Classic Mini 5 port injection (siamese ports)

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tomazcebul
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Classic Mini 5 port injection (siamese ports)

Post by tomazcebul »

Hello,

I have a classic Mini with BMC A series engine with standard 5 port head. The challenges on siamese port injection (same for carb, but you can't solve the issue with carb) is described here http://www.starchak.ca/efi/siamese.htm and here http://jbperf.com/sequential/Fuel_Injecting_the_A_Series.html. The issue was solved with specialized firmware for MSExtra and was not updated for later versions.
Rover developed a multipoint injection cars in late 90's and the solution is described in the attached document. Basically there is a special sequence on how injectors are operated.
image.png
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Is this something rusEFI SW can support?

Many thanks for the response :)

Best Regards, Tomaz
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AndreyB
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Re: Classic Mini 5 port injection (siamese ports)

Post by AndreyB »

tomazcebul wrote:
Sun Jan 30, 2022 3:27 pm
Is this something rusEFI SW can support?
If it's possible at all I am sure rusEFI software could be modified for that.

I am 40% of the total rusEFI software developers pool. I have other higher _for me_ priority items for the next 24 months. You need to find a software developer interested in this work.
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mk e
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Re: Classic Mini 5 port injection (siamese ports)

Post by mk e »

tomazcebul wrote:
Sun Jan 30, 2022 3:27 pm

Rover developed a multipoint injection cars in late 90's and the solution is described in the attached document. Basically there is a special sequence on how injectors are operated.
Image


Best Regards, Tomaz
That looks like something I did many years ago on one of those and you could do it on any ECU with at least 4 fuel channels. It just used 2 drivers per injector and sized the injectors to not need more than about 25% duty cycle. iirc I use injector open angle rather than injector close angle just to try to get a like time for the fuel to vaporize but I don't know if it really helped. But that got the injector pattern you posted with no special anything needed I have a very old V12 with 8 intake ports I'm planning to do basically the same way, but on that engine 4 injectors will be on a single driver, 4 on 2 drivers.

You might look at this thread too...if I read it right it was a single injector like a TBI setup I guess.
https://rusefi.com/forum/viewtopic.php?f=2&t=2249
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Re: Classic Mini 5 port injection (siamese ports)

Post by tomazcebul »

Hello All,

@mk e, many thanks for the "out of the box" thinking. If I understood correctly, I can connect two channels to one injector and then run this as a normal fully sequential setup. In this case the injectors would need to be quite large to accommodate the fuel requirements (I have seen commercial setups with two 440 cc injectors).
The other option is to actually install 4 injectors (2 per port) to make injectors smaller, which will significantly improve idle quality.
I have seen the other thread and contacted JRD McLAREN directly before posting this question (waiting for the answer...).

@AndreyB, thanks for the response. I fully understand the rusEFI backlog is quite long and there are many items far more important than my question. I actually never asked for "new feature", I just wanted to understand if this is doable. And it looks like it is :-).

Again, many thanks for the response. It looks like it is doable. Will do my homework :-).

Best Regards, Tomaz
mk e
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Re: Classic Mini 5 port injection (siamese ports)

Post by mk e »

tomazcebul wrote:
Sun Jan 30, 2022 7:26 pm
Hello All,

@mk e, many thanks for the "out of the box" thinking. If I understood correctly, I can connect two channels to one injector and then run this as a normal fully sequential setup. In this case the injectors would need to be quite large to accommodate the fuel requirements (I have seen commercial setups with two 440 cc injectors).
The other option is to actually install 4 injectors (2 per port) to make injectors smaller, which will significantly improve idle quality.
I have seen the other thread and contacted JRD McLAREN directly before posting this question (waiting for the answer...).


Best Regards, Tomaz
If you want bad ideas, I'm your guy ;)

What you are saying is only partly right. Traditionally, as in back in the old days with low resolution ECUs and pretty inconsistent injectors the goal was 80-85% DC for idle reasons....but those days are gone. My car has 12 1000cc injectors, so idle pulses are pretty short and there is no problem sorting idle mixture. I wouldn't worry too much about that and 4 injectors wont' fix it anyway on your style ports.

On a Siamese port setup the big issue is the ONLY way to know the fuel you're injecting is going to the cylinder you meant is to only inject when 1 and only 1 intake valve is open, that is what the chart you posted is showing you, that is the MAXIMUM injector duration...so you are limited to no more than 180- degrees or 25%DC and you only get that with very mild cams, longer duration cams means short duration left for injection. So 2 injectors firing twice or 4 injectors each firing once only means changes basically nothing, the size of each injector remains unchanged as its driven by the time you have available which comes from the cam....with 4 injectors you maybe can aim them at the active valve a bit better, maybe?..that would be the only difference I can think of.

The other piece that modern ECUs have is cylinder trim. I didn't have that on the setup I did years ago and there were small differences which I figured were wall-wetting related but I couldn't fix with no trim....but it ran pretty well, well enough that I plan to try the same setup again on an upcoming build.
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Re: Classic Mini 5 port injection (siamese ports)

Post by mck1117 »

mk e wrote:
Sun Jan 30, 2022 9:08 pm
On a Siamese port setup the big issue is the ONLY way to know the fuel you're injecting is going to the cylinder you meant is to only inject when 1 and only 1 intake valve is open,
Due to wall wetting effects and such, this isn't how it works. Don't bother trying to trim individual cylinders on a siamese port engine, you're not going to get good control of each cylinder independently.

I wouldn't worry about it, personally. Fit the right size injectors, set it to batch fueling mode, and it'll work fine. 440cc isn't even a big injector, these days "big" is more like 1200-1500cc.

Besides, you actually get better performance and emissions firing the injector at a CLOSED valve than you do an open one.
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Re: Classic Mini 5 port injection (siamese ports)

Post by mk e »

mck1117 wrote:
Sun Jan 30, 2022 9:32 pm
mk e wrote:
Sun Jan 30, 2022 9:08 pm
On a Siamese port setup the big issue is the ONLY way to know the fuel you're injecting is going to the cylinder you meant is to only inject when 1 and only 1 intake valve is open,
Due to wall wetting effects and such, this isn't how it works. Don't bother trying to trim individual cylinders on a siamese port engine, you're not going to get good control of each cylinder independently.

I wouldn't worry about it, personally. Fit the right size injectors, set it to batch fueling mode, and it'll work fine. 440cc isn't even a big injector, these days "big" is more like 1200-1500cc.

Besides, you actually get better performance and emissions firing the injector at a CLOSED valve than you do an open one.
no, NO, NO, none of that works on a siamese port setup. Against a closed intake is best for smooth low power operation normally but if you spray against the closed valve on a siamese set up then both cylinders worth of fuel end up in the port together and get sucked into the 1st intake that opens and you have 2 cylinders pig rich and 2 that don't run at all.

The only hope is to spay to a single opened intake valve....and that will let you trim it as well. You need a little less on the 1st to open, a little more on the 2nd because of wall wetting...I didn't have trim on the ecu I had .. haltech e6k?, I mostly used haltech back then, anyway it worked well but I was wishing for trim and not having it had to try to split the difference the best I could.

The better cams for these engines have mismatched lobe timing too to try to get flow more equal. There's a bunch of really good reasons they don't build engines like that anymore.
JRD McLAREN
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Re: Classic Mini 5 port injection (siamese ports)

Post by JRD McLAREN »

Mmm...
I'm found this thread this evening .. (too late) ...

If we have siamese intake ports, we need full sequential mode ..
(two injectors on a 4cyl engine with 2 intake ports) ...
1st injector for 1 & 2
2nd injector for 4 & 3
for 1-3-4-2 firing order

This is the best setup for this ...
..tested on old ŠKODA engines

EDIT:
maybee not on rusefi ...
.. some Proteus and microRusEFI for sale in Europe ..
JRD McLAREN
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Re: Classic Mini 5 port injection (siamese ports)

Post by JRD McLAREN »

try this ...
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JRD McLAREN
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Re: Classic Mini 5 port injection (siamese ports)

Post by JRD McLAREN »

or this .. ( :?: :roll: )
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Simon@FutureProof
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Re: Classic Mini 5 port injection (siamese ports)

Post by Simon@FutureProof »

Does doubling up the outputs in the software like that not produce a error for the pin conflict?

Agreed on the A-series you have to inject with the valves open, it's just a strange quirk of the design.

There should be no problem at all connecting one injector to two drivers so it is pulsed twice as long as you stick below about 45% duty per pulse (90% total) simply for reasons of burning out the injectors windings with too much on time. Something I doubt you will be able to do anyway.

One thing that may help you is to use a smaller injector at a higher pressure, the extra pressure will help with atomisation, probably also best to avoid disc style narrow spray pattern injectors for the same reason. You basically have to treat it like a backwards ass GDI system without the "direct into cylinder" bit.
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mk e
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Re: Classic Mini 5 port injection (siamese ports)

Post by mk e »

OrchardPerformance wrote:
Tue Mar 01, 2022 3:27 pm
There should be no problem at all connecting one injector to two drivers so it is pulsed twice as long as you stick below about 45% duty per pulse (90% total) simply for reasons of burning out the injectors windings with too much on time. Something I doubt you will be able to do anyway.
I think you need to stay under about 20%. The siamesed cylinders are 180 degrees apart so that would 25% but intake duration on a 2V engine is more like 240 degrees @.050 usually which leaves 120 degrees or 17%, something like that I think. The one I did years ago was right around 20% iirc, but its been a while.

The reason for the normal 85% max DC rule its dead time....over 85% the injector doesn't have time to close so you get a not linear thing plus no real gain in the 90-100 range....or so I'm told, I never trying thought so that could be wrong.
mk e
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Re: Classic Mini 5 port injection (siamese ports)

Post by mk e »

JRD McLAREN wrote:
Mon Feb 28, 2022 8:25 pm
try this ...
That's how I did it years ago. 2 drivers to 1 injector., 2 injectors total.
KLAS
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Re: Classic Mini 5 port injection (siamese ports)

Post by KLAS »

just to be the pedantic Mini Driver, Rover engineers developed the Mini MPi in the early 90s. just to show it is superior to the SPi system taken from other Rover cars to push the car into tighter emission controlled times. but due to cost and maybe other reasons it was rejected. it was pulled out of the drawer as it was clear the New Mini will not arrive in time and new emission rules will ban the SPi system.
and to make clear what Rover did, they took the MEMS2 ECU, fully sequential up to 6 cylinders now in common use at Rover, and use 4 injector channels to drive the 2 injectors. from the ECU side of view it is a simple, fully sequential 4 cylinder engine with 4 injectors. so the drawing of JRD McLAREN is what Rover did.
that works amazingly well, if you get the injector timing right. and that is why a lot of converted A-Series engines run poorly or not at all with a MPi like setup. a throttle body injection is much more forgiving.
is MPi worth the trouble? absolutly, just don't think it's easy. fitting a 7 port head is easy. but who wants that?
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Re: Classic Mini 5 port injection (siamese ports)

Post by tomazcebul »

Gents,

Many thanks for te good discussion and really good suggestions. Now I need to investigate how to define the correct timing in degrees for the injector start the injection cycle, as it need to be aligned with intake valve opening.

Thx & Best Regards, Tomaz
KLAS
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Re: Classic Mini 5 port injection (siamese ports)

Post by KLAS »

look here https://rovermems.com/
you can find some injector timing data here https://rovermems.com/discussion/mpi-injection-timing.html
he even has some apps if you use the factory ECU. surely not as good as Rover Microcheck or Testbook, but it works. i've used the Android app with some cars https://rovermems.com/diagnostics/
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Re: Classic Mini 5 port injection (siamese ports)

Post by tomazcebul »

Hi Klas,

I was researching the internet today and found the rovermems.com website and wanted to add exactly the same as you already did... Thank You :D .

I don't have MPI ECU (I only have SPI one...).

Thx & Best regards, Tomaz
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