Originally Posted by 18psi
(Post 627324)
I don't really understand the idea behind having it in BOTH places.
Just makes no sense to me. Either do 1 big nozzle or 1 small per cylinder. Why create a clusterfuck of potential failure points? The IR zonnles are too close to the head for e-cooling and the water will get slammed into the cylinder before it evaporates in the charge bitchfucker. The unevaporated water will then release it's shitload of latent heat energy when it evaporates when the spark goes off. That shit slows the flamefront of the combustion event, cools off the piston, cylinders, valves, all that shit. My idea (in my mind) would supply a) nice ambient temperature air to engine b) in-cylinder e-cooling As for failiure points that is taken care of by failsafe- check valve, flow senzor, tank level sensor. If any nuzzle fails, flow will take a shit. |
the real advantage of water is getting it into the cylinders to lower EGT....it's high specific heat and all that.
Nice ambient air temp to engine.. are you planning on having the IAT after that nozzle or something for lower indicated temps? |
You're injecting the same shit into the bitchfucker from different distances. I highly doubt there's a point to that.
But I have to say its just my opinion and I'm no expert so I'd love for someone that knows the ins and outs of this shit to prove me wrong. |
How much power are you trying to get out of this engine?
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Originally Posted by aaronc7
(Post 627337)
the real advantage of water is getting it into the cylinders to lower EGT....it's high specific heat and all that.
Nice ambient air temp to engine.. are you planning on having the IAT after that nozzle or something for lower indicated temps? IAT sensor is about 20 inches away. Long pipes :| |
Originally Posted by jayl
(Post 627340)
how much power are you trying to get out of this engine?
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Direct water injection. Be a G.
http://www.knvts.nl/S&W%20archief/Di...%20vessels.pdf It actually looks like more for diesels and low emissions. Your idea for the direct portish wi made me think of this. |
from what I've been reading about water/meth and iat placement.. you want the IAT before any nozzles- reason being if water hits the IAT... its basically going to read the water temp not your air temp. also the water evaporating on the sensor is going to make it read even cooler, the issue here is i am assuming your tuning uses IAT to determine how much fuel to inject. Yeah you can just offset it a little but ideally you of course want open loop fueling to be as accurate as possible.
I was just looking into this debate a good bit today... good discussion on the Megasquirt forum and some good reading I found on evo forums as well. |
Aaron, most dealers will say to put the nozzles before the AIT sensor, and use the sensor to tune for the water meth. At least that is what I get from the SRt forums.
To the OP, I think that the direct port will be the best way to go, but having a nozzle before that will make sure that even if one of the nozzles gets clogged, that that one cylinder is still getting flow. Depending on if you go with a PPS or aquamist style system, you will need at least one more check valve or solenoid because the direct port nozzles will have vacuum that the IC nozzle won't, and the IC nozzle will have gravity feeding that the DP nozzles won't. If you are going to make your own distribution block, give it 5 ports and feed from the middle. T before the block and feed your IC nozzle. Check valve on the port, and check valve on the IC nozzle. |
Absolutely no gain in performance between direct port and 1 nozzle.
WI's real advantage is knock suppression, if you want a cooler charge buy a A/A IC. Another thing worth considering. 4 x nozzles will mean you will have to select very small nozzles, somewhere around 0.4mm, in my experience these nozzles tend to block up a lot more regular than say a 0.7mm. Now think of this. If you have 1 out of the 4 nozzles that has blocked or partially blocked, it's going to be extremely difficult to detect. If on the other hand you have just 1 big nozzle and that blocks up any flow sensor worth it's salt will instantly pick up on this. My advice is to mount just 1 nozzle on the intake. Cheers Mark |
Originally Posted by eunos1800
(Post 627443)
WI's real advantage is knock suppression, if you want a cooler charge buy a A/A IC.
I always assumed that knock suppression was the real advantage of cooling the intake charge, and that both the A/A IC and Water Injection (With its remarkably high specific and latent heat constants) both perform basically the same function. I suppose I am a complete fucking moron. :nxsmile: |
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Speed/Density IIRC is a MAP sensor type management. The ECU's tables are based on RPM (speed) and manifold pressure/vacuum (density). Both systems use an AIT sensor.
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Speed density is basically MAP.. what the megasquirt defaults to etc. MAF is totally different and in my other car... what matters is the flow velocity and temp at the MAF sensor- we have another temp sensor in the manifold (boosted air temperature), but this is only really used for the ECU to determine which load maps to use as far as I can tell. In speed density the air temp plays a pretty huge role from what I can tell in fueling. Open loop idle conditions I will get my AFRs perfect, then the next morning they will be super rich... or vise versa, IAT gets really hot and everything leans out.
I also found a good thread on the MS forums but I can't find it again.. basically the conclusion was put the IAT/AIT before any nozzles etc, that way you are getting the AIR temp (which is used to determine how much oxygen content it has per whatever)..not the fluid temp which will result in the ve tables being as accurate as possible. |
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