Ok, here's my question:

My current goal for my car is 400 HP. people have been telling me that for that kind of power, I need 1200 or 1600 cc secondaries.

someone please correct my math here:

stock TII injectors = 4*550cc/min = 2200 cc/ min. or 2L/min, assuming that they dont really flow 550.

at 400 hp, with BSFC .56 for turbo rotary,

fuel consumption= 400 HP*.56 HP/lb/hr= 224 lb/hr

224 lb/hr = 1766.5 cc/min.

1766.5 cc/m < 2000 cc/min

so im getting that stock injectors could support over 400 hp??

wheres my mistake?

pat

 

A couple of things I see:

1 lb/hr = 10.5 cc/min (the so-called standard)

most people use a conservative 80% for duty cycle


My site has a pretty good calculator for this.

Gordon
WitchHunter performance
fuel injector cleaning & flow testing service

 

You will have to make it 1,56 instead of 0,56
with 0,56 you willactually divide instead of multiply.

400x1,56= 624

 

OK here is my figures, using witchhun performance's help

400hp
4 injectors
.56 bsfc
80%
735 cc per injector
X4
2940
-880 (2 550cc injectors you already have with 80% dutycycle accounted for)
2060/2 = 1030cc each (increase the size 20% to give some room for error)

2x 1236cc injectors
so 1200cc will do it (if your other 2 injectors are 550cc's)

go with the 1600cc's because i think you will be looking for rwhp and not at the fly

 

I think that a .56 BSFC may be a bit optimistic. I have heard that a stock TII is somewhere around .64 BSFC, but I have been unable to confirm this, although it sounds about right to me. I don't know how you tune, but from what I have seen on this forum, most people like to run an insane amount of boost and then run an overly-rich mixture to be "safe". This practice can bump the BSFC into the .70 to .80 range.