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Arouse the DAMPFHAMMER!
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6,090 Posts
Discussion Starter #1 (Edited)
Hi K20A enthusiasts,

once I had a very interessting discussion with Joe McCarthy how much power could be generated with a stock K20A:

  • stock K20A2 block
  • stock K20A2 crank assembly incl. pistons
  • stock K20A2 cylinder head
  • stock K20A2 valve train
  • OEM cams (e.g. K20A or K20Z1 ones)
  • stock K20A2 ignition system
  • stock K20A2 fuel injection position
  • up to 93 octane of fuel quality
only by changing intake and header and of course meeting the local emission limitations. Joe once validated this question with his developed intake manifold and header on a K20A engine with a measured 250+ whp and 165+ wftlb (using VS MP109 fuel and a further afar fuel injection position), which was really impressing me.

So enough of introducing. From that time on my goal was to understand physically what is necessary to lift up the volumetric efficiency (VE) of a NA engine generally and particularly of the K20A. To do that I did approaches with simple semi-empirical- and acoustic-methods to dive deeply into the intake development. Now, I want to simulate it on a K20A engine setup, because VE is a result of the complete alternation of load and combustion. Following that, I did a more sophisticated 1D simulation method including wave dynamics for inlet and outlet and combustion analysis.

For the last approach I really need your help to setup the right dimensions for Vibe heat release function-parameters and of course flows of heat and volume. The wanted inputs are:

  • Block/Crank Assembly
  • Piston pin offset
  • squish clearance (piston vs. cylinder head wall)
  • squish area of piston
  • piston dome radius
    Cylinder Head
  • port diameter directly before inner valve seat
  • inner valve seat diameter (inlet and outlet)
  • valve seat angle (inlet and outlet)
  • exhaust port diameter at manifold
  • exhaust port lenght (outer valve seat to manifold)
    Combustion
  • at best some cylinder pressure measurements over crank angle... :D
Already included are:

  • Block/Crank Assembly
  • bore = 86 mm
  • stroke = 86 mm
  • conrod = 139 mm
    Intake
  • specific CAI dimensions of my Lotus Elise: 280/60.5 mm, Reverie Daytona box and filter with a 78 mm sharp edged inlet ID
  • throttle body: ID = 62 mm, spindle diameter at WOT = 6 mm, lenght = 70 mm
  • manifold PRC: inlet ID = 62 mm, mean runner length = 215 mm, effectiv ID of runner 47 mm, 65/47/10 mm radiused bell mouth of runner inlet, effectiv plenum diameter 80-120 mm from #1 to #4.
    Cylinder Head
  • effective ID at manifold inlet = 47 mm
  • inlet port length (manifold to outer seat valve) = 93.5 mm
  • outer valve diameter, inlet = 35 mm
  • outer valve diameter, outlet = 30 mm
  • lift curve of in- and outlet high speed cam (K20Z1): got degreed data of it from a member of here :D
    Outlet
  • specific dimensions of the 4-1 header of my car: 350/48 mm for primaries into 60.5 mm
  • specific CAT is inlet and outlet ID 60.5 mm, length = 300 mm
  • specific CAT back: 700/60.5 mm, damper of 500 mm lenght, two end pipes with 930/48 mm (should be a Larini muffler)
    Combustion
  • updated :D, there are pretty good Vibe parameter models in literature for even 2 liter high speed engines
Note:
  • if not mentioned length/inner diameter and units in mm
  • if something is stated wrong, please let me know, I will correct it if it is validated
  • simulation will be validated with the actual dyno result (torque curve), status quo: beyond 5500 rpm verified with +- 5 Nm of max deviation, below some potential to improve :D
I appreciate any help you can afford, like values of measured dimensions, detailed close up pictures of parts to do assumptions of dimensions, experiences concerning combustion properties, ...

Thanks :)
 

·
Arouse the DAMPFHAMMER!
Joined
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6,090 Posts
Discussion Starter #2
To summarize the wanted inputs:

  • Block/Crank Assembly
  • Piston pin offset
  • squish clearance (piston vs. cylinder head wall)
  • squish area of piston
  • piston dome radius
    Cylinder Head
  • port diameter directly before inner valve seat
  • inner valve seat diameter (inlet and outlet)
  • valve seat angle (inlet and outlet)
  • exhaust port diameter at manifold
  • exhaust port lenght (outer valve seat to manifold)
    Combustion
  • at best some cylinder pressure measurements over crank angle... :D
Thanks in advance for your help!
 

·
Arouse the DAMPFHAMMER!
Joined
·
6,090 Posts
Discussion Starter #3
Question (s. above) reduced to:

  • Block/Crank Assembly
  • Piston pin offset in mm?
  • squish clearance (piston vs. cylinder head wall)?
  • squish area of piston?
  • piston dome radius?
    Cylinder Head
  • port diameter directly before inner valve seat?
  • inner valve seat diameter (inlet and outlet)?
  • valve seat angle (inlet and outlet)?
  • exhaust port diameter at manifold?
  • exhaust port lenght (outer valve seat to manifold)?
Thanks in advance for your help!
 

·
Arouse the DAMPFHAMMER!
Joined
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6,090 Posts
Discussion Starter #5

  • Block/Crank Assembly
  • Piston pin offset in mm = 0.834, according to K24A2 pistons measurement
  • squish clearance (piston vs. cylinder head wall) about 2.5 mm
  • squish area of piston, depends on the choosen piston design, but up to 0.4
  • piston dome radius, including valve angle is according Joe McCarthy 51°, the first assumption of the radius could be done with the mentioned and the bore diameter :D
    Cylinder Head
  • port diameter directly before inner valve seat, I choose the inner seat diameter
  • inner valve seat diameter (inlet and outlet), calculated with valve face width and valve angle :D
  • valve seat angle (inlet and outlet), intake 45°, outlet 45°
  • exhaust port diameter at manifold, converted into an circle it's 39.9 mm
  • exhaust port lenght (outer valve seat to manifold) = 89.5 mm at centerline
 
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