You should checkout our
turbo recommendation calculator
Basically you need to first calculate your engine's naturally aspirated flow requirements (let's say 300cfm of air at 0psi of boost at 6500 rpm)
Based on that and based on your target boost pressure (for simplicity sake let's assume you want to double your horsepower and you will be using a decent turbo and intercooler)
So let's say you need a turbo that flows around 600cfm at 18psi of boost
Our calculator automates this entire process and even plots your engine demand on compressor maps so you can make sure you have a good fit turbo
The process I described above can take you a good half hour to do by hand if you know what you're doing. Our calculator does it in under 3 minutes.
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