Building the FR-S FA20 engine with Stay Crushing!


For our racing efforts, we have been having incredible luck with King XP bearings and have been using them a lot in our latest builds. We have been pulling down some of our race engines to find that the bearings look nearly brand new with XP bearings after a season of use. So in this case, we decided to use XP bearings again.
The XP thrust bearings are swedged to the main bearing shells.  The XP bearing's P-Max material is a tri-metal bearing with a steel base, a softer intermediate layer, and a soft top layer. Tri-metal bearings usually have a higher load-bearing capacity and have some degree of embeddability to trap debris without damage to the crank. 
Good head gaskets are important for forced induction with its higher cylinder pressure. Cosworth gaskets are made from multiple layers die cut stainless steel stock with a tolerance of plus or minus 0.001″.

The stainless layers are coated with a 0.25-micron thick layer of nitrile synthetic rubber to ensure a good seal between mating surfaces and within the gasket itself. For the FA20 application. the gasket is 0.78mm thick which is great for maintaining proper function of the squish pads in the combustion chamber.

Finally and perhaps the most important feature of the Cosworth head gasket is that it has a folded stopper layer. This is an additional ring around the cylinder bore which provides a much-improved combustion seal and greatly increases blowout resistance due to an increase of clamp load around the cylinder.


Since we were going to forced induction, we upgraded out valves.  The intake valves are made by Supertech and are made out of a hard nitrided stainless steel.  The nitriding provides a very hard skin on the valves and reduces friction at the stem.

The intake valves have a flat profile which helps flow.  A cut-down part of the valve stem near the valve head also improves flow.


Forced induction engines produce a lot more heat, heat that the exhaust valves have to deal with. Supertech exhaust valves were selected.  We chose Inconel for the valve material as it is a very hard and heat resistant material.  Inconel is a super alloy made of chromium and nickel developed for the aerospace industry.

The Supertech valves have a tulip shape which improves flow exiting the combustion chamber which is the opposite to the flat shape of the intake valve. The valve does not have a reduced stem near the valve head as it doesn't help that much on the exhaust valve.  The valve head is swirl polished which also helps flow.


Supertech also supplied us with some of their valve guides.  The intake guides are made of manganese bronze alloy.  This alloy has a super low coefficient of friction when used with Supertech nitrided valves. 

The exhaust valve guides are made of a copper-based alloy which conducts heat out of the valve stem better. This helps keep the exhaust valve cooler under hard track type use. 


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