FA20 - The future of Subaru performance


Fitted to the WRX first in 2015, the FA platform showcases the latest in Subaru engine Technology. Moving to direct injection offers a number of advantages including improved fuel economy however as always thats not the focus for our development!

When we received our first FA for inspection, the differences in comparison to the EJ platform were vast. The change to direct injection provides greater tuning control and more refined calibration. Distribution of oil has also seen changes and Subaru have moved away from timing belts to a timing chain as seen in some of its 6 cylinder siblings. Our main focus for development with the FA platform centres around identifying factory weaknesses or limitations that would prevent the engine from running reliably at "above standard" power levels with the aim of releasing improved performance packages for customers looking for more than what the OEM configuration can offer.

Connecting rods:

While stripping the engine down, something that became evident early on was limitations of the standard connecting rods Subaru have chosen for the platform. Unlike the rods used in EJ engines, Subaru have opted for an off centre rod. The issue this creates in is relation to load distribution when the cylinder fires and how that load is transferred to the bottom end.

Having seen these rods fail or bend under the load of factory power, we started the process of looking at suitable replacements that would allow us to push the platform well beyond factory form. We are currently in discussions with several aftermarket conrod manufacturers and testing configurations to maximise reliability.


Common with most EJ engines, the decking or cylinder walls offers little in regard to structural integrity. Running standard boost levels this does not pose any real threat to reliability however an increase in power quickly highlights the weakness seen here. Deshele Performance is proud to offer one of the most comprehensive closed decking programs available for the EJ platform, developed over 15 years of testing.

We have now taken that knowledge and applied it to the FA platform, creating a solution that ensures strength, reliability and dramatically reducing the risk of cylinder walls cracking or distorting under the load from increased boost. The DP FA closed decking kit is pressed into each side of the casings while correctly positioned water galleries allow coolant to pass through with ease keeping spikes in water temps to an absolute minimum.

Head studs and Sealing:

Our next focus was removing OEM limitations with the engines sealing system. After testing a variety of configurations, we have been able to successfully adapt our proven sealing system used for EJ engines. This includes of the introduction of our 14mm head stud kit. The kit requires the case halves and cylinder heads to be drilled and retapped to accomodate the thicker studs in conjunction with our tried and tested gasket setup. Similar to the EJ platform, we have developed several options here largely based on the power requirements of the customer.

The options change based on predicted power of the vehicle with solutions to support 200kw running our MLS sealing system through to 400+kw which takes advantage of specially design o-rings used in conjunction with copper head gaskets.

At present the biggest element holding customers back from achieving power levels that are double or even triple that of factory are bolt-on supporting mods without a hefty investment in custom fabrication. We are however very pleased to see a number of aftermarket companies rising to the challenge of supporting this platform. Until recently fuel delivery posed a large challenge to the majority of FA customers as the OEM direct injection setup has proved challenging to work with in regard to increasing maximum flow. Recently we have seen products start to become available for this as well as a range of other factors that previously held the platform back.

As we have spent over 5 years now developing our offering for this platform, we are pleased to be ahead of the curve in what we offer however like the EJ platform, we will continue to improve and develop well into the future and as supporting mods become readily available, Deshele Performance will have an engine package to reliably support them.

For more information about the FA platform and what Deshele Performance can offer FA platform customers, please contact us today!