Pushing Engine Power Beyond the Original: New Technologies Revolutionize Restoring the Crown #8 (Part 2)
In the heart of Toyota's Kamigo Plant/Shimoyama Plant, a team of skilled engineers, led by Assistant Manager Takayuki Miwa, have demonstrated their expertise in cylinder bore honing. This team, consisting of Takuya Sato and Hiromu Nakabayashi, is renowned for their work in the Engine Manufacturing Engineering Division, and their recent project on a first-generation Crown restoration has garnered attention.
The project faced a significant challenge: abnormal wear on the cylinder bores of the engine. The cause? Poor engine cooling, leading to insufficient lubrication of the pistons and cylinders. The team's task was to bring the old engine back to life.
The solution lay in the precision honing process, a technique that creates a micron-level finish on the cylindrical inner surface of the engine. This process is crucial for an engine's overall performance and can be considered the cornerstone of engine manufacturing technology.
In the honing process, the engine block is set in a honing machine developed in-house at Toyota, and a cylindrical tool fitted with one of three different types of grindstones—diamond, CBN (cubic boron nitride), or WA (white aluminum oxide grit)—is inserted into the cylinder. The rotary tool that houses the grindstone also has a sensor that serves as a torque meter.
The honing process enhances engine performance by improving sealing, enhancing lubrication, increasing durability, and optimizing combustion efficiency. The fine, uniform crosshatch finish allows piston rings to seat properly, minimizing blow-by gases and increasing compression. The microgrooves trap oil effectively, maintaining a thin film that reduces metal-to-metal contact and wear. Better surface finish reduces the chance of scuffing or cylinder wall damage. Improved sealing and reduced friction lead to more efficient combustion, better power output, and fuel economy.
In the first-generation Crown restoration, the honing process required minimizing the depth of surface machining. Miwa was responsible for controlling the surface roughness at the micron level during the honing process.
The result? The restored Type R engine exceeded expectations in terms of power and smoothness. The honing team's dedication and expertise have once again proven that they are at the forefront of engine manufacturing technology.
Notably, Toyota’s honing process for the cylinder bores on a first-generation Crown engine involves careful control of abrasive grit size, honing speed, and crosshatch angle to achieve the precise surface characteristics needed. This process typically occurs after initial boring of the cylinder block to final dimensions, ensuring the cylinder diameter is exact and the surface ideal for piston ring operation.
The team's commitment to sharing their knowledge has seen them visit engine plants worldwide. Their work on the first-generation Crown restoration, using modern honing technology considered the cutting edge of engine manufacturing technology, is a testament to their dedication to innovation and excellence.
The team's commitment to innovation extends beyond Toyota's Kamigo Plant, as they share their knowledge of cutting-edge engine manufacturing technology in the global finance industry, allowing other transportation companies to benefit from their expertise in the automotive sector.
The delicate balance between technology and tradition is evident in the honing process, a crucial step in engine manufacturing that combines modern tooling and techniques with the skill and craftsmanship of Toyota's honing team, ensuring the best performance in their industries.
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