Project Racer - Thursday 09.02.2012/XNUMX/XNUMX
The steering angles are on the agenda for today.
Different exhaust systems and different engine concepts “like” different timing angles.
There should be one on our floor Big Bertha from Ludwig & Scherer them Polini Evo Whisper performance.
For our concept we choose a control angle of 130 ° overcurrent and 195 ° exhaust.
So that we know in which direction we have to work in order to achieve the desired control angle, we first have to record the “current state”.
To do this, we use the crankshaft with so-called bearing dummies so that we can quickly and easily open the engine housing again if necessary.
The crankshaft, piston (without ring), engine housing and cylinder are simply put together dry.
We mount one on the crankshaft Degree discso that we can measure the rudder angles.
There are various methods of determining the exact height of the duct.
Often the light gap is measured, i.e. as soon as a light gap can be seen between the piston and the upper edge of the channel, the ° CA (degrees / crankshaft) begins to be counted / measured until the piston has passed BDC (bottom dead center) and closes the channel again.
Another possibility is one Feeler gauge on the piston and in the channel to be measured. As long as you hit the thickness of the feeler gauge twice on the piston path after measuring, this is a very precise measuring method. The light gap method can quickly lead to measurement errors, as one often “measures” the radius at the canal edge, whereas with the feeler gauge method only the effective canal height is measured.
Amazingly, our measurement resulted in an overcurrent angle of 129 °.
Measured without cylinder base gaskets, this is so close to our desired values that we simply have to put a suitable cylinder base gasket underneath in order to achieve an overflow angle of 130 °.
The outlet angle is still a bit small at 188 °. Milling has to be done here again so that the desired value is achieved. The upper edge of the duct at the outlet must be raised by 1,6mm in order to achieve an angle of 195 °.
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