Preturbo 335i Strange Results
 

Hey Guys,

I have been reading up on WAI for a while and finally decided to take the plunge. I wanted to make more power, but my stock turbos are already far off the compressor map. I decided on pre turbo hoping to get more efficiency out of them. I settled on a mechanical setup as these are supposedly going to have smaller droplet size. I just got this built and running and my results were not really what I expected.

Base setup before meth/water:

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, fully catted)
   
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 meth/water:


I went with a Wannaspeed mechanical kit that uses air mix nozzles. I modified it quite a bit. Two nozzles one in each cone filter injecting into 60mm stock plastic 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 (not progressive). 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:

http://img.photobucket.com/albums/v4...ps9be9df47.jpg

http://img.photobucket.com/albums/v4...ps03b4b6dc.jpg

http://img.photobucket.com/albums/v4...psfd6dbae9.jpg

Just to clarify, none of the ports below are for charge pipe injection. That is all boost air to the tank or meth nozzles.

http://img.photobucket.com/albums/v4...ps690c684c.jpg

http://img.photobucket.com/albums/v4...ps755b8143.jpg

http://img.photobucket.com/albums/v4...ps0283e56b.jpg

http://img.photobucket.com/albums/v4...ps50e53dad.jpg


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 each other. On the no meth run I was going downhill, on the meth run I was going up hill. Ambient was 55F the no meth run started at 59F and the meth run at 69F IAT.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. Usually I see IATs no more than 10F above ambient. After one pull with meth I was at 25+ over.


No meth:


http://img.photobucket.com/albums/v4...ps372c3733.jpg


Meth:

http://img.photobucket.com/albums/v4...ps9868f79e.jpg

Note the faster rising IAT, identical PWM (wastegate duty), and surprisingly reduce timing at start of run (fluke?).

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 as 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? Do I need more flow?

Thanks guys,

Chris

Re: Preturbo 335i Strange Results
 

Interesting project.

Water at ambient is about 1000 times denser than air. I can only assume the compressor is doing more work when methanol was injected on top of air. It is natural to require more energy (PWM) to accelerate a rotating mass.

How is methanol flow regulated (flow control), is it progressive with boost or engine load?

Re: Preturbo 335i Strange Results
 

So basically the shaft speed may be less, but the work is around the same? Then really the turbo is seeing less "damage" due to overspeed but roughly equal thrust loading wear?

Methanol comes on at a boost switch set too low atm (8psi). It is not progressive at the moment, but I may switch it to be progressive with boost. The check valve makes it not progressive since the tank is pre-boosted to whatever the last pull left it at.

Are other people seeing reduced shaft speed or reduced work with pre-turbo meth?

Re: Preturbo 335i Strange Results
 

I am also seeing something else funky. My DME is pulling timing when the meth hits some of the time. Usually this is due to knock, but it doesn't knock/pull timing at these same RPMs with no meth.

http://img.photobucket.com/albums/v4...pscda37c3d.png

http://img.photobucket.com/albums/v4...ps17dc5306.png

http://img.photobucket.com/albums/v4...psd94845b5.png

Timing loss is only on meth onset and I am not progressive. I wonder if its flooding or something.

Re: Preturbo 335i Strange Results
 

Although water is heavy but compared to the mass of air going through the turbo, it is much less. There will not be to much variation on the BCV's PWM.

You cannot guarantee the distribution of water drop when it travels toward the compressor wheel. Some will pool on the flange wall and migrate/trickle towards the utmost tip of the turbo. This will exert most load on the turbo. Long term, it will unbalance and pit the compressor wheel, followed by excessive shaft wear.

I am not sure why you are using methanol instead of water. Water has more cooling capacity.

Until you have balanced the air against the meth flow fed to the nozzle, you cannot
guarantee how well the mixture is atomised. I suggest running run water for one test, clip the jet on the windshield and see how well the spray is atomised. (driving test)

If you have a air compressor handy, you can do it without driving the car. You can also measure exactly how much water/methanol is injected for 1 minute.

Re: Preturbo 335i Strange Results
 

Are you sure it is knock? I would check the STFT and see you are having methanol inbalance distribution to the cylinders. You can do this by comparing the two banks.

Can you log individual cylinder timing? This is a real useful tool for your kind of project.

Re: Preturbo 335i Strange Results
 

If PWM/work doesn't drop, what is the benefit of injecting pre-turbo? I thought the idea was to get more air through the turbo before going out of the efficiency range (increased efficiency). It seems if work in is the same and so is boost air out, that I haven't changed the efficiency at all. Or is it that the turbo is equally efficient, but can handle more flow before overspeed?

Are people actually documenting erosion? I haven't been able to find a solid source of it yet? It makes sense to me for large droplets or saturated walls, but it would seem the walls of the tubing in the engine bay are quite hot and the speed of the air high enough that pooling probably doesn't occur. I of course have no way of testing for this right now. I do know though that a lot of PCV is diverted through the turbo inlets and that does not erode the compressor despite being likely significantly larger unatomized drops.

Interesting. I might do the atomization test. I am not sure how knowing exact water/meth quantity will help. I do have the aquamist flow sensor feeding into the DME though and you can see it in the logs above. Half scale should be 600ml/min or so.

What do you mean by balancing the air against the meth flow? You mean the flow into the 2-port nozzles? The boost air will always be higher than the pressure of the fluid by a couple points. Say 17.5 psi boost with 15ps or so water/meth.

I am using a combination of water/meth since I speculated meth evaporates quicker (reducing chance of erosion) and because the meth helps out with the fueling a little bit. I could go full water or full meth if I needed I guess.

Re: Preturbo 335i Strange Results
 

I need to flash the DME to log individual cylinders. I could do this if I got a cobb... maybe I should do it. How could there be an imbalance if I am injecting pre-turbo into both turbos? Even if there was imbalance, I have more than enough E85 in the fuel itself to cover the boost targets I am testing at. It could be the DME reducing timing for some kind of torque reduction (according to the tuner), but I don't think that it. Weird.

The STFT are on the graphs as "Trims". They are almost maxed out since I run a lot of E85 with no flash.

Re: Preturbo 335i Strange Results
 

Dismiss the STFT for the time being. In the absence individual cylinder log, it is not easy to go further on finding the cause of knock.

I cannot think of any way to pin point how the timing was trimmed, other than it was caused by meth injection.

Re: Preturbo 335i Strange Results
 

It is quite tricky to set up an air assisted nozzle. You really need minimum amount of pressure on the fluid and ample air pressure. If you have too much fluid pressure, the atomisation is not that good.

Look at the following pictures, the difference is very visible.

http://www.aquamist.co.uk/forum/air-jet1.jpg


http://www.aquamist.co.uk/forum/air-jet2.jpg

Re: Preturbo 335i Strange Results
 

I can throw a pressure regulator onto it no problem - can you recommend a pressure? Currently flow is controlled using a simple valve with a screw on it. I can tighten that up as an alternative.

Re: Preturbo 335i Strange Results
 

I cannot say a specific pressure that will work. You can to get a couple of inline needle valves and calibrate it.

I am not much good at mechanical solutions. It requires patience. I don't have an electronic solutions either. Might look into this in the future.

Just to give you can some idea how sensitive this is. The water is drawn into the nozzle by capillary action, aided by the partial vacuum created by the venturi effect of the pressured air running over the water line (black hose).

When I alterd the height of the nozzle relative to the water level, the atomising quality varied a great deal. I carried out this experiment out of curiosity. I modified one of our standard nozzle to be air assisted with some success but the difficult part is getting it to work with consistence. It turned out to be very involved. Something to revisit in another day.

If STFT and WGDC is not conclusive. Individual timing is not available. You are now left monitoring temperature. Perhaps this will give you some useful feedback. What about mis-fire code?

Re: Preturbo 335i Strange Results
 

No misfire. IAT rising with meth. Maybe too much fluid condensing on the IC driving up temps? Still doesn't explain knock since the E85 is good until at least and 3 psi over these logs. I could see the atomization being poor and droplets of water entering the combustion chamber on first onset if the liquid pressure is 17 psi and the air only 8.

Re: Preturbo 335i Strange Results
 

You need to do two things:

1. Get the atomisation good
2. Either measure the flow or manually measuring it over one minute.

It is difficult to do it without a compressor. May be empty a jet into a sode bottle after one minute of boost (careful, not many roads and sustain one minuter of full boost).

Calibrate the flow sensor with a normal flow. Jeff told me you have problem with the logged sensor signal. If the BMS logger is not reliable, read the floe signal with a voltmeter. You only need to make a quick note of the voltage at full boost. Once done, repeat it on a bench with water from a tap and match the same voltage for one minute. see how much water is collected.

Re: Preturbo 335i Strange Results
 

I can use the retained boost in the tank to check flow. The BMS logger is fine. I think I am getting interference from the car. I suspect the flow readings to be approximately correct though. Will look into it.

Re: Preturbo 335i Strange Results
 

Not sure how your method of measuring flow but will accept your posted flow rate of 650cc/min. Potentially you can remove up to ~30KW of heat if the water is fully evaporated.

I same Jeff's oscilloscope trace of read on more than 0.06V of noise (includes back ground noise). I think your public comment on one of the forum stating the aquamist flow sensor has a oscillating signal of 0.2v to 0.8V. that is 0.6V is unfounded. I would be grateful if you can make a post to correct this finding.

All good logging device should have some sort of high-pass, low-pass or band pass filter. I guess the BMS logging software does not have this facility. This is what I meant before as unreliable.

Re: Preturbo 335i Strange Results
 

I updated that thread just now to clear it up. The jb4 has a fat filter in front of it and reads clear for many other voltages sources. I don't think it is the jb4 but I also don't think its the sensor.

I logged the sensor with the DMM, JB4, and an independent 100hz logger. The oscillation is there. Likely it is not the sensor itself but noise as I have 5ft of line across the engine bay. I also talked to my coworker who is an EE and he suspects bad ground or noise. I will remove the sensor from the engine bay and test. If its still nasty looking, I will cut the wire at the sensor, ground it there, and install an LM7805 to control the scalar voltage to 5V precisely.

The logging on the JB4 reads 0-5V and thus half scale is equivalent to roughly half flow. That is how I got the ~650ml/min figure. That figure is also what the manufacturer quoted the nozzles to flow at, but obviously it can vary.

Re: Preturbo 335i Strange Results
 

This is the 100Hz log using my USB logging tool. 3.33Hz oscillation, again probably interference.

http://img.photobucket.com/albums/v4...psc2718b76.png

Re: Preturbo 335i Strange Results
 

The oscillating signal is 0.8v (pk to pk), quite a large swing.

The aquamist sensor generates a "sensor presence" voltage of 0.53V to alert the controller of its readiness to read flow. above this voltage, it is allocated for flow monitoring. The flow signal peaks at ~4.5V. Above this signal, it is a fault. So the sensor itself has inbuild failsafe to warn the aquamist controller.

Back to the plot. The BMS logging system appears to have picked up some noise and superimposed/modulated itself onto the aquamist's. The source is unknown but worth finding it out. It is definitely not from aquamist.

Jeff (aquamist US representative) has power up a similar age sensor to yours and sent me this captured image from his oscilloscope. this is what it looked like:



Where are those ghost oscillation came from? I am very interested to find out. Try disconnecting the green wire and make another plot.

Re: Preturbo 335i Strange Results
 

I will test. Again, this is NOT the BMS log. This is from a completely different standalone 4 channel logging tool which confirms what my JB4 (BMS) was seeing as well. This oscillation must be coming from somewhere, likely interference.

Re: Preturbo 335i Strange Results
 

I think we can now focus on the job in hand.

Correct me:

Meth off:
no timng pull, iat inceased with load

Meth on:
timing pull, iat increased considerably. (edited)

Re: Preturbo 335i Strange Results
 

Close. More like this (have logs if you want me to email them):

Meth off:
No timing pull, iat increase only 5F (normal)

Meth on:
Timing pull, iat increase 22F (abnormal)

Basically the opposite of what I hoped for. Maybe the liquid is not atomizing? Condensing on the IC walls? Since I have a check valve to the meth tank, when meth comes on at 8psi manifold, the tank is still seeing 18psi or so from the previous run. This is a problem for atomization. I will remove the check valve and have a pressure regulator on order.

Re: Preturbo 335i Strange Results
 

This a very interesting. I like to go a bit deeper.

If you can email me the log richard-at-aquamist.co.uk. The charts you posted are not easy to read, some of the colours are very similar. Please made some simple comments with the log attachment.

Question did you do the windshield observation test? If so, did the spray looked good?

Re: Preturbo 335i Strange Results
 

I'm interested in the outcome as I have the same air assisted nozzle plumbed into an aquamist hsf2. Testing flow without air pressure on the nozzle and with the flow valve turned to minimum I get 400cc min.spraying into a gallon jug by activating the hsf test procedure. I have not verified for atomization but assumed that atomization should be fine by keeping flow down.

I also have a solenoid in the air line going to the air assisted nozzle that opens at the hsf activation.

I don't see how you have it connected but you may want to add an air solenoid in line going to each nozzle so as to avoid over spinning the turbos before 8 psi.

Why do you have a check valve if you are running a water valve? When closed it should prevent dripping.

Is your system maf based? Although the air returning through the system, I would be worried about the effect it had on metering.

I'm worried now about the pressure and atomization.

Re: Preturbo 335i Strange Results
 

I believe the set up is purely mechanical. The manifold pressure is fed to tank (via a checkvalve) as well as to the nozzle.

Re: Preturbo 335i Strange Results
 

I would assume that 2 lines from the charge pipe to open nozzles is a fairly large leak even if the air is being circulated past the maf sensor. I suspect that's one issue for increased iat.

If there's an 8 psi check valve on the water tank wouldn't that mean reduced water pressure as it has to overcome the check valve?

Re: Preturbo 335i Strange Results
 

Yes but there are 2 lines from the charge pipe directly to the nozzles unless he has a second check vslve there too.
Seeing as how I see 3 ports on the charge pipe, I think it goes directly to the nozzles...ie constantly bleeding pressure

Re: Preturbo 335i Strange Results
 

You could be correct, I am not absolutely clean how the setup is routed. There are a few blocks, not sure if they are valves or checkvalves.

He will be posting more, hope to have a diagram to see how the whole thing is connected up.

Re: Preturbo 335i Strange Results
 

I did a boost leak test once and forgot that I had the air assisted nozzle connected. I was surprised how big the orifice was on the nozzle. It's likely a bigger problem since he has 2 of them.

I could be wrong though. Either way, I would switch over to solenoid to avoid the pressure drop from the check valves.

Re: Preturbo 335i Strange Results
 

Do you have the same car, a 335i? I believe he has a solenoid valve as well as a checkvalve. The water line is triggered by boost (post throttle). Not sure he if has the same arrangement on the air line.

If his car does not have MAP in between, it may not have mattered. I think the 335i is a speed-density fueling system.

Reducing the water pressure relative to the air pressure can only improve the atomisation.

In any case. the setup should be bench tested before installation, baseline data helps to trouble shoot should if things are not going according to plan, as happened in this case.

He tests were done on a ~45F environment. Water/methanol droplet will condense when it passes through the intercooler. I expect the cylinders would receive varied amount of water/methanol. The DME was unable to trimmer fuel flow to each cylinder as there are only two lambda sensors, one for each bank of three. This could be the reason why the reason was not good.

I think one should only injection just enough to cool the turbo. He is injection around 650-700cc/min.

Re: Preturbo 335i Strange Results
 

Half knowing what his system consists of, Is it possible the the ECU is pulling the timing out due to the increase in air temperature?

Re: Preturbo 335i Strange Results
 

No, the timing was being pulled from way too much water all at once. I will diagram the system tonight, but basically the check valve kept tank pressure at peak boost but the solenoid would open at 8psi. At this point in time water pressure would be way higher than air pressure and likely the turbos sucked up a lot of unatomized water. As to why that caused timing to be pulled, I don't know, but it did.

The 335i is a map based system. I am not concerned about the miniscule boost leak to be honest. IAT rising does have anything to do with the boost leak. It only rises with meth on, but even with meth off the boost leak is there.

I am trying to turn down the flow with no reported success (sensor shows pretty much the same flow with the port almost completely closed. I am diagnosing this now since I have sensor issues. What do you guys use for flow control valves?

Re: Preturbo 335i Strange Results
 

Im pretty sure its the same flow valve you have. I want you to try something! take the check valve out from the tank, this means the tank will only be under pressure when you turbo is producing positive boost. This will likely help prevent the the sudden spike in flow pressure which could be the reason behind your problems. also make sure your flow sensor is after the solenoid and on the liquid side of the nozzle.

Re: Preturbo 335i Strange Results
 

Just a thought - from reading the preturbo injection thread on here I understand the effect on the turbo efficiency in simple words should be that more air mass is pumped by the turbo at same boost pressure.

Now you say your system is MAP based and you expected to see a difference in wastegate solenoid PWM. If my understanding above is correct you wouldn't see any difference as your ECU is boost referenced rather than air mass referenced, so it keeps the boost as desired and simply may not recognise that the air mass and engine torque produced is wrong (higher) due to changed turbo map.

Now, if this guess is true you should see leaner mixture with preturbo injection. Do you have a AFR meter to check? This would be an extremely interesting info....

Re: Preturbo 335i Strange Results
 

subscribe . interesting test and results.