For automotive DIY enthusiasts and performance tuners, pushing the limits of engine capabilities is a constant pursuit. When it comes to Honda’s F22 engine, known for its robust nature, many look to forced induction to unlock its true potential. However, building a high-performance, turbocharged F22 on a budget can present unique challenges. The stock F22 configuration, while reliable, isn’t ideally suited for high boost applications without modifications, and aftermarket performance parts can quickly escalate costs. This is where innovative solutions and cross-engine compatibility come into play.
One such ingenious approach involves leveraging components from another engine altogether – the Mitsubishi 4G63. Renowned in the tuner world for its strength and turbocharging prowess, the 4G63 engine shares a surprising compatibility with the F22, particularly in piston dimensions. This article delves into a cost-effective engine build strategy, utilizing 4G63 pistons and H22 rods within an F22 block to create a low-compression, turbo-ready powerhouse.
The F22 Turbo Build Hurdle: Rod Ratio and Cost
The journey to a high-horsepower F22 often begins with the realization that the factory rod-to-stroke ratio isn’t optimal for high-revving, turbocharged applications. Furthermore, sourcing aftermarket pistons and forged rods specifically designed for the F22 can be an expensive endeavor, often deterring budget-conscious builders. Exploring alternative, more economical solutions becomes crucial.
The author of the original build faced this exact predicament. Recognizing the limitations and high costs associated with dedicated F22 performance parts, they embarked on a quest for a more resourceful approach. Inspired by the resourceful tactics employed by D16 engine builders using Vitara pistons, the idea of cross-referencing piston compatibility with other engine families emerged.
Discovering the 4G63 Piston Compatibility
The breakthrough came with the realization that the Mitsubishi 4G63 engine shares the same 85mm bore diameter as the Honda F22. Further investigation revealed that the wrist pin diameter of the 7-bolt 4G63 engine was also a match. This sparked the idea of using 4G63 pistons in the F22 block.
Delving deeper, the builder discovered a 4G63 stroker configuration that utilized a 4G64 crankshaft and 9:1 compression pistons. By meticulously calculating deck heights, compression heights, stroke, and rod lengths of both engines, a promising combination began to materialize: 4G63 stroker pistons paired with longer Honda H22 connecting rods in the F22 block.
The Math Behind the Hybrid Build
Let’s break down the crucial measurements that validated this innovative engine build:
Stock F22 Dimensions:
- Rod Length: 5.572 inches
- Compression Height: 1.203 inches
- Stroke: 3.740 inches / 2 (for radius calculation)
- Block Deck Height: 8.643 inches
Calculations for Stock F22:
Rod Length + Compression Height + (Stroke/2) = 5.572 + 1.203 + (3.740/2) = 8.645 inches
This calculation closely matches the F22 block deck height (8.643 inches), indicating a near-flush piston-to-deck relationship in the stock configuration.
Hybrid F22 with 4G63 Pistons and H22 Rods:
- Rod Length (H22): 5.633 inches (longer than F22)
- Compression Height (Wiseco 4G63 Stroker Pistons, Part # K596M85): 1.130 inches
- Stroke (F22 Crank): 3.740 inches / 2
Calculations for Hybrid F22:
Rod Length + Compression Height + (Stroke/2) = 5.633 + 1.130 + (3.740/2) = 8.633 inches
Comparing this to the F22 block deck height (8.643 inches), the calculation shows that the piston will sit approximately 0.010 inches inside the block deck. This slight piston recession is desirable for a turbocharged application as it contributes to lower compression, ideally below 9:1, which is safer and more forgiving under boost.
Parts Sourcing and Cost-Effectiveness
With the calculations confirming the feasibility of the hybrid build, the next step was parts acquisition. The builder sourced Wiseco 4G63 stroker pistons from extrempsi.com and secured a set of H22 H-beam connecting rods from eBay, significantly reducing costs compared to purchasing dedicated F22 performance parts.
This resourceful parts selection is a cornerstone of budget performance builds. By identifying compatible components from different engine platforms, significant cost savings can be achieved without compromising on strength or performance potential.
Engine Assembly and Key Modifications
The engine assembly process involved meticulous attention to detail and several key modifications to ensure the hybrid setup’s success and longevity under boost.
Block Preparation and Sleeve Reinforcement:
To enhance block rigidity and prevent sleeve shifting under high boost pressures and elevated RPMs, the builder filled the engine block with Devcon liquid aluminum. This technique is a common practice in high-performance engine building to reinforce open-deck engine blocks like the F22.
Crankshaft Polishing and Bearing Clearance:
The crankshaft was polished to achieve a smoother surface finish and facilitate looser bearing clearances. Aiming for 0.002 inches of clearance across the crankshaft, this modification is intended to improve lubrication and reduce friction, particularly crucial at higher engine speeds.
Precision Bearing Measurement:
Instead of relying solely on plastigauge, the builder employed a ball anvil micrometer to precisely measure bearing sizes. This method, combined with careful mathematical calculations based on rod and main bore sizes and bearing thickness, ensures accurate bearing clearances. ACL bearings, known for their tight tolerances (+/- 0.0001 inches), were used in the build, further emphasizing precision.
Component Cleaning:
Throughout the assembly, meticulous cleaning of parts was performed using microfiber rags and paint thinner. This practice prevents lint contamination, which can be detrimental to engine longevity.
Piston-to-Wall Clearance:
Piston-to-wall clearances were carefully checked, with a target of 0.0045 inches. While slightly looser than stock specifications, this clearance is deemed suitable for a boosted application, accommodating thermal expansion under increased operating temperatures.
Block Cleaning and Piston Installation:
The engine block underwent thorough cleaning before piston installation. Pistons were installed with the directional dot facing the transmission side of the block, a crucial detail for correct engine orientation.
Piston Deck Height Verification:
After piston installation, the piston deck height was verified. Even after block resurfacing, a slight piston recession of approximately 0.005 inches from the deck surface was observed, confirming the desired low compression characteristics of the build.
Piston and Rod Weight Comparison:
The builder also compared the weight of the forged 4G63 piston and H22 rod combination against the stock F22 components. While specific weight figures aren’t provided in the original article excerpt, this comparison highlights the builder’s attention to detail and potential considerations for engine balancing.
Parts Inventory:
The images also showcase the array of parts accumulated for the build, illustrating the comprehensive nature of the project.
Dyno Proven Results: 365whp and 300tq
The culmination of this innovative and budget-conscious engine build was a resounding success. The hybrid F22 engine, utilizing 4G63 pistons and H22 rods, produced an impressive 365 horsepower and 300 lb-ft of torque at the wheels on 16 psi of boost.
This dyno-proven result underscores the effectiveness of this resourceful approach. By combining careful planning, meticulous assembly, and cross-engine parts compatibility, the builder achieved significant performance gains without breaking the bank. This project serves as an inspiring example for automotive enthusiasts seeking to maximize performance while adhering to a budget, demonstrating that ingenuity and resourceful parts selection can be just as effective as expensive, off-the-shelf solutions. While this article focuses on the mechanical aspects of the build, remember that proper engine management and tuning, often involving OBD2 systems, are crucial to safely and reliably realize the full potential of any performance engine modification.
