Puddlestomper

I understand your thinking, but from my limited understanding of a turbo, wouldn't you overboost pretty quickly with the rpm on your engine increasing so fast? Or are you just thinking about a short shot of water to get the turbo spooled to increase off-the-line power, and not as a continuous boost increase. What I guess I am trying to say is, are you just going to turn it on for a couple of seconds or leave it on?

XLR8R

A few seconds at a time is probably more than enough.

pooperscooper

I think you would have to run a high pressure with the water and a very low gpm nozzle. Not sure when you plan on injecting this but if you do it at to low of temp, you wont get steam. also, i am not sure what kind of pressure there is between the exahust manifold and the turbo, but if it were 50 psi then you would have to have atleast 100psi just to get the water out of the nozzle @ 50 psi. just for instance, i have no knowlege of actually numbers, but i would imagine it would be atleast that of the boost pressure + pressure from the combustion. I think you might want to gather some actual number data before trying this. if water droplets hit that compressor blade at 50k+ rpm you are going to seriously fubar up that turbo. also like said above, steam has an enormous amount of energy, that energy could very easily snap that turbo shaft like it was toothpick if to much is created. if it were me, i would find a co worker with a powerstroke and have him to try it first.

XLR8R

I'm thinking 100 psi through an orifice that delivers sub 15 micron droplets. Shouldn't have a problem phase-changing to steam even at 500* EGT. Drive pressure is typically 10-15% higher than boost pressure. I'm not sure if water droplets would FUBAR the turbine - some have reported drill chips and such passing through the turbine without incident. The enormous amount of energy steam provides is what we're after, so we'd need a stout turbo shaft.

Great idea about finding someone to cough up a test-mule!

pooperscooper

If steam was achieved, and no water droplets were to hit the the fan blade, and indeed the shaft was strong enough, i would say that the power increase wouldnt be significant, but the amount of spool time, and lower egts would definatly help. I think that water injected into the intake would be more effective because cooling your egt's at the motor is more significant than at the turbo. lower egt's in the chamber = the more fuel you can throw at the fire.

bighornram

You guys are getting way to deep for my boots but it sure sounds cool.

XLR8R

Help us to follow your line of reasoning for water droplets being harmful to the turbine. The EGT cooling effect is merely a fringe benefit - water/meth is already being injected into the intake manifold. The primary purpose of the PyroBoost system would be to generate near-instantaneous boost at lower engine rpms. The volume of water injected would have to be small enough to be completely flashed to steam.

pooperscooper

Kind of the same reason you dont plumb your water/meth pre turbo on the intake side. the water droplets and the high rate of speed of the impeller will erode the material causing turbo failure.
(hypathetical)So say you have 15 micron water droplet (assuming a water doplet can be that size under the given conditions)and you inject for instant boost. still not sure the circumstances you would use this but lets play with the theroy. say sled pulling, the theroy would be to build boost instantly, by expanding the steam and increasing pressure in between the exhaust valve and the turbo. so sitting at an idle you have anywhere from egt's of 200-400 F? sound resonable? and a manifold pressure of (guessing) 50 psi? if temps did not reach 300f vaporization of the water would not occur. this would cause your water droplets to not only hit the the impeller, but now because of this conducting heat with the contact of the impeller it will flash, and cause an increase in pressure on the surface, this will cause tremendous fatigue to your impeller. If you were to try to raise your egt's a bit before injection you would be raising pressure some to, so you need to find that line between your flash point of the water with temperature AND pressure taken into consideration. the reason i think that pre combustion injection works well is becuse it is injected at a high enough temperature not to cause it to flash back to a liquid droplet. it is the liquid droplets that will cause the damage not the steam, not sure on the particle size of steam.

Sorry for the scatter brain thought and punctuation/spelling. this is just my thinking, these are things i would consider before venturing into the unknown (at least for me). also i made quite a few assumptions since i have no actual data.

XLR8R

Actually, ABC4YEW injects water in front of the big turbo, apparently without harmful side effects. The droplet size is quite small - less than 15 microns - so inertial/mechanical damage from impact on the impeller should be insignificant; after all, FOD on a jet engine doesn't include raindrops. The 15 micron droplet size is what the sytem's orifices will deliver at the pump's 100 psi - no assumptions there.

To repeat, the circumstances under which this would be most likely useful is instant spooling of a large turbo, in an application such as drag racing or sled pulling (be pretty handy in the stoplight wars, too!).

200* idle EGT is awfully low - I expect 400* to be much more likely, and the drive pressure at idle will be far less than 50 psi, so there shouldn't be any problem with steam production. Let's say you have one atmosphere, or 15 psi in the exhaust manifold; that'd be similiar to the boiling point of your cooling system due to the radiator pressure cap. Also, I can't imagine the turbine being hotter than the EGT, unless it's after lifting from WOT (when the Pyroboost wouldn't be running), so water in a liquid phase shouldn't be able to reach the turbine. As devil's advocate, I was thinking you might take the cavitation approach, such as experienced in hydronic heating systems. Even if the steam was formed on the surface of the turbine, the "explosion" occurs in a compressible medium (exhaust gas), instead of incompressible water.

Pre-combustion water injection is injected at ambient temperature, and has a cooling effect on the compressed, heated intake air.
A running engine can and will readily ingest water in moderate amounts.
The primary reason for tiny droplet size is to promote a homogenous mixture, not to avoid possible component damage (though that's certainly possible).

We appreciate your thoughts!

pooperscooper

Sounds like you got your fluid mechanics down. there are a couple things that i have for comments. i would think your manifold pressure would have to be greater than 1 atm. if it werent there would be no reason for the exhaust to leave the manifold. also, i wasnt stating the impeller would be hotter, but it is a different type of heating, convecting heat vs. conducting heat. there is a greater heat exchange with the conducting heat obviously, but given the idle temperature at 400 degress it really wouldnt matter as the size of the water droplet should not have any problem heating to flashpoint due to convecting heat. I am new to diesels and understand principals, but some of the numbers, like idle temp were unknown to me. as you have stated it sounds like a very plausable system for what you are looking for. also, i might have taken the cavitation route had you forgoten to install a check valve and your compressable system became incompressable due to a large amount of water in the system. Looks good on paper, better do it and see if our ideas are correct.

XLR8R

Sorry - I should have specified one atmosphere or 15 psi gauge pressure, not absolute.

Convecting, conducting and radiant heat are simply different mechanisms of energy transfer; it wouldn't really matter how the turbine became hot enough to boil any water molecules that came into contact with it. Also, I figured you meant turbine when you posted that "conducting heat with contact of the impeller it will flash".

A blow-off valve would be required, but where would you put a check valve?

Until I can find a suitable test-mule, I think I'll run this by the brainiacs on the engineering forum to let them take potshots at it!

pooperscooper

check valve on your water injection line, that way you dont get any siphon, i guess you could use a soleniod just as easy.