Injectors
#1
Injectors
Hi guys!
I am thinking of doing a DIY turbo project and I'm a bit lost on injectors.
Is there any benefit to using a 550cc injector and what kind of fuel pump would make it work, and what kind of boost must i be using in order to justify a 550 injector.
Would a 440cc injector work for most turbo kits and would it, in some sense, work better than a 550cc injector?
I'm looking at the RC engineering injectors. Would these be ok to be paired with a Link ECU? How do the impedance of the injectors affect?
Thanks guys
I am thinking of doing a DIY turbo project and I'm a bit lost on injectors.
Is there any benefit to using a 550cc injector and what kind of fuel pump would make it work, and what kind of boost must i be using in order to justify a 550 injector.
Would a 440cc injector work for most turbo kits and would it, in some sense, work better than a 550cc injector?
I'm looking at the RC engineering injectors. Would these be ok to be paired with a Link ECU? How do the impedance of the injectors affect?
Thanks guys
#2
low-imp (peak'n'hold) injectors respond faster than old style high-imp (saturated) ones ... so for a given cc rating the low-imp ones will be capable of a better idle and flow more at high duty cycles due to less time spent opening and closing. They'll need a resistor pack with the Link tho.
Having said that I can idle OK at 800rpm 15.4 AFR with hi-imp 550cc rx7 injectors ... just... 1.1% duty-cycle... wahlauay!
Having said that I can idle OK at 800rpm 15.4 AFR with hi-imp 550cc rx7 injectors ... just... 1.1% duty-cycle... wahlauay!
#3
Boost Czar
iTrader: (62)
Join Date: May 2005
Location: Chantilly, VA
Posts: 79,494
Total Cats: 4,080
pair the injectors to the amount of power you'll be making.
no point running a 550cc injector on a 200rwhp car.
550cc @ 50psi can support around 300rwhp
440cc @ 50psi can support around 250rwhp
------
The stock fuel pump should flow around 35 Gal. /Hr. at 50psi
thats 210 Lbs. /Hr.
210 * .80 / .55 = 305BHP
So if you think you might be making more than 250rwhp, I'd suggest a new fuel pump.
the new best option...the Walbro 190 Lph flows around 45 Gal/hr. at 50psi
270 * .8 / .55 = 392BHP (325rwhp)
no point running a 550cc injector on a 200rwhp car.
550cc @ 50psi can support around 300rwhp
440cc @ 50psi can support around 250rwhp
------
The stock fuel pump should flow around 35 Gal. /Hr. at 50psi
thats 210 Lbs. /Hr.
210 * .80 / .55 = 305BHP
So if you think you might be making more than 250rwhp, I'd suggest a new fuel pump.
the new best option...the Walbro 190 Lph flows around 45 Gal/hr. at 50psi
270 * .8 / .55 = 392BHP (325rwhp)
#7
Tour de Franzia
iTrader: (6)
Join Date: Jun 2006
Location: Republic of Dallas
Posts: 29,085
Total Cats: 375
I just picked up a set of "new" ones for $120. I need to get them flowed to be sure everything is right before they go in though. www.clubrx7.com
#8
on the same subject, is it worth it to get them flowed? i mean is that gonna work better than some brake cleaner and an air compressor that i can do at my house?
if i was building a kit for 235 hp now but wanted to bump it up to 350 could i use 550cc injectors while i run the 235hp kit? don't wanna spend extra $$ and time if i don't have to.
if i was building a kit for 235 hp now but wanted to bump it up to 350 could i use 550cc injectors while i run the 235hp kit? don't wanna spend extra $$ and time if i don't have to.
#9
Boost Czar
iTrader: (62)
Join Date: May 2005
Location: Chantilly, VA
Posts: 79,494
Total Cats: 4,080
its smart to do...many times the injectors fail the before test...be it spray pattern or leak test....and most of the time when all the screens, etc. are replaced they flow 10-30cc more than they should.
#10
Boost Pope
iTrader: (8)
Join Date: Sep 2005
Location: Chicago. (The less-murder part.)
Posts: 33,027
Total Cats: 6,593
Seriously though, with the right driver circuit you could install 1000cc injectors on a stock engine and they'd "work", you'd just have a really crappy idle. It's all a matter of degrees. The greater the ratio of injector size to actual cylinder displacement, the poorer the low-end becomes. There's a reason that Mazda put staged injectors on the RX-7 engine, and it wasn't to save money.
don't wanna spend extra $$ and time if i don't have to.
#11
OH good thing i'm going for the 235 then!! dodged that bullet! yeah well EVENTUALLY i want to make a 350hp miata engine. but the jump from whats involved for 350 hp is a lot greater than 235.
correction, i do have the time, but i can't afford my car to be down that long, and considering it takes me twice as long as the avearge person to do finish any project i'm already at a disadvantage.....actually my mom said its my super power, SLO MOTION MA-eh i'll finish the rest later.
correction, i do have the time, but i can't afford my car to be down that long, and considering it takes me twice as long as the avearge person to do finish any project i'm already at a disadvantage.....actually my mom said its my super power, SLO MOTION MA-eh i'll finish the rest later.
#20
Former Vendor
iTrader: (31)
Join Date: Nov 2006
Location: Sunnyvale, CA
Posts: 15,442
Total Cats: 2,099
If you aren't doing a standalone ECU (i.e. you intend to run a Bipes/AFPR/O2 clamp) do 315cc injectors and jack your fuel pressure up. If you intend to run a Megasquirt or a Link or something like that, look into the 460cc high-imp injectors from the NA S5 FC Rx7. (non-turbo, later version of the second gen rx7) I got mine off a member from the 7 club (www.rx7club.com, not clubrx7.com) for $75 shipped and got them cleaned for $70. The first mod those guys do when going for power is monster injectors so tons of guys have stockers laying around.