camshaftsbp
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camshaftsbp [2022/01/02 16:22] – imakeyoufast | camshaftsbp [2022/01/03 09:41] (current) – [Quotes] imakeyoufast | ||
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====== Camshaft Theory BP ====== | ====== Camshaft Theory BP ====== | ||
+ | We had never too much lift ([[https:// | ||
+ | - DBilas | ||
+ | |||
+ | **IVC, IC intake valve closes (at)** | ||
+ | |||
+ | * The significant value to estimate the target power rpm of the camshaft | ||
+ | * Later IVC -> More time to overcome the pressure differential, | ||
+ | * Too late IVC -> Cylinder pressure > Manifold pressure, loss of power (but efficiency gain through better expansion (reverse Flow Atkinson Cycle [[https:// | ||
+ | |||
+ | **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' | ||
===== Rotrex Specific ===== | ===== Rotrex Specific ===== | ||
==== Consultation with Jeff David, who developed a Rotrex specific Camshaft for Honda K22 ==== | ==== Consultation with Jeff David, who developed a Rotrex specific Camshaft for Honda K22 ==== | ||
+ | |||
+ | **Preparation** | ||
In my experience it's a combination package. For the bolt on's like inlet manifold, TB, exhaust headers and exhaust system use what a good/ | In my experience it's a combination package. For the bolt on's like inlet manifold, TB, exhaust headers and exhaust system use what a good/ | ||
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* Free Flow Catless: 4 PSI Backpressure ([[https:// | * Free Flow Catless: 4 PSI Backpressure ([[https:// | ||
* Metal Cat, 2,5" Exhaust, Resonator and Magnaflow Muffler: 5-5.5 PSI @ 10 PSI MAP @ Redline, | * Metal Cat, 2,5" Exhaust, Resonator and Magnaflow Muffler: 5-5.5 PSI @ 10 PSI MAP @ Redline, | ||
+ | |||
+ | **Blow Through / High Overlap** | ||
As it's important to trap the fuel/air on the valve overlap, higher lift and longer duration NA cams tend to loose power due to blow through. | As it's important to trap the fuel/air on the valve overlap, higher lift and longer duration NA cams tend to loose power due to blow through. | ||
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So I would try the mildest inlet cam you can find, hopefully with more lift than stock. And a stage 2 exhaust cam as a starting point. Fit a venier exhaust cam gear to advance it's centre line. Position based on dyno tuning but 6 degs advanced is a starting point depending on the duration. | So I would try the mildest inlet cam you can find, hopefully with more lift than stock. And a stage 2 exhaust cam as a starting point. Fit a venier exhaust cam gear to advance it's centre line. Position based on dyno tuning but 6 degs advanced is a starting point depending on the duration. | ||
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+ | |||
---- | ---- | ||
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---- | ---- | ||
+ | k24madness Rotrex Setup ([[https:// | ||
+ | I asked for grinds with around .400 lift and duration between 210-230 @.050 | ||
+ | WebCam grind #264 intake and exhaust, 110LSA, 108in, 112ex. | ||
+ | .264in............Stock in | ||
+ | 243@.010.....248@.010 | ||
+ | |||
+ | 216@.050.....204@.050 | ||
+ | |||
+ | 108@.300.....062@.300 | ||
+ | |||
+ | ..264ex............Stock ex | ||
+ | |||
+ | 243@.010.....250@.010 | ||
+ | |||
+ | 216@.050.....210@.050 | ||
+ | |||
+ | 108@.300.....080@.300 | ||
+ | |||
+ | |||
+ | Forget advertized when looking at cams, .080-.010 is lash spec so .010 is essentially seat time. | ||
+ | |||
+ | Less duration at .010 means more dynamic compression, | ||
+ | More duration at .050 means more flow. | ||
+ | More duration at .300 means the valves are fully open when the piston is at maximum acceleration through the 90 degree sweep. This is a critical part of head flow. | ||
+ | |||
+ | - 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' | ||
+ | Add I/H/E + ECU with the Tomei' | ||
+ | |||
+ | - emilio700 | ||
+ | |||
+ | ---- |
camshaftsbp.1641136951.txt.gz · Last modified: 2022/01/02 16:22 by imakeyoufast