While trying to final tune my 426 Jeep, I have been to more injector sizing sites than what should be allowed. It seems that all injectors are rated using a 43.5psi fuel pump rating. That makes it difficult to figure out what is needed or the formula for our 58psi fuel system. Once you cross over into bigger cubic inches or forced induction you need to size a larger injector. The downside is loss of quality idle, drivability and long and short term fuel trim. Well until a tuner can SIZE the injectors into the tune....and even then I havent seen one that idled perfect! Based on wheel horsepower and roughly a 20% driveline loss(in a Jeep driveline) for a 392/426 hi-po set up I had to swag the crank horsepower...so, For a crank horsepower of; 580hp.... a 45.3 lb/hr or 475cc/min injector is required. 600hp.... a 46.88 lb/hr or 492.19 cc/min injector is required. 680hp.... a 53.13 lb/hr or 557.81 cc/min injector is required Rated @43.5psi 38lb injector @58psi = 43.8 lbs/hr 40lb injector @58psi = 46 lb/hr 42lb injector @58psi = 48.4 lb/hr 50lb injector @58psi = 57.7 lb/hr Out of curiosity I looked up the smallest SRT4 injector which is the 2003 SRT4 injector, rated at (43.5psi) 47lb/hr @ 58psi = 53lb/hr or 557cc/min. 2004 SRT4 injector rated at (43.5psi) 52lb/hr @ 58psi = 59lbs/hr or 577cc/min. I wont even touch the Stage 2&3injector rating. Clearly the 2003 SRT4 injector is a bit overkill unless you are making well over 680 crank horsepower.....and at that point good luck with idle and streetability.
Steve, Where do the Cobra "Blue Giants" fall in to the mix? I know that's what I have and was wondering where they fit in.
I was running the stage 2 SRT4's n/a for a little bit.....with a properly scaled tune they run and idle just fine.
You know Steve, Using the PSC1-003 we can tun idle and Part throttle almost perfect with the strokers and different size injectors. I'm not saying its better, but for drive ability the psc works pretty damn good....
