Quote:
Originally Posted by tim_s
Looks like I've not touched this for over 2 and a half years, probably sums up the story of the car which has pretty much just done family duties for the last couple of years, think I've done about 35k in it. But of late, partly because I had a e93 335 earlier in the year, found a bit of love for the 325 and decided to do a few bits in an effort to stave off boredom! I was impressed at the NA throttle response and it really wasn't much different to the 335 performance-wise (when standard!) which I guess is in large part due to the cab being so much heavier. I'm now firmly of the opinion that for the family wagon the n53 is better for me, esp as running costs are much cheaper.
Anyway, mapping. Having spent a load of time with the n54, thought I'd revisit the n53 and finally actually have a proper look at the main maps etc. Is relatively interesting, 325 is load limited on one map compared to the 330, especially at low-mid rpm and again at over 6k, and the torque monitoring is set lower. The fuel targets are the same between the two, vanos angles a bit different esp again in the midrange, and the 325 actually runs a little more spark advance. Ultimately I'm not sure this entirely covers the difference in performance between the two, but there are many more differences between the files that I can't currently correlate to any known maps, that and I think it would be useful to do a bunch more datalogging on a 325 map. For me that ship has sailed really as I'm running the 330 map and not going back even for testing.
The map I originally bought for the 325 and ran for a bit that actually drove much better than factory was a bit disappointing when I looked into it as doesn't appear to have addressed the load limits/torque monitoring nor does it look much like the 330 map. The way I reported it feeling (perkier at part throttle in particular) appears to mainly be due to a more aggressive torque request at middling pedal %, running more advance and increasing knock thresholds. Basically I'm glad I'm not running it and that I'm running a 330 map as the baseline.
When I get some time I intend to make a few little tweaks to the 330 map including optimising target AFRs for performance as it runs leaner than I'd like on WOT until high rpms, possibly making the inl vanos a bit more aggressive (I've had good success on M cars doing this), possibly see if I can tune the sparks a little. But they'd be trivial changes and I wouldn't expect much for my troubles, and I need to do a load of datalogging on the current setup before I make any changes. Ideally I'd need a few hours on rollers to test changes but I don't really see the point.
In other news I've bought some v3 Depos for it as I don't want to blind people with the LED dip beams I have in there, but don't want to lose them either. I've also bought some eibach springs, a 15mm rear ARB, 3.23 diff and a RacingDiffs progressive LSD conversion. Oh and some rear balljoints as one of mine is tired. I changed my mind on the RacingDiffs and wanted to go for a helical but as no-one's bought the RacingDiffs setup off me and the diff is currently on the bench, I thought I'd stick it in and see how I get on. I'm currently not having much luck with it as I think can't get the pin that holds the spider gears to fit through the LSD sandwich plate assembly, looks like potentially my side gears are closer together than the RacingDiffs kit is designed for. I'm waiting for them to get back to me, their comms so far have been really good so hopefully they'll sort it out.
I wanted to go for a shorter diff ratio but this one was v cheap so decided to give it a go for a bit and keep my eye out for a shorter one. I did toy with changing the gs6-17 for a gs6-37 as in the 330, but with a 350nm max torque and as it's fitted to plenty of turbo 4 pots that make plenty of power, that and mine seems in fine fettle, I've left it alone. At some point I'll probably have it off as the car looks to have a little oil weap probably from the crank seal.
I'll add some photos later!
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Had my N53 325i E91 for a year now and tempted to map it, so this thread has been a really useful read and been good to see your recent update Tim: great work and thanks for the info and updates
