I recently installed an AEM wideband and Fuel Pressure sensor so I can log them in powerlogger. I've had the Alkycontrol system on my car for several years now and it works great, but I've never really pushed the car that hard.
Now that I can watch AFR I'm ready to push the performance. It would be nice to have a "fail safe" add-on to the AlkyControl kit. We have a red/green activation light that let's us know it's making pressure, and a low tank level light to let us know it's getting low on fluid. Could these be made into an active failsafe? For example if pressure is low AND / OR the level is low have the control box activate a solenoid valve to block off the "bleed solenoids" or manual bleed valves making the internal wastegate open at it's minimum pressure. Or have a small pressurized tank at say 20psi that would open up the wastegate fully via a solenoid controlled 3-way valve.
I try to be good about checking the system operation, but a failsafe would give a little more assurance when the boost is at 24psi and you're ripping down the track.
1987 GN, 63K miles, mild bolt on car has gone mid 12's. TA49 / Stretch SLIC / 3" downpipe / 3" exhaust / Walbro 340 hot wired pump / 3.5" MAF w/ Translator+ and Extender chip.
There is a solution out there for what you are doing and it does not need to be elaborate or anything. Nor does it need to be expensive. One such method is monitoring the red/green LED voltage and put a range check on it. Also monitoring the Alky pressure and range checking it. With these signals, try to activate a solenoid of some type to bleed off the boost pressure.
Since I have an GN-ECU I should be able to accomplish something similar should I see the fuel pressure drop drastically during a pass or at WOT. There are a lot of affordable microcontrollers, like Arduino or Raspberry PI, along with tons of source code available to help accomplish your task. Just need to make sure that if you choose a microcontroller it can handle the automotive environment.
I have a couple of Arduino and Raspberry PI microcontrollers that I play around with and I would use them for testing maybe, I would not rely on them for anything safety critical.
I also have an STM32F411E-Discover microcontroller from ST Microelectronics and I do believe it is rated to handle automotive environments and I may use it at some point or I may consult with others and checkout some other microcontrollers to ensure that they rated and have the reliability to use under the hood. I would want to mount a microcontroller under the hood, so I can keep the distance as short as possible and henceforth shorter wires for reading any inputs and/or controlling any type of actuator.
All the microcontroller crap I am talking about is not necessary to accomplish a fail-safe in the event that the alky system fails and/or you lose a fuel pump. I had a fuel pump fail on me in 2008 while doing a 1320 pass. I had just topped my alky reservoir off, did a nice burnout to heat my tires up and I was headed for my first sub 12s pass and I almost had it. At aboot 990' or 3/4th of the way down the track, poof my exhaust made it look as I was powered by jet engines as the all the white smoke was coming out of the tail pipe.
I still managed at 12.4s pass, which was my fastest pass thus far, at a trap speed of 71 MPH. The 1.75 60' is what helped set me up for my first potentially sub 12 pass with my newly installed TE44 and Razor Alky Kit.
My brand new Walbro 255 LPH fuel pump from Full Throttle suffered a Catastrophic failure. Of course, the first thing to get the blame was the alky. The shop that installed it said, "I must have let it run dry" and others just outright blamed the alky system and said that's why they would never run alky and it's my own fault for using alky and not running 116 or whatever. The shop that had installed it, did not believe me initially when I told them I had topped off my alky tank. After they talked me into getting Champion Ported Stock Heads and zipped it up with ARP head studs and tried to start it, they realized the fuel pump was dead and called me and said I needed another brand new fuel pump. I told them I was out of money and I would have my car towed home, but after spending the additional couple grand for replacing the head gasket and the purchasing ported heads that I absolutely did not need, they reconsidered and put a Walbro 340 LPH pump on it. I still have the stock head gaskets and the failure point, I was told, was in a weird spot for popped head gaskets from detonation. It actually melted the gasket right the side water jacket for cylinder 6.
As it turned out, a batch of Walbro's 255 LPH fuel pumps had a generic flaw in them that was causing them to fail prematurely and without warning. No gradual reduction in performance, the pump turned off like a switch. The issue was with Walbro's design and Full Throttle bared no responsibility for the pump failing. I think it is important to point that out, because I have never had an issue with Full Throttle or their products or services. They are also local to me.
Anyway, sorry for my life story! What you're suggesting is a good idea and I am not certain under the circumstances if I would have been able to go to a safe mode tune and bleed off all boost pressure in time to have saved my head gaskets and the additional $3000 I had to spend, but something is better than nothing.
