Bigger Injectors A Problem?

[F6_Tornado]

Bigger Injectors a Problem?

I have some questions on injectors and the use of larger ones in combination with the Edit and/or piggybacks.

We have two basic systems used in petrol engines and from what I gather depending on what mods you have as to what system you use.

Batchfire: Where the injectors are all fired together on the 6 or on one bank on the V8, then together on the other bank, with each fired once per revolution.

Sequential: Where fuel is injected into each cylinder whilst the air is being inducted.

Now to extend this to the next step I would say that at some point @ ~3000RPM the sequential injection must start to behave like batchfire?

My reasoning behind this is the Injection window (ms) becomes smaller as the RPM increases, and as such the injection duration will overlap the intake valve opening duration with STD injectors.

Ok that should lead us to bigger injectors which should allow us to inject more fuel in smaller window/time frame (ms) and hence try and maintain the sequential type injection and keep the injection window within the Valve opening window as the RPM increases.

So to do such we need to do either one of three things with the injector?

1) Increase fuel pressure whilst maintaining the same size injector and orifice producing an increase in flow across the orifice in a smaller time frame window.

2) Increase the Injector size whilst maintaining the same pressure with the same result in more fuel.

3) Increase the number of orifice (sprays)

This leads me to:

Atomisation of the fuel.

As we know we get the atomisation from forcing the fuel through an orifice at pressure, but if the larger injector (same number of sprays as STD) has the same pressure then we lose some of the atomisation and hence the efficiency and fuel mix but maintain the sequential injection.

I realise that as the RPM increases beyond the 4000RPM the advantages of the sequential fuel system diminish somewhat and as such behaves like the batchfire system which is OK, but I’m more concerned with Low RPM at which point injection duration is low and with bigger injectors atomisation will be poor possibly effecting fuel economy, low down power and ultimately A/F.

Going back now to my questions which I’m seeking some answers for:

1) With Edit what do we do when we install bigger injectors in regards to Fuel pressure and controlling atomisation? (mainly at lower RPM)

2) What do the piggyback do to rectify the problem? If you could call it a problem as such?

3) Do we use multi orifice injectors to maintain good atomisation?

4) What disadvantages do we get from “Drilled” out STD injectors?

I personally feel that although drilled injectors are common and are performing well as do some other injectors which are for sale I would prefer to use an injector with multiple orifice to maintain a suitable atomisation.

This I feel might well solve some of the A/F inconsistencies seen by some members with varying mods and at the end of the day produce a much more efficient tune.

The Bosh 0 280 155 968 which is commonly used by members has Dual spray but I’m not sure about the STD injector so maybe someone could post some specs please?

[Far_Call]

Interesting read pal.

There was a post here I read the other day when they swaped injectors after bad Air Fuel and seemd to fix it.

Maybe not related but interesting.

[Far_Call]

I found a PDF fuelinjectors.pdf on the 280 155 968 Dual spray Long Body which seems to be popular.

I think the STD one is a 280 156 123 Dual spray Long Body ??

No idea which one in the list is ugenes though.

3rd page down the bottom you will see them listed

Cheers

[Turbo6man]

The standard injector is also dual spray.

The problem you talk about is probably the reason rising rate regulators are used.

Where sequential firing may lose some of it's benefits at high revs so too does batch firing at low revs because of poor atomisation and wetting of the walls etc.

Good read and good points raised

[ufo]

Hey Guys,

Where the hell do you find 0 280 155 968 Bosch Injectors, I called almost every single Bosch Re-seller. None knows it . Only one said it was original German Bosh number !?!?

So, the question is again, where do you get them (in Sydney)

[Far_Call]

Hey Guys,

Where the hell do you find 0 280 155 968 Bosch Injectors, I called almost every single Bosch Re-seller. None knows it . Only one said it was original German Bosh number !?!?

So, the question is again, where do you get them (in Sydney)

<{POST_SNAPBACK}>

Do you have Coventries in Sydney?

They list the STD Ford BA 9F593 A for the XR6T and the upgraded injector as the 0280155968 its actually comes up on their screen when they lookup the STD part number.

They stock both in Coventries Perth but the 968 is double the price of the STD squirt.

[F6_Tornado]

Thanks for the PDF far_call.

Looking at the spec I can see some interesting info.

The STD injector is a Bosh 0 280 156 123 with a

Flow rate of 213.0 g/min @ 3 Bar and its

Recommended operating Pressure is 2.7 Bar

Resistance is 14.5 ohms

Dual Spray/Long body

The 0 280 155 968 has

Flow rate of 310.0 g/min @ 3 Bar and its

Recommended operating Pressure is 3.8 Bar

Resistance is 12 ohms

Dual Spray/Long body

So I see the Flow rate @ 3 Bar is 30% greater in the second injector But it recommends 3.8bar not 2.7 bar, so it has a far better flow rate that the 30% if the fuel pressure is corrected/adjusted when the injectors are fitted.

I would imagine the atomisation would be poor if left at the 2.7bar also in comparison to its recommended 3.8bar and might well be a problem with HP varying.

I get the impression some guys are just buying the Edit and fitting bigger injectors and not looking a bit deeper and fine tuning, possibly why we see some KW results vary wildly.

This might well be the difference with one Tune being OK in one STD vehicle and not the other if the Fuel pressure is different between the two as the mapping needs to be in tune with the injector flow rate which will increase or decrease with the Fuel Pressure as such.

[macka'sxr6t]

Some good questions and interesting reading.

I don't know if the PCM and the Edit control injector flow using (ms) maybe some kind of calibration map.

Dynowog was able to control fuel atomization at low rpm while using the Nizpro modified injectors by altering the (ms). My fuel economy was brillant

Interesting to read the difference in the ohms required from the standard injector and the 968's. It was my understanding that the PCM is very particular and sensitive in this area. This may explain why Nizpro were having trouble getting the tune consistant while using Eugenes injectors. When they swapped over to the standard (modified) injectors the PCM was happy again with the ohms. Consistency returned.

Eugene has been using his with the Xede and has had no problems. I think Blown BA is using them with as well with no problems.

Maybe one of not many advantages of piggybacks over the Edit :spoton:

macka

[F6_Tornado]

Hi Macka,

No one can tell me the part number of eugenes injectors hence I cant pin down the exact spec to compare them.

The PCM would use known tables of known fuel flow as per the injector size and Pressure and when any of the above changes the mapping will need to be changed as such.

ms controls the volume as the pressure is a constant.... I must ask nick what system he was using with EMS then to gain such good results.

[Paradoxx]

The good thing with the injector impedance though is the bigger ones which are lower can be modified through the use of a small coil to create a second load to bring it up to the 14.5 ohms that the ecu likes to see. If the bigger ones were higher impedance it probably wouldnt bother the ecu much at all.