10103AB910 (2004-2006) vs 10103AB940 (2007) vs 10103AC050 (2008+) which one do I want to bolt my 2005 LGT heads to? I have been advised the LGTheads are same as '05-06 STI heads. Are the newer blocks better (i.e. better oil flow)? Surely there must be some significant difference between them.
I haven't been able to find any difference between the blocks yet. They are being shown as EJ257 blocks which would have 8.2:1 compression ratio and is the same for the LGT EJ255 block for 05-06. The EJ255 short block will have 22cc piston dish for the 06 WRX which has the smaller combustion chamber and a 8.5:1 compression ratio. In later model 08-10 STI's the short block has a nitrite coated crank and rods along with a harder bearing material, i.e. less lead content.
10103AC050 is what you want. However that isn't the part number for an 08+ necessary I have them in stock
Sounds like a significant and sensible upgrade Quoted from from FlatIrons tuning in Boulder CO: Nitride treatment hardens the surface of the crank, which prevents scoring caused by a piece metal getting stuck between the bearing and the crank. By increasing the hardness of the crankshaft surface, any material which gets caught between the new surfaces is simply ground down and filtered out through the oil, potentially preventing bearing failure. I am learning so many wonderful things I wish I did not have the urgent need to learn on such short order.