VR4 injector size

[Bender]

The stock injector size is 390cc? Right?

What is good size update for injector for the vr4's? And what from?

Cheers

[wintertidenz]

Yes they are 390cc top feed high impedance.

Ideally the best upgrade would be the Injector Dynamics ID1000's, but it depends how deep your pockets are. Alternatively you can run Evo 560cc injectors with a resistor pack.

[Bender]

Well I don't want to spend big money on it, It only a daily driver. :)

But cheers, will get some evo injectors

[Adam.Findlay]

evo injectors dont fit. you need to space the fuel rail to make them work.
and as Dan said you need to wire in ballast resistors, or it will fry the ecu as the evo injectors are low impedance

[Davezj]

why do you need bigger injectors?

the only reason i ask is it is an expensive thing to do if you do not need them.

are you getting a duty cycle of over 80% at WOT all the time.?
i was lead to believe that as long as your injector duty cycle at WOT was not over 80% regularly you do not need larger injectors.
this due to the fact that you don't want to be applying power to the inject all the time as they can fail if they are run like that for extended periods.

but i was told this as rule of thumb, i am not sure accurate it is.

[Bender]

Reason why I wanted to get bigger injectors was cause to putting the boost up to 14/15psi but if they are not straight fit into the vr4's I won't worry about them.

[Adam.Findlay]

you pretty much dont need bigger injectors if you still have stock turbos.
I was running 15psi with my bigger cams, FMIC, walboro fuel pump and was only getting high 70% duty cycles.

[wintertidenz]

You will be fine running 14-15 psi on stock injectors, although it's near their limits.

If you want to get a set cleaned and flow tested I have a spare set that you can have for cheap.

[Bender]

How much would you be wanting for them? Cause I would be keen but would wait few weeks and see what my diff hold up... Or it be open diff time I think :)

[Davezj]

i am running stock turbos at about 18-22psi during a 3rd gear pull and my injector don't hit 80% on a regular basis. they are getting close but not a regular occurance.

if you are messing with boost and fuel, you need an AFR and data logger like evoscan to do thing safely. evoscan cost vitually nothing $25 plus £7 for a cable that is capable for logging only.
the AFR gauge will cost a lot more but you can get a innovate MTX-L for about £130 form ebay just search on "VAGcom Cable" for the cable and "innovate MTX-L" for the wide band AFR gauge and O2 sensor.

just thought i would share this.

oh and for completeness you can get a boost sensor for About £25 that you can wire into an unused input into the ECU and log it with evoscan, so you can get evoscan to log AFR against Boost just like you would get done on a Dyno run.

[lateshow]

Looking for bigger injectors. 1000cc seems a bit too big since with gasoline it would be up to 800-1000 hp? And with ethanol to 600-700 hp?

We have set our sights at siemens deka since bosch ev14 series dont fit and youd have to lift the fuel rail. There is a set of 668cc available. Im thinking of having td04- 13 turbos with flexifuel. Have to think of idle too...

[wintertidenz]

You can go for 750's, but the 1000's are the same price - that's why most people here go straight to them.

[lateshow]

We are now thinking of using Bosch EV14 670cc and lifting the rail...

But what about those 1000cc injectors in general ? How is idle? Do they reach minimum pulse width? I read that vr4 drivers have been using Injector dynamics (which isnt sold here in Finland)

[swinks]

Lauri, I have fuel rail spacers laying around somewher at home. They were to fit Evo stock 560cc injectors into 6a13tt engine, but all project and vehicle being scrapped. With them you can fiit PTF injectors, plenty of various sizes on the market from 750, 880 to 1000cc. Not expensive. BTW, resistor pack is must have.
If interested give me PM.

[Kenneth]

But what about those 1000cc injectors in general ? How is idle? Do they reach minimum pulse width? I read that vr4 drivers have been using Injector dynamics (which isnt sold here in Finland)

I have been using ID1000s, which are Bosch injectors which have been closely flow matched. My understanding is that this flow matching is one of the things which results in good idle.

I have no issues with idle or any other fuel related problems using the 1000cc Bosch injectors. In fact, my car idles better, runs better and gets better fuel economy with the ID1000s than with the standard injectors.
It is also great that they are high impedance and do not require anything other than a change (or adaptors) for the plugs. You can even get them in the correct size to not require rail spacing.

If you think 1000 sounds a bit big, Apparently the Evos can run 2200cc injectors without issues

[lateshow]

Yesterday we got the legnum running 670cc injectors. But if you're running 1000cc:s with gasoline maybe we can too.

Better fuel economy might be due to better spray pattern of the injector.

[kiwigalant]

Yesterday we got the legnum running 670cc injectors. But if you're running 1000cc:s with gasoline maybe we can too.

Better fuel economy might be due to better spray pattern of the injector.

The ones in my GDI are probably the original ones that have a bad spray pattern, might be the main reason it runs rough, and as a result has pretty poor economy. Having a GDI do you know, or anyone else, what the stock size is for these and whether I could use these VR4 or Evo injectors?

[lateshow]

Actually i dont know the injector size, is your's a 2.4 GDi as mine?

I heard rumourd that they'd be 240cc. Tried to use that in evoscan in order to calculate fuel consumption. The values were too small which means that the injectors must have some kind of special opening pulse as they are after all in a high pressure system.

****ed up fuel injectors could be one reason for running rough but id say that gdi runs a bit rougher than the others.

[kiwigalant]

Actually i dont know the injector size, is your's a 2.4 GDi as mine?

I heard rumourd that they'd be 240cc. Tried to use that in evoscan in order to calculate fuel consumption. The values were too small which means that the injectors must have some kind of special opening pulse as they are after all in a high pressure system.

****ed up fuel injectors could be one reason for running rough but id say that gdi runs a bit rougher than the others.
Nah 4G93 (1.8). Mainly rough on idle which is when it uses EGR right? Will clean it out at some stage. I also think I saw on here once that they were 1000cc and that explains why they use lots of fuel when o2 sensors are buggered etc. But if the VR4 ones are 390cc then I do imagine 240cc would sound right.

[lateshow]

In idle GDi should run in open loop and both lambdas should say 0 Voltage. And AFR map says 32 for target AFR. :D

You should block the EGR system.

240cc was my guess for the 2.4 engine which i have.

Gdi has special injectors for high fuel pressure featuring direct ignition. So you cant use vr4 or evo injectors.