injectors and fuel pressure?

[Touge Tom]

just swapped my p72 head for a P&P PR3 head, on my B20 block and went from a set of B series 240cc injectors to H series 345cc injectors.

I had the 240's set at 55psi in addition with a air flow controller.

the 345's didnt like this so i kept winding the fuel pressure down till I got to 30psi and now it idles sweet (@15 degrees ignition timing,with brk6e11 plugs. but will be going colder to a set of brk8e11 for summer). but yet to make adjustment's to the air flow correction

has anybody on here had experience with 345cc's on a B series set up? & at what fuel pressure did you have it at, if so?

[Touge Tom]

all sorted. just had to calculate the injector difference which was 40% give or take. And dropped the fuel pressure from 55psi to 32psi. kept the same fuel map settings too. 13.5 A/F across the entire rev range. thank's for all your help?

[ECU-MAN]

just as you figured, if you change the injector size you must compensate by changing the fuel multiplier in your EMS