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My life in the slow lane: Turning a z71 4x4 335I into something respectable.


Chris Welter

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Well, John asked me if I'd do a build log on here and I said I'd give it a shot.  So here is my college try.

I purchased a 2009 335xi AT about 2 years ago and originally had no plans of modding it, but funny how that always changes.  Seriously though I had no idea what engine the car had or anything when I got it, but after some research the wheels started turning.  Like everyone here I started out with the basic "Tune" for the N54 (JB4 G5 ISO).  I was amazed at what the simplest of changes made the biggest power, but about 6-7 months later I started with the turbo rattles. Time slip in picture was only with the BMS cone filters and the JB4.  It was also a green light start (explains the reaction time).  

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However, while in japan on some military duties I tossed the idea around of upgrading said rattles to RB or vargas.  The big problem for me was realizing how far I wanted to take this.  I saw a lot of stuff online about how the xdrives are slow and garbage, so it was disheartening considering this is what my little unicorn was.  So this led me to what I like to call the "F**k It!" phase where I just decided that in order to be fast I'd have to manual swap and go RWD.  Since that was gonna cost a small fortune I went and bought the biggest turbo setup I could fit on an Xdrive with all the accompanying parts.  

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By accompanying parts I mean the PI kit, stage 3 fuel pumps, VRSF 7" FMIC, MHD back end, and all the other requirements to go full e85 with a big single.  As for the turbo size, I went with a 6467 comp.  The original kit came with a 6465 but I was worried about back pressure and new the engine would need more flow on that end to perform well, so I opted for the bigger size turbine.  Once the kit arrived I went and had some ceramic coating done from a family member on the headers.  

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It was at this point (turbo mocked in and ready to tighten) that I remembered I didnt have an oil cooler from the factory.  No big deal though, went and found a blown engine and bought the housing off it.  However here is where the controversy starts, I installed a low temp therostat.  Now the thermostat isnt the issue, its the cooler mounting people have issues with.  I mounted my mishimoto behind the grille (drivers kidney).  Some people say it blocks the radiator (it kinda does) and its an issue, however I havent seen any problems with it as of yet and as an added bonus if I throw my JB4 in MAX COOL mode I can pull the oil temp down from 230 after a good hard long couple pulls to 180 in under 5 minutes.  With that being installed I'll toss up the pic of the turbo mounted as the car was pretty much finished minus the programming part.  

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As it stands I've run the car up to 26psi on the turbo (blew out an 02 sensor and havent replaced it yet).  I can say even when working out the bugs this thing is an absolute terror stoplight to stoplight.  Fun fact: this turbo kit has only been installed on 3 xdrives, one in canada, some guy in arkansas, and me so thats reassuring :P

This year i'm ironing out the rest of the bugs, adding the new manifold and 4 bar map sensor and anti-lag kit.  Going for the xdrive 1/4 record, i mean pick your battles right? :lol:

But seriously, it will break a record, or Im gonna break it trying.  4L80E swap is supposed to arrive this year, so if the driveline breaks i'm going that route. 

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7 minutes ago, Snap said:

The size of that turbo tells me you are trying for 700+hp, is that an accurate assessment?

And

Dont

Stop

Posting

That would be a valid assessment.   Didnt really think it out at the time, but it sure is a lot of fun!  :D  I mean, imagine a FBO car, plus a bunch more power and literally 0 tire slip off the line on the street.  Literally feels like a slingsot is hurling you forward.  If the car breaks i'm upping the driveline and I could see a precision 68-70 gen2 in my future with a built engine.  

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6 minutes ago, suspenceful said:

Great build. Like Snap said... don't stop posting!

Are you still auto? If so, I don't think it will last very long. And apparently the Level 10 upgrade hasn't been working too well for the high horsepower folks.

I'd love to see what that thing puts down on the dyno.

It is still an automatic.  I'm not overly worried since the 4L80E swap will be out soon, but i've done my research.  I have a friend over by chicago that is running the RB's and has close to 600 launches on his xdrive without a single slip.  Rumor mill has it there is something different with the programming, but only time will tell if that is true or not.  Havent seen a slip yet myself either so my fingers are crossed.  Dyno will come once I get it back running right (this spring) and get a trailer to haul it to chicago.  

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The 4l80e swap is being done by a relatively small company.  Supposedly there is a Ford 8.8 rear end swap involved as well.  I've tried to get more info from them but all I got was the basics so here it goes....  The kit should use a 4l80e (you supply it) but will come with everything you need to get it running.  I guess the way the system will function is the car will be reprogrammed to think it's a RWD manual (eliminate s all talking to the other controllers) and a 4l80e standalone controller is used.  I believe the kit also adds steering wheel paddles to send shift signals to the trans.  The rear end kit comes with all the custom mounts and dss axles/ custom driveshaft to make that work.  I have been told the xdrive won't work as the tunnel is too small to hold the trans and fit a driveshaft going forward.  So that also leaves me 2 options..  cut front axles and remove the pumpkin ect, or get a $500 rwd front subframe and switch the front end over while removing the xdrive parts.  I would like to do the latter option as it involves no ghetto axles.  But if it breaks my hands are tied.  The other good part about the latter would be the ability to install M3 control arms and suspension bits.  I know my rear end will be getting the m3 arms ect..  I was told the reason for the 8.8 was because gearing options and cheap parts availability while keeping the bmw suspension as it is.  Combine all this with motiv's closed deck motor and all the tuning advancements made and I think we will see the first 1000+whp N54 this year.  As well as the first 8-9second 335i.  

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awesome thread, awesome car, IMO, despite the automatic transmission. I think you made the right decision here. Honestly on a car like this with a 7k redline and for what the gear ratios are, if you have a big single turbo and are going to end up making 700+ hp, having a manual transmission just becomes useless, truly. And if you don't care about rowing gears, then who cares. I think your plan of upgrading the transmission to the 4L80e is perfect. 

My favorite part of this was reading about people who say that an xDrive 335 is garbage. I personally prefer RWD but honestly, but mainly for track and tossability. How can you argue with a car that's driven on the street, having like 500-700 whp, and having AWD to put it down to the pavement? That's still badass, lol. And it'll put every dumbass Subaru bro kid in their place, to boot. 

When you break into 10's I'll take a ride.

as an aside, with all these cars in our group being up north, I may need to make some rounds this summer lol. I do some software contracting on the side for a company based in Appleton/neenah area and I'm due for a visit and some drinks with the guys I work with. While I'm up there I want to see some of these vehicles. I'm guess the closest in proximity there would be you and Jake. 

 

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