Cylinder Sleeves are sleeved for several reasons. The primary reason is to repair any damage done to the cylinders or prevent any damage from occurring in the first place.
Why Use Cylinder Sleeves?
Damaged and worn-out engine blocks are often repaired by installing dry cylinder sleeves. When a cylinder has excessive damage, taper wear is cracked.
In such cases, installing a cylinder sleeve can salvage its remains and prevent it from facing any further damage. If all cylinders in an engine block are worn out, they can all be re-sleeved to restore them to their original dimensions.
Sleeving a cylinder has an advantage over boring and installing new pistons and rings due to its cost-efficiency. Most blocks are often too thin to protect against overbearing if wet or dry sleeves are not installed.
For instance, in an aluminum block with vital iron sleeves, the only way to save or modify the league would be to machine out the old sleeves and install new ones, either wet or dry.
Diesel engines are more likely to require sleeving than gasoline engines, even though sometimes gasoline engines also need to be sleeved.
This is because high-performance diesel engines produce high pressure inside the bore, and therefore, damage caused to cylinders are more common in diesel engines than gas engines.
In such cases, sleeves that are intended for high-pressure performance can be installed to protect the engine.
Types of Sleeves
Sleeves installed in cylinders are usually of two types: wet and dry sleeves. Most aluminum automotive engines use dry sleeves in their cylinders cast into it or pressed to fit into the bore.
A dry sleeve does not contact the coolant, whereas a wet sleeve often has a coolant gap between the block and the liner. When compared to wet sleeves, dry sleeves often have thinner walls.
Since wet sleeves are more in direct contact with the coolant, they are best used in high-power engines where high cooling power and temperature regulation are necessary. On the other hand, a wet sleeve makes an engine block much less rigid.
The installation of sleeves has a lot of advantages in performance modification in high-performance engines. However, if you intend to install sleeves to increase the displacement, then there is only so much metal to remove to make space for the oversized cylinder sleeves.
One method that can be employed to overcome this limitation is to install wet sleeves in place of the existing sleeves that are machined away.
While this installation may require extensive modifications to be done to the block and prompt one to add exact CNC machining to accommodate the wet sleeves, it is still worth the results.
Here, since the coolant is in much closer contact with the outside of the sleeve, wet sleeves can withstand much higher horsepower and heat conditions, which in turn increases the strength, reliability, and displacement of the engine.
When installing sleeves, the sleeves are either chilled or frozen while the block is heated up. This makes fitting them together easier as cooling shrinks the sleeves, and heating makes the cylinder expand.
This is a far more effective way of installing sleeves than hammering them in, as was the practice in earlier times, because it prevents any alterations of the original dimensions.
When both the sleeve and cylinder return to room temperature, their dimensions also return to their original state.