.
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{{Note1}} Some dynamic compression ratio calculators (like KBs) ask for an additional 15 degrees of duration be added to the IVC @ 0.050" lift point nnbfigure. This works OK on older, slower ramped cam lobes, but the faster lobe profiles may need to have 25 degrees or more added to be accurate.
  
 
===Cam phasing===
 
===Cam phasing===
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[[Category:Camshaft]]
 
[[Category:Camshaft]]
  
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<pre style="border:none;">
 
General Application Chart *
 
General Application Chart *
 
Advertised
 
Advertised
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290°+ 3.73+ 3400-8000
 
290°+ 3.73+ 3400-8000
 
10.5 to 12 3500+
 
10.5 to 12 3500+
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</pre>

Latest revision as of 07:00, 17 July 2023

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