each situation is different
 

I think the answer to your question can only be answered in context of a specific engine turbo setup, and your specific performance goals.

If the turbo is of adequate size, so it can feed the engine without straining at max rpm, and your going for max power, then post intercooler would likely be the best in my opinion.

If the turbo is a bit undersized and your pushing its air delivery capability, then I think either pre-compressor or a bit of both would be best.

There is also the consideration about ease of implementation. If its nearly impossible to squeeze a spray nozzle inbetween the intercooler and the throttle body (which is almost the case for the WRX) then the simplicity of pre-compressor injection has to be considered as well.

There may also be an advantage to over injection pre-compressor or pre-intercooler and then cooling to super saturation. It would be hard to beat a true fog of microscopic water dropplets for detonation protection I suspect. Only testing will tell for sure.

It's obvious that the WWII military aircraft did quite well with pre-compressor injection, so it may be that the only thing that really counts is the suspended water fraction and it may not matter much how it gets there once its in the cylinder.

I guess the question is, which of several problems is the most urgent for you to resolve on YOUR setup. Detonation (not an issue for a diesel), might depend on the degree of evaporation vs suspended dropplets in the combustion chamber, high EGT's (probably only dependent on the total water fraction, max power ( depends on highest VE so pre-intake valve cooling would dominate).

I think we sometimes forget that WI can be used to resolve several different problems and the setup that most effectively solves one, may be less effective for another.

Larry

Well put. Evaporation would seem to me important also from the combustibility aspect. Using a meth solution, meth drops (liquid) are worthless to cylinder power enhancement (correct me if I'm wrong). Only once it is a vapor, is it explosive. Dry air (desert SW) would seem to be a real advantage, as so much water AND meth can be vaporized. (thinking out loud)

A friend on-line claims he has reached 127HP using WW fluid, in dry Colorado, 6000 ft altitude, won't share much of the details, but he claims to have unusual nozzles and very high pressure.

humidity and dropplet size
 

There are several WI diesels up here that are very quick for their size. A couple of them run in the 13 second range. It's kind of funny to see a heavy duty diesel pickup beat a supposedly fast car in the quarter mile. We also have a turbocharged diesel dragster up here that runs in the low 10's high 9's. It's so much quieter than the AA fuelers that you can litterally hear its slicks chirping the full length of the strip.

As you know from where you live, ultra-low humidities are pretty common up here, and in the desert sw. During our forest fire summer a couple years ago, the fire fighters were absolutely stunned when they got morning fire weather reports that they had temps of 80+ deg F and RH humidities of 6%.

That is one of the reasons I have such good luck in the summer with the pre-compressor injection.

Your correct that only the vapors are flamable, but dropplet size is also important. Very small dropplets of fuel vaporize very quickly during combustion due to their very large surface area to volume ratio. It's only an issue if the fuel dropplets are too big to evaporate during the combustion time. This becomes a problem with fuels that have high 90% evaporation temperatures, (like xylene spiked pump gas) that can end up blowing still burning fuel drops out the exhaust valve, giving very high EGT's.

Larry

Re: each situation is different
 

Could you elaborate on this part? You are talking air charge density I think. Drops vaporizing in great quantity at the 1000 F valve opening to do what, lower temps and condense more air into the cylinder before detonation? The liquid is important then. Does the meth enter in?

intake charge cooling
 

There are some differences between diesels and gasoline engines so that needs to be considered. As far as VE increase is concerned, it is clear that charge air cooling due to evaporation helps inprove VE all else being equal.

In one of the NACA studies they tried injecting the WI mix both well before the intake valves and immediately before the intake valve. The postion that was "pre-vaporization tank" was several feet from the intake valve and the other injection point was only inches from the intake valve.

Study E5E18 page 5.

"For vaporization-tank injection, the mixture temperature decreased as more internal coolant was injected until the fuel-air mixture became saturated (fig 12) and then the mixture temperature remained relatively constant. In a corresponding manner, the power at peak-power spark advance increased because of the increased charge weight inducted into the cylinder until the internal coolant-fuel ratio for saturation was reached ( fig 13), at which point the power leveled off. After complete saturation of the incoming mixture with the internal coolants, any additional cooling of the mixture must occur after the intake valve closes, which makes it impossible to increase engine power through an effect on air flow. From this point, the power obtainable at peak-power spark advance dropped slightly as the internal coolant-fuel ratio was increased because some heat of vaporization was extracted from the air during the compression stroke, resulting in a decrease in cycle efficiency. When the internal coolant was injected at the manifold elbow, the power increase at peak-power spark advance was relatively small (fig 13) because there was insufficient time for charge cooling before the intake valve closed."


As you can see on a gasoline engine the intake charge cooling due to evaporation of the WI mixture can have an effect on maximum cylinder filling and hence power up to the point you reach 100% humidity (saturation) of the intake charge, AND if there is suffecient time for the evaporation to take place. Spraying beyond, that will increase the cooling effect on the engine due to reduction in combustion chamber temperatures, but at a slight cost in power. You might be able to recover that loss in power by upping the boost more to levels that couldn't be reached at lower injection rates, so you need to consider the fact that you are not only changing cylinder filling but also how much boost, and spark advance you can get away with. This interaction of multiple variables means you have a very complex system to optimize.

Now in your case, your dealing with a diesel, which has too much air to begin with, so the power limit is mostly determined by the amount of fuel available to burn and maximum EGT numbers, and how much cylinder pressure you can tolerate before you start blowing head gaskets or lifting the heads.

If you went with a WI mix that was pure water or low in alcohol content you would maximize cooling at the cost of some reduction in the power gain possible. If you upped the alcohol content you would be increasing the fuel load, and power.

If you increased the alcohol content injected by overspraying a lower alcohol mix, you should be able to get both a power increase and a strong cooling effect on the combustion temps. Only some experimentation would tell you the ideal balance of the variables. For testing purposes you may want to experiment with a 2 nozzle system where you inject water alcohol from one and straight water from the other. That would allow you to sort out the ideal total injection weight of water and alcohol for your goals.


My guess is that on diesels you will need to spend more time sorting out how much extra fuel you can accept (ie alcohol ) to reach your power goals without blowing head gaskets and then control cooling by increasing or decreasing the total WI spray mix and increasing or decreasing the alcohol fraction so you don't exceed your max additional fuel level.



As far as engine cooling due to WI, this paragraph is worth noting.

NACA report 756 ( page 71 , Conclusions item 3.)

Water injection had a marked cooling effect on the engine head and cylinder. The exhaust-valve guide was the only point on the head at which the temperature showed a tendency to increase with indicated mean effective pressure. The temperature was less, however, than that obtained with a straight fuel permitting equivalent power.

Larry

This some very dynamic conversation. I do appreciate someone who understands the science behind result. I am going to read those reports, they (indirectly) seem to make a case for SOME pre-turbo injection for it's contibution to evaporation. Heres one for ya:

Meth, as a more volatile liquid than water, evaporates at greater rate than water. Given a droplet of mix, won't a greater fraction of meth evaporate per unit of water? Seems as though water will still be liquid when the meth is mostly vapor. Hypothetically, a WW fluid mix, 70/30, might be 90/10 by the time the remaining liquid hits the cylinder.

BTW, I don't plan on playing with proportions. Will use water or WW fluid.
Study E5E18-where can I see this?

fractional distillation
 

Your correct, the various chemicals will evaporate independently of each other. The methanol does not know or care what the water vapor content of the air is, and likewise the water does not know about the methanol.

(okay there is a very slight impact because methanol is so hygroscopic but not enough for us to worry about).

Due to this you are correct that as the air cools and water evaporation falls to near zero, methanol will still see an environment it can evporate into. That is one of the reasons your temperature drops in the pre-compressor intake tract, exceed the expected 30 deg F you would get with water only before it gets to 100% RH.

For any of the NACA studies you can usually find them with a google search of the form: +NACA +(study number)


A google on:
+NACA +E5E18

Returns the link in the first hit.

If the NASA server does not work -- they are in the process of "improving" the site. You can try the UK mirror. I personally think the recent changes in the report server are a step backwards but what do I know.

http://naca.central.cranfield.ac.uk/

It still has the old interface and lets you search on key words.

Larry

Thank you. I thought I would mention, I used to fly B-52G models, which had WI for takeoff high GW.

10,000 lbs of water in 90 seconds (8 engines). I'll have to break out the manuals and look at where the rings were placed.

Funny looking at typewriter print. Now on to the patent office website to scout out other ideas.

WI pre - Impellar
 

This thread really has been one of the most impressive threads I have read, thanks to all for a read, that has led me to getting littel work done this afternoon! :wink:

However, apart from a couple of subjective reports, there does seem to be little objective evidence for the use pre-impellar in cars, such as rolling road printouts etc.

I currently am running a Fiat coupe 20vt with a T28 hybrid 60 trim comp wheel, EVO6 uprated IC and aqumaist 1s system with DDS2.

I can run 340bhp with some mild detonation, 320bhp without, and have trimmed the base ignition map back to 303 bhp for safety.
However, although I get excellent spool up, just over 3000rpm, my current turbo simply runs off the edge of its comp map at 1.3bar and 6000rpm, and as you see torque drops off post 5500rpm quite dramatically.

http://homepages.which.net/~j.machen...dualtorque.jpg

The Top line

I've been thinking of increasing my jet size from 0.4 mm to beyond 1mm to get on top of the detonation, but this thread got me thinking as well. I could inject pre-impellar, and as well as cooling the charge, I will increase my relatively (still small) turbo efficiency, and keep the same sppol-up, sounds all too good to be true!!

I would activatee it on boost says over 1 bar like I have at the moment and I can place it about 15" pre impellar.


Main concern will be as my IC entrance and exit are lower than the turbo ,will I run a risk of my IC simply filling up with condensed water?, and then running a risk of hydrolastic lock?

If I do this, if I have the money for experimentation, then I will run RR power graphs before/after so we can some objective results :)

Joe

Near the bottom of this page, it shown power increase and temperature reduction also.

http://www.aquamist.co.uk/phpBB2/viewtopic.php?t=645

Those are good concerns Joe.

If injection pre-turbo is implimented with moderation, I don't think you will have any problem. Freezeup more of a concern for many. I have been thinking along the lines of a temperature switch post-IC that would inhibit pre-turbo spray if not hot enough.

You really should play around with atomization, though. You need a very fine mist, more like fog. The biggest danger is impingement on the blades from larger particles. Maybe try fog nozzles under the highest pressure you can get, at least 100 psi. Multiple nozzle array vs single large one.

I am going to be trying some of this as our weather warms up.

WI pre turbo
 

Thanks, hopefully I'll get a chance to chat with Richard as he really knows his stuff ;)

I need to get a mist rather than droplets as you say. Gelf got some moderate results, it is hard to know whether that was just due to more WI, not specifically pre-turbo. Also I think the pre-turbo will only work if you are out of your efficiency island with your turbo, in other words the turbo is too small

http://photos.fotango.com/p/eba00496747f00000002.jpg

Here you can see, on the right vertical line ,that at 6500 rpm, even at 1.2bar I am actually off the map :shock: :wink: , although I normally will only run 1bar or so at the redline. I am mapped to 1.3bar, so really my turbo is only efficient between 3000 and 4500 rpm, so if I can shift the island to the right I will be pleased :)

Joe

Can you post a better image?

Present day feeling is that the effect of misting will move it to the right as you say. Usefull for all temps and speeds however, apparently most helpful at increasing compressor efficiency, so more of the work performed is applied to compression, less to heat loss: hence higher comp ratio (boost). Add a little fuel (meth), lower charge temps, all = power increase.

imjection pre impellar
 

http://www.turbocalculator.com/compr...maps/t3-50.jpg

this is for a T3 '50' trim, as I can't get a compressor map for my turbo.

Mine is a T25/28 hybrid, the standard turbo on fiat coupe 20vt, and using a larger compressor wheel '60' trim, has a T25 inlet.

I'm going to try a 0.3mm jet preimpellar to see if this makes a good difference.

do you have any further thoughts? :)

regards

Joe

It is my opinion that a nozzle that is oriented with the air stream is much more effective, than a nozzle pointed at the opposite wall of a conduit. Keeping water from recombining into larget drops and facilitating evaporation, rather than pooling so much, as evident in videos. A nozzle with a narrow angle of spray, vs a wide angle. 2 smaller nozzles, perhaps back to back, one pointing into the wind, one pointed leeward (with the wind). A simple plumbing T could do it. Just need some way to keep the fitting aligned, concentric with the conduit.

If you do something like this, i am very interested in your results. Just remember that you need heated air to hold the water, so be sure pre-turbo misting cannot occur till relatively high boost. The lower the boost cut-in, the more likely it is you will have condensation in the IC. And this will occur at higher speeds where the IC is most efficient. In reality, since misting is only a short duration event, I don't see any real need to be concerned about condensation, since even if there is some, it will quickly evaporate (within seconds) in a heat soaked IC. The atomization challenge is the big hurdle.

There is another article on this board about swirl flash atomization you might find interesting.

pre impellar injection
 

Thankyou Michael, for you points. :smile:

I have a short induction route pre-turbo with a metal pipe and could run a jet into there, or jets.
My current jet comes on at 1 bar boost, and I would probably keep the same there, you have reassurred me about the condensation, as it would only come on when the boost is on, in test we recorded post turbo temperature of 135degC, so I don't think much water would hang around in the intercooler for long.

I will speak to richard about the atomisation, I run at 1.3 bar midrange which drops to around 1-1.1 bar at the redline, fitting a bigger downpipe will help the turbine efficiency, but this science has got me thinking about improving the efficiency, I amy even see more boost?, but as said befoer ned to get the water atomized.

regards

Joe

1.3 bar pump pressure? Doesn't the aquamist go higher?

the following increase atomization effectiveness (smaller particle size):

higher pressure
lower viscosity (warmer fluid)
lower surface tension (analagous to lower viscosity but using surfactant)
smaller nozzle flow capacity


ideally 500-800 psi and fog nozzles would get you all the "fog" you need, but the practical limit to pressure, hoses and fittings is a limitation. Where this may not be so important in post IC misting, your effectiveness will be measured in your ability to achieve the smallest micron size possible, for the pre-turbo application. Some think it is only important in order to keep blade damage at bay. Not so. With only milliseconds of interaction during compression, it happens so fast that so much of the water cannot evaporate, because even a 50 micron droplet takes time. And the turboine efficiency will depend on the amount evaporating during compression. There is no help to turbine efficiency if water is evaporating after the heat has been produced, and the particle is downstream. Hence the repetition on stressing atomization.

I believe aquamist did not design for pre-turbo. While I have no numbers on aquamist nozzles, I doubt they are set up to "fog" under low pressure. Some nozzles are better than others though. Perhaps someone can host a particle distribution chart on aquamist, I have not seen one. Bete makes a PJ nozzle that is a impingement fog nozzle. I will be experimenting with them under 100-200 psi. I have some charted data on those. If interested in researching further, get aquainted with Sauder Mean Average particle size. You may find that even at 100 psi, 50-60 micron is a common SMA. Fog is considered 20 or less. So it's not an easy challenge. But you can play around. Maybe a little soap will make a big difference. Do an easy experiment. Get a narrow funnel and a quantity of water. Add a drop of DW detergent, see how much faster the water flows thru.

just some thoughts. Post your results. Looking forward to it.

pre impellar injection
 

thanks Michael,

I meant 1.3 bar turbine pressure.

Yes, from what I've read Atomisation is the key, it is no point having larger drops, as you may as well have the nozzle downstream then.

I am running the Aquamist race pump, will keep you informed :cool:

regards

Joe

I've got all the stuff at home to start pre-turbo injection, but I'm still not sure about a few things.

So I've got a few questions (and forgive me please if the answers are to be found in this thread already, although I read it completely, I might have missed something):

1) Is it wise to inject methanol into the turbo (80W/20M)? Isn't the stuff too aggresive for the poor turbo?

2) I got a suggestion (from Richard, thx) to inject pre airfilter. But I have a few reservations:
2a) Will my MAF survive?
2b) My airfilter is a Cold Air Intake, foam with oil. Will the methanol ruin the foam? Or will the water stay in the filter until it forms puddles and ruin both my MAF and the turbo?

Thanks,

Jains

I suspect the air filter would gather the droplets into much bigger ones. The droplet sizes are supposedly bigger then the meshes of filter, thus physical contacts should happen & slow the droplets down....

And no matter how the droplets change, the MAF would certainly be affected by the water, especially hot wire type. It's hard to predict the changes to sensor reading & it's reliability.

:(

I'm fairly confident the changes would be adverse. Hotwire sensors are very vulnerable to surface contamination, so water droplets reaching the element would cause an instantaneous overread and also affect the accuracy subsequently.

Oh well, I think I must quit this pre-compressor injection camp, too. :sad: .....

I've been using the pre-compressor injection since early Nov. last year, so it's more than 5 months.

The jet was 0.5mm initially & swapped to 0.4 later, placed near an elbow in front of the compressor, only about 20cm away. It injects when high flow/high boost, controlled by a comparator circuit & a solenoid, metered by system 2D, and shares the pressure source with another pre-throttle jet.

The turbo in my car is installed deeply between fire wall and engine block, hardly accessable. Today I finally have some time to dig these all out & take a look. Actually I can not see it directly, through a camera instead.

Here's the pic:
[img] I have contacted PuntoRex to retore this picture[/img]

As can be seen, the outer edges of the blades are damaged obviously.

I think the pressure is still not high enough, thus the droplets are too big for this application.

Anyway, in these days, the turbo was working fine & giving me 22psi of boost. And, on the driver's seat, I always feel the turbo & engine love this pre-compressor injection.

However, seeing this damage, I can not persuade myself to keep using it. I disassembled the jet, plugged the hole, took out the hoses & solenoid...

That looks rather nasty. I've no experience with turbos, but I assume that much erosion is abnormal and is definitely caused by the water?

Obviously the blade speed would be highest at the outer edges which would explain why the damage occured there. If somebody clever could think of a way to focus the water droplets towards the center of the turbine, would that reduce the problem? Perhaps it would be possible by mounting the jet axially quite close to the turbine, or something like that? Always easy to speculate when it's somebody else who has to do the work and foot the bill. ;)

Strangely enough, with this damage, I never felt the turbo was working badly. I didn't see boost drop or slow spool up.

So I'll keep using this turbo until it's bearing & seal go bad.

The picture posted has exceptional details, goog steady hands.

It is most annoying that this has happened because we have had great results from it. I would if I can develope special 5-50um nozzle for you to continue this test rather let it continuing eroding the blades.

I need some time but I have a few ideas how to design this nozzle.

dropplets
 

Its my suspicion that that sort of damage ( which I also had) is due to small water dropplets collecting on the walls of the intake tract and running down the surface toward the turbo compressor like rain drops being blown up a windscreen.

Note that only the lead blades are eroded the second set of blades look nearly perfect. My theory is that the front most blade blasts these dropplets apart and they never make it back as far as the second set of blades.

If that theory is correct, than I think there is a solution but I need to build a test rig to verify it. If you installed a small step (about 1mm high) in the wall of the intake tract facing upstream toward the air filter, when the water dropplet hits that step is should be ripped apart by the fast moving air as it tries to climb the step. There are other possible configurations, like golf ball dimples on the interior of the intake tube ahead of the compressor to try, but I really need to build a flow bench with a few vacuum cleaner motors and some plexi tube so I can see what the water spray does.


It will cost me several hundred dollars to put together a home brew flow bench but I think it would be really useful to get live action shots of the water spraying into a fast moving air stream to see what nozzle locations and designs do in the real world, not in free quiet air.

Larry

Punto Rex, How many miles on the turbo? How many miles using preturbo misting? It must be said. Unless you shot a pic of the turbo before you started misting it, you can't make a conclusive statement on the cause of the damage.

Larry,

Superb observations. You beat me. I am sure you are 100% correct. And the biggest problem with the hardware is that the nozzle shoots right into the opposite wall. Right on target! The water just collects into large drops or a stream more likely (water surface tension is a very strong force..)

Richard, you may be able to reduce the drop size a bit, but I don't think that will solve the problem unless you can get an 80% distribution under 30 micron (true fog). I hate to say it, and be a doubting Thomas. I haven't seen anyone do that under 500 psi. I don't really feel that particle size is the biggest problem.

(Thinking out loud) Even fog shot to the opposite wall with any velocity may still get to the wall. And while a larger particle does erode more effectively, this picture (nice pic) is classic leading edge erosion from FOD, caused by large drops or wall stream. It looks just like my lawnmower blade. Some degree of the wear must be considered normal wear and tear. While some impingement damage is visible across the entire leading edge, the majority of the damage is on the outer 10% of the blade, no doubt from something traveling up the wall.

Good ideas Larry, not knocking your step idea larry, I hadn't thought of that. In my mind, the real solution is aligning the nozzle(s) into the airstream, from the CENTER of the conduit, and using a narrow cone pattern (to minimize wall pooling), and then only at the highest practical MAF threshholds. If we can brainstorm to create a dual nozzle setup that will help even more. a smaller capacity nozzle (better atomization) then can be used at the highest practical pressure. Maybe put the nozzles back-to-back.

Larry a leaf blower can be used to show how 2 different nozzle orientations (within a conduit) will have dramatically different pooling characteristics. I will have to do this myself. Just collect the pooled water at the end of the conduit over time and compare.

Michael

co-axial spray
 

I agree, a co-axial spray setup is one of the things I have been thinking about.

Imagine a carburator venturi type nozzle suspending centrally in the air intake. The high air speeds in the venturi should keep the spray as a relatively compact plume that should travel down the center of the duct, with the mist impacting the compressor impellers near the center where their radial speed is relatively small.

In my next version I will be only using the pre-compressor injection at high engine rpms and boost ( pressure switch and rpm switch in series ). I could do the same with some sort of a maf voltage, trigger as well.

Larry

Well, fair enough, I totally agree.

Here is my records:

2/28/2002 83125km The first turbo service
12/28/2002 99094km The second turbo service + engine rebuild
11/06/2004 131593km Pre-compressor injection installed
4/2/2005 139671km Damage blades were found

I have a photo of the turbo before the 2nd turbo service (12/28/02). Which is, it's 10-month-old & had serviced for 15969km.

Unfortunately that picture is not so detailed as this one. (it's a hard copy & I don't have a scanner to share it here) However, on that picture, the outer edges of the blades were obviously in a much better shape than this. The tips are mostly in a pretty sharp right angle, instead of rounded out like this current one.

Pre-compressor injection has been deployed for 5 months & approx. 8000km on it. TBH, it's only a short service time.

It's a pitty that I missed the chance to take a picture when the first service to the original stock turbo with 4 and half years and 80 thousands km of service. And I don't have many experiences with old/abused turbos... Maybe someone around here with more experiences could share more info.


Richard, thanks for the compliment. This photo is chosen from a collection of about 10 shots.

This is(was) my pre-compressor jet seat:

http://home.pchome.com.tw/personal/r...JetonElbow.JPG

The compressor inlet is on the left bottem of the picture. In the engine bay, the whole thing actually turns 90 degree...

As can be seen, the jet is facing a half-open space. Even when no air is flowing, near half of the spray cone should hit the compressor directly, well, sort of. The spary cone is so wide that unavoidably hitting the wall.

Without significantly higher pressure, samller droplets, much narrower spray pattern & precisely injection angle, I think we can hardly get away with the damages. :sad:

As to close co-axial installed jet, in my car, it's almost impossible to deploy. :cry:

I tried to make pictures of my 4 year old turbo that has 112.000 Miles on it but I don't seem to be able to make sharp pictures like you PuntoRex.

Anyway, my point is. My compressorwheel doesn't look as damaged as yours, the edges are still sharp, well, not 100%, but better than your wheel.

My pre-turbo-injection plans just went into the fridge...

Sorry to hear it didn't work out in your case!

Janis

How accessible is your turbo inlet area. Is there a room to accommdate an inline narrow angle nozzle (super-fine droplet) right in front of the turbo blades?

The hose to my turbo looks very much like puntorex's. I'd have to mount the nozzle in the bend of the hose.

hmmm... not so simple.

May be puttng a 1mm ridged sleeve inside the bore of the turbo inlet will do the trick, just try to explore hotrod's idea.

http://www.aquamist.co.uk/forum/sleeve.gif

janis,

I took that picture by a Canon digital camera, with the built-in flash light & close up mode.

With the turbo in car, it's very hard to get a good angle, I just guessed & saw what I got.


Richard,

How narrow spray pattern you can get with a fine enough droplet?
At the elbow near inlet, I think maybe it's more easily to aim the target, like this:
http://home.pchome.com.tw/personal/r...oInjection.jpg

Or in a straight pipe, the co-axial nozzle is more difficult to install. However, the air flow would probably tilt the water injection pattern near the turn.

PuntoRex,

I can try making it as narrow as possible - need to do some experiemnts after designing it.

Cound this sleeve adaptor arrangement work on an existing nozzle?

http://www.aquamist.co.uk/forum/sleeve2.gif

You guys are really talented. Very impressed with this concert effort.

Another 2 cents? Any mod in the airstream coaxially (off the wall) is going to be hydraulicly restrictive, defeating the improvements sought. Especially anything that reduces the apparent inlet diameter at the turbo inlet mouth (such as an ID sleeve), as this part of the housing is probably finely engineered to work correctly by an aero engineer.. IOW, I believe you may very much disrupt the intended airflow characteristic, angle of incidence, to the blades. These are just my educated guesses. I never designed turbos, so a better opinion is needed. But I do understand aero and hydraulic engineering concepts.

I can't see the benefit of this sleeve, then perhaps I'm not understanding. If the purpose of it, is to form a step that diverts pooled water toward the center of the blade, how can that be done without severely pinching off air flow/reducing inlet ID?

May be it is just effective to bore the ID by 2mm just short of the turbine tips.

I like! Concepts to keep in mind. The heavier the drop, the harder it is to change its direction, or put another way when considering spray before a bend: a more coarse spray will have more collisions at the bend (collecting a larger stream). Hope that makes sense, it is a key concept.

The finest spray possible, in a conduit with the least change in direction, when concentrically implimented, using the largest diameter conduit, smallest practical cone pattern, at the highest possible conduit airspeed, will produce the least pooling. Nonetheless errosion WILL occur if a significant fraction is over about 40 micron, due to impingement. I do believe that the above outlines how to drastically (90%) minimize the occurence.

Another thing to consider. If a turbo ranges 0-15 lbs of boost, what good does it do, from a performance perspective, to spray it at 10 psi? Answer: none

You don't get the maximum vehicle performance until the foot is on the floor, 15 psi. To enhance top end, spray at 13 or 14. That change alone just reduced exposure and water damage 50% maybe (even using the wall nozzle). Moderation, properly implimented, is key. You guys with photographic baselines, probably are going to be the likely candidates for testing something here, not much to lose at this point. Please consider it.

Here again, I will make my opinion, but in no way should you stop the thought process. This is a wonderful collaberation.

I am fairly certain that the turbo compressor is designed around the concept of "specified inlet" flow. (if someone can say I am wrong then the following is meaningless)

A notch at the turbo inlet could be turbo suicide, if it induces stall. If it does, you will know right away, water or no water. On the other hand, maybe you stumbled onto a very rich patentable idea, like the golfball dimples.

Edited: for clarity