Trionic

iTrader: (4)

1. What would happen if you took the output if an FJO injector driver: http://www.fjoracing.com/products/injdrvr/ and ran a S-HSV with one of the channels directly, both coils in parallel?

2. It appears that the FJO injector driver has an exceptionally high impedance input so it should not load injector drivers, stock or PFC. 200 ohms is quoted as input impedance. Chuck says 13.8 ohms per stock injector here: https://www.rx7club.com/showthread.p...&highlight=fjo which seems okay and resonable. (200*200)/(200+200)=100.

3. Considering the above and assuming that a S-HSV will respond correctly to a pure peak and hold injector signal, it would seem like it should be possible to slave/duplicate injector signals with an FJO.

For example, I have some 1600 cc/min injectors on the way to me(http://www.xcessivemanufacturing.com...?pid=78&step=4) and an FJO to run them. The FJO has 4 independent input and 4 matching independent outputs, since the input inpedance is so high per channel, it should be possible to parallel the front and rear secondary injector signals and pipe them into channels 1 and 2, and 3 and 4, which would give outputs to drive 4 injectors, or 2 injectors and 2 S-HSV's(?)

Anyone see anything wrong with this?

What is the frequency for the stock PWM injector control? I have a portable o-scope, but unfortunately the engine doesn't seem to be in the car right now. Anyone know that stock frequency?

Richard L

This is perfectly feasible and should work well. Check for linearity of the S-HSV, if it does match the injector's flow, you will be wasting your time. The stock PWM should vary between 30-80Hz or close to that. During this ramp, the duty cycle % also vary depending on engine load.

Howard Coleman

iTrader: (6)

interesting

hc

Trionic

iTrader: (4)

Yes, and that's the other thing. To make something like this work it will need a proper manifold referenced pressure regulator setup like a regular FI system.

It's nice that no one has any major objections or sees any major flaws with the idea because I already ordered two S-HSV's (one per primary runner) and a 250 psi pump yesterday. Also ordered a couple of different nozzle sizes because the basic mechanical proportion will be set that way, then trimmed with injection pressure adjustment. I plan to start with a 1:1 adjustable FPR I have laying around here, but if that's not sufficient there's always rising rate regulators available to compensate for non-linear valve output.

edit: My concern right now is that it will likely be necessary to run the pump at 100% duty cycle. Despite the fact that they sell systems specifically designet to operate that way, I can't seem to get a straight answer as to whether or not that's a reasonble thing to do.

I was previously scheming a more elaborate control scheme based on a car-PC/DAQ setup with USB I/O ran off of LabVIEW, but then I got to thinking that I really don't want a Windows product responsible for running something as critical as WAI.

Slaving off the secondary injectors, I think should work to give a nice 1:1 control over the injection with the proportion determined by the nozzle sizing and trimmed by adjusting *manifold referenced* system pressure.

Trionic

iTrader: (4)

On a related note, since the car is out of service right now, I just Googled to see exactly what a true Peak-And-Hold signal looks like and found this article. http://autospeed.com/cms/A_109873/article.html It's a pretty good basic writeup of stuff that's good to know for making one of these S-HSV work (or for selling one for that matter).

Richard L

I like to go into this in greater detail...


This will depend on the impedance of the the S-HSV and the fuel injector. As lomng as the FJO "doesn't" go into "peak and hold" mode, both coils will recieve full 12V. Not problem there.

As soon as it goes into "peak and hold" mode, the drive will change from "constant" voltage to "constant current" During the "hold" mode, the current will be shared between the two coils. The coil with a lower impedance will receive a larger portion of current.

For example, if the Fuel injector impedance is 2 ohms and the S-HSV is 40 ohms. 1:20. Under this circumstances, the S-HSV will have a 1/20 of the 1A "holding current). This equates to 50mA. I don't think this current will open the valve at all.

If you want this to work, don;t parallel it up with a low impedance fuel injector. Just drive the S-HSV on its own.

In fact you can do away with the FJO altogether, just parallel the S-HSV with the original 16 ohm fuel injector.


The input is find as it is.

For example, I have some 1600 cc/min injectors on the way to me(http://www.xcessivemanufacturing.com...?pid=78&step=4) and an FJO to run them. The FJO has 4 independent input and 4 matching independent outputs, since the input inpedance is so high per channel, it should be possible to parallel the front and rear secondary injector signals and pipe them into channels 1 and 2, and 3 and 4, which would give outputs to drive 4 injectors, or 2 injectors and 2 S-HSV's(?)[/QUOTE]

Covered on 1.

Have you tested the S-HSV linearity? I read from a thread posted soem time ago, the S-HSV has a limited dynamic span, something like 40% to 60%. Which really puzzled me. A claim of 1.5mS response time equate to 7 to 93% dynamic range at 30Hz. With the added water pressure, you are going to reduce the range fuirther.

Worth looking into thia first before spaning too much time on the electrical side.

Trionic

iTrader: (4)

1. You're not understanding what I'm saying, let me clarify, a single S-HSV is two valves and two coils combined into one (valves plumbed internally in parallel. Coils wired however you choose). The two coils of a single S-HSV should approximately be the same. Those will be run in parallel together off of one designated FJO driver circuit. I'll be running two total S-HSV's, each ran off of it's own designated FJO driver circuit, each injecting into one runner directly (that way I don't erode my throttle plates too)

3. The valves will be linear enough if the jets are sized such that the valves are operated in their linear range. Further tweaking can be made as necessary by controlling the feed pressure to the valves. For example a RRFPR could be used to manipulate feed pressure to overcome non-linearity’s if needed. Acceptable pressure ranges to operate within are actually pretty wide, so there's tons of flexibility availability between manipulating the pressure and changing jet sizing. The lowest would be max manifold pressure+30 psi for good pattern, say 50-55 psi all the way up to 120 or 150psi, or wherever the valves begin to not work anymore up to whatever the 250psi pump can deliver (whichever is the first limiter). Details are sketchy on these valves and even the vendor seems confused as to exactly what the spec.s are but I'm confident that I'll be able to find the linear portion and control within it. As long as the PRECISION is good and repeatable, the ACCURACY can be manipulated by other means.

It's speculation that it'll work right now; I can't see why it wouldn't though. The parts are on their way right now. Assuiming everything arrives this coming week I'll have the engine back together next weekend, installed in the car the following weekend, and then started and tested the weekend after that.


So there will be answers soon enough.
Covered on 1.

Have you tested the S-HSV linearity? I read from a thread posted soem time ago, the S-HSV has a limited dynamic span, something like 40% to 60%. Which really puzzled me. A claim of 1.5mS response time equate to 7 to 93% dynamic range at 30Hz. With the added water pressure, you are going to reduce the range fuirther.

Worth looking into thia first before spaning too much time on the electrical side.[/QUOTE]

Richard L

I now know how you are going to wiring it up. FJO is only used for WAI only.

Sometime ago, I gathered the OE injector driver transistor can switch up to 6A. There are plenty of power there to drive the OE injectors as well as the twin S-HSV (draws about 0.5A). It is strictly not necessary to use the FJO. No harm done if you are using one.

3. As long as you are happy with the linearity and operating range, compensated mechanically, all is well. By the way, I am not concern about the non-linearity caused by the pressure diferential. It the matching lineaity of the S0-HSV and fuel injector. (fuel injector' response to duty cycle % is very accurate.

Look forward to the update.