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

[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

[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

[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.

[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.

[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

[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.

[Dift]

It's not a B5 S4, it is a C4 (AAN engine).


I assume there is some confusion with Pacmans posts which are based on his friends car

[Dift]

There is always the option of a stand alone, however I'm hopeful 370 bhp should keep me entertained.

If I go down the route of more power, I do think a standalone would be the sensible option.

The Chevy injectors are often referred to as RS2 replicas... So thanks for the link. I'll have a look in there.

[Dift]

PositronicRay said:

I always had a soft spot for these. I had a (slightly) later version badged as an S6 after the 100/A6 facelift, as a company car. Trouble was it was and auto totally killed it and liked a drink.

Yes they do like to drink, but the power and noise make up for it. The only downside is the availability of parts. For the price it's a great fun car for those with a small family. Best of both worlds!