For Honda enthusiasts and those diving into H22 engine modifications, understanding the nuances between different cylinder heads is crucial. Specifically, the PDE (likely referring to a performance-designed or Euro-spec) head, often associated with the Euro-R H22A engine, sparks considerable discussion. Let’s delve into a side-by-side comparison to highlight the key distinctions between this sought-after head and a standard H22A head.
The Standout Feature: Enlarged Intake Runners
The most significant and immediately noticeable difference lies within the intake runners. The Euro-R head boasts enlarged and ported intake runners directly from the factory. This isn’t just a minor tweak; these runners are gasket-matched to accommodate the Euro-R intake manifold, which is designed with correspondingly larger ports.
This factory porting is a key advantage of the Euro-R head. It’s designed to optimize airflow right out of the box. This leads to a crucial point: installing a Euro-R intake manifold on a standard, unported P13 head might not yield the intended performance gains. The bottleneck at the cylinder head’s intake ports could negate some of the benefits of the larger manifold runners.
Internal Components: Surprisingly Similar
Despite the external difference in intake runner size, internally, the PDE/Euro-R head and a standard H22A head are remarkably similar. Components such as rocker arms and cam caps appear to be identical between the two. Past debates have suggested variations in valve angles, with claims of changes from 60 to 75 degrees. However, careful examination of valve seat machine marks indicates that the valve angles are, in fact, virtually the same. While precise measurements weren’t taken, the visual similarity is too strong to suggest any significant alteration in valve angle.
External Dimensions and Mounting Points: No Change
Beyond the intake runners, all other external aspects of the heads are consistent. Studs, bolts, and mounting holes are located in the same positions on both the Euro-R/PDE head and the standard H22A head. This ensures compatibility with other engine components and mounting points within the engine bay.
Focus on the Head: A Key Differentiator
While the complete Euro-R engine package includes numerous upgrades compared to a standard H22A, this comparison specifically focuses on the cylinder heads themselves. The debate surrounding the heads has been ongoing, and this closer look clarifies the primary difference: the factory-enlarged intake runners of the Euro-R/PDE head.
Conclusion: Intake Runner Size Matters
In summary, the key distinguishing feature of the H22 Euro-R intake manifold PDE head is its enlarged intake runners, designed for improved airflow and optimized for the Euro-R intake manifold. While internally and externally similar in most other aspects to a standard H22A head, this difference is significant, particularly for those seeking to maximize engine performance through intake modifications. Understanding this distinction is vital for anyone working with Honda H22 engines and aiming for optimal power gains.
