Rs2 alternative injector question.

[Dift]

Remapped RS2'd S4...

RS2 injectors flow 360cc @ 3 bar, but I cannot find any for life nor money... I've found some similar Bosch injectors which flow 11.5cc more @ 3 bar.

Will the car run like an over fueling dog if I use these larger injectors?

Bare in mind the RS2 injectors will be close to maxxed out in this application. I won't have time to remap the ECU to suit these injectors

[227bhp]

Audi don't sell them?

[stevieturbo]

Dift said:

Remapped RS2'd S4...

RS2 injectors flow 360cc @ 3 bar, but I cannot find any for life nor money... I've found some similar Bosch injectors which flow 11.5cc more @ 3 bar.

Will the car run like an over fueling dog if I use these larger injectors?

Bare in mind the RS2 injectors will be close to maxxed out in this application. I won't have time to remap the ECU to suit these injectors

11.5cc more ? Really ?

I'd be surprised if you even seen a difference.

Really no idea what you're trying to achieve here ?

What can you not find ? And why would you even waste time or money on injectors almost identical in flow to what you already have ?
11.5cc more is around 3% more.

Total waste of time.

[Dift]

Perhaps I wasn't clear, sorry.

My car has a full RS2 setup, however the person supplying the chip and 440cc injectors is AWOL, leaving me car-less one week prior to a road trip.

My question is, can I run the slightly larger injectors on a generic RS2 map if I buy another ECU (which has been mapped to 360cc injectors).

Will an increase of 11.5-12cc cause any issues, or is it so small it won't matter?


348.5cc @3bar rs2 984s
416cc @4bar rs2 984s
V
359cc @3bar Saab 431s
428cc @ 4bar Saab 431s

11.5cc @3 bar
12cc @4 bar

Edit: I can buy rs2 injectors new, but they cost >£100 each.

Edited by Dift on Tuesday 7th July 07:04

[stevieturbo]

Dift said:

Perhaps I wasn't clear, sorry.

My car has a full RS2 setup, however the person supplying the chip and 440cc injectors is AWOL, leaving me car-less one week prior to a road trip.

My question is, can I run the slightly larger injectors on a generic RS2 map if I buy another ECU (which has been mapped to 360cc injectors).

Will an increase of 11.5-12cc cause any issues, or is it so small it won't matter?


348.5cc @3bar rs2 984s
416cc @4bar rs2 984s
V
359cc @3bar Saab 431s
428cc @ 4bar Saab 431s

11.5cc @3 bar
12cc @4 bar

Edit: I can buy rs2 injectors new, but they cost >£100 each.

Edited by Dift on Tuesday 7th July 07:04

It's still unclear about what you're trying to achieve or need.

Why would you even waste money on injectors 3% larger than what you think you have or need ?

Why are you quoting flows at different fuel pressures ? Do you have an ability to adjust your fuel pressure ?

And what is so special about RS2 injectors or whatever you're using that there arent dozens of options ?

And is the car not driving at the minute or something ? What is preventing it from being driven ?

And certainly a google for your Saab 431's suggests they are a bog standard Bosch high impedance injectors. Which that fitment would literally give you hundreds of injector options being the most common about.

[Dift]

The car has recently been converted to a bigger turbo. It has no suitable injectors installed. It also has no ECU.

I have sent off my ECU for mappong and 440cc injectors, however the supplier is now not responding to any communications.

I am asking wether I can buy the SAAB injectors and run them on a new RS2 ECU designed for 360cc injectors.
I will be running at 3 bar, no ability to change FP.

The Saab injectors are the closest I can find to RS2 spec injectors. New RS2 injectors are prohibitively expensive, even if you can find genuine ones, Saab injectors are cheap and plentiful.

Will 11.5cc make cause any issue with the engine/cat etc?

As soon as I receive my original ECU back with new injectors from the supplier, I will swap them in. Using the Saab injectors will be a temporary measure to get the car moving and for a road trip.

Edited by Dift on Tuesday 7th July 07:55

[packman10_4]

A friend of mine is running a mk6 Golf 2ltr TFSI 4x4 with just over 517 hp @ 1.5 bar ... as far as I know he is running RS3 injectors and fuel pump and running the stock ECU thou modified he also runs antilag ...

Forged pistons
H section rods
Head flowed
Cams
Stock inlet manifold
stock valves
Titanium valve springs & caps
Hybrid turbo
RS3 Injectors and fuel pump and regulator with the bigger lines
RS3 Rear diff , propshaft , cradle ect ect and Hydrex unit

[227bhp]

packman10_4 said:

A friend of mine is running a mk6 Golf 2ltr TFSI 4x4 with just over 517 hp @ 1.5 bar ... as far as I know he is running RS3 injectors and fuel pump and running the stock ECU thou modified he also runs antilag ...

Forged pistons
H section rods
Head flowed
Cams
Stock inlet manifold
stock valves
Titanium valve springs & caps
Hybrid turbo
RS3 Injectors and fuel pump and regulator with the bigger lines
RS3 Rear diff , propshaft , cradle ect ect and Hydrex unit

What CC/min are the RS3 injectors?

[Pumaracing]

Does anyone in here understand what this question is really about? What I glean is that the engine has been modified, bigger turbo, but the mapping is supposedly being done by post. How the hell does that work? And if the new turbo really does need 440cc injectors how is going to operate on 360cc ones?

All very bizarre.

[Dift]

Perhaps I should keep it simple.

If an ECU is set up to run with 348cc injectors.
Is it ok to run 359cc for a short period ~1000 miles?

Assuming the spray pattern is similar.

[Pumaracing]

Dift said:

Perhaps I should keep it simple.

If an ECU is set up to run with 348cc injectors.
Is it ok to run 359cc for a short period ~1000 miles?

Assuming the spray pattern is similar.

Which bit of "only 3% difference" do you not understand? It's utterly inconsequential in terms of the fuel air mixture and it's also very doubtful if any injectors, of any make, test out on average within maybe 5% of their rated spec on a calibrated test rig.

What exactly do you think is going to happen to an engine if it runs 3% rich of its theoretically perfect target, even if any rolling road operator could get that close, which they can't? Catastrophic meltdown?

Sheesh.

[stevieturbo]

Pumaracing said:

Does anyone in here understand what this question is really about? What I glean is that the engine has been modified, bigger turbo, but the mapping is supposedly being done by post. How the hell does that work? And if the new turbo really does need 440cc injectors how is going to operate on 360cc ones?

All very bizarre.

Blood...stone etc. But we are getting there.

From his post above, he did fit different parts then send away his own ecu, so has nothing to run the engine.

"Mail order" type tuning is very common these days, and quite easy with OEM ecu's and generic setups. No different that people replacing chips at random over the years, or any of the thousands of clueless people flashing in generic remaps with no knowledge whatsoever of tuning.

However there is still the "trust" that whatever ecu he is buying, is what it claims, and for the very exact spec he intends to run.

So as stated several times. A 3% change in injector size will make almost no difference whatsoever, so yes from the scenario you are describing would be perfectly fine to use.


If you need cheap injectors, albeit from the US, Five O has plenty. http://www.fiveomotorsport.com/

ASNU in the UK would have many options too, but would be more expensive.

[Dift]

Pumaracing said:

Dift said:

Perhaps I should keep it simple.

If an ECU is set up to run with 348cc injectors.
Is it ok to run 359cc for a short period ~1000 miles?

Assuming the spray pattern is similar.

Which bit of "only 3% difference" do you not understand? It's utterly inconsequential in terms of the fuel air mixture and it's also very doubtful if any injectors, of any make, test out on average within maybe 5% of their rated spec on a calibrated test rig.

What exactly do you think is going to happen to an engine if it runs 3% rich of its theoretically perfect target, even if any rolling road operator could get that close, which they can't? Catastrophic meltdown?

Sheesh.

I didn't know what would happen, hence the question.

I'll leave asking about the importance of the spray pattern.

Thanks for the help.

[Pumaracing]

If the engine still has lambda feedback it'll map itself anyway but even if it doesn't engines run from circa 15:1 at cruise to 12.6:1 at WOT which is a 20% spread so why would you fret about a theoretical 3% difference on any of that.

[packman10_4]

Not sure will ask him later , he was at GTi International at the weekend was hoping for low 11,s 1/4

[Dift]

Pumaracing said:

If the engine still has lambda feedback it'll map itself anyway but even if it doesn't engines run from circa 15:1 at cruise to 12.6:1 at WOT which is a 20% spread so why would you fret about a theoretical 3% difference on any of that.

This is info I didn't know, your posts have been very helpful. I am unfortunately a 'bought not built' kind of person

There is little interest from tuners for old Audis nowadays. MRC and others are reluctant to help unless the car is in extremely good condition (which is completely understandable). Few people can remap the old motronic ECUs, so many rely on historic chips from the likes of MTM and T+S.

I'm just trying to get my car running ASAP for a road trip without spending too much. The Saab injectors and new ECU are temporary measures till I receive the goods I have paid for from another supplier (overseas).

Thanks

[packman10_4]

Owe he is also running "Devils" Water/Meth injection again mapped through the ECU ... this mod was worth nearly 40hp on its own

[Dift]

stevieturbo said:

Blood...stone etc. But we are getting there.

From his post above, he did fit different parts then send away his own ecu, so has nothing to run the engine.

"Mail order" type tuning is very common these days, and quite easy with OEM ecu's and generic setups. No different that people replacing chips at random over the years, or any of the thousands of clueless people flashing in generic remaps with no knowledge whatsoever of tuning.

However there is still the "trust" that whatever ecu he is buying, is what it claims, and for the very exact spec he intends to run.

So as stated several times. A 3% change in injector size will make almost no difference whatsoever, so yes from the scenario you are describing would be perfectly fine to use.


If you need cheap injectors, albeit from the US, Five O has plenty. http://www.fiveomotorsport.com/

ASNU in the UK would have many options too, but would be more expensive.

Thanks Steve, the ECUs in question are old motronic units from the early 90s so difficult to get any support for it. Chips are plentiful but agree it is a gamble. The original ECU was sent to a highly regarded tuner of old 5 cylinder Audis, however I have not heard anything for 3 weeks leaving me car-less.

[packman10_4]

Right he is now running stock TFSi injectors. He was using RS3 (leaning out at the top end) injectors but they was not up to the job. He said the stock TFSi injectors are for direct injection and have a really good spray pattern and these running at 110 bar stock he is running 155 Bar using a Zytec pump and regulator.

[SuperchargedVR6]

Confused.com

So it's an Audi S4, fitted with the 5 cyl 20V RS2 engine, which has been converted to run direct injection?

How was the latter achieved in a port injection head? DI ports are tiny and sealed tightly on the injector with Teflon seals and very robust retaining clips, and how is the pump controlled to vary the pressure across the load / rev range? All sounds a bit weird to me.

Vince Saiya at Stealth Racing is the guy to see for older Motronic, although he only has a 2WD dyno.