Does any one know how much decrease in injector duty % would one see for an increase in 1.0AFR on stock 550 injectors + upgraded walbro fuel pump @~20psi boost?

 

maybe your question needs to be clearer, are you deciding on larger injectors ? Or are you trying to tune without a wideband? What duty cycle do you have now? Are you going from 12 to 13 or 10.5 to 11.5?

do you have a tune-able ecu or stock?

 

I'm deciding if I should go w/ the 660s. I got a flash from Al and I'm thinking of utec/WI. Thinking from ~10.5 to ~11.5.....

 

I do not think you will need bigger injectors.
your thinking is correct, with WI you can trim the fuel a bit.


unless you are going for a bigger turbo, but in that case just wait to view your own logs (if you get the utec tuner)

as an example, at 18 lbs boost and WI, I never saw anything over about 73% duty cycle. That was a bit leaner AFR than you plan. you should be good up to 80% before you go to bigger injectors, no?

 

You do not need larger injectors.

 

Thx guys, saved me ~$400!