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Old 03-01-2011, 08:09 PM   #1
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Default Megasquirt Water Injection Failsafe Mechanism

Came up with this. Would appreciate a critique.

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Old 03-01-2011, 09:05 PM   #2
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I am going to do a similar thing with a pressure switch except I have a MBC so I will be using it to Table switch to a more aggressive spark map.

I have had the parts for a yr now. I will finally do it in the spring. Sounds good to me!
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Old 03-01-2011, 11:30 PM   #3
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Seems like a good start. I'm running a similar concept on the red car.

A few suggestions:

240's advice is sound regarding table switching. On mine, not only is the boost control bypassed, but the MS switches to a much more conservative ignition map.

You could add a measure of additional protection by also monitoring pressure in the line between the pump and injector. If you want to really do it right, configure the system such that the float switch has to be closed and line pressure has to be high in order to enable boost control and the more aggressively tuned ignition map.
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Old 03-02-2011, 11:31 AM   #4
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Quote:
Originally Posted by Joe Perez View Post
Seems like a good start. I'm running a similar concept on the red car.

A few suggestions:

240's advice is sound regarding table switching. On mine, not only is the boost control bypassed, but the MS switches to a much more conservative ignition map.

You could add a measure of additional protection by also monitoring pressure in the line between the pump and injector. If you want to really do it right, configure the system such that the float switch has to be closed and line pressure has to be high in order to enable boost control and the more aggressively tuned ignition map.
I was hoping you would reply Joe. You've been a big inspiration.

I'm planning to handle ignition timing reduction by using the squirts IAT-based timing feature. This is going to be (at least for now) an IC-less install. Therefore, the WI nozzle would go immediately post-turbo to try and vaporize as much of the water as possible prior to the IAT sensor. Based upon this, the IAT would be my indication of water-flow and how effective the cooling is.

The reason I hesitate with table switching is that at the moment my table switching is tied to the AC relay to boost idle timing when the AC is on (one of your ideas). I think I could make the table switching dual purpose without interference (since one purpose is at idle while the other is at WOT). I'd have to think about that a bit.

As for monitoring line water pressure, the "WI Pressure Switch" is that mechanism. I think it does what you describe.

Thanks for looking.
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Old 03-02-2011, 11:43 AM   #5
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BTW, these are the mods/options being used on the MSPNP to support this:

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Old 03-02-2011, 04:36 PM   #6
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Quote:
Originally Posted by hornetball View Post
I'm planning to handle ignition timing reduction by using the squirts IAT-based timing feature.
Ok, just be aware that even the open-element GM style IAT sensor has some latency. It's fast, but it's still made of physical matter, and thus, it has thermal mass. I would personally be hesitant to use it as a reactive safety feature in an environment where a probable failure mode consists of going from "full charge cooling" to "zero charge cooling" instantaneously.


Quote:
The reason I hesitate with table switching is that at the moment my table switching is tied to the AC relay to boost idle timing when the AC is on (one of your ideas).
Out of curiosity, how did that work for you? It was just a theory that I came up with, and I've never had a chance to actually test it.
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Old 03-25-2011, 03:42 PM   #7
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Quote:
Originally Posted by Joe Perez View Post
Ok, just be aware that even the open-element GM style IAT sensor has some latency. It's fast, but it's still made of physical matter, and thus, it has thermal mass. I would personally be hesitant to use it as a reactive safety feature in an environment where a probable failure mode consists of going from "full charge cooling" to "zero charge cooling" instantaneously.


Out of curiosity, how did that work for you? It was just a theory that I came up with, and I've never had a chance to actually test it.
Sorry Joe, didn't see that you had replied.

Good point on latency. Keep in mind that I do have the system setup to cut out the EBC when water pressure drops. Here are my revised schematics:
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As for the table switching, I haven't used it yet (car still on jackstands). But Brain swears by it. Your other idea on using a solenoid air valve tied to AC clutch activation to bleed past the TB is a dandy too. If I were to use that, I could recover map table switching fo WI safety. Hmmm . . . . Good thing I'm a slow builder.
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Old 04-08-2011, 01:23 PM   #8
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Hornetball do you already have your high-speed nozzle? I still have mine from the WI build in the turbo car I parted out. It is a true high-speed nozzle. I am willing to sell it since I do not think I will need it anytime soon.
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Old 04-08-2011, 01:38 PM   #9
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Originally Posted by ZX-Tex View Post
Hornetball do you already have your high-speed nozzle? I still have mine from the WI build in the turbo car I parted out. It is a true high-speed nozzle. I am willing to sell it since I do not think I will need it anytime soon.
PM sent.
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