The Volvo 5 cylinder whiteblock turbo motor came with three types of exhaust manifolds.
The 850/early P80 manifold, #1270242009, was fitted to 1992-2000 engines.
The ‘Japanifold’, part #9207688, was fitted to 2001-2004 engines.
The ‘R’ manifold, part #30637921, was fitted to all engines 2004+, not only the S60R/V70R, as is commonly thought.
Here is a picture of all three manifolds. From top to bottom – ‘R’ manifold, 850/early manifold and Japanifold.
The firing order of the Volvo 5 cylinder engine is 1, 2, 4, 5, 3. This means that with the ‘R’ manifold, exhaust gas pulses from cylinders #1 and #2 collide with each other in transit to the turbo. Unlike the ‘R’ manifold, the Japanifold gives cylinder #1 its own runner, which greatly improves exhaust flow. In addition, the Japanifold’s merge collector outlet is larger and the ports are slightly larger in diameter than that of the ‘R’ manifold. Without even considering the improved runner arrangement, the Japanifold flows more than the ‘R’ manifold and maintains higher air speed. A Swedespeed user tested the manifolds on a flow bench – you can find the results here: https://www.swedespeed.com/threads/japanifold-vs-r-manifold-vs-early-p80-manifold-w-actual-flow-bench-data.678876/
In our experience, simply swapping from the ‘R’ manifold to the Japanifold, without any other changes, nets an 8% increase in power.
While the the 850/early style exhaust manifold has the better runner layout, the runners and merge collector are considerably smaller. In addition the collector has significant restrictions in the form of ridges that continue from the runners into the merge collector. While the Japanifold is the most preferred manifold, swapping the 850/early manifold for an ‘R’ manifold is a considerable upgrade.
When swapping manifolds, make sure to reuse the factory beveled washers. Theses washers are very expensive new and do not wear, so they never need to be replaced. The 5 individual gaskets can be replaced with the single piece gasket used on later RNC motors, only a small section needs to be trimmed to clear the water pipe. The part number for this gasket is 8699467.
For exhaust manifold studs and nuts, we recommend Dorman 03411.
