EFI Test Engine UPDATE 12/01/08
Turbo Mini Forums

Ok, so its not a turbo, but first stage in developing EFI for my 998 Turbo.

It's a 1275 MG Metro with a SW5 cam and a slighly modified head. Fitted with a 2.76:1 diff.

This will eventually find its way into my wifes Mini 35 and has been built for high torque, high mpg and low noise but will initially go into my Sprite for the EFI work.

Fitted with mechanical fuel pump and dizzy just to get it through the MOT.

Apologies for the poor choice of brakes but I bought them before I had the benefit of TM wisdom! I'll change them whem I go onto 10s next year.



Lambda sensors on each branch. There will be a wideband on the outlet. I've used the standard Metro 3 into 2 exhaust manifold.


Spanner Bitch pulley with homemade sensor mount.


Inlet Air temp sensor.


Water temp sensor.


I've got the rest of the week of work to get it in the car and get the welding done for the MOT!

Edited by Paul S on 12th Jan, 2008.

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."

Its looking a good base to do some development work on, look forward to the results.

The test plan is as follows:

Establish a baseline from the lambda sensors. Does the carb give perfect distribution to all cylinders? It will be interesting to find out.

Then:
1. Use Megasquirt for ignition.
2. Try to control flow into the SU using Megasquirt, hence the air inlet temp sensor in the carb manifold. If this works, then thats it, I'll use the standard Turbo carb and plenum on the 998. However, I doubt it will as the concept is too simple.
3. Use an MPI inlet and Megasquirt and see if we can overcome the port robbing isues. I'm hoping the jbelanger will let me use his code. However, I've programmed extensively in 'C' in the past and may do the code myself.
4. Finally, fabricate an inlet manifold with two MPI injectors per port and a single throttle body. This will then be the system I use on the 998 Turbo.

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."

Good stuff that man :)

I'm liking your stategy with testing the balance of the SU first - and then testing the two EFI manifold options, before switching to the dual-injector setup - and THEN to the turbo...

Dave,

Is there any other way?

I could just go the tried and tested carb/plenum route, but wheres the fun in that!

I've been looking at designs for an inlet manifold and whichever way I go I keep coming back to your design with the long curly inlet tracts and a cylindrical plenum.

So, I'm apologising in advance for simple plagiarism.

The plus side is that I hope to prove the design by CFD before I make it and will post the result on here.

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."

sounds good

are you going to connect up the mainfold heating?

Just thinking of the effect that would have on your ACTs...

Alex

AlexF

AlexF2003,

Yes, I'm going to plumb in the manifold as the engine will be in use all year round.

I dont think that it will make much difference to the ACT. The sensor that I am using extends well into the air stream and has a separate bulb from the brass body. Anyway this is just for the electronically metered SU test.

Plus you can set megasquirt to work on a closed loop below a certain throttle opening, so it will self compensate.


Mini1071s,

Good news about the code. Let's hope Jean gets it finished soon.

Edited by Paul S on 7th Aug, 2006.

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."

Hey Axel, have you seen the Rover MEMS air-temp sensor setup? This has a piece of high-density plastic (the insulative kind - I'm not a ploymer expert) that the ATS screws into - which in turn screws into the manifold.
A good place for it is the big cast 'lump' where a brake servo would be attached. I think the plastic insulator is threaded M20 or somet like that...

Dave,

Yes the MEMs ATS is the same as on the MPI manifold I'm planning on using.

This is the sensor I'm using just for the SU trial. The bulb is directly in the airflow.

http://www.bosch-motorsport.de/pdf/sensors...e/NTC_M12-L.pdf

Even if the SU trial does not work, it will be a very useful way to learn the use of magasquirt at its simplist before moving onto timed injection.

Edited by Paul S on 7th Aug, 2006.

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."

coolio!

oh - and my efi manifold looks somewhat like Marcels did... I too tried lots of different things, but this just seemed the most obvious!
If you need any alloy 'bananas' give me a shout and I'll source some for you.

Guys,

I haven't made that much progress for the reason that I've been more busy than expected but mostly because the standard Megasquirt code has issues with wheel decoding which is essential for our use. I didn't want to put too much effort on code that wasn't going to be useable and I wasn't sure I could debug that code because it's not the easiest to understand.

The good news is that a new version of the code has been published which solves most of the issues. Also, there is another development that is close to a first release (MS2/extra) which will have a bunch of useful features. This means I'll be able to have something useable soon.

Axel, as has been said above, I like your plan. Go with a known setup and add the new stuff one piece at a time. This way you know exactly what going on.

And I agree with Dave's suggestion. There has been a lot of people having issues with heat soaked air-temp sensors on the Megasquirt forum. If you can isolate it from heat sources you'll have a much better running engine under all conditions and it's going to be much easier to tune and diagnose issues.

Jean

http://www.jbperf.com/

Ok, I'll re-think the positioning of the sensor in the carb manifold, although as I plan to use the servo, there are not many places it can go.

Jean,

Glad to hear you're making progress. I'm at least a couple of months away from trialing the MPI setup with Megasquirt anyway, so no probs.

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."

Interesting stuff Axel, When I was running mapped ignition only on my 5 port 1380 with Weber 45 I set the engine up from exhaust gas temps. One temp probe in each branch - each connected to a digi gauge. Running equel ign advance across all cylinders showed the central pair to be down on temp by 80-90°C. In the end we put up to 6 degs more advance into the centre pair of cylinders across the range to bring the exh temps within 10°C of the end pairs. Power went up 4 bhp at peak and the torque band was widened with gains in most places. Will be interesting to see if the your SU/lambda sensors show similar results.

John

If Carling made Mini engines
it would probably be like this one!

Axel, just get yourself a 8/10mm hosetail and drill/tap the manifold to take that for the servo. Makes for a pretty nice install.

D

Does it *have* to be in the manifold?

Alex

AlexF

Hi,
No it doesn't have to be in the manifold. I would have thought it would be better in or near the air filter. Most EFi cars have them in the MAF or air filter housing, presumably to help with the heat soak issues.....
Cheers,
Gavin :)

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I suppose if you run a turbo you do need it after the turbo/IC....

AlexF

For a turbocharged engine, you need to put the sensor after the IC because, in a speed density system, you need the temperature to compute the mass of air going into the engine to inject the correct amount of fuel. The temperature before the turbo does not linearly reflect the temperature at the inlet manifold depending on the efficency of your turbo and IC and how long you've been in boost.

For a NA engine, you can get by putting it at or near the air filter because the relationship between this temp and the one at the inlet manifold is much more linear.

Jean

http://www.jbperf.com/

I was under the impression that you need to fit the sensor after the throttle/butterfly for it to work correctly, particularly at part throttle.

Remember that this is a road going engine and I regularly do 200 miles in a single day, hence part throttle is very important.

The effect of the throttle reduces the pressure and temperature of the incoming charge, hence reducing the air density. As Megasquirt works on air density correction and it measures inlet pressure downstream of the butterfly, then surely you also need to measure temperature downstream of the butterfly.

I've been trying to access the megasuirt.info site to check but it seems to be down at the moment.

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."

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

Axel,

You're right that the ideal is to measure the air temperature after the throttle because that's what the engine is seeing and you're also measuring the pressure at that point for the speed density computations. However, in an NA engine there won't be as much change as in a turbo engine and at part throttle you will have (or should have) correction of the mixture through the O2 sensor, ideally wideband. You're better off measuring a slightly off air temperature rather than measuring the manifold temperature being heated by the exhaust (heat soaked temp sensor). And at higher load, you won't have O2 sensor correction but the amount and speed of the air means it won't have time to warm too much between the air filter and the engine.

Of course, if you can find an inlet manifold mounting position that won't get heat soaked that's ideal. But it is probably a better compromise to mount the sensor further upstream rather than have a heat soaked one.

As I said above, a turbo engine has to have the air temp measured after the IC. There is likely not a lot of difference between just at the IC exit and at the inlet manifold (unless there is a lot of plumbing or the routing is done too close to the exhaust). It's also easier to find a non-conducting or less conducting surface on which to mount the sensor if you're not mounting it on the manifold.

That being said, if you can have a few sensors along the inlet tract and log the temperatures, you'll have a better idea of what's happening. If you also log the AFR and the O2 correction, you will be able to see if you have heat soak and if you need to move your sensor. Megasquirt has a couple of auxiliary analog inputs and can log all those parameters.

Jean

http://www.jbperf.com/

http://www.jbperf.com/

Edited by Paul S on 9th Aug, 2006.

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."