Help with building your Speeduino, installing it, getting it to run etc.
#66978
Please correct me if I'm wrong:
1. If I have reg fuel 5.2ms, then with 1 squirt per engine cycle it will be 10.4ms every 720*?
2. If 2 squirts, it will give 5.2ms 2x every 720*? So 1x 5.2ms every 360*?
3. Odd fire applies to ignition control or also to injectors?

Which injector will be better for this setup?
Will a larger one shorten the duty cycle and provide greater precision?
I have 430cc/min currently at 4 bars
Actual Engine 662cm3
Next engine under construction 740cm3
#66979
I'm not sure and cant check anything without my laptop, but conceptually req fuel is the duration of injection required for one combustion cycle per cylinder, so the numbers should reflect that. But I believe TS interferes, at least, with sequential.
Yes, the odd fire angle is the angle between channels for both injection and ignition.
As I said before, I don't think its in play when you only use one channel of each.
Do wasted spark coil packs need both outputs connected per channel? (Just thinking about how it would work if you were to use two channels)
#67014
noisymime wrote: Mon Jan 29, 2024 8:44 pm OK, thanks for the clarification. In your current arrangement I would try the following settings:
  • Squirts per cycle: 2 (You need at least 2, 1 will cause all sorts of issues with the single injector/shared inlet arrangement)
  • Engine Type: Odd fire
  • Channel 2 angle: 0 (If you had a cam sensor, 360 would be fine)
  • Injector Layout: Paired
That should allow you to use the single injector and a wasted spark ignition layout.

This is specifically for what you've described as your current setup. The changes you're talking about with a 2nd injector, different inlet arrangements etc WILL mean you need to change these, but it should be right for your current setup.


Thank you very much for your help Josh :)

Your setup works much better, more evenly, the response to the gas is much better.
We have fired it many times and there is repeatability of correct operation every time.
The bug working on 1.5 cylinders has been resolved. Zero sync losses.


Now we need slight corrections to the VE map because the AFR in the middle part of WOT is poor, but it is not a problem.

Out of curiosity, what should the setup look like on a head that has its own intake channel for each cylinder? (two throttles, two injectors, ITB)
Isn't it the same, just two PAIRED injectors (operation without a camshaft sensor)?

Thanks again for the help from everyone on the forum.
I delved deeper into the topic and now I am more aware of what is happening in the engine during injection.

I will try to make measurements with an oscilloscope in the future.
#68825
Hi

There is no test with an oscilloscope yet, because there are shortages in the equipment... but:

I am replacing the head with one intake channel common to two cylinders with a head where each cylinder has an intake channel.

There are two cylinders and they work simultaneously - just to remind you ;)
Air-cooled engine, but that's a detail.

How to set the "Engine constant" correctly in this case?
The same as for one injector and common intake?

Now each cylinder has its own injector and throttle valves.
I will try to measure the cc/min of these new injectors tomorrow.

this is how the car drives now:
https://www.youtube.com/watch?v=-c-u5A_5bd8
#68826
There is one more topic:
I still have the feeling that the engine has more power at the start of the race, and then during a long ride at WOT it seems to drop by 5-10%... Temperatures are stable EGT / IAT / CHT and AFR approx.

What could this be caused by?
Driving at WOT for a long time and I feel that there is less power than when accelerating.
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