bigger injecters

[all_motor_baby]

hey guys, just wanna ask by upgrading to bigger injecters from your original ones what what the hell happens, my mate keeps going on and on about how he just got bigger ones in his car and i have no idea what he's going on about can anyone please enlighten me lol.:)

regards, Jace

[tinkerbell]

it puts more fuel in per RPM...

this only helps if the engine is running too lean and is usually last resort, as it is much easier to just turn up the fuel pressure with an adjustable fuel pressure regulator than replace the injectors...

most people get "bigger injectors" because it sounds cool? or they got ripped off by a workshop...

[Tobster]

Depends on the type of engine -- some respond to it better than others.

[Zdster]

Here is a decent start on what injectors actually do:

http://auto.howstuffworks.com/fuel-injection3.htm

Oh yeah, plus PQ points to Tink.

[tinkerbell]

and if you want to see how the relationship between fuel presure/fuel injector size/horsepower interacts, see here:

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

[BiLL|z0r]

most people get "bigger injectors" because it sounds cool?

LOL, heaps of lancer drivers put Magna injectors in cause it sounds cool, so that would explain the rice factor :)

All it's gonna do in reality is use more fuel and make it run rich and who wants to use more fuel at the price it is now. If you're car in tuned and you have a piggyback/ecu etc then bigger injectors have their place.

[Tobster]

I think in some cases it can make a difference: the ECU will still read how much fuel is going in and can tell if it's running rich. What it does is supply the same amount of fuel in a shorter space of time, so you get an increased throttle response...

[tinkerbell]

ummm, i dont think so Tobster...

a) an ecu does not "read how much fuel goes in";
b) injector 'time on' has no influence on "throttle response";

[Zdster]

What about this?
http://yarchive.net/car/injectors.html


















To be honest I have no idea what it means - to many big words I dont understand :p.

[tinkerbell]

the first link you posted in this thread was much better Zdster...

[Zdster]

the first link you posted in this thread was much better Zdster...

Agreed. Any idea what the second one is on about? It went straight over my head.

[Tobster]

OK -- I could be wrong -- and I'm talking partly in theory here and trying to reason my own way through it.

The ECU controls the amount of fuel injected -- when to stop and start the fuel -- that's what EFI is all about. The ECU is also determining how much fuel to deliver from throttle, air intake, and exhaust sensors.

A bigger injector will deliver the same amount of fuel in a shorter space of time.

I don't really know where I'm going with this. I just vaguely remember a conversation with my mechanic brother-in-law about putting bigger fuel injectors in a (ordinary) Lancer -- and I'd trust his opinion on that because he crews for Ed Ordynski and looks after most of the Evos in Adelaide. It makes a difference on some cars. I'm just trying to work out exactly why...

[all_motor_baby]

HAHA geez thanks guys you all have been awsome lol, never thought i'd learn so much :), thnx tink, thnx zdster for all the links.

regards Jace

[dsp26]

to make it simple lets pretend ur engine uses 1 injector rated @ 100cc.

ur ecu tells it to pump out 50% cycle duty at a given rpm... 50cc right?? put 300cc injectors in to replace it without aftermarket management and your ecu would still tell it to pump 50% at that given rpm... thats 150cc... uber uber rich dude!!!!

hypothetically...if i had same major NA mods including aggressive cams, high duration/lift and stiff ramp rate and High CR.. say 11:1 CR... lets say i was doing 15:1 A/F.. thats lean as and ****ing dangerous... i can then justify putting in slightly bigger injectors (in my case stock 259cc to something like 333cc) without getting management as that would most likely bring me back down to ~13:1 which is acceptable for an NA beast so yes it can net you power under SOME circumstances.

i don't know what the stock A/F of SOHC 1.5l/1.8l lancers are.. their econoboxes and i'd assume they'd have small injectors prolly running close to ~14:1 A/F ratio.

put a set of V6 magna injectors (i'd assume alot bigger) and the A/F could drop as low as 11/12:1 which would actually make it lose power...........

conclusion... YOUR MATE IS WRONG!!!!!!!!!


***EDIT***
btw all_motor_baby... love your avatar.. just don't get those thoughts near me ;)

****EDIT AGAIN!!!****
ha thanks fellas!!

and as tinkerbell said, raising fuel pressure via an afpr would be an easier way to get a bit more out but theres only so much you can get out of it (my fuel lines burst once from 55psi)

the reason to get bigger injectors with tuning is to "be safe".

IF i was revving high and from 5krpm-redline my 4 injectors were ever to reach ~90% duty cycle, just imagine what would happen if one of them fouled?? go lean = engine boom espesh would turbs.

[Zdster]

Very interesting, and nicely explained. Plus PQ points for you :thumbsup:.

[all_motor_baby]

lol thnx bro "dsp26" and dont worry i wont lol :p also zdster whats PQ mean lol i know i know im a noOb lol.