Greg Arehart
Well Known Member
I've been changing out my injector nozzles (this is a Silverhawk system on a Superior IO360 if that makes any difference) in an attempt to better balance my engine for LOP operations. At this point I have 4 different nozzles to get the EGTs to go over peak at the same time/fuel flow: 0.028 (cyl 1); 0.027 (cyl 2); 0.026 (cyl 4) and 0.024 (cyl 3). Comparison of the area of the injector nozzles by simple math says that the orifice on cyl 1 is ~25% larger than that on cyl 3.
So my question is basically what is controlling the absolute amount of power in each cylinder? As I see it, there are two possibilities:
1) the air volumes going to each cylinder are different, and therefore one has to compensate for lesser air in some cylinders by reducing the orifice size. If this is the case, then I would expect to get less power from cyl 3 than cyl 1 (because less overall fuel is burned). This might ?? result in a rougher-running/misbalanced engine. In summary, both less air and less fuel in some cylinders, but still all cylinders are stoichiometric at peak EGT.
2) the air volumes going to each cylinder are (approximately) the same but the fuel pressure/flow through the smaller nozzle on cyl 3 is higher than the larger nozzle on cyl 1. This would result in approximately the same amount of fuel in each cylinder, and the same amount of power coming from each cylinder. In summary, nearly the same amount of air and fuel in all cylinders, and all cylinders are stoichiometric at peak EGT.
I'm hoping that option 2 is what really happens, but I don't know and haven't been able to sleuth out the answer on the internet.
So my question is basically what is controlling the absolute amount of power in each cylinder? As I see it, there are two possibilities:
1) the air volumes going to each cylinder are different, and therefore one has to compensate for lesser air in some cylinders by reducing the orifice size. If this is the case, then I would expect to get less power from cyl 3 than cyl 1 (because less overall fuel is burned). This might ?? result in a rougher-running/misbalanced engine. In summary, both less air and less fuel in some cylinders, but still all cylinders are stoichiometric at peak EGT.
2) the air volumes going to each cylinder are (approximately) the same but the fuel pressure/flow through the smaller nozzle on cyl 3 is higher than the larger nozzle on cyl 1. This would result in approximately the same amount of fuel in each cylinder, and the same amount of power coming from each cylinder. In summary, nearly the same amount of air and fuel in all cylinders, and all cylinders are stoichiometric at peak EGT.
I'm hoping that option 2 is what really happens, but I don't know and haven't been able to sleuth out the answer on the internet.