BMW 335i Software Tuning

Everybody knows the E90/91/92/93 335 with the N54 twin-turbo engine (now also the E60 535 and E82 135) is a tuner’s dream car.  It’s a simple formula:  if you have turbo(s), you can increase their boost output by changing the electronic codes that govern them.  This means you can achieve big power gains with only software modifications instead of altering the engine’s internal mechanical components.  And now that the engine has been in service for a good while, we’re seeing more and more software modifications on the market.  There are two basic types: downloads to the ECU, and “piggyback” systems.  Downloads actually modify the ECU software while the piggyback systems change the information going to the ECU, resulting in more boost, among other things. I’ll try to cover as many as I can, and bear in mind I don’t know nothin’ bout them newfangled computer thingys. 


Steve Dinan is very thorough to say the least.  His company took a long time to introduce its software download for the N54, and for good reason.  Dinan painstakingly researched and developed this software so it would not harm the engine.  Sure, it delivers a big bang at the dyno: 384 hp and 421 lb.ft. of torque.  But it also optimizes fuel and air mixtures at all rpm’s, increases the water pump’s flow as rpm increases, and has a lot of other features that make it safe for your engine.  You must have an oil cooler (factory or other), and Dinan even makes a higher-capacity oil cooler, along with an intercooler.  There’s an even hotter version out there, which requires the Dinan oil cooler, intercooler, and free-flow exhaust good for 398 hp and 429 trq. If you simply don’t want to buy an oil cooler, there is a milder stage 1 version, that still delivers useful gains.  If you want the full monty, Dinan will incorporate the engine mods into a Signature Package that includes their amazing suspension upgrades.  Dinan is expensive (about $2K for the download alone), but they have a warranty, and you do get what you pay for.


Like Dinan, Turner Motorsport offers a software download product.  You have to remove the computer and ship it to Turner, where they reflash it and send it back.  You’ll get a good +40 hp over stock; Turner’s dyno pull indicated 367 hp when corrected for driveline loss.  This reflash increases boost, adjusts the throttle, and changes fuel and spark mapping.  It costs around $1600.00.  I’m inclined to think this is another superior product, especially given Turner’s extensive history developing and racing BMW’s.


This is a “piggyback” system that consists of a computer and harness that plugs into the BMW factory plugs.  It has been on the market for quite some time, and it now in its third version (v3). This product produces some really big gains: it should get you 390-400 hp according to the website.  Owners who have installed this system are all over the forums and blogs, and they seem very impressed.  Vishnu often chimes in on thses blogs offering product advice and support. The system has some user-specific configurations, including a “valet mode” that puts the car close to stock.  Vishnu also offers upgrades to the intake and an exhaust system.  The baseline price is around $1495.00 for the PROcede, more if you go to a Stage 1 engine package, etc.


The Juice Box comes in a few different forms: the Stage 1 (JB1), Stage 2 (JB2) and the JB2 with “hot pill” and “X” upgrades for even more power.  The JB1 claims 20-30 hp and 30-40 trq. gains at the rear wheels.  The JB2 claims 40+ hp and 50+ trq. gains at the rear wheels.  Once you add a “hot pill” the gains increase even more, but you will have to run 93-94 octane (JB2H and JB2HH).  The “X” upgrade can be added to further increase boost, even allowing 16 psi with race gas mapping.  The Juice Box appears to be getting some good customer reviews, also.  The best part is the price: $99 for JB1, $379 for JB2.  There will be a JB3 soon. Looks like bang for the buck to me!


Active Autowerke has some experience with boosted Bimmers.  For the N54, they are marketing the Active Processor, which is a “plug ‘n play” type installation.  The processor can allow for “map switching” to tailor the system to the customer’s needs.  Active claims 55+ rwhp and 70+ retrq. gains with the sotck exhaust.  All for the relatively reasonable price of $795.00.


The Split Second Turbo Tuner is available from Bavarian Autosport and some other websites.  It appears to be the easiest to install, with just two wiring harnesses.  The SSTT claims an increase of 40 hp over stock.  It works in the same ways as the other piggyback systems, although it doesn’t appear to modify all the parameters they do.  The word is that the SSTT will rpoduce most of its gains at lower rpm’s, and the horsepower increase is mainly the result of a “spike,” and is not spread as evenly across the rev range as the others, especially the JB2.  Six Hundred Bucks.


I listed what appear to be the most popular software upgrades for the reader to peruse.  I really know next to nothing about computers, code, etc., so I can’t get into too much detail without ending up writing something that is totally wrong.  There is a wealth of information on the forums and blogs that has a lot more detail, and even objective empirical analysis.  The bottom line is you have to do the research and decide which product is the best for you and your budget.  And remember, be careful with increased boost.  Also, be careful with your car: you may have an N54 with the v29.2 (Progman) ECU; some systems will simply cause the ECU to throw a limp home code with v29.2, and possibly void your warranty.  Here are some links:


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