View Single Post
      01-06-2013, 10:24 PM   #136
Skunk
New Member
 
Skunk's Avatar
 
Drives: E93 M3
Join Date: Jan 2013
Location: United States

Posts: 28
iTrader: (1)

Quote:
Originally Posted by BMRLVR View Post
One major drawback I see with sleeves in the S65 is heat transfer is greatly reduced when going from an aluminium bore to a cast iron liner (Alusil conducts heat at a rate 400% higher than that of cast iron). Since the S65 is very sensitive to knock, and knock is usually a result of higher cylinder temperatures, any means a person can take to get rid of heat will benefit the engine by means of additional timing and reduced detonation risk. Sleeves may be good, but I have yet to see the S65 block itself fail without a rod first failing and going through the side of it. Personally I don't think anyone has gotten to the HP celling of the block casting yet and I would like to see it pushed harder before people just start doing sleeves out of fear.
FYI, not all cylinder liners are iron. There are some Aluminum Metal Matrix Composite liners, but the do cost more (more expensive materials and manufacturing processes). The MMC liners do have a thermal conductivity near that of aluminum, but depends on the volume fraction of ceramic particulate, which usually ranges between 20-60%.

Cylinder liners will also be used on blocks when the increase of the bore diameter leads to rather thin cylinder walls that can no longer handle the stresses of the combustion. Some engine designers utilize sleeves to their advantage to try to get the smallest and lightest block possible and work in into the design from the beginning.

Good job describing the oleophilic nature of Alusil

Quote:
Originally Posted by dvpouldar26 View Post
A dry sump setup allows for a much shallower pan. With a shallower pan, you have much more clearance to lower the motor down (Yes, that means new motor mounts if you do want to lower the motor down). The dry sump system itself would not lower the center of mass, but because of the shallower pan, it gives you more room and allows you to run the motor lower in the car, which in turn lowers your center of mass. A dry sump setup does not cause a lower in CG. The ability to lower your motor because of a shallower pan however does.
I think he was getting at why the dry sump would lower the CG if the engine was not lowering. There is still the transmission, which isn't changing unless you want to fork over some $$$ for an Xtrac, Ricardo, or Hewland, so the engine would not be moving lower otherwise. In addition to the reduced windage, as mentioned, you could also see a reduction of the amount of oil needed if the system is well designed. This would result from work on reducing aeration of the oil from spinning it in the reservoir tank. The reservoir can be place closer to the CG than where the oil pan is located and less sloshing of the oil can also make the CG slightly more stable as well.

Quote:
Originally Posted by Mike@VAC View Post
How many nikasil/alusil engines have you built/sleeved? How many sleeves have you supplied to people with these engines? We have done a bunch .
Mike, many years ago, I was working on sleeving a motorcycle engine. One of the things that needed to be considered what the deformation of the bore at temperature. When you guys are sleeving the engine, are you mounting a heat exchanger to the top of the block to simulate the operating conditions, thermally?
__________________
Cheers
Skunk is offline  
0
Reply With Quote