What is the percentage of fuel change from going fomr 30lb SVO injectors to 36lb SVO injectors? Assuming the same injector constants and fuel pressure. Basically I left my injector constant the same in LT1 edit and fuel pressure but changed from 30lb injectors to 36lb injectors. I was running a 14.7-15-1 A/F ratio @ WOT on the dyno before the swap and was curious as to how much fuel I have added by swapping the injectors and leaving everything else constant. I remember Fred saying that I was x % away from making my A/F be where it is supposed to be and I am curious as to how much fuel I actually added percentage wise. Any info will be appreciated.

Thanks

Matt

 

Not sure I understand.... you went from 30's to 36's, and left everything the same, including fuel pressure and injector constant in the PCM (31.6???). You want to know how much more fuel you are flowing as a percentage?

The injectors flow 36/30 = 20% extra. But you BLM's are capable of pulling 15% of the fuel back out, and the INT's will take the rest out in closed loop. Problem is, when you go WOT, since the PCM was pulling fuel out in closed loop, it will lock the BLM's at 128 and you will be flowing 20% more fuel than you need at WOT.

But why are you trying to tune that way?

 

Thanks for the info Fred. I am not trying to tune it this way but the car seemed to run good with the 30lb injectors so I left the tune the same and just installed the 36's to see how the car would run. The car seems to run really good now and pulls a lot more in the upper RPM range. I just wanted to get a ballpark as to if the car is still running lean or if it is closer now. I still need to dyno it though and confirm.

Matt