AFR Tuning After Adding WI

cewrx7r1 · 01-23-2012, 11:35 PM

My engine is a FD 13B-REW with all the supporting mods for power and reliability. Initial safe tune without any WI was 11.1 AFR at 16 psi boost which has been run for a few years without mishap.

For safety I added 350 cc / minute water only injection back in late 2010. With this, AFRs richen up to about 10.9 and I lose a little power.

I want to now tune to gain that power back or increase power a little. What is a good way to do this? Should I reduce fuel enough to lean out the AFR back to where it was before adding water, go a little leaner?

IN THEORY: If I want to maximise power, would I:
(1) calulate and adjust fuel by: (11.1/12.2) * fuel which would give an AFR of 12.2.
(2) add enough water so that with the above fuel my new measured AFRS would be again 11.1?

01-23-2012, 11:35 PM	#1
cewrx7r1 The Judge Join Date: Feb 2008 Posts: 196 Rep Power: 18	AFR Tuning After Adding WI My engine is a FD 13B-REW with all the supporting mods for power and reliability. Initial safe tune without any WI was 11.1 AFR at 16 psi boost which has been run for a few years without mishap. For safety I added 350 cc / minute water only injection back in late 2010. With this, AFRs richen up to about 10.9 and I lose a little power. I want to now tune to gain that power back or increase power a little. What is a good way to do this? Should I reduce fuel enough to lean out the AFR back to where it was before adding water, go a little leaner? IN THEORY: If I want to maximise power, would I: (1) calulate and adjust fuel by: (11.1/12.2) * fuel which would give an AFR of 12.2. (2) add enough water so that with the above fuel my new measured AFRS would be again 11.1?