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Help with building your Speeduino, installing it, getting it to run etc.
By Torslund
Are building next V12 and need some advice on injector driver. How can I make Speeduino drive 3 high imp injectors on every channel?
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Most boards that use Speeduino code are designed to fire multiple injectors per INJ channel. You should check with your specific board's specifications for the limits your board version can handle, which is based primarily on the copper trace size, but the MOSFET capability may be a factor.

For example, the v0.4-series is stated as capable of 8 amps maximum average on its traces, and in-fact there are many V8 engines running 4 injectors on 2 channels, and 4-cylinder engines running batch fire with the same channel loading, as real-world examples.

Run your calculations for the average amps you will place on your injector channels, and check your board design for ability to handle that load. Example calc with 12-ohm injectors on a V0.4.x board at 15-volts:

injector amps: 15V / 12ohms = 1.25A at max voltage, each

Avg Amps per Channel: (1.25A * 3inj) * .90maxDC = 3.375A average at 90% max duty cycle

Channel load %: (3.375A * 100) / 8A = 42.2% channel capacity (rounded)

In this particular example, you would be fine for 3 (or more) 12-ohm injectors per-channel using a v0.4 board. 8-)
By Torslund
Yes, you are right as usually. I have the v 0.3 board. Have thought about it, there is no heat sink on the board. Can it take 8A?
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The v0.3 series boards have single-side 1-ounce copper PCB traces, and they are long, but also are wide at 70 mil. What this means is that each injector channel of the v0.3 can handle roughly 8 amps with a trace temperature increase of 60°C, by calculation. Real-world, this means the v0.3 board can handle what you're doing (if confirmed with calculations), IMO.
Last edited by PSIG on Mon Jun 14, 2021 3:21 pm, edited 1 time in total.
By Torslund
I have change distributor to one with VR output and use a GM HEI module and coil. The signal from distributor is very clean and would be usable as trig. Is there any way fool TS and speedy accept that as RPM? And use the 4 injector outputs.
By theonewithin
Sorry what is it you want to do?

What type of pattern do you have ?

Do you have a VR conditioner?

Fooling your ECU is never a good idea so please explain what it is you actually wish to do.
By Torslund
I want clean trig. No I don't have a VR conditioner installed. Still running on Hall sensors. But if I could take the VR sensor signal, 12 pulse as trig I save wiring :) And use as much as possible of oem parts. One way would be use a counter and divide with 3. But I can't do that circuit any more, long time has gone since I did work with gates. Maybe some one here could do a schematic for me.

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