Author Topic: intake/crankcase stuff  (Read 2012 times)

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Offline 1manband

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Re: intake/crankcase stuff
« Reply #20 on: March 27, 2016, 10:50:02 am »
looked into the looming question of intake port cross sectional area as it relates to both porting and crankcase volume.

did this by using both the time*area program and the crankcase res program.

went like this:
in the t*a program, wrote down the intake port t*a value and port area for the stock example saw.  0.00013539 sec cm2/cm3 and 0.428 in2

then, raised the stock 5500rpm (@peak tq) value by 2000 rpm.   (as rpm goes up, t*a values get smaller).  0.00009928 sec cm2/cm3

so, to raise the peak torque rpm, by 2000 rpm to 7500 rpm...... you would need: 

0.00013539 (-) 0.00009928 = 0.00003611  <that much more t*a

then adding that result back into the stock number:

0.00013539 + 0.00003611 = 0.00017150 <this becomes the time*area goal, to get the 2000 more rpm.

keeping the t*a rpm, at 7500, i changed durations until the t*a for the inlet port was close to 0.00017150 sec cm2/cm3.

the area of the intake port needed to get this goal t*a was 0.496 in2.

finally, (all this took all of 5 minutes), plugged the 0.496 in2 inlet port area value into the crankcase res program.....to see just how close, the rpms would be by changing areas........

<edit> added screen shot of error or difference.





hiatus

 

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