Connecting Rod Ratio

Rod Stroke Ratio is the ratio of length Handlebars Piston (B) and stroke length (A).
By way of B divided by A.

According to many articles, usually the manufacturer ratios between 1.4 to 2.0 in the smallest number in the largest ratio. Indeed there are some more than 2.0 but very rarely encountered. The ratio of long and short each has advantages and disadvantages. Just how goals will be achieved. , That compromise is common in the design or build the engine. Still according to the article that a lot of it, Rod Stroke Ratio or what they call the "n" values​​, have the ideal number in the middle between the short and the long is 1.75 to 1.80.
Stroker further in the article, the purpose of replacing the piston they take longer to shift along with their step (replacing the crankshaft) longer stroke, is that maintaining Rod Stroke Ratio as before. One reason is wear and tear in the wall of the liner. Then there is the term angle piston or Rod Angularity.

Rod Angularity or on the picture above is the corner of P.
The greater the angle (the smaller the rod stroke ratio), then the received pressure cylinder liner walls would be even greater ..
Here's a more detailed picture, if the same stroke, but with a different length piston then P is also different angle.

 

The greater the angle P .. (eg in the figure below) then the sideways pressure / friction / friction / power loss who received the cylinder wall when the crankshaft rotates even bigger..

So still according to the article, the greater the angle other than the wear problem, also believed that the existence of greater power loss due to friction with the walls of the cylinder are also getting bigger. Still according to another article, purpose built race engines generally apply a large ratio even up to 2.2 or more. However, it is difficult for the mass production of engines for large machinery and the total length will be too large in terms of cost and space in the engine bay.
The perpetrators riser stroke in the article it does not need to move or block the cylinder block that is longer (out) as is commonly done in the scooter in Indonesia .. Or the clever language, its offset .. so its fitting TMA and TMB in connection with short block length cylinder ..
Because according to them (stroker) .. piston design also influenced Rod Stroke Ratio, especially the long wall of the piston and piston pin position .. (so no meaning piston design)
So that the piston rod is not stuck like this ...

Then they use a different piston design especially in the laying of the piston pin (small end)..

The greater the ratio of the piston stroke Rod could become shorter its total length and pin positions can be approached third ring or oil ring, or getting up.
So far it seems it is more prefer to Rod Stroke Ratio is greater, but everything is very relative.
Rod Stroke Ratio also affect the ability of the suction machine other than bore and stroke of course .. Rod Stroke Ratio is very influential on the piston position are relatively from and to the TDC. The piston position not only TMA and TMB.
Suppose a machine has a 50mm stroke ..
One stroke crankshaft rotation is equal to a half circle or 180 degrees.
For example when the rotation of the crankshaft 90 degrees, or half stroke (stroke full 180 degrees), it is less likely to be right in the middle position of the piston stroke or 50mm / 2 = 25mm from TDC or BDC.
Rod stroke ratio will determine the position of the piston is different .. ratio, will make the piston position differently to TMA and TMB, respectively ..
For example, the ratio of 1.7, while a 90-degree crankshaft, piston position 23mm from TDC.
While the ratio of 1.4, when the crankshaft 90 degrees the same, the position of the piston at 26mm from TDC.
With the example above, the ability of the suction machine was different .. because it is believed the design more quickly move from and to TMA than other designs. And it is believed Rod Stroke Ratio is crucial.
based on the position of the piston and the piston speed when approaching TDC or BDC, can be determined the magnitude of the umbrella valve, port design, short length ports, large and small ports, and importantly the optimal duration camshafts especially when the benchmark should be placed .. lobe peak early, or slower .. Peak lobe called the lobe Centerline, which is the maximum time the valve will open its lifts.
It is said also of Rod Stroke Ratio can predict which one takes precedence over port design, valve and cam, which prefer the velocity or cfm.
Of course based on the speed of the piston down and the piston position ..
If the reading of the article, eg maximum lift occurs too early in the engine air-rod stroke ratio is large, when the piston moves away from TDC slower, but given the maximum lift, and big port design .. then everything is so wasteful and should not lift maximal optimal .. given when the piston begins to rapidly move towards TMB .. as piston speed and not the same from TDC to BDC as well. While Rod Stroke Ratio Small, piston movement away TMA is currently believed LBH suction step quickly .. and will slow down as it approached and TMB, TMB away. Certainly when compared to Rod Stroke Ratio disproportionately.
I think this theory is very interesting and make sense to me, and not merely wants to shift the stroke but also so that we can better understand our own standard engine .. Rod stroke ratio, how the angle of our machines? Then klo this theory combined with the theory of machine angle, eg V 90 degrees .. it will be more interesting again .. maybe just the angle of the slope of the tilted engine is not original? or for reasons of oil circulation or the force of gravity that helps also imposes on the engine work .. but it might just be the angle of friction cylinder also to outsmart the rod stroke ratio ..