View Single Post
Old 06-14-2009, 06:51 PM   #70
gabedude
Scooby Guru
 
Member#: 10108
Join Date: Sep 2001
Chapter/Region: TXIC
Location: Lake Travis, Austin, TX
Vehicle:
07 STI
60Trim TQ monster

Default

Quote:
Originally Posted by jpirrung18 View Post
when do you need to use fuel rails?
You don't ever really need them according to most tuners. However it is of my opinion that when changing from stock injectors, you should use them because the OE fueling mapping has compensations in them per cylinder for the series configuration. Once you change injectors, your fueling will not be as close as the factory fuel setup and each cylinder will be even more offset in the true AFRs they are running. Ideally you would want a WBO2 in every cylinder and a knock sensor or more advanced device + the logic to control it. However, that gets very expensive. Old WW2 planes used an FPR and equal length lines on every cylinder. They tuned the engine with a knob to lean out the fuel and watched the temperature sensors in the heads of the turborcharged engine. We gave lamba sensors these days and EGT sensors.

So if you change injectors at least I think it is a good idea to run a true parallel configuration, 0 out those tables (perhaps add in a tad extra for the second injector in each bank nearest the return line). Also, your knock sensor is over #4 and there is a table that adds in extra timing over 4 to detect the onset of knock. that is why 4 goes out the most because it takes the brunt of detecting knock. It is not that 4 gets starved of fuel. 4 gets fuel before the other bank does.

* Registered users of the site do not see these ads.

Last edited by gabedude; 06-14-2009 at 06:59 PM.
gabedude is offline   Reply With Quote