Siamese Code Trial - Take Three
Turbo Mini Forums

Edited by Rod S on 14th Mar, 2009.

Schrödinger's cat - so which one am I ???

Edited by Rod S on 14th Mar, 2009.

Schrödinger's cat - so which one am I ???

so higher pressure and shorter opening times should prove interesting....

One further thought....

Paul, do you have an .msq of your best "pre cam sensor" siamese code so I could run that and display it.

Just a thought....

Schrödinger's cat - so which one am I ???

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

http://www.jbperf.com/

Schrödinger's cat - so which one am I ???

yes rod i agree ,....but as a quick and dirty 'see what happens' without any more expense its worth a try .. i seem to remember a calculator on ms forum for finding flow increae with pressure change.. ill see if i can find it .

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

newRate = oldRate * sqrt(newPressure/oldPressure)


even better heres a calculator

http://www.csgnetwork.com/fiflowcalc.html

oops heres a better one

http://www.injectorrx.com/sizing.html

Edited by robert on 14th Mar, 2009.

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

The flow increase is equal to the square root of the pressure ratio. So, for example, if you go from 45psi to 60psi fuel pressure you increase flow by 15.47% (square root of 60/45 = 1.1547).

Jean

http://www.jbperf.com/

so even 70psi is only going to give 468 cc odd,25 % more ...
if the pump can do that ..worth a try to see if the logs change though .

bigger injectors deff worth trying .

trouble is it all costs !

Edited by robert on 14th Mar, 2009.

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

OK,

Paul, if you are only testing on two injectors, what about trying putting the other two wired in parallel and halving the VE tables ???

That should put you back with a big gap between (like my 3000 RPM photo).

Although I'm probably missing something obvious as the alcohol kicks in.....

Schrödinger's cat - so which one am I ???

Increasing the fuel pressure is not going to give much of an advantage. Plus I want to leave enough for the pump to cope with up to 30psi boost!

I still have the other two injectors connected to the fuel rail so I can easiy bring them back in.

Ultimately, the only solution may be to go full sequential with Jean's new board.

Rod, can you please try and merge the two pulses? Just need to be sure that the ECU fires the injector when the first pulse starts and stops when the second pulse stops and not before.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

Paul,

If you want a single pulse don't do it with 2 pulses merged but with one table set to 0. Merging 2 pulses has side effects in the code because it does delay the second pulse to try to cope with the overlap.

With a single pulse from a zeroed table you keep full control over timing and pulse width. Of course you have to either up the VE table or the req fuel.

Jean

http://www.jbperf.com/

Schrödinger's cat - so which one am I ???

After writing the last post it just reminded me of something. Another reason not to have pulses too close together is due to how the injection timing is done. It starts a timer at the wheel tooth just before the injection angle and then fires the injector for the pulse duration using the same timer. However, if the injection from the previous pulse is still going, it can't use the timer so it sets a flag which says to fire immediately at the next tooth.

So this has a side effect of changing the timing of the second pulse and potentially reducing the first pulse if the overlap is too big (more than the equivalent of 1 tooth). This method was chosen because it handles 100% duty cycle very well in a normal engine sequential injection and it should be ok with siamese engines if people are careful about it (since you don't more than 60% duty cycle if that).

I'm sorry not to have mentioned that before but there are so many things in the code that some aspect of it still need to be written down.

Jean

http://www.jbperf.com/

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

Edited by Paul S on 15th Mar, 2009.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

Schrödinger's cat - so which one am I ???

http://www.jbperf.com/

One thing to add. If you do the single pulse with 0 VE in the second table and you want to have 2 pulses at low RPM, you have to be careful how you do the transition.

Because the code interpolates between the VE table cells, you can't simply keep the table you have now and fill it with zeros starting at one column. That would result in a diminishing pulse width between the RPM before the table transition and the RPM with 0. Since you will need to increase VE (essentially doubling it) in the first table to compensate and if you have the same RPM points then it should compensate to give the correct overall fueling. But you will have to adjust the timing table such that you get the fuel where it is needed which might be tough.

So what you could do is to have the transition as small as possible with the first column with 0 being 1RPM more than the last column with non-zero values. Then the transition would pretty much be like a switch from one mode to the other.

Jean

http://www.jbperf.com/

We have had some success today.

We are still working with single injectors per port and 3 Bar fuel pressure.

We have spent considerable time adjusting both timing tables in each direction to find the optimum.

We have advanced the first pulse so that the mid-pulse is at 145 degrees and retarded the second pulse a bit so that is at 35 degrees, both at 6000 and 100% MAP. Hence the pulses are 290 degrees apart at peak.

Still with 20% less fuel in the first pulse.

There is an obvious benefit from separating the pulses at high rpm, but not as much as I had hoped.

The AFRs from 3800 to 5500rpm are now at 11:1, inners and 12.5:1, outers.

At long last we have managed to get some more fuel into the outer cylinders, but still cannot lean out the inners.

We might try playing a bit more with the VE tables now that we seem to have optimised the timing.

Edited by Paul S on 15th Mar, 2009.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

A little bit of log for your enjoyment

Attachments:

40.75kb

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

That's interesting. First, congratulation on the progress.

Second, it's interesting to see that during fast transitions (around 223s and, less visibly, 292s), the AFRs get reversed in that the inner cylinders get richer than the outer cylinders as opposed to what we see at high RPM.

I'd really like to see a Megatune log to see what is happening within the code because, while this really shows what is happening in the engine, it gives absolutely no reason why the code is doing what it's doing. It could provide great clues as to why you can't lean out the inner cylinders because they obviously can be leaned out as shown by the transitions.

Jean

http://www.jbperf.com/