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Official: US Spec 335d/X5 35d Performance Mods

40K views 100 replies 24 participants last post by  TDIwyse 
#1 · (Edited)
While this isn't quite the performance mod crowd, I figured it'd still be nice to have a collection of the information. With the 335d/X5 35d still pretty new to the states (just over a year now, with 3 MY's), I expect this list will be short still for a while, but I'm hoping that other people know some things I don't and we can add to this list. If there are other categories I should include, please don't hesitate to tell me. You'll notice the only thing I have listed is tunes, because frankly, I'm unsure of any other performance mods for the car. So, if you know of any others, please, feel free to chime in. :)

Tunes
JBD by BMS
DTUK Multichannel Unit
DTUK Multimap System
VAC Intelligent Diesel Control Module

FMIC

DCI/CAI

Exhaust

Propane
 
#39 ·
I'm about to send VAC an email about my impressions, and until I get their feedback, I don't want to say anything yet.

I will say that I noticed an improvement in gas mileage. :)
 
#40 ·
Does anyone know how high of pressure these boxes are pushing the common rail system? I know from the early days of the common rail trucks in the US (Duramax, Cummins) that the first power modules where devices that plugged into the common rail sensor connector and fooled the ecm into making more psi which gave more fuel per injection event. The problem is the injectors start to crack if exposed to too much psi and extra wear and tear on the HPFP can occur. Increasing pressure can lead to radically decreased injection system lifespans.
 
#43 ·
Depending on the unit, I get SES and error codes specifically citing common rail pressure plausbility...if that gives you any idea. :p
 
#44 ·
Received the tuning box from VAC today just before my lunch meeting. Just as I was getting ready to leave, UPS dropped it off so it l can say that I installed it in under 10min wearing a suit. Not bad for "plug and Play" but I assume the competitors are just as easy.

It was easy to notice an immediate difference in both throttle response and seat feel. As strange as it may seem, it even sounded like the motor was happier. Probably result of more HP revving up more quickly.

From what I've read, it looks like the JBD would be even more of a difference. It is tempting so maybe I'll go that route once her legs are stretched a bit. I'm in contact with VAC and it sounds like they may consider making some adjustments/stage options. For now, I can say that I am pleased knowing that its a bit more of a conservative approach as these things really haven't been tested long term. Either way, I am happy enough for now.

My wife drove tonight and was very impressed as well... For the 5min she drove:yikes:
 
#46 ·
I have had my VAC module for about 4 months now and I love it. It gives you a nice extra punch and makes the car feel so quick, especially from 70-110mph. I am really curiors to see have the JBD fairs against this module as I know at some point I am going to want even more power/speed!
 
#47 ·
Any updates on an exhaust? Had a lot of people mention how quiet the car is for a diesel. I still hear the knock inside the cabin but would like to drown it out with a nice sounding exhaust.

I have always ran Milltek on my Audi's. Is there anything available yet for the D's?

Same question about the CAI - is it really necessary or just drop in a K&N?
 
#52 ·
You will see an increase on the car's computer but that isn't accurate because it's tricked into thinking the car is lean on fuel. If you make more power and use it, your mileage will drop. Mileage is certainly good enough for me with the JBD at 100%. Around 27 mpg.
 
#53 ·
I know the JDM or whatever it is called does the false readings on the computer. That is not the one Ronin said he saw an actual increase in mileage with and I'd think he would know best since he has tried out a few of these now. I'd also think he would be smart enough to be commenting on real world increases and actually pretty certain he said that.
 
#54 ·
I also think he's smart enought to know if you make more power and USE it, your mileage will drop.

I know you have doubts about the JBD but you really should try it. On the other hand, if all your concerned with is mileage, I'd stay stock.

Where is the lad anyway??
 
#56 ·
Ronin's comments were not about Terrys product. Ronin has already said he say no increase in mpg from Terrys product. He said with one of the others though that he did see an increase. If you have more power and use it then yeah your mpg will drop. I care because guess what, most of my driving is just normal driving and an increase in mpg then becomes a selling point. That is why here soon I will order an SCT for my truck.
 
#57 ·
Sounds awfully vague to me. Do you have some documented proof ? Don't you think they all do the same thing, which would be dumping more fuel in to make more power ? I guess I don't understand the mindset of needing a few more miles to a gallon in a car like a 335d. High twenties is plenty good enough. :dunno:
 
#58 ·
Documented proof? If you don't want to trust my memory of his posts and you don't want to search for it on this forum then send him a PM and ask him directly if you really care that much. If one thing adds power and mpg v. another that just adds power then I am going with the one that gives me gains in both. The SCT for my truck has added power and a 1-3 mpg increase for five of my friends, do the math and it quickly pays for itself then puts money in your pocket. I never have been overly happy with high 20s in this car, my 26 year old Mercedes does better than that and has more seating room and can fit a dead body in the truck, obviously if I compare the two I ignore the power differences because they mean nothing to me while cruising down the road at a constant speed.
 
#59 ·
I never have been overly happy with high 20s in this car, my 26 year old Mercedes does better than that and has more seating room and can fit a dead body in the truck, obviously if I compare the two I ignore the power differences because they mean nothing to me while cruising down the road at a constant speed.
Your 26 year old 300D does better because it puts out 90hp. It's a freakin tractor motor. :tsk:
 
#60 ·
My experience with the Vac module is about a 1-2 mpg drop in MPG. I routinely get about 28 MPG in mixed driving and about 34 MPG on the highway with cruise set at 80 MPH. Prior to the Vac I was gettting 36 MPG on the open road. Remember that I live in South Florida, so driving is pretty much all flat and temps are typically in the high 80's with humidity even higher.

The small loss in MPG is of no concern for me because the increase in fun greatly outwieghs this.
 
#61 ·
As with any mod though that adds power if you actually use the power then you use more power. I have a buddy with a chip on his truck and will say it can pass anything on the road but a gas station. But he has a really heavy right foot and literally all the time. Then I know others with same exact setup who actually see a gain in their mpg but they pretty much never use the added power instead of Mr Lead Foot. I don't know if the Vac is even the one he said he saw the gain with. All I know is he said with one of them he did see an increase in mpg and he is the only person who seems to be comparin them all.
 
#63 ·
OK,

I'll take the bait.:p

You can add Power and Increase MPG. The two can certainly go together assuming you were not using the fuel most efficiently before the mod was made.

I see it all the time in our large bore medium speed engines putting out some 1,300 hp per cyclinder, with a total of 18 cylinders. These are single engines putting out some 24,000 hp each.

There are plenty of ways of doing this. Boosting charge air pressure by improving efficiency of the turbos (tweaking with the pitch of the nozzles and/or turbine blades, use of anti-fouling materials, etc...). Basically you are making the turbo more efficient at using the waste gas and heat. You can get more power and you can improve efficiency.

Another way is to tweak with inlet and exhaust valve overlap. This used to require replacing valve cams but now they have electronic adjustable cams that can shift forward or reverse to advance or retard valve opening.

Same goes for fuel injection. You can improve the design of the injector tip, improving atomization and spray pattern.

You can also tweak with the piston crown, changing the shape and contours, increasing compression ratio and improving the swirl effect during injection and combustion.

In some large diesel engines recently they are using something called Miller Cycle which requires higher charge air pressure (so very efficent turbos) with increased valve overlap timing (which makes the increased charge air pressure actually push the piston downward near the bottom of the combustion stroke. These engines have demonstrated markedly better fuel efficiency with same or better power.

Now the hot item is same as seen with our diesel cars, electronic common rail fuel injection, where you have highly accurate timing of start and end of fuel injection.

You can also employ high tech ceramic materials and coatings that retain heat better and use TBC (Thermal Barrier Coatings).

So, in conclusion, there are plenty of modifications that can increase power and increase MPG.:thumbup:
 
#64 ·
I meant to peck more mpg but as usual was being rushed off my phone and pecked the wrong thing. Btw a member on here claims his real world mpg increased with the JDB. So either he is full of it or something about his driving needs and style combined with the mod have resulted in that benefit.
 
#68 ·
Well, we know the JBD mod only messes with the computer controls, so there is no actual tweaking with the mechanical components.

Doesn't mean you can't still improve power and MPG however.

As far as I understand about the posts the JBD is allowing the computer to deliver more fuel (and I would assume more air) and thus more power given the designed program.

I would also assume that with the increased power and perhaps increased efficiency, they may be giving up on some of the emission controls. You can't get everyting.

Stugouts posted some dyno graphs that demonstrated increased power as I recall, so it is not a myth.

I would not debate any improved mpg until I saw that as well, as there are a lot of variables associated with proving that is real.

We also know that the OEM's generally put controls to protect the vehicle and these are going to be somewhat conservative, so there is definitely room to improve.
 
#69 ·
I think it might be tricking the computer to run more boost and therefore more fuel. But I do not know for certain.

13.1 seems to be a good bit faster than what the guy here got on the dragstrip in San Antonio. I did not read the thread though, are those times actually from a dragstrip or times from some sort of tool used on the street?
 
#70 ·
I think it might be tricking the computer to run more boost and therefore more fuel. But I do not know for certain.

13.1 seems to be a good bit faster than what the guy here got on the dragstrip in San Antonio. I did not read the thread though, are those times actually from a dragstrip or times from some sort of tool used on the street?
From what Terry says, there is very little increase in boost. As I already stated, the gain comes from tricking the computer into thinking the motor is running lean therefore dumping more fuel in, which is how most of these type of diesel boxes work.
 
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