I think the only way to do it would be to have a hybrid ecu complette with oxygen sensor.
Yes, I think you're right
I think, though, that diesel has more energy per unit than LPG, as it is a longer chained hydro-carbon. The problem with this, is that it burns too slowly to allow high rpm's, limiting power that way. Thats how the torque is so huge, because it burns well low down, but as you get through the rev range, less is burnt completely, which is also why its more smokey. Petrol is in the middle, burns slower than LPG, but has more calories, but burns faster than diesel, but has less calories.
The idea behind LPG injection is to make the diesel burn quicker, meaning that at low rpms you don't notice much improvement, but the torque doesn't drop off, as the diesel burns just as well higher up the rev range with LPG present in the cylinders.
My peak torque is 325lbft, but at 4,200 (peak power - 200bhp) the engine is only putting down 250lbft - about 77% efficient. Assuming that at peak torque the engine burns the diesel 100%, then that means that 23% of the fuel is not being burnt properly at 4,200rpm. If we could use LPG purely to ensure the diesel was burnt properly, meaning torque stayed at peak right along the rev range, this would mean that at 5,000rpm (the red-line), the engine would be producing 309bhp!!
My workings assumed that the following formula is infact correct:
Horsepower = Torque x rpm / 5252