Can someone clarify the principals of both designs. I heard that closed-deck designs are beter at withstanding higher RPMs.
How do u conver a open-deck to a closed deck?
Are ours (CLS) closed-deck by any chance?

TRELOS

 

Closed deck motors have aluminum "bridges" to secure the top of the cylinder to the deck where the head mounts. In this way the bottom and the top of the cylinder are secured to the outside of the water jacket. In the open deck design, only the bottom of the cylinder is secured to the block, the top near the head is completely free from the outside of the block or waterjacket.

The open deck design, from the top of the cylinder, looks like the cylinder is a coffee can size aluminum tube, 3/8" wall, placed in a cavity in the block surrounded by coolant.

The advantage of a closed deck design is that under severe conditions, high turbo boost or extreme combustion pressures, it is more stable and less prone to breaking a head gasket and other important parts by moving around. However, the cost of sand casting thousands of closed deck blocks is much more than their die cast open deck cousins.

That being said, I don't know if the CL motors are open or closed. And while it's theoretically possible to convert an open deck motor to a closed deck one, I wouldn't trust anybody to weld bridges in my motor after it's already been cast in a certain manner. Who knows that the bridges will all be providing support in the right places as the motor warms up.