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The mathematics of the 8V vs. 16V problem

This makes for interesing reading, but the value of multi-valve heads is the increased valve circumference, not increased valve area. (or so I've been told...)
  For some reason unknown to myself, more circumference equals more flow equals more power.

Larry
  ----- Original Message ----- 
  From: Adrian 
  To: scirocco-l@scirocco.org 
  Sent: Monday, October 20, 2003 7:12 PM
  Subject: RE: The mathematics of the 8V vs. 16V problem


  Well here is my non-biased opinion, engines are engines.

  Doesn't really matter how many valves it has (I seen engines having 1,
  2, 3, 4, 5 and even 6 valves for each cylinder!!!), it still performs
  the same task: Takes the gas, burns it and turns that thermo-chemical
  energy and turns it into mechanical energy. But what really matters is
  how much air can flow through it!

  As we all know engines are like big air pumps. The more air you can get
  into it the more power it will make. So here is the scientific aspect of
  it...

  Air Capacity (in CFM) = ((CID * RPM) ? 3456) * VE

  Where a 2 valves per cylinder engines, use a VE of .8-.85 at torque peak
  and .7-.75 at power peak and 4 valves per cylinder engines, use a VE of
  .9-.95 at torque peak and .85-.9 at power peak.

  To find out Displacement in CID = # Cyls * 0.7854 * bore * bore * stroke
  Or you can convert CC to CID -> CID = CC*061037

  If you want to get the results in Lbs/min then -> Lbs/min = CFM * 0.069

  The pressure ratio is simply the pressure in compared to the pressure
  out of the turbocharger. The pressure in is usually atmospheric
  pressure, but may be slightly lower if the intake system before the
  turbo is restrictive, the inlet pressure could be higher than
  atmospheric if there is more than 1 turbocharger in series. In that case
  the inlet let pressure will be the outlet pressure of the turbo before
  it. 

  Injector Sizing
  lbs/hr = ((BSFC / #Cylinders) * HP / Injector Duty Cycle 

  Brake Specific Fuel Consumption is normally (lb/HP x hr) 
      0.42 BSFC - Race Engine
      0.47 BSFC - Hi Performance Engine
      0.52 BSFC - Stock or with Light Modifications Engine
      0.57 BSFC - Supercharged / Turbo Charged Engine

  Injector Flow Rate Conversion
  CC/Min = LBS/HR * 9.71 
  LBS/HR = CC/min * 0.103

  BTW Most Injector burst pressures are at 125 PSI.

  The density of air also varies with its temperature. A cubic foot of
  cold air weighs more than a cubic foot of hot air. A round average for
  airflow vs. hp is 1.5 to 1.6 cubic feet per minute for each hp
  developed. 

  So as we can see here the more flow the more power the engine will
  produce.
  Sorry for the Long post but someone got to put an end to this.
  Each engine has its advantages and its disadvantages.  

  If anyone might have any other concerns or questions please email me.
  I used this as a Guide to Build my engine that is about to be completed.
  I more information regarding engine builds and operation.

  Thank you, for reading this and taking your time to understand where im
  standing at in this 8V Vs 16V Feud.

  Have a Good Night.

  Adrian C.
  Project Scirocco R2.oT - "The Turbocharged 16Valves of Fire Breathing
  Fury"
  ( 2.0L 16V T66 )
   

  -----Original Message-----
  From: scirocco-l-bounces@scirocco.org
  [mailto:scirocco-l-bounces@scirocco.org] On Behalf Of C Boyko
  Sent: October 19, 2003 6:53 AM
  To: scirocco-l@scirocco.org
  Subject: The mathematics of the 8Vvs16V problem

  This is a preliminary post resulting from my dyno yesterday, and I
  though 
  I'd better post it, since this is such a popular topic for discussion. I

  believe this should lay to rest forever the 16V vs 8V discussion...(as
  if)

  Hypothesis:
  That doubling the number of valves doubles the horsepower

  Method and all that crap: Toss my two cars on the dyno

  Observations:
  1987 16V 132.8 hp to the wheels
  1979 8V 66.6 hp to the wheels

  Analysis and Conclusions:
  2^3 = 8  (or 6 in certain circles, when used in probability questions)
  2^4 = 16

  2^4/2=8, or 16/2=8
  132.8/2= damn close to 66.6

  Next Experiment:
  Toss a 20 V on the dyno....WTF, over 300? Well, now we need a formula I 
  guess...


  Seriously, dyno day was fun as usual, and after all that tuning (with
  Klaus 
  making the day's low, and Josh C's red beast making the high)
  Since Klaus was supposed to have 76 at the crank according to the
  owner's 
  manual (and you lose a bit getting that to the ground) , 66.6 (though a
  bit 
  evil sounding) is damn fine for a car with 171000 miles on the engine
  (just 
  nicely broken in). I guess there is even a picture with his needle
  buried, 
  despite the fact that you could go have lunch while he got to redline.
  (see, 
  there is that time component in the hp formula...)
  A few surprises, but most dynoed about where they figured they'd be.

  I'll post more about the weekend later, but that should get the flames 
  fanned...
  cathy, resident stirrer of the poo

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