xr4tic

Problem is, I'm stuck with using stock injectors, because I'll be running the car with the stock ECU system (w/GIAC chip) at least for break-in, and probably a little longer (I need to let the mod fund recuperate a little) Plus I want to do a lot of data-logging to try and get some ignition and fuel maps made to for whatever EMS I use.

I figure the stock injectors are pretty much maxed out with the K03, and there's no way they can keep up with a 2.0 at even 12psi.

Here's what I figure:
The stock injectors flow 277cc @ 4bar (240 @ 3bar)
This is good for a max of 180 g/s, or 648 kg/hr (as recorded via VAG-COM)
The 2.0 will hit 180g/s at 5500rpm and 12psi, if I raise the boost, the rpm limit drops as well, which severly limits the fun factor

What I'm proposing:
If the stock injectors flow 277cc, and my new injectors flow 440cc (3bar), then that's an approx 60% increase.
If I increase the MAF area by 60%, then the air/fuel flow rates should stay the same. Correct?
I think the stock MAF is around 2.25", so a 60% increase would be a 2.85" housing.

The Mustang guys do this, change the MAF flow curve to match the injectors.

There is a drawback however, the load calculation will be wrong, so the timing and fuel may not be optimized. This is a lot better than running lean though, and hopefully the O2 and knock sensors will help adjust accordingly.....

Just keep in mind this is a short-term solution.

What do you guys think?

Pelican Blue-T28

Oh john there is a nice article in this months(july) issue of Sport Compact Car on page 20. It is called DONT BOTHER and goes over full techs on rod lenths cons and pro's.

4kq

That assumes perfect linearity on the injectors. Is that true?

Why not just run lower boost with a stock MAF?

I don't see how the logs would transfer, since they are for WOT mainly anyways. Are you talking about new basemaps?

If you are really going to a new full EMS, then you will have a lot of new variables. Personally, an Autronic/Hal3 etc. would burn a new map that was accurate with a proper UEGO, so save your time.

Now, multiple butterfly intake would give you monster response.

WYSIWYG

i understand you can weld?

xr4tic

I agree with him, sortof. For most cars, a tall-deck block is not an option unless a race block is available, and that's $$$$ However, VW/Audi has one that came stock, and it's available cheap. I only paid $285 for mine, and that came with a forged crank.

Like he said, it's not worth it to get a longer rod at the cost of things like stroke, but in my case, I'm not losing anything, and it's really not costing me that much more to do it.

One thing that may be worth noting, is that a long rod should approach TDC with faster acceleration, theoretically, this should push the exhaust gas out faster, leading to quicker spoolup.

Brent V

This would allow you to manually adjust MAF sensor voltage down from normal and at least give you a ballpark idea of how much less of a signal will be required to compensate for the larger injectors. Easier than fabbing up multiple different MAF housings and testing them I would think.

-Brent

xr4tic

the injectors should be linear with the airflow, if you have 60% less air, you should have 60% less fuel. As for linearity between two different size injectors, I would think they would be linear, once they are fully open, and the on/off time should be negligible.

If I get a new EMS, I would like to have a good base point to start from, that's where the datalogging would come in.

Multiple butterfly intake, hmmmm.... Not sure how you'd fab that up.

xr4tic

plus the turbo inlet is 3", so I won't need to narrow the housing down at all.

I can weld OK, but I usually let my dad do it, he's muuuuch better at it

zain

But I agree it would be easier than empirically changing tube sections. Because that whole compressability of air thing is going to make it a bit more complicated than just cross section changes.

A gizmo potting compounded into a temporary wiring harness would also be easier to back out, as this is just a temporary modification, right.

xr4tic

If it's 2 3/8", then a 3" housing is perfect for a 60% increase