Yep, looks like someone's gonna have to suck it up and provide some data. I was hoping for an easy answer. I've found rare instances where individuals have put test probes everywhere and the results look promising. Nothing well-controlled though - as you state no serious testing. I've seen people report everything from tons of horsepower to no horsepower - huge drops in EGTs to actual increases in EGTs. Very difficult to sort out. This is the work for someone working at aquamist or a race car tuning shop perhaps.

Ah well - thanks to those that responded.

 

I know all about compressor efficiency, maps, intercooler efficiency, pressure loss, etc etc, but I fail to see how it would matter pre and post turbo. I alsoy don't really view it as making the compressor more "efficient" as I see it as counteracting the effects of compressing air itself. It's like saying that by installing a more efficient intake manifold or a larger intercooler that you're increasing compressor efficiency, which really isn't directly true.

But anyway, you're still cooling the intake charge one way or another. Do you have any hard data stating that water injection is more effective before the turbo compressor than after? Why even risk turbocharger longevity if you don't even know if it matters or not?

Edit - just saw your last response. Water/meth injection definitely works, but I see no reason to do it in a non conventional manner as you're suggesting.

 

Compressor efficiency is inversely related to the temperature increase from pre-turbo to post-turbo given a fixed pressure or "boost", agreed?

Tout = Tin + (Tin x [-1+(Pout/Pin)^0.263]) / efficiency

If the difference between Tout and Tin decreases (whatever the cause, sticking an intercooler in there for example) then most would consider that an improvement in turbo efficiency. Nothing physically is changing with the turbo (if that's what you mean by "directly true" changes in efficiency). I think this is just a semantic distinction. By pre and post turbo - I just mean the air before it is compressed and the air after it is compressed (could be pre-IC or post-IC if there even is an IC). Maybe "turbo system efficiency" would be a better wording?

 

One last link I was having trouble relocating - found, finally - this guy measured at multiple different points, experimenting specifically with pre-turbo injection:

http://www.aquamist.co.uk/phpBB2/viewtopic.php?t=559

... unfortunately it is not well-controlled with more than a few confounding variables. Too little data out there to even consider this from an end-user standpoint. As Gary has pointed out above, unless you absolutely have to get rid of your IC, there does not seem to be a reason to warrant pre-turbo WI.

At least now there's a thread on this topic should someone reconsider this in the future .

EDIT: Just received this note back from an authorized Garrett turbo repair shop:

- just to provide an idea of the cost (minus labor to R&R) each turbo should some long term compressor damage occur.

 

rcdash, sorry for bringing back this two year old thread, but I find this to be a very interesting topic and was wondering if you came to any conclusion when doing your research?

I have been using W/M injection for about 3 years successfully, and recently started thinking about pre-turbo injection again, in the past I stopped the thoughts for the same reason mentioned in this thread (damage to the wheel), but now that I am re-thinking this, can a very small shot of water/meth really be that big of a deal as far as hurting or pitting the blades? For example a 3gph nozzle sprayed at 150psi. I am really thinking of trying this out very soon, maybe tomorrow, just wanted to get more opinions and see what you concluded.

 

I am planning on doing this very soon. Currently i have the AEM w/m nozzle inbetween both my intercoolers (JWT KIT). HP gain waste much to even mention. but the turbos are out of breathe @ 14 PSI.
I will doing this not for the purpose of more power but help with heat soak we have here in Saudi Arabia. the nice thing about the JWT kit is that its one pipe for both turbos (pre turbo) i will T my current line and keep the one between the intercooler and put another on the intake pipe (smaller nozzle) and log and see what happens.

 

In power plants moisture in the turbine is avoided at all costs due to erosion.

 

It's taken me 2 years to finally get around to installing a W/M injection system. I put in an HFS-6 over the winter but I have yet to take it to the dyno. This spring I have been running distilled water only and have turned up the boost. I am very impressed with the air intake temperature reduction. A 5 second spray provides a 20-30 deg F drop.

I have a dyno tuning day scheduled on May 18th though. I have a solenoid feeding a pair of 3 mm nozzles up near the air filter intakes (pre turbo). I can flip it on and see if it has any impact on power. For the most part I will run pre-throttle body injection with 50/50 W/M. I have an 8 mm and 4 mm nozzle up in the charge pipe. When all are spraying, I'll be pumping close to 1000 cc/min into the intake (pre and post turbo). Of course, by design, the pre-turbo injection should be completely vaporized as it leaves the compressor, resulting in isothermal compression vs adiabatic, in theory. In regards to the compressor wheel damage - I'll likely change out turbos at some point anyway, so it's a non-issue for me. If the dyno shows no significant improvement with pre-turbo injection, I'll remove the plumbing and cap off the pre-turbo injection ports.

I'll be posting data up after ZdayZ, unless I blow up the car on the dyno, in which case I won't be going to ZdayZ, and I'll have plenty of time to post sooner. If all goes well, those folks that attend the airstrip event will see it first hand.

 

That sounds good man, thanx for the response. How did you go about positioning? I have been reading that it should be as close to the wheel as possible with a spray patter thats narrow so it does not hit the outer blades but the inner, but also without spraying onto the nut. I am thinking of just spraying it from the top of my filter, since I have my filter right on the turbo. Thinking about using a .75GPH nozzle at 150psi, dont know how that compares in mm though.

 

i'm going to try pumping 1000+cc/min right into my TB (so only ~3 mins total capactity with my 1gal tank)

maybe i'll meet ya on the 18th to see how it all goes.

 

12-3 at Staples. I'll text you to see if you're available - I could use another set of eyes to watch gauges and/or dyno LCD as I do the runs. It's not like Sharif's set up - the computer screen is across the room at Staples. Craig helps with the runs by operating the dynojet, but I cannot watch the screen to see if power goes up or down without getting in and out of the car - it's a PITA. I might ask him if I can move the monitor if I bring a long VGA cable.

I think it's crazy to aim at the compressor nut and position near the wheel though that's the way many advocate doing it. The spray is wide and dispersed - aiming at the nut seems pointless to me. I position right by the air filter in a section of piping that angles down away from the compressor. That way, condensation onto the pipe flows towards the air filter, not the compressor wheel. The spray also has the most time to atomize properly before getting sucked in. If you have your filter right on the turbo, then you have few options...

 

so what happened?? I am very interested in your results because thinking about doing this myself. I think there is alot to gain but would love to hear about the results from your testing.

 

yep, in for results.....been many moons after zdayz, give up the info raj

 

I saw no horsepower increase with pre-turbo + pre-TB injection vs just pre-TB injection. That said, I was having fuel pressure problems that stopped me from fully testing the W/M injection system. I had trouble with air in my injection lines that I wasn't equipped to deal with, had to leave for ZdayZ the next day and it was getting late. I now have a bleeding system in place that makes it quick and easy to get rid of air. So I have to go back to the dyno. Sorry didn't update this thread but no definite data to share. I still have the pre-TB injection lines hooked up, but I usually run with the solenoid off. No point risking compressor wheel damage if I don't even know if pre-turbo injection actually makes power...

No scheduled date to re-dyno. I will post up when I do.

 

So I was wondering... pre turbo injection cools the air as it is being compressed (or makes it denser), so with that said wont it be possible to inject right after the blades, straight to the inside of the housing and still have the same affect? I have not researched exactly how a turbo works at that level, but I am assuming the blades are just pulling in air at X rate, the actual compression is happening within the housing. What do you guys think? This will eliminate the "issue" or the worry of hurting the blades.

edit:
Now that I think about it, I think it would be better to have multiple nozzles spraying on different sides such as four sides to keep the pressure within the housing equivalent, otherwise if one side suddenly is injected with water/meth perhaps there wont be equal pressure on the other side of the housing and the wheel would lose its balance.. Dont know if it makes sense, I can visualize it better than explaining it lol

 

Raj...why cut corners.????....just upgraded to the 850bb and get it over with!!!

 

^ I don't want to give up the car for months at a time anymore. If I lived in Atlanta, it would've been done already I think. Besides, I feel kind of bad messing with a good thing - everything is working just fine and I still break traction with "only" 500 to the wheels...

 

I guess my idea is no good.

 

It might be good - no way to know. Few people would be willing to drill their housing to test. The heat is generated in the compression process so I would think having the atomized droplets available for vaporization prior to compressor entry would be ideal. I use 3 mm nozzles all the way up front by the air filters where the piping has a downward slope towards the filter. This is to preclude condensation from trickling back towards the compressor. I may well be vaporizing all of the w/m before it ever reaches the compressor... Not really sure - a lot more testing required - and no time on my hands currently (and my local dynojet has shut down )

 

most turbos have 1/8 NPT ports on them for wastegate reference on the compressor housing.. just put the nozzle there. no need to tap anything