13B Rotary Engine Exhaust Street Port Template

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This is a simple exhaust port template that I designed for my 13B-REW engine, saving me $40 for a similar template. After researching port shapes, I created my own port in CAD to mimic medium-sized street ports commonly used on turbo engines. My design philosophy focuses on the following principles: I aimed to leave as little material untouched upwards as possible to avoid adding to the intake/exhaust overlap already present in the stock engine, which is often viewed negatively for turbo engines. To achieve this, I removed approximately 3mm of material downwards with a rounded shape, opening the exhaust port more gradually and earlier. This helps spool the turbo better and promotes linear expansion of the exhaust gases with the gradual opening. The sides were opened up by 1mm overall but with a more squared shape instead of a rounded one, maximizing the area of the port and allowing you to match the housing to the exhaust sleeve. To use this template: First, print both the stock port template and the street port template. Then, line up the stock port template with the stock exhaust port and mark the top edge of the template on the rotor housing. Next, take the street port template and line it up with the mark you made on the rotor housing (the arrow should face upwards). Mark the port shape with a marker. Finally, start grinding using a carbide burr on a dremel.