For discussion of Speeduino compatible boards designed / built by other members of the forum and for guidance around making such a board
#40160
Hello,

I am curious if the current speeduino firmware would function as an ignition only device using just a few input signals.
Specifically:
1) Cam or Crank signal 24-1
2) TPS

would any other sensor inputs be required to have a tune able spark advance curve? If not what other inputs would be needed for an ignition only system.
#40161
That should work, though the more sensors you have, the better

Coolant sensor can give more advance when cold.
IAT can retard ignition where air is hot.

I'm running 60-2 , and TPS (until I locate the the safe place I've stored the MAP pipe) only. :)

Plus resistor spark plugs if you don't already have them.
#40165
Huh mo TPS? what is the real-word shortcomings of a 2D table? I assume a 2D table is SIMPLY RPM VS Ignition timing, with no outside influences?
I will still be running carbs so I am more than happy to not have to fabricate AND Implement TPS,

Schematics will be up tonight!

A few more questions:
Can the vvt function be used to PWM a oil 12v pump relative to rpm and load (MAP)?
Is there a provision in the software to for; example constantly check that a oil pressure flow sensor is within a specified range and issue a short warning follows by a shutdown?

Thanks for all your Help,
JOSHUABENJAMINM
Last edited by Joshuabenjaminm on Fri Jan 03, 2020 1:14 am, edited 1 time in total.
#40166
TPS is not commonly used in ignition system timing as it is a transitional load request rather than representing the current engine load. Minimally, timing is based on RPM, though typically ignition is primarily based on speed and load (RPM x MAP) as the two largest influences on timing requirements. This may be modified with many other factors that affect burn rate (and therefore best timing), such as engine temperature, intake air temperature, variable fuel type, etc.

David
#40167
:cry:
Joshuabenjaminm wrote: Fri Jan 03, 2020 12:55 am Huh mo TPS? what is the real-word shortcomings of a 2D table? I assume a 2D table is SIMPLY RPM VS Ignition timing, with no outside influences?
I will still be running carbs so I am more than happy to not have to fabricate AND Implement TPS,
Yes, it's the equivalent of running your old mechanical distributor with the vacuum advance disconnected. Downside is you can't advance idle for leaner burn at low load etc.

It's much better with a load signal, but I guess you can choose when to add it.

Adding a MAP port somewhere might be easier, but It wasn't so hard lashing this potentiometer up on my carbs as a TPS.

@PSIG where do you connect the MAP? engine side of the throttle or air side? I did think about this when I was running ignition only and couldn't decide.
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#40179
LPG2CV wrote: Fri Jan 03, 2020 9:42 am Ok, at this point, it may help if you tell us what you want to achieve. Where you are coming from, and where you want to get to. :D

If you just ask individual questions, it doesn't provide a context to answer them. :)
^^This. we are only talking in generic terms, as we do not know the project or its goals. Without those we cannot estimate the effects of each variable or make suggestions if we have them and if you want them.
jonbill wrote: Fri Jan 03, 2020 9:24 am @PSIG where do you connect the MAP? engine side of the throttle or air side?
In order to use it as a load sensor, it must be reading manifold pressure — so after the throttle. This follows convention and Speeduino, which uses Speed Density as the primary basis for both fueling and ignition timing calculations.

@Joshuabenjaminm using load for ignition is always used for calculation when applied, except for absolute WOT on an NA engine, in order to apply best timing for best efficiency. Best efficiency means best performance (max torque, max power, max economy, etc). It applies to all. For other engines such as with power adders, load is used for benefit all the time, including WOT.

Fixed (1D) timing is only useful for engines that run at one speed and load. 2D timing only helps to compensate for the burn rate changes due to speed, in relative timing, turbulence effects and effective compression. This works well enough for engines not operated dynamically, such as static generators and some boats, etc. Substantial improvements in efficiencies are found by also adding load to the brew, and allows nearly unlimited manipulations for specific special purposes. Win, win … win.

My point in this is only to emphasize that an engine will run with fixed ignition, run much better with 2D timing, have another leap forward with load, and incremental additions from other data. At any given moment and conditions there is only one correct timing point, and as @LPG2CV said, more sensors (data) means finding that point easier or better or both. Whether you wish to apply that or need it for your project goals is entirely up to you.

David

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