ask yourself why knife edging is done
then ask yourself why would you create a sharp edge to solve the problem that you are trying to solve with knife edging

 

I thought it was to make cutting through the oil easier... so why wouldnt a knife edge be a logical solution?

I could be absolutly wrong though.

 

Knife edging has several advantages. First and formost, you are lightening the drive train. This promotes less wear (based on the fact you don't go too light), better response, potentially more power. The other upside that knife edging has is that it stops the crank from smacking the oil. It very easily goes through the oil which promotes the life of the oil, as well as lubrication to other parts since much of the oil is not being sprayed around. One last upside is by doing this you are precision balancing the crank (theoretically). This is also done with all the rods and pistons to insure the entire rotating assembly is balanced within itself. Most of the times within less than 1g of each other, where as the factory typically specifics normal a +/- 5g.

There are upsides, its just whether the cost of basic knife edging ($600 or so) and exotic knife edging ($1000+) are worth it. No real downsides if done correctly. The most common missed step though is balancing every single part, so when not done the lighter crank creates more vibrations, similar to a lighter flywheel.

Wes

 

whakiewes,
the crank is never smacking the oil unless you hit a bump and the oil in the sump is brought up. also when the car is running a lot of that 6 quart capacity is circulating through the engine, thus there is less oil in the pan than when it is just sitting not running.
the sharp edge created after knife edging increases the velocity of the air coming off of that edge, which will then hit the crank. think about it this way. if you were trying to walk forward, what would be easier, walking through still air or walking through wind coming right at you?

 

I haven't really seen a 944 engine in depth, so you may or may not be correct, but I will assume you are. So in that case, the rules out the oil theory. I don't understand your air theory though? Could you elaborate? Are you saying a crank produces no drafts, and when its knife edged it does? What I know about knife edging is just what I have been told by various sources and read in books, so there is a lot I probably don't understand.

Wes

 

There is an EVO crank that they round the leading edge and knife the trailing edge so the crank is more like an airfoil.

From what I can see the major reason for knife edging a crank is as part of lightening the reciprocating mass of the engine. It goes with lightweight flywheel, lighter rods, lightened valve train and reduced accessory load.

How about this?

You thermal coat the exhaust headers and crossover to take more heat/power to the turbo.
How about thermal coating the piston, head, and valves.
Wouldn't this blow more heat out the exhaust port to operate the turbo instead of being soaked up by the piston, head, and valves.
My car has thermal coated pistons and I notice a bit higher EGTs. And my mechanic says the cooling system works better than any 944 turbo he's ever tested.

 

https://rennlist.com/forums/showthre...t=knife+edging

Old thread but lots of good info.