How to work out what injector size you require

[p055um5]

[SIZE=medium]Start with what rwkw you want (say 250rwkw)[/SIZE]

[SIZE=medium]Then allow 20% drive line lose and get you bhp at crank (250*1.25=312.5bkw)[/SIZE]

[SIZE=medium]Now convert bkw to bhp (312.5*1.34=418.75bhp)[/SIZE]

[SIZE=medium]Divide bhp by the number of cylinders (418.75/4=104.6875hp per cylinder for a 4 cylinder)[/SIZE]

[SIZE=medium]Now divide cylinder power by 2 gives lb/hour minimum flow rate required (104.68/2=52.34lb/hr)[/SIZE]

[SIZE=medium]Multiply lb/hr by 10.2 for cc size (52.34*10.2=533.9cc) [/SIZE]

[SIZE=medium]534cc minimum injector size (buy 550cc)[/SIZE]
[SIZE=medium] [/SIZE]
[SIZE=medium](ok just start with either the rwkw or bkw or bhp you want to work out what injectors you require minimum)[/SIZE]

 

[EVOCPE]

Good info, how did you get 1.25 for 20% drivetrain loss?

 

[4piknup]

30% loss for awd.
And buying 550cc would have them at 95% duty.

 

[EV0300]

im guessing it would be different for e85?

 

[DOUGMO]

you need to add 20% headroom than those calculations for some headroom.

then about 30-40% more for e85

this is at standard base fuel pressure

 

[4piknup]

I thought e85 was 50% as a guide.
So say 1650s for 250kw on e85.
1800s for 300kw, 2200s for near 360kw. (Roughly)

 

[DOUGMO]

I have 1600s and im at 86% duty making 385kw

 

[p055um5]

Good info, how did you get 1.25 for 20% drivetrain loss?

312.5/100*20=62.5
or 312.5/250=1.25
or 312.5-62.5=250

 

[EVOCPE]

Never mind, I understand now. The purple monkey dishwasher made me ask

 

[khubner1]

so my 200AWKW 1.8l would require ~450cc injectors my 510cc evo3 item should be plenty until i go e85 where i'd want ~800cc

 

[DOUGMO]

510s will do 210-220ish on 98, if you go e85 you need more fuel at the same power, but you can make more power

I would go 1000s

 

[evo-gsr]

Khuner buy my 850s ?

 

[OLDIE]

Tables I have seen say that I need 1000's to make 400 hp ATW in a RWD or 500 HP @ the flywheel @ 80% DC on 98 RON

 

[GeoKez]

You need an accurate VE number to do the calc. Big difference between 78% and 85% VE when you run it through the injector calc. And that could just be the difference a good valve job makes.