Discussion and questions related to the course Practical Dyno Tuning
what is a good place to start with for boost on a 2jzgte 9.0:1 93oct fuel? Thank you
There's so many variables that can affect the ultimate boost you can run on a given engine that it's a little hard to be specific unfortunately. What you will find on a low octane pump gas is that as you raise the boost the engine will become more prone to detonation which requires you to retard the timing. You then tend to go around in circles adding boost, retarding timing, and making roughly the same amount of power but with more stress and heat being placed on the engine. If you're on a dyno then it's very easy to know when this is happening but it's a little more tricky on the road.
So for some generalities, I'd start with about 15-16 psi boost which you should have no trouble running on that combination. From here you can start raising the boost and monitoring for knock until you either reach your target power level or you get to the point of diminishing returns I mention above.