Originally Posted by 97qwikcat
if I do run the 150 shot which injectors should I go with?
That requires a little guessing and a little math.
You should calculate your fuel requirements to determine the size of your fuel pump and injectors.
The size of fuel pump is based on the brake specific fuel consumption (BSFC) of your engine. BSFC refers to how much fuel in pounds per hour the engine consumes per horsepower. For nitrous, you can use a bsfc of .65 I think I read.
The formula is:
(Estimated HP x BSFC) x (1 + Safety Margin) = pounds/hour
((lbs per hour / 7.25) = gallons per hour) x 3.785 liters = Liters per hour.
The safety margin should be greater than 20%. But lets use 20%. SM = 1.2
Lets assume (unless you already know) that your engine puts down 250 hp and you add a 150 shot. Lets further assume that that will actually add 150 hp to give you a total of 400 hp.
400 x .65 = 260. 260 x 1.2 safety = 312 lbs/per hour
(312 / 7.25 = 43.03 gph) x 3.785 = 162.89 lph
Since fuel pumps are rated at 0 lift and I don't have the calculation here for figuring out loss of flow per foot I would say a 190lph pump may be fine. You can go with the 255lph pump so don't have to worry about it.
To figure injector size:
((Power x BSFC) / # of injectors) x (1 + Safety Margin) = pounds/hour
Using above numbers we get 400 x .65 = 260lbs. 260 / 8 = 32.5 lbs/hr/ injector. 32.5 x 1.2 = 39 lbs/hr/ injector.
You could use a 36# injector but if you want that safety margin a 42# injector is what you would use. Although a 190lph pump would flow enough fuel to feed the 42# injectors on paper, it doesn't take into account lift. I would use a 255 lph pump with 42# injectors.
I hope my math is correct...