Montreal Subaru Club

Snake a écrit :de ce que j'ai lu sur le NASIOC, le 2.5 de la WRX serait OPEN deck

Zack a écrit :Arrêtez de voir un block semi ou full closed deck comme du rock solid!!! Le STI V2 que j'avais était open deck et il supportait très bien ses 300HP. L'interne va imploser bien avant le block. Alors à moins de vouloir 400HP, je me concentrerais à parler d'interne fiable plutot que je 'closage' de block!

C du métal... c'est SSSSOLID!

The early turbo motors have a closed deck block. Up to 1995 they were build for the World Rally Champioship and were expected to see 400+hp fro just two liters. Pure racing engines. The open deck N/A motors have open spaces between the cylinders and the edge of the block that comprises the mating surface between the block and the cylinder head. The early turbo motors have a flat-machined mating surface with the cylinders and several water and oil passage holes visible on a deck of solid aluminum. The early turbo block is much stronger and more stable for this reason. It is designed to withstand the thermal stresses of turbocharging and stay together atmuch higher specific outputs than the N/A motors. The coolant circulation in the upper block and head region is particularly improved.

In 1996 the WRX turbo motors were revised to use an open deck configuration. There were two reasons for this change. The rally car rules were changed to restrict the intake to 32mm, limiting horsepower to about 300 at 6000 rpm. Second, there were several advances in coatings and thermak control of the upper cylinder area, giving much better stability of the gasket surface. The cost of sand casting thousands of closed deck blocks is much more than their die cast open deck cousins the change was made.

Aside from lower compression pistons and oil spray piston cooling, the cylinder heads are also of slightly different design. The intake manifold, exhaust manifold, cooling system, and sensor technology are all of different design. Different still from the WRX engine, the WRX-RA engine uses a hardened crankshaft and sand-cast, larger water-jacketed heads. It is interesting to note that the RA motors still share connecting rods with the N/A 1800cc motor. The quality is in the N/A motors, it is just put to different use. The 2.0, closed deck, 1995 WRX-RA short block is still the drug of choice in Japan for the "Big Power" motor.

LoosePiston a écrit :

The early turbo motors have a closed deck block. Up to 1995 they were build for the World Rally Champioship and were expected to see 400+hp fro just two liters. Pure racing engines. The open deck N/A motors have open spaces between the cylinders and the edge of the block that comprises the mating surface between the block and the cylinder head. The early turbo motors have a flat-machined mating surface with the cylinders and several water and oil passage holes visible on a deck of solid aluminum. The early turbo block is much stronger and more stable for this reason. It is designed to withstand the thermal stresses of turbocharging and stay together atmuch higher specific outputs than the N/A motors. The coolant circulation in the upper block and head region is particularly improved.

In 1996 the WRX turbo motors were revised to use an open deck configuration. There were two reasons for this change. The rally car rules were changed to restrict the intake to 32mm, limiting horsepower to about 300 at 6000 rpm. Second, there were several advances in coatings and thermak control of the upper cylinder area, giving much better stability of the gasket surface. The cost of sand casting thousands of closed deck blocks is much more than their die cast open deck cousins the change was made.

Aside from lower compression pistons and oil spray piston cooling, the cylinder heads are also of slightly different design. The intake manifold, exhaust manifold, cooling system, and sensor technology are all of different design. Different still from the WRX engine, the WRX-RA engine uses a hardened crankshaft and sand-cast, larger water-jacketed heads. It is interesting to note that the RA motors still share connecting rods with the N/A 1800cc motor. The quality is in the N/A motors, it is just put to different use. The 2.0, closed deck, 1995 WRX-RA short block is still the drug of choice in Japan for the "Big Power" motor.

steph z-24 a écrit :la seule place ou le semi/ full closed vas faire la diference c'est sur la durabilite a tres long terme a condition que tu eclate pas l'interne avant

si l'interne tient et tu boost tres fort pendent 50kkm les cylindre vont finir pas ovaliser et la ca va peter.

steph z-24 a écrit : et meme si vous avez le bloc du chef avec les internes du chef et bin si ca detonne vous aller passer a travers du piston quand meme!