Mitsuturbo
20+ Year Contributor
- 87
- 5
- Feb 5, 2003
-
Seattle,
Washington
Here's the scoop. I have a galant vr4 with 8.8:1 compression, a ported head, tial gate, RC550s, safc, sitc, 2g maf, 2.5" upper ic pipe, walbro 255lph.
I was running 17psi (91 octane) and getting no knock, but my SAFC settings were up around 19-23+ between 4500rpm and 6500rpm *i have my points in 500 increments between 3000 and 6000*
This was required to eliminate knock. Well we checked my injector duty cycle, and it was peaking at 124%!!!
So.. in order to get the injector duty cycle in check, i lowered boost to only 15psi, and took my afc setting down to 3000=12 3500=12 4000=13 4500=13 5000=14 5500=14 6000=14 (all are +)
This got me no knock, and injector duty cycle of 97-100%. My karman readings were about 1850, and my o2s were about .89, however, at 17psi, with injector duty cycle through the roof, i could definitely feel a power difference.
My question is this, i guess... why is my injector duty cycle maxxing out at only +14% on the afc up around 4500rpm and higher? Do i need bigger injectors? (like 660's) And most importantly.. how much should i take duty cycle into consideration? Does it even matter? Am i running into fuel problems due to higher compression?
Any experienced advice would be greatly appreciated!
I was running 17psi (91 octane) and getting no knock, but my SAFC settings were up around 19-23+ between 4500rpm and 6500rpm *i have my points in 500 increments between 3000 and 6000*
This was required to eliminate knock. Well we checked my injector duty cycle, and it was peaking at 124%!!!
So.. in order to get the injector duty cycle in check, i lowered boost to only 15psi, and took my afc setting down to 3000=12 3500=12 4000=13 4500=13 5000=14 5500=14 6000=14 (all are +)
This got me no knock, and injector duty cycle of 97-100%. My karman readings were about 1850, and my o2s were about .89, however, at 17psi, with injector duty cycle through the roof, i could definitely feel a power difference.
My question is this, i guess... why is my injector duty cycle maxxing out at only +14% on the afc up around 4500rpm and higher? Do i need bigger injectors? (like 660's) And most importantly.. how much should i take duty cycle into consideration? Does it even matter? Am i running into fuel problems due to higher compression?
Any experienced advice would be greatly appreciated!