Another Big One, Hope you're not too sick of these developments...
Recently my car has been back to Big Fish for further development tuning. A few interesting things to take note of and document that relate to the widespread tuning of these cars:
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Here's the updated graphs, (red) stock vs (green) previous tune version vs (blue) updated tune
So the takeaway here is that the torque is much more linear and power doesn't tank at 4300 rpm. This happens on the previous tune because there's a RAM encoded limiter that slowly caps boost capping it at 2.5 bar absolute at 4300rpm and tapers down to a measly 2.1 bar absolute by redline, this is applied regardless of what you demand out of the turbo and there's no definitive alteration to patch this out as of yet. What you're probably thinking is "oh so they have gotten round this now"... the answer is yes and no. And the same goes for EVERY i20N tuner at least in Europe (I have no clue what those guys in Türkiye are doing but that 338hp build that runs 100-200 in 9.8 seconds is nuts. Speedy González if you're seeing this, hats off to you my friend).
The way the power is achieved in the top end by all the EU tuners is by messing with the closed loop boost control, demanding a flat and inflated boost value out of the turbo in the relevant maps and using torque modelling, WGDC and other limits to keep torque and boost within somewhat safe tolerance. This is also the case for hybrid turbo builds, being bigger and capable of flowing more air, it can make that extra power in the top end. Interestingly enough, from the very limited portion of this I've seen, no turbo efficiency maps have been altered on hybrid builds essentially making the ECU think the stock turbo is still in place which is interesting, there could be some more juice to extract out of full control over the turbo.
This works BUT the ECU has NO idea how much boost the car is making as a result... It's almost like using a tuning box if you want to think about it that way, obviously there's so much more control over everything else that a tuning box can't do so I'd still argue this is much safer than just tricking the fuel and MAP sensors into reading low to make more power. What this can do is cause a bit of funny behaviour with aftermarket blow off valves, I've noticed mine at very low pressures when downshifting sometimes just won't open causing very minor off throttle surge (flutter), sounds cool but it's not good for turbo life which I'm not so bothered about, you might be though so just keep that in mind. Also, when downshifting at higher revs it opens quickly and then closes again until you fully come off the clutch, which again sounds a bit funny but I'm not hearing flutter (surge) in that scenario which I suppose is better than it surging heavily.
The car does feel immense with this smooth power rather than being very diesel-esque though, just keeps on pulling all the way to redline, which you may also notice has been upped to 7k. I daren't rev it out that far often though. it's much faster over timed runs with my car managing 60-120mph in 15.39 seconds, down from about 19 on the previous tune and you might think 19 is barely faster than standard and that is true but obviously that's down to the lack of power gain over stock post 5000 rpm where you might expect the car to spend most of it's time during a timed run like that.
I've also opted to cap the torque on this tune which is why it makes slightly less power before 4000rpm (the power after more than makes up for it and it's barely even noticeable) I've done this for the life of the clutch, I made another post on clutch replacement options as at 400+Nm, these do love a good slip. I think with them being NEW cars and many being tuned before the clutch is even close to end of life, we thought it was a super sturdy unit, but it's not at all, it can hack 400Nm for about 5000 -10000 miles from fresh depending on your driving style and then repeated hard use will have it slipping often. Since capping at 380Nm, I've barely noticed any slippage even after being brutalised by such an immense amount of torque for 6000 miles and even with my spirited driving style. It still needs replacing but this should extend the life of the stock clutch and I'd recommend when tuning, you have your tuner cap torque below 400Nm so you don't end up replacing the clutch "prematurely".
Obviously there's still work to be done on the ECU as this isn't 100% ideal and patching that top end limiter whilst maintaining control over the boost means you can hold a much flatter and safer value on command rather than relying on other factors to maintain boost instead. Hybrid is the next step for me personally but I'll be waiting until full software control of the boost is available.
Thanks for the read,
Tom
found a few 1x1 values in the image that are linked to abs manifold pressure that've been changed and still limited, i'm aware of an airflow limit in the RAM section of the .bin file but it shouldn't limit boost really until 5k onwards which is why a lot of tuners get that dip in the high revs. I'm thinking it's the MAP sensor voltage but at this point I'm not sure, still looking for that table. It's one of those, money to be made by people who do know and could lock it behind paid mappacks in the EVC portal so to be fair, it's only expected they'd keep it to themselves.
