Water/Meth Theory for F6 engine

[Prche951]

In order not to pollute the blown engine thread with this discussion I am starting a new one. The following has been said in the other thread and I am quoting it here. This is not a Meth bash thread, but more of an understanding thread of how in theory for these engines it is supposed to work. I do want to learn more about this, I think that properly used it is incredibly upgrade. So here goes: Originally Posted by BLKMGK Oh geez, here we go. I sprayed it into an intake meant for dry too. It was a Supra and I was spraying a single nozzle 6 inches down from the TB. This is fine until you try to flow too much and use it for supplemental fuel and not just some octane boost and cooling. I watched my knock sensors, I checked my clean shiny plugs, my motor was plenty happy. <shrug> As stated above - we don't know what killed this motor. But every time someone says meth the drums begin to bang and people say don't run it. The RPM or possibly the timing could both have had something to do with this failure, maybe even the oil getting polluted from too much meth. No way to know just yet. Personally if I can get my stupid boost issue resolved I am pondering running meth on my current car. We'll see, since *I* won't be able to tune it then it might be pointless. well first, I am not saying that meth killed this engine, cause of death remains to be seen. OP himself stated that proto did not change their tune for the added water/meth, so the tune was never changed, so advanced timing on 91 octane seems a little nuts here doesn't it? These cars have a 90 degree plenum, it is a big air chamber with no direction of feed to any cylinder. This big chamber receives air and directs it to all cylinders. The fluid mechanics of this system is designed for the density of air, not water/meth. If you inject water/meth into this chamber you are gambling on which cyliner gets what. You cannot tell in any way what cylinders will get most of the meth or none of it or some. The plenum is not directional and there are no individual runners to each cylinder. If you installed six injectors, one near each cylinder this would help, but this is not how it's done to my knowledge. This intake was not designed to spread a water/meth mix. You would need a wideband at every cylinder to really know. So based on this, I would like to know how you can guaranty that each cylinder gets meth equally? Originally Posted by Tony@epl In theory you are correct... But keep this in mind. The me7.8 has individual cylinder injection control... Bosch/Porsche has opted not to use this and all 6 injectors are the same size. With proper atomization of meth, distribution will be proportionate to air distribution through out the engine. I trust that Porsche has designed a manifold that can flow fairly evenly.... If they didn't, more people would be burning up a single specific cylinder, over and over and over again. Do you hear of this happening? Tony, Audikp, yes my concern is that water/meth is not being spread evenly. I am sure the porsche plenum is very well designed for air flow into the ports. However, how is this any different than NOS. How much atomization does it take to make sure that there is no separation of mist and air before it gets to cylinders? one reason why I have not gone to this. Again, maybe this is a discussion best on a meth thread as I don't believe that meth was the cause of this engines failure. I think the tune already had that covered (my opinion). Sorry to OP for inserting this discussion here. I believe you will know very soon what happened to your engine. Then you can hopefully tell the rest of us. Originally Posted by Tony@epl Are you comparing meth to nitrous? You are correct... this isnt the correct thread for this discussion. Feel free to start another if you would like. no not comparing, meth/water is denser and has a higher chance of separation.

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[Tony@epl]

Originally Posted by Prche951

In order not to pollute the blown engine thread with this discussion I am starting a new one. The following has been said in the other thread and I am quoting it here. This is not a Meth bash thread, but more of an understanding thread of how in theory for these engines it is supposed to work. I do want to learn more about this, I think that properly used it is incredibly upgrade. So here goes:




well first, I am not saying that meth killed this engine, cause of death remains to be seen. OP himself stated that proto did not change their tune for the added water/meth, so the tune was never changed, so advanced timing on 91 octane seems a little nuts here doesn't it?

I agree that the fate of the engine in the previous thread remains to be seen, but I think that we both agree.... it had nothing to do with the water injection.

These cars have a 90 degree plenum, it is a big air chamber with no direction of feed to any cylinder. This big chamber receives air and directs it to all cylinders. The fluid mechanics of this system is designed for the density of air, not water/meth. If you inject water/meth into this chamber you are gambling on which cyliner gets what. You cannot tell in any way what cylinders will get most of the meth or none of it or some. The plenum is not directional and there are no individual runners to each cylinder. If you installed six injectors, one near each cylinder this would help, but this is not how it's done to my knowledge. This intake was not designed to spread a water/meth mix. You would need a wideband at every cylinder to really know. So based on this, I would like to know how you can guaranty that each cylinder gets meth equally?

Its difficult to calculate the true atomization across a given area with out knowing true air speed, pressure (not constant) and temperature (not constant)...

But at a volume of far less then 10 % of total mass injected in to the engine, with and average air flow under boost, and IAT of 100+, atomization in straight tube will happen in a space allowing for nozzles to be placed less then an inch before the intake valve if you so choose. This is if you were spraying a stream of water....and your not, the water/meth enters the system as a mist. Now I know we aren't dealing with a straight tube...but Im willing to work with that unknown based on the results we have seen here.

We have tried to figure this multiple times with out any real success due to the complexity of different vehicles intake system, and other variables that are unknown...

Given the space to work with, we are dealing water/meth flow will be proportionally nearly identical to air flow. Seriously, I spent alot of time on this in the past trying to determine optimal nozzel placement.


Tony, Audikp, yes my concern is that water/meth is not being spread evenly. I am sure the porsche plenum is very well designed for air flow into the ports. However, how is this any different than NOS. How much atomization does it take to make sure that there is no separation of mist and air before it gets to cylinders? one reason why I have not gone to this.

Again, maybe this is a discussion best on a meth thread as I don't believe that meth was the cause of this engines failure. I think the tune already had that covered (my opinion).

Sorry to OP for inserting this discussion here. I believe you will know very soon what happened to your engine. Then you can hopefully tell the rest of us.



no not comparing, meth/water is denser and has a higher chance of separation.

Do you want to check the up the density of both and report back . Keep in mind density isn't constant. Nitrous is injected as a gas (not liquid) and is injected at VERY high pressure...

See above.