is my injector sizing math correct?

[goeatpaiste]

I installed 450cc injectors in my ka24e. I am using a S-AFC II to tune. Since the original injectors were 270 cc, i came up with:

450 = 270 + (270 * x) where x is the fraction of fuel increase

therefore (450 - 270) / 270 = x

hence x = 0.66 which is 66%

That means for the same MAFS reading, there is 66% more fuel going into the engine. I dont believe my AFC will take out more than 50% of the fuel.

Anyone have any ideas?

Thanksstevo

[neverlift]

thats my main thing about afc's... your right, it is a little more then 50%, but you can reduce fuel pressure slightly, to drop a few cc/minute, but atomization will be less wiht lower rail pressures.

[goeatpaiste]

well i set the afc to -50 all the way and started her up. She runs but only when I have the throttlebody cracked, so shes still rich as hell. Do I bypass the stock FRP when installing a new one?

stevo

[480sx]

You dont bypass anything, you take out the old FPR and put in the new one.

[goeatpaiste]

Most adjustable FPRs dont go much below the stock fuel pressure. There has to be another way. There has to be people on here running 450cc injectors with a SAFC and dont have their rail pressure dropped. Anyone?

stevo