Swapping an Evo 9 Cylinder Head onto an Evo 8 Block

Compatibility of the Evo 8 and Evo 9

The Mitsubishi Lancer Evolution VIII (Evo 8) and Evolution IX (Evo 9) models both utilized the potent 4G63 engine. This 2.0L turbocharged power plant is beloved by enthusiasts and tuners alike for its immense modification potential. However, there are some key differences between the Evo 8 and Evo 9 engines that need to be examined when performing an engine swap.

Cylinder Head Design

The Evo 8 uses a more basic 7-bolt cylinder head design without Mitsubishi's MIVEC adjustable cam timing technology. On the other hand, the Evo 9 implemented an upgraded cylinder head with MIVEC and flowing ports. This gives the Evo 9 better top end power production. Fortunately, the Evo 8 block can accept the Evo 9 cylinder head with some additional upgrades.

MIVEC Compatibility

To properly utilize the Evo 9 head on an Evo 8, the MIVEC variable valve timing system must also be installed. This includes swapping over the timing belt tensioner, cam gears, camshaft position sensor, and crankshaft position sensor from the Evo 9. Upgrading to a manual timing belt tensioner is also highly recommended for reliability.

Benefits of the Swap

Putting an Evo 9 head onto an Evo 8 motor provides some great benefits. The MIVEC-equipped Evo 9 head offers superior airflow resulting in more top end horsepower compared to the Evo 8 head. This flexible design also allows for more aggressive cam upgrades down the road.

Higher Rev Capability

The valve train and components in the Evo 9 head are built to handle more rpm better as well. This raises the rev ceiling from 8000 rpm on the Evo 8 to a 9000 rpm limit with the Evo 9 head installed. Chasing big horsepower figures will necessitate high rev capability.

Still uses 7-Bolt Gasket

Luckily, the Evo 8 block utilizes the same 7-bolt head gasket design as the Evo 9 head. So no block modification is necessary and the swap is simplified by using the existing Evo 8 head gasket. Customers have reported excellent sealing and longevity with this setup.

Considerations for the Swap

While conceptually simple, there are still some important considerations when adapting an Evo 9 head to an Evo 8 short block. Proper planning of the build process can ensure everything mates together correctly.

ECU Tuning Required

The increased airflow and advanced MIVEC components will need to be properly controlled by the ECU. This means getting a reputable tuner to optimize ignition timing and fuel maps after the build. Standalone ECUs like AEM's Infinity unit unlock maximum performance.

Aftermarket Engine Management Recommended

Speaking of which, upgrading to an aftermarket ECU standalone unit provides much more tuning flexibility for the swapped combination. The factory Evo ECUs were not designed to control the Evo 9 head and modern standalone units improve drivability.

Allow Clearance for MIVEC Parts

Carefully check for adequate spacing around the variable cam gear housing and drives. Some minor clearance adjustments to the valve or timing cover may be required with surging big boost levels.

Conclusion

Mating an Evo 9 cylinder head to an Evo 8 short block unlocks exciting performance potential. With proper planning and ECU calibration, 400+ horsepower is achievable. The Evo 9 head swap process has been performed countless times by the Evo community over the years to great success.

So for those looking to build a monster Evo VIII, utilizing the Evo IX cylinder head is a popular and robust way to efficiently generate big power numbers reliably. This potent combination retains the tunable 4G63 MIVEC turbo engine character that enthusiasts expect while providing room to grow.