Secondary injector upgrade - which ones?

[carswaps]

I've been given some Cosworth '400' light blue injectors for the GT3 but I'm not sure which secondary injectors will work best with these?

Any ideas?

[dodge1979]

Have you done any other mods? Injectors need to be suited to the engine and mods really...bigger injectors doesnt neccassaril y mean power...theres a lot more to it..secondaries hardly get used anyhow. .so unless your tying in other improvements I doubt youll see any benefit...

[brian.harper@netassoc.net]

I think the secondary injectors are like 190/cc/minute on the s4, I'm going to 270 cc because of upgrading from std s4 to s4s eprom, raising the boost to 1 bar.

 

Brian

[sailorbob]

The stock secondary injectors are sized to handle 1 bar of boost. Putting in larger injectors without remapping will cause excessive richness.

[brian.harper@netassoc.net]

Derek,

The 270's were recommended by John Welch for use with the S4s Mk V chip. Does not disconnecting the ecu (stock gm ecu) clear the maps, and should remap itself in usually 30 minutes of driving? That is the general time I have seen, I guess to gather enough samples. I stayed with stock size primaries.

Brian

Edited July 14, 2013 by bharper

[sailorbob]

The ecu will not adjust for larger secondary injectors as they are used in the rpm and boost ranges where no adaptive learning occurs (i.e. not where closed loop operation occurs). The adaptive learning upper breakpoints are pretty low down (3600 rpm and 1.21 bar IIRC) and so will only learn from the fueling of the primary injectors.

[dodge1979]

As derek says..unless you do additional modifications you dont really need to change the secondaries. The ecu will do nothing with them. If you do change injectors you should fit an adjustable fuel regulator in place of the standard unit..and then youll need to go on to a dyno to get the fuelling set right..perhaps read my post in the esprit chat section on a tweaked s4 and realistic expectations. ..this may give you some usefull pointers?