Sand Cast Blocks-EJ-22

[Quidam]

Hey.

 

I searched. I remember GD mentioning that block, but it didn't show up. I remember it from elsewhere too.

 

What year do I look for to source one of these? Oh, probably a new one, which reminds me to check with a dealer for price.

 

Doug

[svxpert]

most, if not all subaru blocks are sand cast. thats how most manufactures make aluminum blocks. what are you exactly asking?

[Quidam]

Well, if I remember right, the EA are die cast. They did some EJ-22 in sand, the rest is die cast.

 

Die cast is cheaper to make. I take it as, "inexpensive, and built that way". Or something.

 

If someone knows for sure, I'm all ears one way or the other.

 

Doug

[Quidam]

I did a quick google:

 

 

Subaru introduced the Subaru Legacy Sport Sedan to the US domestic market for the 1991 model year. The Sport Sedan was a 2.2L 4-cylinder, SOHC, turbocharged, non-intercooled variant of the JDM Legacy (which was fitted with a 2.0L 4-cylinder, DOHC, turbocharged and intercooled engine to compete in the World Rally Championship). The USDM engine produced 160hp @ 5600rpm, and 181lb/ft of torque @ 2800rpm. Pretty modest numbers for a turbocharged car. This is due to the lack of an intercooler and factory-limited boost at 8.7psi (http://www.xmission.com/~dac/library/turbo_info.htm).

 

ENGINE BLOCK (information and pictures adapted from: http://www.sdsefi.com/air17.html). The engine has a closed deck providing a much stiffer cylinder assembly and better head gasket sealing. Cast iron liners about .125 thick are cast right into the aluminum. The block is a precision medium-pressure sand-cast unit, which affords the block the necessary rigidity to withstand closed decking (SAE technical document #890471). The majority of Subaru blocks are instead high-pressure, die-cast aluminum, and although stout, do not have the same rigidity to withstand high boost pressure. This is due to high-pressure casting forcing air pockets into the aluminum mass as it cools. The result is a block with more localized stress areas within its structure. Conversely, a medium-pressure cast aluminum crankcase will be denser and more rigid. Subaru spared no expense in the development and manufacture of the block as the medium-pressure casting procedure is quite extensive, and more importantly, expensive, when compared to the typical high-pressure castings (xephyr).

 

It should be noted that the increased density of the M-P aluminum block has the propensity to retain heat to a greater degree than its H-P brethren. Subaru has addressed this issue by incorporating plenty of coolant passages in the head to block area and a wide bore spacing, which allows for higher boost levels to be maintained. The coolant flow path has split passages in the block to force coolant from the lower block, through the head and back into the upper block. This setup uses natural convection to aid direction and efficiency of coolant flow.

Closed Deck Block

 

Oil Jets/Main Center Bearings

 

Engine Block Half

The turbo engine has piston oil jets to cool the piston domes under boost. In order to feed these jets (and the turbo) Subaru utilized a higher pressure, larger flow oil pump (xephyr). Extensive ribbing in the casting on many of the water and oil passages help to dissipate heat from these areas as well. The block halves are attached with ten 10mm bolts and seven 8mm bolts, creating a very rigid design. The 3 center main caps which span the cylinder bores are 2 inches thick and carefully radiused to preclude any chance of cracking.