Do you think there's a chance of chip tune for X6 anytime soon?

[Timbuktu]

Hey, it looks like X6 35i has a very similar engine to N54 (if not identical).
Plus, the 50i seems to be tunable as well.
Do you think there's a chance of Vishnu or Dinan coming up with a quality tune for them anytime soon?

[shenard]

Originally Posted by Timbuktu

Hey, it looks like X6 35i has a very similar engine to N54 (if not identical).
Plus, the 50i seems to be tunable as well.
Do you think there's a chance of Vishnu or Dinan coming up with a quality tune for them anytime soon?

Not sure but I am sure hoping so. I would think 500-600HP should be achievable with a good tune on the V8 and I am sure Vishu, Juicebox, Helix, Dinan, among others will have a tune for the X6 35i pretty soons since it will be almost identical to the 335i tune.

[Suzie's Dad]

I would be inclined to take it easy on "chipping" the BMW TT engines until plenty of other people have done so without any expensive problems.

According to BMW, software is BY FAR the most complex part of the 35i and 50i engines. The engines use piezo-electric injectors, which open in about a millisecond, 30 to 40 times as fast as traditional solenoid injectors. They inject directly into the combustion chamber, diesel style. Because they open so quickly, they give very precise spray patterns and can be operated up to three times per cycle. One way BMW uses this is to reduce turbo lag. If the throttle is opened suddenly at low RPMs, a single spray is injected into the combustion chamber and ignited. This is a lean mixture. A second spray is injected when the piston is already a fair way along its power stroke. This late injection is still burning as the piston starts its exhaust stroke. The exhaust valve is opened early -- thank you double-VANOS -- so that a still-burning, still-expanding mix of gases is pumped out into the turbo. You can see in the many cutaway pictures that have been published that the turbos on the V8 are mounted on a small manifold very close to the exhaust valves. The still-burning mix expands in the turbo and gives it a "bump", spinning it rapidly up to speed. Very clever, but enabled by some pretty complex software.

BMW uses this same process to achieve their dramatic reduction in emissions. In fact, almost all that reduction takes place during the cold-start cycle. Again, you can see in the cutaway pictures that the first pair of catalytic converters is mounted right after the turbos, up there on top of the engine. First-stage catalysts only work well when hot. So BMW uses the same double-injection process to send still-burning gases to the catalysts, heating them up very quickly. "Lighting" them, in BMW speak. Also very clever, and enabled by equally complex software.

Finally, because of the precision offered by direct injection by piezo-injectors -- coupled with slick new spark plugs that double as knock sensors by detecting ionization in the compustion chamber -- BMW can run these engines at compression ratios above 10:1, which again enhances response. Hope the software that controls this doesn't hiccup.

Engine chip tuners generally modify the various 'maps' that the software uses to determine how much fuel to inject (and as a bonus they usually remove the top-speed limiter, which is just a simple software setting). They rely on the fact that the original engine designers leave a safety margin between what they think the engine is capable of and what the manufacturer's bean counters are happy with in terms of engine longevity and warranty claims. Turbocharged engines are particularly responsive to modification in this manner as you can increase the pressure at which the wastegate opens in concert with the various map changes. But once again, BMW has changed the rules somewhat, because their wastegates are not opened by intake air pressure but are vacuum operated under control of the ECU. Sometimes, in an ideal world, you want to be able to close the wastegate before it would normally be desirable, and vice-versa, you want to pop it open earlier than might be the usual case. BMW does this. More complicated software.

All of which is a long-winded way of saying that it will take some very, very talented tuners to fiddle around with software that is this complex without making a single mistake that could result in a pile of molten metal under the hood. I did see in one of the car magazines that somebody has released a kit ($600 or so?) that bumps power in the 35i engine, but I would like to see several hundred users drive 10,000 miles or more without any problems before I entrusted my mega-dollar engine to them!

Sorry about the long post. I get carried away...

[Palbay]

Suzie's Dad, A very informative post!! Thanks much. PalBay

[cheaptrick]

Great post as I was going to do a turbo tuner mod but will wait to see if others can get some problem free miles out of it. 600.00 for 40hp seems like a bargin. cheap