Stock injectors?

[Injuneer]

300-shot (dry) on top of 500HP at the flywheel, with a 7,000 RPM nitrous shutoff. I run 78 #/HR (flow rate at 58psi) Bosch injectors at 58psi (4 bar). Max BSFC on nitrous is 0.53 per extensive engine dyno tuning, yielding less than 70% DC. The system is operated with with a MoTeC M48Pro ecu that can shift between the NA and nitrous program, depending on whether the nitrous system is armed. So all the fuel is added by the injectors based on tables specific to the nitrous tune. Tune is open-loop, speed-density, no knock sensor.

How do you plan to add the fuel? Switchable program, increased fuel pressure, etc.?

This is the only dyno sheet I could find in this PC.... we did add another 35-40HP of nitrous after this but that was with it on a chassis dyno. It gives you a decent idea of the BSFC. For an unknown tune, I'd say assume a 0.55 BSFC and stick with 80% DC for your calculations.

Balance of the fuel system is dual Bosch 205 LPH high pressure pumps, one in the stock tank location and the other off a sump at the bottom/rear of the stock tank, SX billet fuel filter in stock location, single -6AN line to the rear of the stock fuel rails, where it splits into a -6AN feeding the back of each rail, single return welded to the diagonal cross-over tube at the front, a single -6AN to a Weldon AFPR mounted under the cowl, and then back to the tank.

[ws66]

Thanks for the advice. Guess I need to put it on a dyno when I get everything. Ill probably start at 36 or maybe a little more and bump the fuel pressure up. Sounds like you have a killer setup though.

[Injuneer]

What are you thinking the engine will make without the nitrous? Nitrous cams typically have a wide LSA to minimize blow-thru. My setup is 230/242 114LSA 0.590 I / 0.590 E. Pistons have a heavy crown for the nitrous, and with 5.85" rods the ring pack is dropped down to the point it needed ring rails for the oil ring. All that hurts NA HP, and we actually wanted this to pass NJ rolling emissions. That limited it to about 500 HP at the flywheel on straight motor.

Add your projected NA HP (flywheel) to the nitrous added HP, and use the BSCF and DC that I suggested to get the best guess at minimum injector size. I don't think your answer will be 36 #/HR. Not if you are running an additional 175 HP of fuel through the injectors at the fairly rich A/F ratio for nitrous. You don't want to have to buy multiple sets of injectors to dyno tune it.