Injector size change. Help me math
 

Old injector at old fuel pressure: 1265cc
New injectors at new fuel pressure: 2255cc

78.5% increase in injector flow

Base fuel table only-
My tuner says to multiply my current base fuel table by 0.569

I think I need to multiply it by 0.215

Whos right? Or neither?

1265/2255 = 0.561/1

Thats reducing the values by 44%

Thats what I dont understand

Why not? 1265 is approximately 56% of 2255, so 44% less, though i don't believe that's correct terminology.

I cant wrap my head around why I would only reduce PW by 44% when the injector is flowing 78% more. Seems like it would be super rich then

Math, mostly.

2255 x 0.215 = 484.825.

Is that what you're after? No.

You want the number that when multiplied with 2255 gives you your original number.

So.... 0.561

If you increased the injector flow by 100%, would you reduce PW by 100%?





Your new injectors flow 78% more than your old one. IOW, you take your old injectors and multiply by 1.78 to get the flow of your new injectors. Thus, you need to divide your fuel map by the same 1.78 to keep the same flow. Or, you can multiply it by ~0.561. Same thing.

had a good laugh when I read that to myself slowly. I understand now.
Thank you both for the explanations

Why would you change your fuel table rather than Req Fuel? What kind of ECU?

fcking hydra

No way, hydra doesn't use VE?

AEM Gen1 does not either, they both use raw pulsewidth. Granted, the AEM also has a tool which allows you to quickly rescale the fuel map for injector and/or pressure changes. I forget if Hydra has something similar.

You can chose pw or ve. I use pw

Why?

Life's no fun if you make it easy for yourself

The first basemap that FM sent to me was set up as PW so thats just what I've always used. Its the first and only ecu I've ever played around in. I make fuel adjustments and its always worked out so if its not broke I don't fix it