Currently my R1's (single turbo) set up has the injectors doing 90% duty cycle – preferably, I want it to be around 75%.
Therefore I'm considering upgrading the secondary injectors. But before that, can someone tell me if the secondary come on at higher RMP and load point? If that is the case, I'm assuming that the primary are on all the time. Right? Considering all of that, should I change the primary or secondary? Also, what size? I've heard of people only upgrading the primary ones - but I assume that they have the stock set up. The specs. list the primary at 550cc and secondary at 850cc.

Aside: Installing additional injectors and an AIC is not an option, I'd rather reconfigure the fuel map.

Any input is appreciated.

 

Yes, the primary injectors are on all of the time. What people usually do when upgrading their fuel injectors is to leave the primaries alone (or upgrade them only a bit), and then install large (1300 / 1600 cc per min) secondaries. this allows for good driveability at low-load conditions, and plenty of fuel under high-load.

 

Use the fuel calculator on www.maxcooper.com or www.rx7.com to calculate how large of secondaries you need. You will also need a higher flowing fuel pump, which you should probably have already. I take it you have a PowerFC or similar that can adjust for larger injectors?