rudypoochris

Hey Guys,

I know I am in the "wrong" forum technically, but this was one of the few sites on the web with more knowledgeable pre-turbo WAI members. I hope you guys will help me out. I just got this built and running and my results were not really what I expected.

I think the information here will be applicable to your platform as well. At least that's what I hope.

Base setup:

1. 2008 335i N54 Coupe
2. Compression 10:1 with direct injection running 50-50 E85/91 mix
3. Boost set to 17.5 psi (stock is 7.5 or so) so way off the map making 430whp
4. After market intercooler and tune, no other modifications (stock DPs)
5. Currently limiting boost to save turbos. I am NOT octane limited at this time and could probably hit 19-20psi without losing significant timing
6. Turbo Tout is probably in the 350F range

Adding WAI:

I went with a Wannaspeed kit I modified. Two nozzles one in each cone filter injecting into 60mm intake tubes which have bends and such for about 2 feet before entering the turbos. The 50% meth/water mix is driven from a trunk mount tank with a check valve on the air line. Flow is measured using an Aquamist sensor with 100-1500ml/min scale (half graph is 750ml/min or so). Preturbo meth is triggered by boost switch at probably 8psi (just setup last night).

Pictures:















First Results:

I ran the car with and without the meth water running last night. I used the exact same map and ran within 5 minutes of eachother. On the no meth run I was going downhill, on the meth run I was going up hill. The intercooler is heat soaking way quicker with meth on presumably since the specific heat of the meth air mix is much greater than air only.

No meth:



Meth:



The curve to look at specifically (at least I believe) is "PWM". PWM refers to the duty cycle of the wastegate as controlled by the car. More PWM means the wastegate is held more shut. You can see PWM spike during spool up and rise the RPMs increase and the turbo is working harder to supply the required boost. In both logs, PWM is nearly identical. That is to say despite pouring 600-700 ml/min of meth water into the intake, the amount of work the compressor is doing has not dropped. I thought it would since the WA mix should be sucking up heat during compression leading to more air out of the compressor per turn (higher efficiency).

Am I thinking about this wrong? Am I set up wrong? Should I try biasing more water or more meth? Maybe the mix has completely atomized before the compressor due to my long intake tract?

Thanks guys,

Chris

Shaman

Try changing the turn on point until higher in boost. Have you seen a flow map to know when the turbos starting getting out of efficiency range? Also, what is going on in the 4th picture? I see what looks to be another nozzle setup, but want to make sure.

rudypoochris

Picture 4 are 2 feeds of boost air to the nozzles and 1 feed to pressurized the meth tank. None of those are injectors.

I haven't tried to turn the meth on later, but I m not really sure how that would change the work into the compressor?

I am well out of the turbo efficiency range. 50% or so if I had to guess (over 200k rpm easy), maybe less.

Shaman

Rudy, I was considering changing turn on to see what would happen. I didn't have any sensors or electrionic devices to show what was going on on my last car. I was thinking that since water injection can keep EGTs down, but isn't nearly as good at bringing them down, it might transfer over that adjusting the turn-on point. But now that I think about it, I do remember someone having the same experience on the Mazdaspeed board last year or two years ago. I can't remember what happened. Have you talked to RiceRacing, or posted on the aquamist forum?

rudypoochris

I was going to try the aquamist forum tonight. I will look up RiceRacing again, but last time I emailed them I didn't hear back.

Shaman

I didn't get much either from him when asking questions.

neit_jnf

iTrader: (17)

a long intake track for the water spray to travel may cause it to stick to the pipe walls and run as large droplets that may increase chance of compressor blade erosion and at the same time less atomized water actually entering the compressor. Can't comment on overall effect if any though.

Also, Rice Racing will just direct you to search for his posts online and not give much support unless you own one of his kits.

arghx

iTrader: (3)

Please, if possible export the data to a file that can be opened in Excel. Those screenshots are difficult to analyze.

What are you using to tune? Is it an external controller that intercepts DME signals or is it a reflashed ECU (Cobb AP etc)? BMW uses a Bosch Motronic MED system. Wastegate control is handled through the torque and air mass request calculations. It's very model-based control.

arghx

iTrader: (3)

Sorry, it's not Motronic MED, it's Motronic MSD. The point is boost control on this engine are very complicated and model-based. Here's a block diagram that BMW has published for the N54 boost control:

rudypoochris

Yeah, its Siemens MSD I believe. The boost scheme is strange, but the DME isn't controlling boost. The boost control is isolated and handled via piggyback (no flash). I may stack a Cobb on it to bring STFT down.

The files were CSV, but I had to convert to TXT for the forum limitations.