MatraSport Forum

Each model => Murena => Topic started by: krede on January 01, 2007, 01:47:31 pm



Title: Voltage or amp-meter?
Post by: krede on January 01, 2007, 01:47:31 pm
At the extreme risk of sounding foolish, I ask the question... is it a volt ot amp meter thats fitted to the dash of the murena?
I havent had the chance to mess with mine yet(mine isnt working like it should), so Id have to use what written material I have on the issue.
On the wireing plans I have its listed as a voltmeter, but in simons spare catalogue its an amp meter!.. so... wich one is it?  ???
From the top of my head id guess voltmeter.. but its really just a guess


Title: Re: Voltage or amp-meter?
Post by: Anders Dinsen on January 01, 2007, 05:17:08 pm
It is a voltmeter... or as I posted previously a combination of an interior thermometer and voltmeter ;)

In fact it consists of a bimetallic strip with a coil of resistor wire around - when heated, the strip bends. The amount of heat the coil produces depends on the voltage.

DO NOT rely on it to claim either generator or battery to be defective, always measure on it with a real voltmeter.

- anders


Title: Re: Voltage or amp-meter?
Post by: Lennart Sorth on January 01, 2007, 05:33:40 pm
DO NOT rely on it to claim either generator or battery to be defective, always measure on it with a real voltmeter.
And I will add: DO NOT rely on an external voltmeter either, unless you fit a fresh battery in it :-)

I just almost condemned my battery/alternator/regulator, as my digital voltmeter measured 16 Volts (!).  The dash voltmeter was fine, - and in this case it was actually the most accurate!  A new battery in my digivoltmeter at the voltage read 14.5 on the battery while charging :-)

/Lennart


Title: Re: Voltage or amp-meter?
Post by: krede on January 01, 2007, 05:56:59 pm
Im fitting digital instrumentation to my murena when i get home... I know some might not approve of this as its a "classic " car, but I think they will suit a wired french car like the murena quite well.  :).


Title: Re: Voltage or amp-meter?
Post by: Anders Dinsen on January 01, 2007, 06:27:25 pm
DO NOT rely on it to claim either generator or battery to be defective, always measure on it with a real voltmeter.
And I will add: DO NOT rely on an external voltmeter either, unless you fit a fresh battery in it :-)

I just almost condemned my battery/alternator/regulator, as my digital voltmeter measured 16 Volts (!).  The dash voltmeter was fine, - and in this case it was actually the most accurate!  A new battery in my digivoltmeter at the voltage read 14.5 on the battery while charging :-)

/Lennart

And while we are in the DO NOT section, I'd like to add that you should never rely on a cheap 100 kr (10£) multimeter either!

Quote
Im fitting digital instrumentation to my murena when i get home... I know some might not approve of this as its a "classic " car, but I think they will suit a wired french car like the murena quite well.

NOOOOOOOOOOOOOOOOO WHAT'S HAPPENING TO YOU MAN!!!!???? (banging head hard into the wall, think it will need fixing - wall and head)


Title: Re: Voltage or amp-meter?
Post by: krede on January 01, 2007, 06:40:44 pm
I guess its a matter of taste.
I think it goes well with the style of it... I was considering using the panel from the citroen bx digital.. but those were just plain awfull
I will make a complete dash to fit in place of the original, and thus not make any "irreversible" changes to my car.


Title: Re: Voltage or amp-meter?
Post by: Anders Dinsen on January 01, 2007, 06:47:17 pm
I guess its a matter of taste.
I think it goes well with the style of it... I was considering using the panel from the citroen bx digital.. but those were just plain awfull
I will make a complete dash to fit in place of the original, and thus not make any "irreversible" changes to my car.

Hey, you're a nice guy, so I guess we can forgive you.... ;D
Is it a modern racer style panel or something you rip off a used car?


Title: Re: Voltage or amp-meter?
Post by: krede on January 01, 2007, 06:54:50 pm
My first  thought was, to piece something togeather from what is availeble on ebay. Various vdo porsche 911 and 944 gauges are nice, but I finally came across some from a manufacturer called "Nordskog".
They are digital, with red numbers that completely blacks out when not in use.
it will be ok.. I promise..... I wont "go german" on the poor eel... I just want some fancy gauges....I CAN TRUST!!  ;)


Title: Re: Voltage or amp-meter?
Post by: Lennart Sorth on January 01, 2007, 08:46:42 pm
Owning a car with digital instruments (Espace JE) I must say it is NOT my favourite. I really dislike it when I get distracted to look at the dashboard just because the amount of light emitted by showing "109" is much more than "111" (km/h that is)

However, I think having a more or less hidden digital readout of a number of nifty parameters would be excellent. Maybe one could fit a fold-up LCD display in the ashtray - sort of like the Blaupunkt GPS system. Pull it out, and you have a multifunction "telemetry" readout of everything your heart desire.

Possibly also with the ability of showing just one of the readouts in huge, (friendly?) digits, so you can see them while driving.

Now what would we like such a system to show us?
  *  Coolant-temp near engine
  *  Coolant-temp near radiator
  *  Coolant-temp near heater matrix (?)
  *  Inlet air temp
  *  engine oil temperature
  *  engine oil pressure
  *  gearbox oil temp (?)
  *  Voltages - several places
  *  fuel-gauge
  *  speed
  *  engine revs
 
And how about using a lambda sensor to tell about the amount of oxygene in the exhaust ? - just for the measurements sake.  Could also be nice to know, when adjusting carbs.

Personaly I'd love to also include support for some webcams, - as I really would like to see how much the engine moves about while accellerating, or parts of the suspension. Does anyone e.g. know how much the trailing arms flex while driving through a curve ?

Maybe what I'm looking after is a full-scale telemetry system, with and interface to a laptop, rather than a little multifunction display.


/Lennart


Title: Re: Voltage or amp-meter?
Post by: Anders Dinsen on January 01, 2007, 09:58:40 pm
My first  thought was, to piece something togeather from what is availeble on ebay. Various vdo porsche 911 and 944 gauges are nice, but I finally came across some from a manufacturer called "Nordskog".
They are digital, with red numbers that completely blacks out when not in use.
it will be ok.. I promise..... I wont "go german" on the poor eel... I just want some fancy gauges....I CAN TRUST!!  ;)

The Murena gauges are qute reliable and trustworthy. Except for the voltmeter, that is, but this was obviously never intended to display anything but a rough indication of the voltage. The speedometer is in fact very precise, and far more than most other cars that has a mis-display of about 5-10% (usually to the high side). The rev counter could be better, but when you think about it you don't really need an exact readout of the engine rpm.

The same applies to water temperature and oil pressure, in fact: You cannot really use the exact numbers for anything. Coolant temperature is dependent on the water pressure at the pick up point, and the exact number will tell you nothing about whether the coolant is close to boiling or not (or even whether it does local boiling inside the cylinder head). As for oil pressure, what you will be looking for are pressure drops that could indicate problems - whether the oil pressure is 3.0 or 3.5 bars will tell you nothing. By the way, oil pressure will also be dependent on engine temperature (since the viscosity of the oil is). This is why your gauge shows a higher number when cold than when hot.

If you want something reliable, why not stick with what has worked in the car for the last 25 years?

Lennart, I like your idea of a small display hidden in the ash tray. Telemetry is an interesting issue, but the problem is not so much the read out or the recorder - it's the sensors. Besides, engine data isn't quite enough, you'd also want to record suspension travel, drive shaft torque and real time tyre pressure! But then, you'd be able to compete with the professional racers :D

- Anders



Title: Re: Voltage or amp-meter?
Post by: Lennart Sorth on January 01, 2007, 11:51:03 pm
but the problem is not so much the read out or the recorder - it's the sensors.

Oh yes, I am fully aware of that - and yes, getting suspension travel input too would be marvellous. I'm a data-freak, which is why my new job in the UK concerns petabytes of storage :-)

I recently spoke to a guy racing a Ginetta, who had the entire car rigged with sensors, which were recorded while he was driving. Then when he got home, he could spend hours looking through the data, and look for possible optimization. That car went like stink! - outpacing almost anything out there - and it sounded gorgeous, despite it being (I think) a tiny 1000ccm.
(http://www.sorth.dk/p/20060910/Med/dsc_5630.html)

In my son's P106 (well, my spare-car) he fitted a huuuuuge (1600W!) stereo, which initially looks quite normal, - everything exceptional is hidden.  There is a remote control to adjust the 12"  subwoofer, hidden in:    the ashtray!      Cool feature :-)

(And none of my cars will ever see their ashtray used for ashes anyway, - smoking is banned)

In the same way, I'd love to "rig" my Murena for data-collection, while keeping its appearence close to normal. I have sometimes thought of replacing the voltmeter with a real calibrated voltmeter - but in 11 years of ownership, I have learned to interpret the original one so well, that it really makes no difference.


Title: Re: Voltage or amp-meter?
Post by: Anders Dinsen on January 02, 2007, 12:39:27 am
In the same way, I'd love to "rig" my Murena for data-collection, while keeping its appearence close to normal.

Sounds like we should get something going there, Lennart...!


Title: Re: Voltage or amp-meter?
Post by: krede on January 02, 2007, 10:10:32 am
Apart from the speedo, and tacho Ill be fitting voltmeter,fuel gauge, oil pressure, air- fuel gauge (i got it cheap on ebay) and water temperature.. so pretty much the same as is in the car at the moment.
perhaps oiltemp, charge perssure and inlet airtemp will follow later on..   


Title: Re: Voltage or amp-meter?
Post by: Anders Dinsen on January 02, 2007, 07:39:09 pm
Apart from the speedo, and tacho Ill be fitting voltmeter,fuel gauge, oil pressure, air- fuel gauge (i got it cheap on ebay) and water temperature.. so pretty much the same as is in the car at the moment.
perhaps oiltemp, charge perssure and inlet airtemp will follow later on..   

Good luck with the project! It will be fun to see it in action :-)

I noticed that the documentation on the sensors is in the workshop manual, you will probably need that to adjust the instruments.

- Anders


Title: Re: Voltage or amp-meter?
Post by: Matra_Hans on January 03, 2007, 07:36:09 pm
I can see on Nordskog homepage that they have some rather interesting stuff. In the Bagheera Type I Matra tried to make an instrument panel that blacked out when the ignition was not on but it did not work so good. So Krede’s coming Murena instrument panel might end up looking like something that the Matra engineers dreamt about.
Nordskog’s speedometers can be adjusted to fit any gearing or tyre size. Further they have speedos that are based on GPS signal so you get the correct speed reading no matter how much wheel spin you have maybe not so useful on the Murena that gets the speed signal from the front wheels. Nordskog also has speedometers that is good for up to 300 mph that is 480 km/h how much power do we need in a Murena in order to utilize that?

Regards Hans


Title: Re: Voltage or amp-meter?
Post by: Lennart Sorth on January 03, 2007, 07:52:09 pm
Nordskog also has speedometers that is good for up to 300 mph

300mph is for Hamsters  ( http://www.bbc.co.uk/topgear/richard_hammond.shtml )  :-)

However, the invisible dash sounds very 1970'ies  - just think back at the B&O stereos of that age. And since both the Bagheera and the Murena can be said to be from that age it would make sense.

The only modification I have made to my dash is to wedge something in at the top, to tilt it slightly further back, as I got reflections when driving under streetlights. Something to do with my height, I suppose :-)

/Lennart


Title: Re: Voltage or amp-meter?
Post by: macaroni on January 04, 2007, 11:58:54 am
I like my dash as it is because it reminds me of the Simca 1100 my mum used to have when I was a kid. The most comforable car I have ever been in.


Title: Re: Voltage or amp-meter?
Post by: brinkie on January 04, 2007, 01:04:53 pm
Hi Lennart and others, after a long time of reading this forum only, I decided to register and join the discussion  ;)

Possibly also with the ability of showing just one of the readouts in huge, (friendly?) digits, so you can see them while driving.

Now what would we like such a system to show us?
  *  Coolant-temp near engine
  *  Coolant-temp near radiator
  *  Coolant-temp near heater matrix (?)
  *  Inlet air temp
  *  engine oil temperature
  *  engine oil pressure
  *  gearbox oil temp (?)
  *  Voltages - several places
  *  fuel-gauge
  *  speed
  *  engine revs

I was thinking of getting/building a digital system like they fitted in the Tagora V6 models. It fits the era of the car nicely. From my experience as an electronics engineer, it must be possible to make something out of that.

My in-dash voltage meter only reads when I knock on it. It is usually stuck and so is the temperature gauge sometimes. The oil pressure meter is for informational purposes only, it reads 8 bar when the engine is cold!
By the way Lennart, I've got TWO digital multimeters and an analogue one, so I really know for sure which part is failing :D

Risks of fitting electronic readouts
- The Murena is a bumpy car. It is easy to crack printed circuits and soldering connections. Home-made stuff is likely to fail.
- The temperature range of automotive-grade electronics is definitely better than consumer-grade electronics! Things really can get hot, especially in the engine bay, but the temperature inside the car on a hot summer day is enough to degrade consumer-grade electronics as well.
- The information must not distract the driver. The Espace JE does have a digital speed readout, but lacks a rev meter, probably for that reason.

What gauges are useful
Except from the obvious speed, rev and fuel gauges, I think the following gauges are useful:
- Coolant temperature (measured at the engine)
- Coolant flow (Especially with a Murena this can save your car's life!)
- maybe coolant level?
- Fuel consumption (requires fuel flow sensor and some processing)
- Oil pressure
- Oil temperature (which gives the best indication of your engine's current status)
- Oil level?
- Battery voltage
- Alternator current
- Digital clock and (if a speedo signal is present) a trip computer

All these can be fitted at the centre panel, where currently the analogue clock and the parking brake, rear fog light, rear window heater and oil level indicators are located. Because I want to keep the rest of the dashboard the way it is, the display does not need to show everything at the same time, simple pushbutton operation of going through all the functions is all I need. Maybe just a few extra warning lights.

At all means I would like to keep the original dashboard as much the same as it is when it left the factory, or maybe change it in such a way that everything can be retrofitted.


Title: Re: Voltage or amp-meter?
Post by: krede on January 04, 2007, 05:53:37 pm
Quote
- maybe coolant level?

Indeed!!
Hans showed me a gauge from the header tank a bmw what he had fitted to his murena... a feature that I am going to copy for sure!!! should be easy to install, and your coolant system running dry, its a very usefull piece of information to have if you ask me! 


Title: Re: Voltage or amp-meter?
Post by: Anders Dinsen on January 04, 2007, 07:33:17 pm
Quote
- maybe coolant level?

Indeed!!
Hans showed me a gauge from the header tank a bmw what he had fitted to his murena... a feature that I am going to copy for sure!!! should be easy to install, and your coolant system running dry, its a very usefull piece of information to have if you ask me! 

Bernhard has this on his page:
(http://www.technikhomepage.de/kfz/motor/bilder/wasserbehaelter.jpg)

Scroll all the way down to read the details:
http://www.technikhomepage.de/kfz/motor/heizung.html (http://www.technikhomepage.de/kfz/motor/heizung.html)


Title: Re: Voltage or amp-meter?
Post by: Lennart Sorth on January 04, 2007, 08:57:59 pm
after a long time of reading this forum only, I decided to register and join the discussion  ;)

You are so very welcome aboard Robert!


Quote
By the way Lennart, I've got TWO digital multimeters and an analogue one, so I really know for sure which part is failing :D

haha - except, "a man with ONE watch knows what time it is, a man with TWO watches is never sure".   Not sure how that chinese saying adapts to three, though. :)

However, I used to have a very nice analogue multimeter, which was so much easier to read out of the corner of your eye - but it went belly-up some years ago.

My current digital one is admittedly a piece of junk, and rest assured it will be replaced by something better really soon - think I'll wait until I'm settled in UK though (moving end of January)


Quote
- Coolant flow (Especially with a Murena this can save your car's life!)
- maybe coolant level?
Brilliant - as one who has once cooked his engine, how could I forget these!

Quote
- Fuel consumption
better not distract a Murena driver with such irrelevant information - we might run the risk that (s)he stops enjoying the drive, and be concerned about economics :-)

/Lennart


Title: Re: Voltage or amp-meter?
Post by: krede on January 05, 2007, 01:04:35 pm
Anders : I allready did!!  :D
As for the digital instruments, I just got the price..!!!.. lets just say that there are more pressing matters that need attention first!!  ;D


Title: Re: Voltage or amp-meter?
Post by: Anders Dinsen on January 05, 2007, 05:14:45 pm
Anders : I allready did!!  :D
As for the digital instruments, I just got the price..!!!.. lets just say that there are more pressing matters that need attention first!!  ;D

Did what? (sorry, what have I missed?)
Does that mean you are postponing your project?

- Anders


Title: Re: Voltage or amp-meter?
Post by: krede on January 05, 2007, 05:25:11 pm
Quote
Did what? (sorry, what have I missed?)
Read the bit about the header-tank with build in sensor
Quote
Does that mean you are postponing your project?
Only the instument bit of it.. the turbo project is still on


Title: Re: Voltage or amp-meter?
Post by: Anders Dinsen on January 05, 2007, 07:19:41 pm
Quote
Did what? (sorry, what have I missed?)
Read the bit about the header-tank with build in sensor

Oh of course. So you have gotten yourself one? Bernhard has all sorts of pictures and descriptions, but it would be nice to be able to see how it fits. Converting to a better part is always good idea, particularly with a thing like coolant, but since I'd like to keep my car as close to original as it makes sense, I will only do it if it can be done so that it looks okay in the engine room.

Quote
Quote
Does that mean you are postponing your project?
Only the instument bit of it.. the turbo project is still on

Oh, yes I know you've already got most of what you need, so I can understand that that will not be stopped. It will be interesting to see how it comes along!

- Anders