Differences

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--- camshaftsbp [2022/01/02 22:27] – [Camshaft Theory BP] imakeyoufast
+++ camshaftsbp [2022/01/03 09:41] (current) – [Quotes] imakeyoufast
@@ Line 5: / Line 5: @@
 **IVC, IC intake valve closes (at)**
-- The significant value to estimate the target power rpm of the camshaft
+  * The significant value to estimate the target power rpm of the camshaft
+  * Later IVC -> More time to overcome the pressure differential, usage of the high velocity gas, favors HIGH RPM
+  * Too late IVC -> Cylinder pressure > Manifold pressure, loss of power (but efficiency gain through better expansion (reverse Flow Atkinson Cycle [[https://en.wikipedia.org/wiki/Atkinson_cycle]])
+**OL, O/L overlap (OL duration = IVO + EVC)**
+  * Overlap can be used to evacuate the remaining intert gas out of the cylinder
+  * Free Flow Exaust -> Inertia of the exhaust gas helps via scavenging effect
+  * Positive Pressure Intake -> Inertia of the intake charge pushes the remaining inert gas out
+If air or intake charge is pushed into the exhaust, NOx / HC emission increase. Also precious charge is wasted, resulting in higher BSFC.
+**EVO exhaust valve opens (at)**
+  * Too early -> Gas goes through the exhaust valve and doesn't participate in piston downforce -> power loss
 ===== Rotrex Specific =====
@@ Line 128: / Line 143: @@
 - k24madness
+----
+The BP powerband shape is very sensitive to duration @.003. The few degree increase from a 4W to a 5A shifts peak torque a few hundred rpm. We found that an Integral stage 1 NB2 cam with a bit more lift but 10° more duration at .003 was no faster on track than the stock cams even though it made a bit more peak. If it is a 5 speed or driven on street with a stock longblock, we prefer stock cams for best driveability. Breathe on the longblock or do a full I/H/E +ECU and you can afford a little more duration as the low end improvements from the other stuff over up the losses from cams. For instance, the Tomei's we offer on a stock engine with just an ECU, are awful.
+Add I/H/E + ECU with the Tomei's, particularly with a 6 speed and you have a great balance between powerband and peak power.
+- emilio700
+----