To port or not to port??

SR, here are the inputs for the inlet duration calculation:
Stroke:
Conrod Length:
Piston Crown to Top of Barrel at TDC:
Piston height inlet side:
Inlet Floor Depth, Top Barrel to Bottom Port:

I think you confused "piston height inlet side" with top of port height. Don't confuse piston with port.
Notice that the last input is for the distance from top of barrel (cylinder) to the bottom of the port, not the top of the port.
 
I'm not confused except by your reply The intake duration is really mesured by how many degrees of crank rotation take place between it's opening as the piston skirt clears the bottom of the port and the window is opening to the top height the skirt travels or the top of the port witch ever it is!In the case of the op and my original point was that the skirt clears the port compared to the generic one's that are blocked and when more rotation is required to get to the top of the port the duration is also raised!
This stuff throws me off because 180 deg. taken up in a 40mm stroke is 4.5 deg. per mm. In a 38mm stroke it's 4.73. I'm guessing there is something lost in the change of movement from linear and circular at TDC and BDC, but I don't know how as each mechanical movement should have the same effect on the other.
Your right there is 4.5 degrees per mm on the 40mm stroke so if the window messures 14mm in height then x 4.5 is 63 degrees and that gets doubled for the total open duration of 126 degrees.
 
NO NO NO!!!
there is not any set degrees per mm because of the circular action of the crankshaft.
it is a trigonometric calculation which is why you always use a special calculator to figure out the port durations
 
SR you can block the top half of the intake port and the intake duration remains the same. you have no argument. please stop wasting our time and valuable forum space with your inability to perceive the truth.
 
I'm not confused except by your reply The intake duration is really mesured by how many degrees of crank rotation take place between it's opening as the piston skirt clears the bottom of the port and the window is opening to the top height the skirt travels or the top of the port witch ever it is!In the case of the op and my original point was that the skirt clears the port compared to the generic one's that are blocked and when more rotation is required to get to the top of the port the duration is also raised!

Your right there is 4.5 degrees per mm on the 40mm stroke so if the window messures 14mm in height then x 4.5 is 63 degrees and that gets doubled for the total open duration of 126 degrees.
That is what I was thinking. The same as how ever many mm's of exhst. and tran. are opened x4.5x2 gives their duration. Then 5mm top of exhst. to top of trans. is 22.5 deg. of blowdown.
 
SR you can block the top half of the intake port and the intake duration remains the same. you have no argument. please stop wasting our time and valuable forum space with your inability to perceive the truth.
How can you take something that is regulated mechanically to open and close fully in 1 stroke created by 1 revolution, remove half of it's height and tell me the duration of it's opening is the same. Do you hear what you are saying. That to me makes no sense at all.
 
it is still open no matter how "open" you allow it to be.
restrict its normal openness to a height of only 1mm and the duration stays the same. Only its ability to have maximum flow will be limited.

I think you are throwing all the parameters into one basket and mixing them up.
Both duration and "average" port area affect how much intake charge can be brought into the crankcase.
You can change the port height minimally or maximally without affecting its duration. That only holds true for the intake port though.
 
NO NO NO!!!
there is not any set degrees per mm because of the circular action of the crankshaft.
it is a trigonometric calculation which is why you always use a special calculator to figure out the port durations
Exhaust Duration Calculator
Stroke: 40 mm
Conod Length: 90 mm
Piston Crown to Top of Barrel at TDC: .7 mm
Height over Port, Top of port to top of barrel: 26 mm

Exhause Duration (degrees): 162.14
Auto Fill Other Fields
Once you have filled in your Stroke, rod length and Crown to top of barrel above. Click Auto Fill Button.
Auto Fill to clear the fields press Clear
Transfer Duration Calculator
Stroke: 40 mm
Conod Length: 90 mm
Piston Crown to Top of Barrel at TDC: .7 mm
Height over Port:, Top of port to top of barrel 32 mm

Transfer Duration (degrees):122.83
Once you have calculated your exhaust and transfer timing click this to give;
Blowdown


Blowdown degrees:19.65
Inlet Duration Calculator for piston port motors
Stroke: 40 mm
Conrod Length: 90 mm
Piston Crown to Top of Barrel at TDC: mm .7
Piston height inlet side: 44 mm
Inlet Floor Depth, Top Barrel to Bottom Port: 56 mm

Inlet Duration (degrees):117.72
Ignition Timing in mm Before TDC Calculator
Timing Degress A:
Conrod Length: mm
Stroke: mm

mm before TDC: mm
CC Calculator
Bore: 47 mm
Stroke: 40 mm

CC = 69.4
Corrected and uncorrected compression ratios calculator
Bore: 40 mm
Stroke: 90 mm
Height over exhaust port, top of port to top of barrel 26 mm
head volume (head cc) cc 6

uncorrected 12.57 :1
corrected 8.52 :1
Two stoke oil mix calculator for %
oil %, enter your chosen oil %: %
litres of fuel: Litres

ml of oil required ml
Two stoke oil mix calculator for ratio
oil ratio , enter your chosen oil ratio (eg. for 25:1 enter 25): :1
litres of fuel: Litres

ml of oil required


This is the lambretta port calc's results now if you raise the height by one mm in the piston height inlet side feild the duration changes to 123.65 so what now your telling me that they are wrong!And this is the calc you refer to!
Exhaust Duration Calculator
Stroke: 40 mm
Conod Length: 90 mm
Piston Crown to Top of Barrel at TDC: .7 mm
Height over Port, Top of port to top of barrel: 26 mm

Exhause Duration (degrees): 162.14
Auto Fill Other Fields
Once you have filled in your Stroke, rod length and Crown to top of barrel above. Click Auto Fill Button.
Auto Fill to clear the fields press Clear
Transfer Duration Calculator
Stroke: 40 mm
Conod Length: 90 mm
Piston Crown to Top of Barrel at TDC: .7 mm
Height over Port:, Top of port to top of barrel 32 mm

Transfer Duration (degrees): 122.83
Once you have calculated your exhaust and transfer timing click this to give;
Blowdown


Blowdown degrees: 19.65
Inlet Duration Calculator for piston port motors
Stroke: 40 mm
Conrod Length: 90 mm
Piston Crown to Top of Barrel at TDC: .7 mm
Piston height inlet side: 43 mm
Inlet Floor Depth, Top Barrel to Bottom Port: 56 mm

Inlet Duration (degrees): 123.65
Ignition Timing in mm Before TDC Calculator
Timing Degress A:
Conrod Length: mm
Stroke: mm

mm before TDC: mm
CC Calculator
Bore: 47 mm
Stroke: 40 mm

CC = 69.4
Corrected and uncorrected compression ratios calculator
Bore: 47 mm
Stroke: 40 mm
Height over exhaust port, top of port to top of barrel 26 mm
head volume (head cc) 6 cc

uncorrected 12.52 :1
corrected 8.57 :1
 
AHHHH!!!!!!
f***
PISTON HEGHT (from top edge to bottom of skirt) HAS NOTHING TO DO WITH THE TOP OF THE PORT (which is what you are claiming affects the duration).

Please turn off your computer, get some sleep, let the halucinogenic drugs filter out of your system, and then come back when you are "normal"
 
AHHHH!!!!!!
f**k
PISTON HEGHT (from top edge to bottom of skirt) HAS NOTHING TO DO WITH THE TOP OF THE PORT (which is what you are claiming affects the duration).

Please turn off your computer, get some sleep, let the halucinogenic drugs filter out of your system, and then come back when you are "normal"
Dude chill the f*** out!Did you even look at the two sets of results?How do you explain that?Are you saying they are wrong?If so why do you recomend people to use it?I think you need to start using a degree wheel so you can see for your self what's going on!Here's the one I use try it for your self you should have one anway!
 

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