Open And Closed Blocks?

[TUF250]

Just out of my own interest can someone explain what it means when someone says its an 'open' 'closed' or 'semi closed' block? very curious thats all

[handbrake]

the internet is your friend! google it

from my discussions with Trent at mercury it is for aluminium blocks where an iron sleeve is used. in production cars that utilise an aluminium block there is normally a gap between the iron sleeve and aluminium block that can be filled or 'closed' to varying degrees. I think once closed it is sometimes drilled for cooling? see pics below

maybe a pro can answer more specifically as to when you would consider this application.

[handbrake]

cut and paste from elsewhere on the intertubes

open....

closed...

[TUF250]

interesting! thanks for the pics.

so what would semi closed be?

is that gap filled by the water system? or just air?

pros and cons of each?

[scotty nm35]

Sealing the gap by fitting an alloy spacer, drilled for coolant flow. Usually the coolant is wanted near the exhaust valves first.