Speeduino 2T EFI Project

[TZ350]

TZ350 I might be being dumb here, but have you measured the exhaust temperature in the pipe?
I don't know if you are aware but there is a correlation with temperature, that equates to the combustion temperatures and when the pipe is working better. So if the exhaust is around 520-600ºC the pipe should be performing pretty well, below this, it isn't doing much, and as it goes towards 720ºC it is very likely in a lean burn condition, as the pipe is much shorter, and dragging fuel out of the cylinder.


So there maybe scope in using temperature sensing to activate fuelling changes when the pipe is working better, or adversely affecting things.

There are some issues with that approach like leaning out the mixture to heat up the pipe for more over reeve, and the situation where detonation heats the head and cools the pipe. If the mixture is then leaned out because of the cooler pipe the detonation just gets worse.

[TZ350]

I was hoping I made a good decision on the injectors, but if my two primaries of 107cc/min @3 bar equal 214cc/min are too big I’m stuffed. These were the smallest I could find at the time.

You might be stuffed.

38 g/min (50cc) is what I use for the primary injector. I found 60 g/min (80cc) with a min on time of 1.7ms was to big for a 125cc cylinder. The smallest injector available in the style I use is 30 g/min.

[TZ350]

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I developed a Arduino Nano to measure the crankcase pressure at a set crank angle and present that as a pseudo MAP value to the Ecotrons.

The Ecotrons could log the changing MAP values but because the Ecotrons 2S software would only run a Alpha-N table it could not do anything with the information. As much as I begged or tried to explain, Ecotrons was not interested in making the VE table available in their 2S software.

Making VE available would not have been much of an issue for Ecotrons because their 2S system was just their 4S program with the VE table turned off because the MAP value as measured in the inlet tract of a 2S did not produce meaningful information.

Now I need an enhancement for the Speeduino that allows for an instantaneous MAP measurement at a chosen crank angle.

First picture shows the variations in peak viz min crankcase pressures at different power conditions.
Second picture is the Arduino Nano. The MAP sensor is hard to see but it is plugged into the green hose on the brass crankcase plug.
Third picture shows the MAP value as recorded by the Ecotrons logging system. The yellow circle shows where the step is that we saw in the averaged MAP lines previously.

[TZ350]

The picture shows the variations in peak viz min crankcase pressures at different power conditions.

With that, I can see using Speeduino instantaneous MAP, timed to ~135° (assuming pressure timing slightly advancing at lower rpm — more rpm plots needed), then using MAP multiply to modify the Alpha-N fueling calculation. Would be a place to start, anyway. 65 to 130 kPa is a good range of values to work with.


Conversely, Speedy can do minimum MAP value of each cycle, but change it to max, and use that with MM as an un-timed max value. This would promote greater fueling with higher max, and less with lower values. That's the direction you need to go when twerking the throttle , in order to recover after it has fallen off-pipe, yes? This last option would likely be simpler to mod the code for testing.


Have you tested response using Speedy with basic MM on crankcase pressure yet?


David

Hi David. Yes I will do some more plots at different RPM.

[TZ350]

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Some simulated crankcase pressure traces with the minimum in the middle because I wanted to see if there was anything useful there, but I don't think so. Open to suggestions though.

The peak on the left looks like air that went into the crankcase then bounced out again, as it does. Or more likely, exhaust gases back flowing down the transfers into the crankcase.

This pollution from the exhaust may explain why the minimum crankcase pressure can be the highest and much the same at idle and low RPM whatever the throttle position. The exhaust pollution in the crankcase may also explain why the motor idles when the throttle is near shut in spite of the average crankcase pressure being the highest, much higher than at WOT.

A 4S motor has a throttle plate with an inlet tract attached to a fairly good piston pump so its inlet MAP is low at idle and high at WOT.

A 2S also has a throttle plate but its inlet tract is attached to something that acts more like a pulse jet engine than a pump.

A 2S crankcase MAP is high at idle and lower at WOT. So MAP behavior for a 2S is quite different to what we are used to from a 4S.

My current thinking is to take the difference between the minimum crankcase pressure seen in the middle of the graph and the maximum that is seen on the right hand side where the piston is compressing the actual air that was trapped in the crankcase and using the difference as an air flow indicator.

To me this difference seems to give the best indication of mass air flow. With the difference at 65% being about 0.33 bar, 15% 0.20 bar and 5% 0.15 bar at a rough guess.

If we do something like MAP = (Max - Min) * 3

Then 65% on the pipe would be 0.99 bar
And 15% on the pipe would be 0.60 bar
And 5% on the pipe would be 0.45 bar

They Look like useful traditional 4S MAP values that Speeduino can use and off the pipe situations would easily show up as a lower MAP values.

,

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Like most people I guess, I just assumed that a 2S crankcases pressure behaved like a 4S inlet manifold. Low pressure when the throttle was closed and high when the throttle is open. But for a 2S that is not true, in fact its the complete reverse and another example of the mistake of trying to apply 4S thinking to a 2S.

I expect rotary valve, 24/7, reed, case reed or piston port would all have the same crankcase pressure scenarios. If anyone wanted to, they could use something like EngMod2T to check.

The lowest crankcase pressure is with the piston at TDC, and that makes sense.
The highest crankcase pressure is with the piston about 140 ATDC, sort of makes sense too.

At 140 ATDC the inlet is closed and the transfers and exhaust port are open. Some mixture is flowing out the transfers but not fast enough for all of it to escape before the piston gives the remaining mixture in the crankcase a hurry up.

The pipe should be starting to suck real hard around that point too, so you have a real push pull situation accelerating the transfer of fresh charge into the cylinder.

If the pipe is not sucking that hard you will have a higher residual pressure left in the crankcase. That explains why at idle and low throttle at low revs the crankcase pressure is higher than when the throttle is wide open and the motor is singing on the pipe. With high crankcase pressure exhaust gas pollution explains why when the throttle is closed the motor slows down to an idle.

At idle the motor is running on a very small amount of fresh air mixed with a lot of pollution that has back flowed from the exhaust. I am not sure if the crankcase is full of pollution or its full of clean mixture and only a small amount is being transferred to a cylinder full of un scavenged pollution, maybe a bit of both so the story is not completely told yet.



But one thing is for sure, the crankcase pressure is higher at idle and low throttle than it is at wide open throttle with the motor making real power.

[ceci]

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Yes, 1980's Suzuki GP100 commuter fitted with a NSR250 cylinder, crank de stroked for 110cc. The spacer in the middle is so the 5 speed gearbox can be replaced with a 6 speed TS125 unit.

An ancient GP with everything plus fuel injection..... 31 RWHP


Attachment 338947 Attachment 338949 Attachment 338948

Tu ya estas al final del camino, está a punto de alcanzar tu éxito.

Yo al contrario esto al comienzo del camino, y me falta mucho hasta que llegue alcanzar el éxito.

Por ahora solo he realizado las dos primeras fases:
1º El estudio de que piezas, de que motores, me valen para hacer mi prototipo
2º La adquisición de las piezas principales y de mayor importancia (están tal como las he recibido).


Aun me falta:

3º El adaptarlas y unirlas entre ellas

4º transformar cada una de estas piezas para que realicen las funciones extras que realizaran cada una de ellas.

Nuestros caminos son paralelos pero distintos, distintos ya que yo voy a emplear la inyección mecánica en lugar de la electrónica.

Si he reflexionado y ya que mi prototipo tendrá un circuito de aire secundario creado por un pistón bomba auxiliar, el empleo de un mini carburador para alimentar el motor de la mezcla necesaria; esto es a modo de lo ya empleado por:

ttps://patents.google.com/patent/US4276858

Con diferencia de donde tiene que ir el carburador y como emplear esa masa de aire secundaria

[ceci]

3º El unirlas entre ellas

[TZ350]

Tu ya estas al final del camino, está a punto de alcanzar tu éxito.

Thank you for your post, I translated and read it, you have a very interesting project there. But as we are a former English Colony best to post here in English.

[Drew]

The fuck is that rooster on about?

[ceci]

Thank you for your post, I translated and read it, you have a very interesting project there. But as we are a former English Colony best to post here in English.

I do not know English, I use google translate.
When I review what I have translated, sometimes it is not what I want to say.
So if it's something important I put it in Spanish and everyone who interprets it

[Drew]

I do not know English, I use google translate.
When I review what I have translated, sometimes it is not what I want to say.
So if it's something important I put it in Spanish and everyone who interprets it

Google is how we translate anyway.

To make sure its correct, translate to English then back to Spanish. The errors will be clear.

[TZ350]

I do not know English, I use google translate.
When I review what I have translated, sometimes it is not what I want to say.
So if it's something important I put it in Spanish and everyone who interprets it

Good on you Ceci, thanks for making the effort, I enjoy your posts.

[ceci]

Good on you Ceci, thanks for making the effort, I enjoy your posts.

Thanks to you, your publications are more relevant than mine, I just try to give another approach, but always respecting yours.
The approach that I have chosen is mechanical injection, even so I will need your contributions since I will have to use some electrovalve

[ceci]

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But one thing is for sure, the crankcase pressure is higher at idle and low throttle than it is at wide open throttle with the motor making real power.

With these data that you contribute, you make me imagine what was the result of the test of this prototype.
Which I assimilate them to an experience lived in the youth, in which an Amal carburetor was obstructed the low conduit (without air filter, exposed) throttle closed, the engine revolutionized

[ceci]

With these data that you contribute, you make me imagine what was the result of the test of this prototype.
Which I assimilate them to an experience lived in the youth, in which an Amal carburetor was obstructed the low conduit (without air filter, exposed) throttle closed, the engine revolutionized

I'm constantly discovering that you always go hiding or hiding things, in the case this prototype I begin to understand why I do not progress