Best AFR Ratio

this is my drift car/nissan cefiro-rb26

running 620hp on pump gas 98 with 17psi of boost

what is the best air fuel ratio & fuel pressure on idle and full boost.

thanks

Do you have a dyno sheet and datalog?

no i don't have it

Being an RB it'll most likely have a return style fuel system, which will have its pressure referenced to the intake collector manifold pressure. This means your absolute fuel pressure will vary, but should be set to around 3bar (43.5psi) above whatever the manifold pressure currently is. This will depend on the fuel injectors fitted however, and you should consult the injector data to see what pressure to run them at. 3bar across the injector is pretty common though.

For your AFR, it'll be specific to your engine and will need to be found during the tuning process, but I would start with an AFR of around 11.8:1 at full load and maximum boost.

I'm using ID1000cc injectors