View source for M20 - e2i Conversion

[[File:M20B27 e2i Swap.jpg|thumb]]
The '''M20 "e2i" conversion''' is a popular modification for BMW enthusiasts seeking to enhance the performance of the M20B27 engine found in "eta" models by integrating components from the higher-revving M20B25 "i" engine. This conversion combines the torque-rich characteristics of the eta engine with the improved airflow and higher RPM capabilities of the "i" engine.

== e2i Forum Threads ==

* [https://www.mye28.com/viewtopic.php?t=131610 Maytag's M20B27 'e2i' Engine Build Thread (87 528e)]

== Key Features ==
* '''Increased Displacement''': Retains the 2693cc displacement of the M20B27.
* '''Higher Compression''': The conversion often results in a compression ratio of approximately 9.4:1 when using the stock eta block and pistons with an "i" cylinder head.
* '''Power Output''': Depending on tuning and supporting modifications, the e2i conversion can achieve power outputs of 170–190 hp and similar torque figures.
* '''Notable Identifiers''': Combines the "eta" bottom end (long-stroke crank) with the "i" head, which features larger intake valves and improved flow.

== Required Components ==
# '''M20B25 '885' Cylinder Head''': Includes the camshaft and intake valves from the "i" engine for better high-RPM performance.
# '''"i" Intake Manifold and Throttle Body''': Provides increased airflow compared to the eta components.
# '''"i" ECU (Motronic 1.3)''': Enables proper engine management and fueling for the higher-revving setup.
# '''"i" Wiring Harness''': Simplifies the installation and integration of the "i" electronics.
# '''Additional Items''':
#* New timing belt and water pump.
#* "i" injectors for proper fueling.
#* Appropriate gaskets and seals for assembly.

== Performance Gains ==
* '''Low-End Torque''': Retained from the eta engine's long-stroke design.
* '''Improved Top-End Power''': Provided by the "i" cylinder head and intake system, allowing the engine to rev freely to higher RPMs.
* '''Versatility''': The e2i conversion offers a balance of low-end drivability and higher-end performance, making it suitable for street and light track use.

== Considerations ==
* '''Tuning''': Optimizing the ECU and ignition timing is essential to fully realize the performance gains.
* '''Compatibility''': Ensure the "i" head is compatible with the eta block, especially in terms of cooling channels.
* '''Additional Mods''': Complementary upgrades such as a freer-flowing exhaust, a lightweight flywheel, or a performance camshaft can further enhance results.
[[Category:Tech FAQ]]