Originally Posted by stefan
Hello everyone,
there is a BIG misunderstanding about the silicone insert in crankshafts.
This insert is NOT put there to enhance performance!!!!
When an engine is modified (as in JP, Murnan,etc) the crankshaft is drilled out (towards the clutch) to make it lighter. The whole needs to be closed to keep crankcase volume consitant. Here is where the silicone is used. It does build a ramp that might help with gas flow, but that is NOT the primary reason to put it in.
Smearing silicone into an un-drilled crank is crap and won't do anything!
Well given that the air enters a chamber , that chamber is now shortened. Will allow the air to travel through that chamber or volume quicker. As well its guiding it away from a pocket that was there that was more or less a dead end for air. Keeping air around that area preventing new air to travel in. Now its ushered away more quickly and effectively , allowing more fresh air to come in.
At least thats my theory.