AA tune on an Australian E82 125i

[MBan]

Hi all,

A brief history of my car:
• 2009 E82 125i manual
• Australian/European spec which means the same N52B30 as the E87 130i (195kW) but detuned (160kW) to keep a decent performance gap to the 135i
• I installed ARMA Speed headers (cat-less), and new high-flow cats in July
*note: the Aus 125i doesn’t have secondary cats, only those in the stock exhaust manifolds so putting in cat-less headers would result in no catalytic converters, hence why I installed high flow cats, downstream from the headers, at the same time
• Before- and after-headers dyno runs didn’t give me the gains I was hoping for (3% at high revs) but I have a theory that at least some of the gains seen with AA and SS headers is from having two fewer cats than the stock exhaust system
• I started researching the tunes available for my car including P Torque, Evolve, OE, Digitec and Active Autowerke
• For a number of reasons I decided to go with AA

Read, upload, download and write went fine (one minor hiccup but fixed by an AA tuner remoting into my computer).

My first drive of the car was a real eye-opener: it felt much stronger everywhere.

The only issue was a flat spot at higher RPMs in 1st (~6,000rpm) and 2nd gears (6,750rpm). The AA tuner provided a second tune which helped a bit but we haven’t completely resolved it yet. The tuner (Pedro) has been great and he’s still helping to iron out this bug.

I drove around for a couple of weeks (I don’t do a lot of km per week so it took a while to build up some time with the tune) and when I had the chance to sink the clog, the tune continued to impress.

I think there is some throttle remapping done with the tune which I was a little dubious about but it’s been really good. One of the things I didn’t like with the stock car was that the throttle wasn’t very linear: part throttle felt really snappy but when I’d go from part throttle to WOT, it didn’t feel that much faster. It was like 50% pedal would give 75% throttle and 100% pedal, therefore, didn’t feel that different.

This week I had the car dyno’d again. See below. At peak power, the car is now making 24% (42hp) more power than stock. Unfortunately, I don’t have a chart showing stock and AA tune traces together; the one below is ARAMA headers vs ARMA headers + AA tune. But from the dyno below comparing ARMA to ARMA + tune, the average hp gain over all RPM is 16% with a peak gain of 21% right at the top.

If you assume that my baseline of 178hp at the wheels equals 160kW at the flywheel, then the car is now making 197kW at the flywheel or pretty much bang-on what a 130i makes. The Dyno Dynamics charts I’ve seen for 130i also back this up.

Peak torque is up about 10% but the average over the whole of fourth gear is actually up nearly 15% and high in the rev range the difference is over 20%.

So, we now know that there are at least four tuners that can deliver 130i levels of power from an Aus/Euro spec 125i and it does seem that getting that kind of result isn’t magic, the tuner's software simply has to be able to alter the valvetronic maps.

[Bimmer-Bob]

Nice. Thanks for the data. Why'd you choose ARMA speed headers? Are they the only company that offers RHD fitment? I don't think too many people run those over here (US), which is the only reason why I ask.

What type of high-flow cats did you put in? And what does your exhaust system look like downstream? All stock?

Sort of off-topic, but I think the "final step" to really get these cars up to 130i spec is a gearing change. Both the 125i & 128i MT's run a stock 3.23 final drive versus the 130i's more aggressive 3.46 (despite nearly identical gearing otherwise). I think our more conservative gearing accounts for much of the car's de-tuned feel. For example, oftentimes when coming out of a corner in 2nd gear (as in AX), I find that the car takes a few moments to build RPM's back up to the power band, and feels somewhat sluggish in the interim. A more aggressive FD would put you back in the power band more quickly, mitigating (if not entirely alleviating) this problem. Unfortunately, the 3.46 FD does not seem to be readily available in fitment for our cars, but 3.64 & 3.73 units are common. I've got my eye on one for the springtime. I'm encouraged by the fact that Quaife makes an off-the-shelf "sport diff" for the 130i in 3.73, which leads me to believe that this may not be too much for our cars.

[Taskmaster]

Awesome, love the follow up on this!

[MBan]

Bimmer Bob - there are only a couple of 'off the shelf' header options for RHD cars and of those, the ARMA ones looked the best. Given the choice, I would have bought AA or SS headers but that wasn't an option unfortunately. Even to my limited understanding, parts of the ARMA headers look compromised to fit in RHD cars, short primary pipes with tight bends for example. Having said that, the quality looks good, and fitment was spot-on. I'd love to see a back-to-back comparison with AA or SS headers but that's never going to happen.

After the headers, the new system is dual pipe to the 200 cell Magnaflow cats then a merge just before a Magnaflow resonator and subsequently into the stock rear muffler. It sounds quite nice and I have some video to upload when I find a minute or two.

I totally agree about the gearing and I'd love to reduce the final drive ratio. A change is still a while away for me - if I ever do it - but I'm keen to see how you go.