going sequential on siamese port?

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going sequential on siamese port?

Postby stevemgbgt » Fri Dec 22, 2017 4:50 am

With retirement looming I am thinking of converting my 1800 MGB to sequential injection.For the last 8years it has run on an MS1 with 4 injectors near to the inlet ports.Is this possible?I should be able to work out the amount of time that there is available to reliably inject into the correct port but it escapes me as to how.I am considering MS3 to achieve this.Looking forward to any input.Thanks, Steve
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Re: going sequential on siamese port?

Postby racingmini_mtl » Fri Dec 22, 2017 10:27 am

Yes, it is possible. Rover has done it with the Mini MPi and it had been done with the MS2 and MS3 (I'm mostly aware of the Mini A-series engine stories but there are also a few MGB B-series engines).

You don't need or want 4 injectors but only 2 (one per intake port) unless you go for high power and need staged injection (where you may need 2 or even 3 per port). You don't need to work out the amount time but you will need to monitor the AFR for the inner (2,3) and outer (1,4) cylinders with 2 or 3 wideband O2 sensors: you need one for the inner cylinders in the middle exhaust branch and one or two for the outer cylinders in the first and/or third exhaust branch (or the combination of these). You will need an LCB or a 3-branch exhaust manifold. You will need to adjust the injection timing with respect to RPM and load and keep the AFR equal for the inner and outer cylinders.

As I said, it has been done with the MS2 and MS3. The MS2 has a dedicated mode for the siamese engine specific needs so it has more flexibility in what it allows you to do to get the needed injection timing. The MS3 is more limited in that you have to use the standard sequential injection which is not designed for the siamese port needs. However, you do get a better hardware platform and the MS3 firmware is still being developed which is not the case with the MS2 (only maintenance). The MS3 firmware also has a lot of features not related to siamese port injection that are not available on the MS2.

There is a lot more information available on all this. Some of it is scattered around on this forum. More is found on the turbominis forum (http://www.turbominis.co.uk/forums/index.php). You might want to have a look at Marcel Chichak's site (http://www.starchak.ca/efi/siamese.htm) but some of the information is outdated. There is small article on my site from Paul S that gives a good overview: http://jbperf.com/sequential/Fuel_Injec ... eries.html. But that is also a bit old. If you do a search, Paul S is on this forum and the turbominis one. Rod S is another good resource who is on the turbominis forum and here (his username here is 'retired').

So you should set aside a good chunk of time to simply go through as much documentation as possible to get a clear idea of what the issues are, what the potential solutions are, and how you will need to use all this come up with your preferred setup and then install it and tune it.

I hope that helps you start this up the right way and that I haven't instead discouraged you. There is quite a bit to learn on this and there are a few things that are not intuitive but once you get over that, it should be rather straightforward.

Jean
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Re: going sequential on siamese port?

Postby stevemgbgt » Sat Jan 06, 2018 3:42 am

Sorry for the late reply.There is certainly a lot of things to consider and thanks for your detailed reply.Steve.
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