S55 Stage 3 Cylinder Head

It’s pretty rare that we find an area on a BMW Motorsport engine that we can really improve on, so when we find something that can really benefit from modification we get pretty excited! Our Stage 3 S55 cylinder head is one of those areas.

BMW does a great job on its naturally aspirated cylinder heads. Back to 2000 the M3 came with CNC ported intake ports. This has been true of every M3 until BMW made the switch to turbocharging. With the S55 the bean counters decided to leave the intake and exhaust ports cast, but not only that, they were very restrictive with lots left on the table to be improved upon. BMW also had to design around reversion into the intake port and the carbon deposits that would be left in the intake tract as a result. Anyone familiar with these direct injection engines knows that they require the carbon deposits walnut blasted from the intake tract to maintain the performance of these engines. BMW shrouded the intake valves significantly on this engine to reduce reversion into the intake port. This is great for reducing the frequency we have to clean our intake tracts, but it hurts cylinder head flow and power production.

Stage 3 S55 Cylinder Head Gallery

Looking at this cylinder head with a clean slate we started by manually porting the intake tract and exhaust measuring flow as a result. We went through many iterations of this manual process before we finalized the design we were happy with. We then converted our idealized port designs into a CNC program. We also addressed the inefficiencies in the combustion chamber by unshrouding the valves and maximizing flow on the other side of the valve. There is shrouding behind the valve as well that is addressed in our porting work. The downside to this of course is that walnut blasting will need to be done more frequently, this is the trade off for power.

Besides our porting work to increase flow we know that this cylinder head will be combined with higher flow turbos creating additional boost pressure. We have seen issues with valves sealing incompletely at higher power levels on these engines so we increased the spring rate to 82lbs from 58lbs. We’ve also replaced the standard BMW valves with super alloy Ferrea valves designed to handle extremely high combustion temperatures of 2400° degrees.

With all the improvements we were able to make on the S55 cylinder head we are excited to see the kind of power gains we will achieve on this platform.

Where to Order

Available in the Lang Racing Store
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