AFR Sample Chambers
Turbo Mini Forums

I completely missed another point yesterday (as the GP was about to start) but the other comments above have reminded me.....

Isn't the pressure on the outside of the turbo discharge bend slightly higher than the overall discharge pressure, the opposite of what you want ???

I don't suppose there's much in it as its gas of relatively low density, but I remember we used the inner/outer radii differential pressures as a diverse method of measuring primary coolant flow at work, although obviously a much denser liquid !!!

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

your right rod , more of a dynamic take off that would be ideal.

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

This is a highly complex subject on which the professionals do not appear to agree. It is also dependant on a number of variables that change thoughout the operating range of the engine/turbo, so I doubt that there is a one size fits all solution.

Fluid, flow, pressure, laminar or turbulent flow, pulses etc etc all affect how this will work.

Pressure gradient is the most important feature to get right. If the pressure gradient is right then the gas will flow in the right direction.

I think that the velocity is higher on the outside of the bend. It speeds up as it has further to travel. Any fluid that has to increase its velocity to travel faster will get the extra energy from its pressure (Watch water flowing fast under a bridge). Hence, it can be argued that, under certain circumstances that the outside of the bend is the correct place to fit the pipes.

Ideally, I would have fitted them further away and at an shallower angle, but that's very difficult to achieve.

I've made it as simple and as cost effective as possible and although we may conject on its technical merit, I'm going to fit it as it is and see if it works.

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 ???

I think that with laminar flow and an incompressible fluid, then certainly the pressure on the outside of the bend will be higher.

With turbulent compressible fluid, then I don't know..... yet.

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."

Back to the installation rather than the techy bits...... (I've just been measuring up mine as you might now guess), in your "nearly done" photo, do the large stubs clear the normal slave cylinder or are you using the double verto on this engine ???

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

No, the stubs would foul the pre-verto slave cylinder.

I'm using verto at the moment, but have the parts ready for a double verto when it slips.

The main reason for taking the stubs out near horizontal was so that the compression fittings were in a similar axis to those on the manifold.

It would be difficult to assemble on the car otherwise.

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."

Thanks Paul,

I've worked out a run that will allow me to mimic yours but still have the pre-verto slave - but it will need a steel/copper tube from the slave running underneath it to a remote connection to the flexible, otherwise the hose will melt !!!

Mine will have to be assembled off the car, mainly because the sample tubes will be coming off the bottom of the T3 manifold - top would be far too close to my injectors - but that's not an issue for me as I've changed to flip/removable front to be able to drop the whole assembly in/out in one go (just one single exhaust connection at the back/bottom of the subframe).

Anyway, parts ordered....

Are you going to test without boost first, ie, turbo installed but air side disconnected, to see if your readings match the N/A setup with your previous wideband tappings ???

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."

Paul,

Another question, slightly O/T but related.....

Are you going to move to the staged four injectiors for the first boost tests or just stick with your current pairs doubled up as two. If so, what cc are you intending to use, the same as at present ???

The reason for asking is threefold,
1 - mods to the daughterboard for staged (and all the un-necissary components that have to be removed to allow the "spare" pins to be accessible) - have you tried it yet ???

2 - the additional driver chips required - although mine will be different to yours as I have low z injectors so will use Jean's P&H board - but still significant mods.

3 - I've started buildin my four injector manifold but am not sure whether to persue it in haste at the expense of everything else I need to do.....

You said much earlier in another thread that you had ordered another MS2 (in kit form) from the States - are you going to be using that one - because I'm seriously thinking of ordering a new kit too, just to be able to build it withOUT all the un-necissary bits.

Rod.

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

I'm not going to use staged injectors with this setup. I've proved it will idle OK with 855cc/min per port and 1710 cc/min total is enough for the 120hp target on this 998 turbo.

We have assembled another MS board without all the uneccessary parts but with drivers for the coil-on-plug ignition plus Jean's Quad driver board for the staged injection. We will be modifying the MS2 board for the staged injectors. However, this is for the 200+hp 1293 turbo engine.

I would think that you will need all four injectors unless the ones you are using are huge.

You may have to stage them if you cannot get a reasonable idle. I'm afraid it's going to be case of trial and error.

This is the MS board built by Sturgeo with all the unnecessary bits left out:

Edited by Paul S on 22nd Jun, 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."

By the way, you don't need to remove the components, if they're already there, to add the new drivers. They can both be there in parallel without any bad side effect. You just use the new injector outputs and ignore the old outputs.

You could even go back to using the original drivers if you need by just connecting the injectors to the old outputs and ignoring the new ones. And of course, change the settings in Megatune or TunerStudio.

Jean

http://www.jbperf.com/

Jean,

As I understand it, the crystal and clock circuitry on the mainboard still need removing to allow the extra injector connections to be to the mainboard, not the daughterboard.

Seems to me, looking at Paul/Sturgeo's picture above (which is exactly what I expected), it's easier to just buy the PCB and daughter board, and the few components required, and start again.....

ie, just use the one I have for setup and testing with two injectors (and software PWM for the injectors) and then use your P&H for the four injectors on a bare board....

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

Rod,

You're right that the crystal/clock circuit components need to be removed from the main board and this is not used for MS2 in any case (so can be left out for any MS2 build regardless of code/options used).

And you're also right that a new board with only the needed components will make for a cleaner setup. And you can even use the empty heat sink for the ignition drivers even though you'll have to use wires to connect them.

If I knew there would be enough interest, I'd get a license from B&G to produce a board specifically made for the siamese (and sequential) code with the correct CPU connection, 4 ignition drivers, 4 injector drivers, 2 VR conditioners, and the other extra features. That would make for a much cleaner setup.

Jean

http://www.jbperf.com/

First, Paul - sorry to be hijacking the thread a bit.....

Jean, I hinted at this a few months ago when I got your P&H board and realised how little else was necissary (apart from the daughterboard and embedded code) and said I would seriously think of making my own PCB - but still using B&G's daughterboard and code - but didn't know where the rights/licencing stand on that issue.

I know from the MS-Extra forum your sequential code is being taken up fairly well - there might only be three of us using the siamese version so far, but that may grow subject to our success.

What's the break even point in terms of people wanting a hybrid board, to make it worthwhile ???

Rod.

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

Yeah, sorry for the thread hijacking.

I would need to have more details on the licensing myself since I only have very partial information. But I would say that around 25 is probably close to what would be needed to cover the initial development (and I'm not counting my time in there).

As you say, there seems to be interest in the sequential injection on the MS-Extra forum. And I also expect there will be more interest once Paul and you have proven the concept. And the sequential code also makes it interesting for the twin cam conversions here even though there are a lot of choices for those.

Jean

http://www.jbperf.com/

Jean, thanks - 25 sounds interesting, and I would be happy to help with development (within my limited abilities.... !!!) if this proves to be a viable way forward.

Paul, back to the original point of the thread....

How did you decide on 4mm for the sample tube ??? Half my bits arrived today so I've been bending up some trials, and 4mm "looks" quite small.

I decided to follow the same sizes as you so we can compare results on a "like for like" basis, the only difference being my pipe routing and I used 1/8" NPT fittings into the manifold so the largest sample tube is 6mm OD (4mm NB) with that size fitting. I didn't want to go to 1/4" NPT as it's a rather large hole to drill/tap plus the thermocouples use 1/8" NPT so I can move things around.

However, you can get 6mm OD stainless with a 0.5mm wall giving 5mm bore rather than 4mm. I think I might order some just in case.

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

I wanted to keep the bore small, so that I did not loose too much flow under boost.

4mm seemed about right and was available in a 6mm OD tube.

It's a compromise after all. Bigger would be better off boost and smaller better under boost. I'm hoping 4mm is in the right ball park.

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."

Latest:

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."

Coming on nicely, fingers crossed that all goes as planned when you start the testing.

We've just come in from completing the fitting of the turbo, intercooler and all the plumbing. I wish I'd bought shares in a jubilee clipe manufacturer going by the amount we used today. Anyway, it's all fitted and I'm knackered. Working outside in full sun all day as the other Minis occupy the garage and ramp.

It's idlling high for some reason, but we were getting 16:1 on the inners and 12:1 on the outers at a 2000rpm idle. I'm not surprised at that because that's not an area of the injection timing map that we had done any work on. It leveled out to 12:1 on the inners and outers when we revved it.

On that basis, I would say that the AFR sample chambers are working well.

No smoke from the second hand turbo either so as long as the clutch can handle some boost we should get some testing done tomorrow.

Big thanks to Sturgeo for his help today, poor lads knackered.

Edited by Paul S on 4th Jul, 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."

Do you think the difference at idle could be down to lack of flow (or even reverse flow) through the chambers when you haven't got a decent dp acropss the turbine to drive flow through the chambers ???

Although you may not have worked on the map in that area, do you have any logs to compare.

Just me being pedantic as usual....

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

No, it sounded like the inners were running lean. Not the usual smooth idle you get when the AFRs are equal.

I'll have a look at the last log to see if that's what was happening.

EDIT: The log from last weekend shows that it was going lean on the inners just off idle, so I'm happy.

The real test will be under load to see if we get a decent response and similar values under acceleration.

Edited by Paul S on 4th Jul, 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."

Just to update this thread with an actual log from the first trials.

Still work to do on the mapping and cleaning up the signal, but you can see from the attached, the AFRs change instantaneously at the gearchange, showing that the chambers are working fine.

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."

Even at 1500RPM and low load, the changes are immediate. That's good.

http://www.jbperf.com/