Quote:
Originally posted by rbehny
the cams aren't the only difference... remember the sodium filled valves aren't part of the XT package. So the short block is identical and the heads have a few differences. That sums it up.
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According to this
"Forester XT technical description supplement" PDF posted on the Subaru Australia web site, the XT heads do have the sodium exhaust valves:
XT Cylinder Head Features- Four valves per cylinder in cross flow format with straight tumble airflow being achieved by manifold and intake port design.
- Tumble Generator Valves (TGV) for good combustion efficiency and low emissions during cold start. After starting, the TGV immediately opens to maintain good airflow and performance.
- Twin camshaft per cylinder head, with direct valve actuation and Active Valve Control System (AVCS) variable valve timing.
- Camshaft weight has been reduced 1700g by using a hollow shaft and an assembly of sintered cam lobes.
- Sodium filled exhaust valve stems for low inertia and improved heat dissipation.
- Single timing belt with self-adjusting tensioner. (100,000 km replacement interval)
Lots of other interesting XT info in that doc as well.
-tom