i was looking at new injectors becausemy current rc 440's for my new setup wont cut it. i come across the rc injector cc calculator , type my stuff in as follows :

desired BHP 450

number of injectors to be used 4

brake specific fuel consumpsion - .65(what rc recomends for turbo)

max duty cycle 50%(i thought that sounded like a nice conservitive number)

fuel pressure i put 45


this thing said i needed 1511 cc injectors , that sounds outragous for 450bhp!!!!

heres the link to the caculator

http://www.rceng.com/technical.htm#WORKSHEET

 

I would try your duty cycle at 80%
When I had RC Engineering flow my injectors, (80% duty cycle) is what was used on their flow sheet.

 

i dont wanna run my injectors that high.....

 

Then you're going to have to get bigger injectors.

My fuel spreadsheet if you don't like RC's

You could also raise fuel pressure and run smaller injectors, but its up to you.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Hella_JDM &raquo;</TD></TR><TR><TD CLASS="quote">i dont wanna run my injectors that high.....</TD></TR></TABLE>

Why not. That is the norm. If you want your duty cycle to be low, you will have to run really high fuel pressure, or larger injectors. There is no other way around it. Most people run their injectors in the 65-85% range of duty cycle if not more.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by norcalcrx &raquo;</TD></TR><TR><TD CLASS="quote">Why not. That is the norm. If you want your duty cycle to be low, you will have to run really high fuel pressure, or larger injectors. There is no other way around it. Most people run their injectors in the 65-85% range of duty cycle if not more.</TD></TR></TABLE>
Ya if you get larger injectors you will have more problems idling them

 

General rule of thumb is to not go ABOVE 85% duty cycle...right?

 

Yeah that is correct Dax.

 

Any good injector is designed to run at 80%. High fuel pressure is lots harder on them. Your either going to have too run big injectors or stage them at 50% duty cycle to make 450HP.

 

There is absolutely no reason you should run at 50% duty. The car will idle erratically since the injector won't be able to open for the tiny duration needed for idling.

Also .65 BSFC is way too conservative. This isn't a V-8 we're talking about.

 

so you think maybe 75%?

 

ok i tried it with 50 psi fuel pressure and 75% duty cycle and it came up to 956. sounds better but that seems like alot for 400whp....

 

75 is still low...

honda's stock run in the mid 80's

 

rc doesnt recomend going over 80% tho....

 

honda doesn't recommend you put a turbo on their motor either

 

beepy's right, .65 BSFC is a "safe guess" based on traditional V8's with poor VE - not even the more efficient LSx from GM or the Ford mod motors, much less cracked out big bling built Honda engines with lots of aftermarket refinements.

85% duty is the recommended max, Honduh runs the OEM ones at 100% duty as well as stock cars putting out 12:1 AFR WOT, and limiting yourself to 50% duty is completely gay!

Uhm, Ford 1600cc injectors are cheaper than any other... and the price difference allows you to afford an injector driver box that will give good quality idle and part throttle on big cc low Z injectors.

 

Grab some 800cc's, or whatever is just above it and call it a day.

RC doesn't recommend going over 80% - fair enough. So how long do you stay in boost - minutes upon minutes? My point is, you're not living at 80% for any great length of time.

 

Your thinking is full of "donkey poo poo."
Do a little more research.

 

The guy doesn't even understand how fuel injection works!

 

type R

190BHP
4 injectors
.45BSFC assuming the most effecient in the range(go honda)
43psi @ rail w/ 240cc Inj

94% Duty cycle

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Pelican &raquo;</TD></TR><TR><TD CLASS="quote">type R

190BHP
4 injectors
.45BSFC assuming the most effecient in the range(go honda)
43psi @ rail w/ 240cc Inj

94% Duty cycle</TD></TR></TABLE>

Not 240cc

Not .45 BSFC under WOT

Not 94% DUTY - 100%

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by DRAGLS &raquo;</TD></TR><TR><TD CLASS="quote">The guy doesn't even understand how fuel injection works! </TD></TR></TABLE>

your an idiot

 

There is nothing wrong with 80% duty cycle. anything higher and the injector can't keep up with when it is supposed to be open.

but think about when you will need that 80%, only when you are going wide open throttle and full boost and how long do you do that for like EE_chris said its for small periods of time so unless you want more than your 450whp in the future you don't need an injetor that will put out that much at 50% duty