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      11-29-2012, 02:51 PM   #1
peeti
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Drives: 2011 M3 e90
Join Date: Apr 2012
Location: Chicagoland

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Dinan SII for 135i n55

I've read a ton of posts here on the merits of one tune versus another, the true HP/TQ versus posted by the manufacturers etc. This isn't one of those posts.

I am not afraid of tunes or messing with the engine having been the testbed of custom tuning for my old c63 mercedes. But I still tend to take a conservative approach, hence my choice on the Dinan. Had one of the "injector" style code sets been available for my n55, I would have gone that route, but since not a one is out there, I got tired of waiting.

I'm really glad I did. Sure it's not cheap, but my dealer did the work, the did not void out the warranty when doing so (I thought they would have considering) and the whole process was smooth as all hell.

What I mainly wanted to get across in this post is the secondary benefits of this particular tune. Others may do this too - but this is something I've not experienced in my previous (non BMW) tunes.

Sure there is additional TQ throughout, and mainly in the higher RPM bands. But what no one has mentioned thus far are two pretty key things. First, throttle response: in a word, this is how every drive by wire car should feel. Ironically, watching the tach needle, and tapping the gas pedal produce two very different observations. The tach needle spools up just as you'd expect, but at first you've got this "WTF? I just paid lots why didn't it improve" thought. Then your ears kick in and you realize it's just the indicator needle - the engine is revving MUCH quicker, in fact there is nearly 0 delay from tap on gas pedal and engine revs.

Second, and this one is really surprising to me, the Dinan tune looks to hold the wastegate a bit on clutch-in. What I mean by this is picture... driving, 1st gear, clutch in, revs drop a bit, change gear, clutch out, gas (all in a second or so). If done slowly enough, you can visibly see the RPM drop in the time it takes to clutch/shift/declutch/gas. Unless you're really power shifting, it's usually enough to make the car stumble a bit due to the RPM mismatch after declutching.

On the tune, however, the pressure in the system is kept a tiny bit longer. The wastegate doesn't dump the pressure on clutch-in right away. As a result, the period of tolerance increases a bit. Maybe .5-1 seconds, after I realized it and paid attention, it almost seems too long. But I won't complain. Shifts are silky smooth now - and I've been driving stick over 25 years exclusively.

All in all, the car is much more lively and the power is nice, but these two undocumented features are worth the price of admission on their own.

Hope this helps one of you guys that's on the wire deciding which way to go.

Cheers.

P.S. Yes, I've had a CDV-ectomy prior to this.
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