Originally Posted by
Roelof
It gas several functions but with all of them they are maybe slight noticeable. I have a N21-5T and it has that hole in the crankschaft without the putty and that engine is running awesome.
The main reason is weight and the ease of production. They drill out the crankshaft and drill it a bit deeper to the front bearing. It saves weight and for adding the flow they put in the putty. There is a topic on ths forum of what people are using. Most of them are using Permatex high-temp RTV silicone or ThreeBond 1211 silicone liquid gasket.
But be aware the visable tuning like flowing, teardrops etc does not add much more power to an engine, it can make the engine run more smoother. Changing timings will make the huge improvements.
Roelof:
I have always simply trimmed (knife-edged) the opening and closing sides of the crankshaft. Very little on the open and quite a bit on the closing. Is that the wrong way to increase duration, or is it better to cut the recommended 2mm from the closing side only? Also, if you don't mind, what else can I do to these engines for maximum horsepower for drag racing?