There are failsafes, failsafes and failsafes...
 

I think we have discussed most of the systems available and their capabilties. It is a good moment to see what failsafe mechanisms are available from the simpest to the most complex. I will update the list when more contributions are posted, if any.

Direct detection:

1. Fluid tank level sensor :
Advance warning but only good for early warning but little use for system power failure or blocked nozzle.

2. Loss of system power:
If power is interrupted to the WIA system, it will de-engergise a relay and performs "Plan B", will not detect blocked jet or cut pipe or no fluid flow.

3. Inline pressure gauge:
This is very cost effective but require user paying attention.

4. Inline single pressure switch:
If the system looses fliud pressure during activation, an inline preset pressure switch can action a boost drop etc.

5. Two inline pressure switches:
Detects blocked nozzle (over pressure) and "lost of fluid pressure" (under pressure). This method is quite cost effective and within DIY capability.

6. Flow switch:
In inline flow switch, comprised of spring-load magnetic plunger inside a tube where the water flows through. The rate of spring determines the promixity of a reed switch again the pluger deflectiion. Output: on/off. - cost: low

7. Turbine flow sensor:
Good for progressive system but requires complex electronics circuitry to report a differnce between the "actual" and "planned" flow in real time.


More..?

In-direct detection:

1. Knock detection:
2. AFR tracking:
3. EGT tracking:
4. Inlet temperature tracking:

I leave it as it is until the this topic attracts more interest. It is important to know what how "safe" is a "failsafe" .

Richard

I would be hesitant to rely on some indicator to tell me to ease up on the throttle. At 27 psi my attention would be on trying to avoid running into the back of the Cobras in front of me. The engine damage may have already started.

With flow, the system would have to be fast - the WG act would need a solid air command with quick solenoid actuation inline of perhaps short as possible tubing, not to flexible either. Yanking timing in respect to underflow conditions or both (timing/WG act) would be best but too expensive for me.

If safed by venting boost, I assume that the flow monitoring system should require periodic ops checks to make sure the flow sensors, solenoids, and works are in working order. Can easily be done with a pressurized system (use leak test procedure that includes nipple to the sol.) while blocking flow and looking for WG act movement from up top, but depending on the kit complexity, you may have to find additional ways to fool the system of thinking your driving spiritually - I dont know yet.

wouldn't number 5 be the best?

I concur with his statements. When you are WOT and boosting 26-28PSI there is virtually no time to fix nothing, we are talking about a couple of seconds, you are already in charge of having to read boost gauge, RPM and by the time you realize there is a problem then your engine is gone.

I think people want to hear or a mechanism that you plug in and forget that is there and that it would shut down boost or would minimize damage by other means but without the human factor.

Number 5 is good for am on/off system but may be a bit vague for a progressive system.

Richard

We have #2, we plan on adding #1 & #6 as soon as we have time. This will likely become an option due to cost. At $299 for our kit, it is one of the most affordable options for those getting into A.I.

On my setup I have an air valve that directs complete boost presure to the wg in the event of low fluid level in tank. this drops the boost to 11psi instantly. cost about 20bucks to do and a easy install. also works with the should the system loose power. But how i really use it is in town i have the switch turned off, this means no alky and 11psi of boost. Gives me great gas milage. then when playing around turn switch on and alky is powered up and so is high boost. I would like to hook it to a presure sensor inline too. Hum.........problem is you only have alky pressure when the pump is running. Any ideas?

snowperformance.net
safe injection $99
The unit will send dcv out to energize a solinoid ($39) t'd parallel with mbc in the event pump output flow goes below a certain ml/min

Shiv is working on a function on the XEDE that would work as a great as a water/alky injection failsafe.

From Shivs post,

1) Lean Run Protect
You define the leanest allowable on-boost AFR curve (5 RPM points) and decide how long it needs to be triggered for (0.5 sec is long enough to not induce false triggers caused by sensor lag) and let the XEDE do the rest. By "rest" I mean a sudden boost drop. If it still remains leaner than that threshold at the lower boost (say another 1 second), it'll do a hard fuel cut. The user can change the conditional logic (allowable time durations, actions, etc,.) This is critical for Methanol use where a pump failor or a jet clogging will destroy a motor in no time. Also good for protection in the case of fuel pump failure or anything else that could induce leanrun.

Along with the direct port injection, I also have added a safety feature. The engine, without a boost controller, boosts around 15 psi. In the last picture, you will see a bleed hooked up to a solenoid, that is t'd into the line running to the wga. When the water/meth injection activates, the nozzle pressure sensor between the water solenoid and the injectors will trigger, which in turn does a couple of things. The first is it will light a small led in the cabin that will be mounted in my gauge pod. The second, and most important, is that it will activate the solenoid with the bleed, instantly increasing my boost to 20-21 psi. The best part is, no pressure to the injectors, then the boost will stay at 15 (peak). But if the water injection system is working correctly, the boost will increase.

http://img132.imageshack.us/img132/2...ebay7pg9xc.jpg
http://img132.imageshack.us/img132/7...port2la0np.jpg
http://img132.imageshack.us/img132/1...rbox0jl0hc.jpg
http://img132.imageshack.us/img132/8...yebc2df4an.jpg

If one of the four nozzles gets clogged the psi sensor wont notice.

The only way to have a system like that totally failsafe would be four separate flow sensors.

Nonetheless, very clean setup you have.

Good point. $400 worth of flow sensors.

You are correct that the clogged nozzle feature gets lost, but truthfully, that has never even come close to being an issue. I have a 40 micron filter between the tank and the pump, and each individual injector has its own filter. I have never even had any of those come anywhere close to becoming clogged either, so I am not worried about losing that feature.

I haven't had a chance to dyno the new setup versus the old one (single injector mounted just after the intercooler), but the good ole butt dyno sure feels it. The nice part is, since the bleed only activates after the w/i activates, I don't have to deal with massive part throttle boost. I love when I punch it, it takes about 1 second for the boost to build, and once the boost passes through about 12 psi, the whole setup kicks in (w/i and ebc), and then I get another 5-6 psi. Makes it feel like a nitrous shot.

1 second is about a half second or more too long for an Evo 16g.

Impressive. So your saying from a stop, at idle, then punching it, you will reach peak boost in .5 seconds?