bigger injectors.... better or bad?

[Fenvy]

yada yada, have a s13 blacktop and a s14 t28, want to raise boost

of course, I'll need bigger injectors. I will probably be wanting to run at 12 to 14psi

I am currently looking at a set of "Tomei 740cc Injectors" or "Nismo 555cc Injectors" since they're about the same price range.

1) Will bigger injectors always be better than smaller injectors? I am under the impression that the 555cc is enough to run 14psi so I am leaning toward the 740cc but is bigger always better in this case? I am concerned that when not utilizing the injetors to the full capacity, the gasoline mist created might be uneven?

2) would you ever buy used injectors? why?

3) do I need a fuel regulator with either injectors?

4) will apexi safc ii + z32 maf + walbro 255lph fuel pump enough to run these injectors?

[w1ngzer0]

you can buy # injectors for 75% cheaper then expensive overrated universal japanese injectors.

ka24de.com sells i think 30# and 50# injectors.

[SoCalS14]

I like that idea, but what the heck does 30# mean? 30 pound? anyone have a conversion to cc??

[w1ngzer0]

google.com is your friend.

you don't need to find out how many #'s = how many cc's

You just need to figure out the max hp rating for the 30# or whatever # injector your buying.

[Fenvy]

wait a sec! you guys didn't answer my question?! for under 300whp at around 12~14lb of boost, is it better to have 555cc or 740cc?

[w1ngzer0]

wait a sec! you guys didn't answer my question?! for under 300whp at around 12~14lb of boost, is it better to have 555cc or 740cc?

Would putting 1000cc injectors on a stock 1.6L be better? No, it wouldn't but you can do whatever the hell you want with it when you need that much gas if you do lol....

But with any new injector your going to need to saulder new injectors and still have a fuel controller not dumping a **** load of gas.

Someone can correct me if they wish.

[Fenvy]

well, my car is not stock, and like I said, I am ready to raise to boost, it will be under 300hp at 12~14lb of boost.

740cc better or 555cc? I was just wondering if the gasoline output of the injectors woudl be off when not used at full capacity

[w1ngzer0]

whats the ka24de motor or whatever you have stock injectors size?

[SeVa-S13]

He/She is running an S14 SR which sports 370CC side feed injectors for stock I believe. The KA's have 270CC. (Topfeed for SOHC and Side for DOHC)

If you don't plan on upgrading beyond them, I'd say go for the smaller of the sets because the bigger the injectors, the less precise to sprays are generally, which makes it hard to tune to a fine point.

[Saltman]

I've heard that with the bigger injectors, your car can shoot flames when downshifting. If you plan on going with a bigger turbo later, I say go with the Tomei's. That way you won't have to change again when you increase more boost.

[SeVa-S13]

The injectors themselves have nothing to do with the uber sweet jdm flames out the fart can--it's just because the engine's running too rich. I can do it with stock 270CC injectors and my Wlabro with too high a fuel pressure or a rich mixture. If you're shooting flames, get your engine tuned.

[w1ngzer0]

i can figure out the injector thing. But i just need to know the Max Duty Cycle of Injectors (%).

Another thing i don't think that t-28 is going to handle more then 10psi. I could be wrong but i have never herd of any civic running more then 10psi on a t28. They usually go t3/t4. Intercooler sizing to match would be good too.

will apexi safc ii + z32 maf + walbro 255lph fuel pump enough to run these injectors?

agian i need to figure out the fuel injector part first then the rest can be answered.

Would i buy used injectors? yes, why? ka-t owners buy SR20 injectors all the time. I don't hear anything wrong with it.

So get the max duty and we can get rollin'

[98s14inaz]

I like that idea, but what the heck does 30# mean? 30 pound? anyone have a conversion to cc??

I'll save you the search. #'s X 10.5 = cc For example 50# X 10.5 = 525cc

Bigger isn't always better but if or when you ever experience boost spike you'll be happy you have the extra fuel. Detonation is a *****.

[SeVa-S13]

T28's are good to about 1 bar, ~14.7psi.

[Hijacker]

Another thing i don't think that t-28 is going to handle more then 10psi. I could be wrong but i have never herd of any civic running more then 10psi on a t28. They usually go t3/t4. Intercooler sizing to match would be good too.

my stock T25 goes to 14 psi, a T28 should be good to the same boost rating as well.

[w1ngzer0]

wow never knew

[SeVa-S13]

As for the question way back - like i said, aslong as they're big enough and allow a little ehadroom, the smaller injectors will be better. And 550's will be more than ample for 300whp.You will need somesort of management to control them though.

[Hijacker]

here's an easy formula for you.flow rate = (HP X BSFC) / (# Injectors x Maxcycles)

HP = no brainerBSFC is brake specific fuel consumption in pounds horsepower-hour (Normally this is 0.4 to 0.6 at full throttle. Assume 0.55 for turbo charged engines, 0.45 for NA engines)# Injectors. DuhMaxcycle is the maximum duty cyucle of the injectors. (Above 80 percent, some injectors could being to fibrillate or overheat, which could eventually cause the to lose consistency--or even fail completely)

So,on an S13 SR running an S14 T28, I don't see much more than 300 HP being seen, so we plug that in the formula.

flow rate = (300 x 0.55) / (4x0.8)flow rate = 165 / 3.2flow rate = 51 lb/hryou convert lb/hr to cc by multiplying by 10.5 (Thanks blake!) which leaves us with:flow rate = 541 cc

You will be fine with a 550cc injector. Going any larger is overkill and seriously hurts your economy.

[SeVa-S13]

(Thanks blake!)

Damn straight, what would the world do without me and my random useless knowledge? Har.

[Nameless EJ6]

Read this, there's some basic fuel injector info here:

http://www.meggala.com/injectorscss.htm

And much more on google!

As said above, too big is overkill. You'll be running way too rich and likely be smoking and leaving carbon deposits in the combustion chambers.

550's are fine for 300-350whp. Typically you want to be in the top 20% of the duty cycle with TUNING. If you're curious about the duty cycle take your car to a shop and have them hook a scope to the injector/s.. that'll tell you where you are.

[Fenvy]

so....

Nismo 550cc injectors for 325 picked up, what you guys think?

by the way, how do I know if the injectors or the maf is working or not from visual inspection?

[SeVa-S13]

Well you probably have no way of checking if they "work" or not but I guess they should generally be clean and not all gunked up...

[Hijacker]

the only way to see if they work or not is to install them. Then either grab a stethascope or a screwdriver and listen to them and listen for any sounds that would be indicative of a bad injector. As for maf, you can't tell until it's installed.

[w1ngzer0]

thx. I had no idea what the flow rate was so thx agian man ^^;

[usdm_180sx]

wait a sec! you guys didn't answer my question?! for under 300whp at around 12~14lb of boost, is it better to have 555cc or 740cc?

Proper tuning and having a safe duty cycle is key.

[hannibal]

There is a limit on the size of injectors that teh SAFC2 can control. I believe its 50% bigger than stock. So those 550cc are right at the limit. (370 x 1.5 = 555)I think youre better off with the smaller injectors anyway.

[Nismo_Freak]

Would putting 1000cc injectors on a stock 1.6L be better? No, it wouldn't but you can do whatever the hell you want with it when you need that much gas if you do lol....

But with any new injector your going to need to saulder new injectors and still have a fuel controller not dumping a **** load of gas.

Someone can correct me if they wish.

New fuel rail, pressure regulator, and a number of other things are required to run the cheaper injectors.

By then you're better off with some off the shelf 550's.

[Nismo_Freak]

here's an easy formula for you.flow rate = (HP X BSFC) / (# Injectors x Maxcycles)

HP = no brainerBSFC is brake specific fuel consumption in pounds horsepower-hour (Normally this is 0.4 to 0.6 at full throttle. Assume 0.55 for turbo charged engines, 0.45 for NA engines)# Injectors. DuhMaxcycle is the maximum duty cyucle of the injectors. (Above 80 percent, some injectors could being to fibrillate or overheat, which could eventually cause the to lose consistency--or even fail completely)

So,on an S13 SR running an S14 T28, I don't see much more than 300 HP being seen, so we plug that in the formula.

flow rate = (300 x 0.55) / (4x0.8)flow rate = 165 / 3.2flow rate = 51 lb/hryou convert lb/hr to cc by multiplying by 10.5 (Thanks blake!) which leaves us with:flow rate = 541 cc

You will be fine with a 550cc injector. Going any larger is overkill and seriously hurts your economy.

flow rate = (205 x 0.55) / (4x0.8)flow rate = 113 / 3.2flow rate = 35 lb/hryou convert lb/hr to cc by multiplying by 10.5 (Thanks blake!) which leaves us with:flow rate = 370 cc

See how that formula is flawed? ... it fails to have a pressurized conversion as well as a real world aspect towards the SR20DET engine.

370cc injectors hit 100% duty at 270rwhp or so, and the stock MAF hits 5 volts around the same area.

The 550cc injectors will be able to flow 33% more fuel and support roughly 30% more power, however this is without factoring in the rail pressure. Meaning the 550's will be good up till about the 340whp range.

At a peak HP value of 270rwhp which is about the S14 T28's limit from my experience is gonna push duty cycles into the optimum range for the 550's.

If you plan to run this setup for a long time get the 550's, if you plan to run this setup for a short while then upgrade then get the 740's.

We have a VG30DETT engine that idles better than any SR I've ever heard using 740cc injectors. The idle is 100% up to the engine management and the tuners ability. With a S-AFC it's like showing up to a gun fight with a .22 bolt action and one bullet.

Motec M400 > *

[Nismo_Freak]

the only way to see if they work or not is to install them. Then either grab a stethascope or a screwdriver and listen to them and listen for any sounds that would be indicative of a bad injector. As for maf, you can't tell until it's installed.

Send them to RC engineering to be tested and cleaned.