MatraSport Forum

Krede and Anders? You've spoke about it in other section, what does it mean?

Heh, good question, sorry for keeping it private.

EWP is just short for Electrical Water Pump. There's a company in Australia that manufactures a selection of eletrically powered water pumps for engine cooling, the idea is that you can run them instead of the belt driven pump - or as a booster pump.

http://www.daviescraig.com.au/ (http://www.daviescraig.com.au/)

One of the things you can do with an electric pump is to eliminate heat soak - the effect where your engine actually heats up (and may even boil) after you switch it off. This can happen because the exhaust manifold is heated up far more than the head, so when the coolant flow stops, there is nothing stopping the temperature from rising. I've noticed it a couple of times on my car, especially if I have been driving slowly in city traffic and then turns off the car. Turning it on a few moments later, the water temperature gauge will be higher that when I turned the car off!

My idea involves using the EWP as a booster pump only - fitting it in the return circuit from the radiator and controlling it using a temperature controlled relay in the other hose to the radiator so that the pump is activated when the thermostat is fully open. It should be run directly from the battery, so it will maintain a coolant flow after engine shutdown - to prevent heat soak.

I did a crude drawing here:

(http://tmp.dinsen.net/ewp/ewpmurena.jpg)

The more advanced solution is to remove the water pump entirely, AND the thermostat, and run a computer controlled cooling system using a digital controller from the above company. For that, Krede needs a water pump assembly without impeller, and probably a secondary pump to run the cabin heating circuit?

- Anders 8)

I got the waterpump for the turbo of a late 80'ies vw passat turbo diesel... ... I salvaged it from a car (military) before they dragged it away and blew it to kingdom come with a couple of heavy machine guns... thus i got it for free... Might work if placed in the heater hose and wired up to the  ventilator fan, or just with an on off switch... :)

Btw you can leave the thermostat in if you want, if used with a controller the pump wont start before the engine reaches a certain temperature.. It would actually help in regards to the cabin heater

I guess you liked watching that...

This will be your booster pump for cabin heating, right?

- Anders

Hi Guy's,

A cheap source of electric water pumps will be the Volvo 400 series turbo cars, they have them fitted to continue the circulation of cooling water to the turbo after the engine is switched off. They are controlled by a thermostat and the object is to prevent heat soak from killing the turbo.

Is cooling a problem with murena's?

I have just acquired one of these as my daily driver. I have also bought a "spares" car, so if anybody wants this pump and it isn't too hard to access, I can supply one.

Hey Gizmo..
The Murenas seem have a reputation for overheating.. as has most mid engined cars come to think of it..(mr 2's for instance) but weather this has any truth to it Im not sure.
My car runs an "s" spec cam, and twin dellorthos.. gets a good thrashing on a regular basis and gets to drive 10-15 minutes through city traffic right afterwards, and it has NEVER shown even the slightest signs of overheating.. sure it gets hot, but only very rarely does the ventilator fan kick in... I actually sometimes let it run hot enough for the fan to start simply to check that the thermo switch IS working.
Thus any reputation for overheating Is IMHO highly exaggerated, Indeed I have spoken to a few guys who have run a 505 turbo engine (with the water cooled T3 turbo) in a murena with standard radiator etc.
I think most of the faults people have regarding the cooling is due to poor maintainance... they are old cars now.. and most people seem to be ok with just topping up the coolant tank when it gets too low....a little more is needed on 25 year old Murenas :)

The reason that  Anders and I are considering the EWP has less to do with faults in the cooling systems design... and more to do with our irrisistable urge to pamper and spoil.... the prrrreeeeecious ... ;D
 
   

Krede,

I tend to agree that neglect is a powerful enemy of the 'old car' and the mid engine/front radiator layout could lead to problems if not regularly maintained. My MR2 runs rather cold and I think the thermostat my be stuck open (another job for the list). As cylinder heads seem to be the biggest casualty with overheating perhaps using the EWP just to circulate extra water through it might be a good option. What about fitting an oil/water intercooler (easily sourced from a modern car) to help to moderate the oil temperature.

I recall reading in a book on racing car design that a radiator only requires an intake 1/6 the size of the radiator to function correctly, perhaps some of the air feeding into the murenas over large intake could be stolen to cool the brakes, also less air taken into the radiator will mean less air to exhaust from the radiator cavity which should reduce the aerodynamic drag.

As Anders Wrote, the main reason for the EWP is to keep cooling the engine even AFTER it has stopped!
This is possible with an electric pump and fan.
I have considered fitting an oil/water cooler, but, Im not too keen on adding more strain to the cooling system, be it in ok shape.
However, as soon as I find out what adapter to use, I will be fitting an oil cooler.. possibly one from a 911 as they are designed for rear engined cars.

While on the subject of cylinder heads you are on to one of the Murenas real trouble spots!! (the 2.2)
The cylinderheads on these cars (indeed on most older aluminium heads) are prone to cracking if overheated.
I know of many that have had to replace them.. mine too has had a new head not long ago. Matra Hans too I belive

While reading up on intercooling etc, I came across some similar pages about air ducting to the radiators... after seeing the front of the Murena, I believe that some thought have gone into the designing the "mouth" to increase the air speed onto the radiator.. if this is the case , its very high tech for a 1982 car.. but then again.. its French. :)     

 
Yes, heat soak after switching the engine off is the potential problem, especially in the aluminium cylinder head. The point I was making (not very clearly, after rereading my post) is that primarily it should be the cylinder head that is kept cool by the continued flow of water. The coefficient of expansion of the aluminium is much greater than that for the cast iron block and this is where the stresses of the heat soak will be greatest.

Check out this link for oil coolers and components  http://www.thinkauto.com/

Hmmm....Yes.. using different materials can be a problem... but I believe to ahve read that aluminium has the capacity to dispose of heat 4 times quicker then cast iron... so maybe for this reason it would be advantageous to get the engineblock cooled faster? just guessing here.
 
Cooling the oil after the engine has stopped wont make much of a difference since it isn't circulated by the oil pump.

My car failed the head some years ago due to overheating caused by a failing water pump.

In ideal state, the cooling system is adequate for the car, but running a tuned engine and a stainless manifold that doesn't dissipate heat as well as the cast iron, there's really a good chance that sooner or later, it will boil and risk destroying the head.

Another thing that can cause overheating (I've learnt this only recently), especially on tuned engines, is the ignition being retarded too much in idle. The workshop manual instructs the static idle timing at 10 degrees, but Des Hammill in his book on ignition systems recommends up to 14 degrees for a cam like the S-cam (279 degrees period) and even 16-18 for a Holbay (296 degrees period). Otherwise the engine will simply run too hot in idle!


Tey also carry the Davies Craig EWP's in the range, though the price seems slightly higher than Demon Tweeks.


Water cooling will cool both, but as the exhaust manifold heat enters through the head, that's where the cooling needs to be, I think.

- Anders 8)

Well, this is big true!!! I bought my Murena S very cheap, because the engine was totally damaged, and I´ve got the second engine which had the same problem - hole in the cylinder, and terrible damaged cylinder head

(http://sweb.cz/michaltalbot/auta/Murena/B16.JPG)

But the rest of the engine (timing chain with wheels, 3 pistons, bearings) looked very very new. Do you know where I found the reason of all problems? Yes - the car was equiped by 4 - 1 Devil exhaust. And many other Murenas with damaged engine had this exhaust tuning... Heat from this exhaust is so big, that the carpet in my trunk was burned right in the place where the exhaust pipes are.

I agree with that if everything is O.K., original cooling system is sufficient, but you must calculate, that it is middle engined car, so for sure, everytime when I came from the way through the city, and temperature is on the 90 or a little bit more, I turn on the heating system, then I stop the engine, but turn on the ignition till the wind from the heating is cold and than I turn on the engine again. Then the temperature goes under 90 degrees.

Hi Michal


That's an interesting finding you have there, but I don't think the exhaust is the only source of the problem: The thing is that stainless steel has less heat conductivity than iron, so the amount heat dissipated from the cast iron manifold will actually be higher than from a similar stainless one.

I think there's another source - when you fit a free flowing manifold like the devil, the cylinder filling will improve significantly, especially to an S-cam with its overlap of 56 degrees. It will therefore develop more heat. Further, if ignition suffers on one or more cylinders, the energy produced in the cumbustion will not be extracted mechanically (since the combustion will be slower or delayed), and even more heat will develop. An ignition problem could be the reason why your engine had one broken cylinder, and three fine ones?

My car has been running with a stainless 4-in-1 manifold (similar to the devil) for years - there's nothing to see in the trunk, so I think something was seriously wrong on your car, and that's why it blew the cylinder.

Heat soak is different, though - since the manifold is not dissipating the heat efficiently, it will transfer to the head and cause boiling after ignition is turned off. I experienced that about a week-and-a-half ago - cooling system had a small leak so pressure coulnd't be maintained properly, and stop-and-go city driving combined with very hot weather one morning caused serious boiling almost immediately when the engine was switched off. The leak is fixed now and I'm very careful to keep the gauge below the 90 point, but this is why I want the electric water pump!

It seems we are equally paranoid with our temp-gauges ;)

It's a magnificent photo, by the way - do you still have the blown up block?

- Anders 8)

These are my experiences...
I have a Holbay cam and a 4-1 manifold and there is no evidence of overheating anywhere.

When my "fanbelt" broke a few months ago, the temp gauge hit 130C for a mile or 2 and still the head is OK.

Also, why would having the ignition timing too retarded cause overheating? Surely more advance would cause pre-detonation, hence excessive heat?

In fact, I recently replaced the thermostat as the previous one wouldn't let the car get anything like warm enough. The replacement 'stat now has the car sitting at a nice 90C and it goes much better.

I would say that, with a functioning cooling system, the Murena is well protected against over-heating.

Detonation is destructive to the engine, but advance to the point where its just about to pink is a good thing because as much of the energy produced by the combustion as possible will then be extracted as mechanical energy by accelerating the piston - less heat produced (and more power to the crank).

Whereas if ignition is a little too late, the piston will be in motion, rapidly moving away from the flame front - and more heat will be produced. This is well known.

You have had your ignition set up professionally and are not seeing any problems - which IMO adds to my theory.


I tend to agree, but lots of things can go wrong, and then it can be worse than the average, I think.

- Anders 8)

Most 2.2's are fitted with 4-into-1's because of the failure of the original cast iron manifold.

However as the manifolds crack in the same place as the heads it's hard to be sure whether the heads or the manifolds were faulty in manufacture.  Whatever, it's the excess heat from one of them that cracks the other.

So don't blame the 4-into-1's, they are not the cause of the problem

Agree, but they can contribute in different ways to the problem.

Very interesting informations! I am happy that I've found this forum!

My English is not perfect, so I must to explain my last contribution. When I bought the S Murena one engine (that one on the picture) was in the car, and the second one (also broken) was for free. All engine parts was in the trunk, luckilly also with the original exhaust (which was looking like new). I bought the car with all papers including the technical papers for Spax suspension and also for 4-1 Devil exhaust with 4 fishtails. On the middle glass, there is sticker Hennes tuning (does somebody knows it?) and previous owner (he already bought it with broken engine) told me, that is said, that maybe there was or is tuned camshaft. So from all informations the history was: In 1998 somebody made complete renovation of the engine (pistons, bearings, timing chain+wheels, etc.) and used tuned camshaft + 4-1 Devil exhaust. After cca 5.000 kms one piston was broken and it damaged the block and the cylinder head. Well, he made it again - new cyl.head (it has 5 bolts on the rear cap), new block, pistons, bearings, etc. and after next 5.000 kms it happend again, so he put the car out of service in 2000. In 2006 I bought the car and observed the first damaged engine too.

But how is it possible, that it works in your cars??? My idea is that, with normal using of the tuned engine (cam + 4-1) you needn't to have problems, but when is hot weather and somebody kept the engine in max.torque for longer distance (for ex. 20km with full throttle), it starts to be overheated and one piston went grinded. And because it is in high torque the damaging of the engine is too big, because it isn't possible to stop it in short time. This engine is from Chrysler/Tagora where 70% of cooling is done by water and 30% by air. But when they put this engine in the middle of the car, I think that the cooling system was so-so sufficing.

So because of it, I though that the reason of all problems was the exhaust - especially when I found fired carpet in the trunk. But I must to say that it wasn't original carpet, maybe that's why it didn't resist high temperatures,  the glue which held the carpet was brown in that one place and yellow everywhere arround.

The spare - broken engine was without cam, and the camshaft which I demounted from the car I didn't knew if it is original or tuned. I have very good experiences with one firm in Belgium where they are renovating camshafts, so I sent it them and they made original S timed camshaft.
So now I have everything original including the exhaust, and I have no problems with it. When I drive on the highway, gauge is arround 80 and in the city is on 80-90, when I stand in trafic jam it goes to 100, but after some time it goes down to 90 (cooler fan is working good).

I have some questions, but I will start a new reply, because I must to drive a picture at first :)

I don't think I will be going to Hennes tuning for any work...

If they fitted a hotter cam and 4-1 exhaust and didn't alter the fuelling, that would explain the destruction of 2 engines in a short space of time.

Well, don't laugh too much to me  ;D ;D ;D

(http://sweb.cz/michaltalbot/Murena%20cooling.jpg)

Question is, how is cooled the yellow zone?

You know Hennes tuning?

What kind of alter the fuelling You think? How it can damage the engine?
You are right, because in the car there stayed the original Solex carburetors, please explain it to me, thank You so much.

And which pre-ignition is optimal for orig S engine? I had set up 12 degrees.
BTW: yesterday I tested my compression and all cylinders have 13!  ;)

I don't know Hennes tuning, but they seem to have built 2 engines that grenaded within a few thousand miles!

If the cam and exhaust make the air flow much more and the carb jets/chokes/barrels are too small to supply the appropriate fuelling, the mixture will run lean and therefore the cylinders will get too hot and go POP!

It is far better for a car to run too rich, than too lean. It is best to have the optimum air/fuel ratio though.

12 degrees should be OK at static, but more important is how the ignition curve advances with revs. It should be about 32degrees at 3000rpm or something like that. If the distributor centrifugal advance weights aren't working, then the ignition won't get advanced with revs and the situation Andres talked about would occur. I'm still not convinced that would cause overheating though.

Nice picture, no idea how that area is cooled or how hot it gets, but next time I drive my Murena, I will fit a thermometer there and see.

Hopefully someone else will comment on this too.

Antony

Hi,

My car has an uprated camshaft, carbs and a 4 into 1 stainless exhaust and apart from discoloured primary pipes there are no other signs of excess heat in this area. The boot carpet is original and in good condition. I assume the alloy heat shield between the engine and boot compartments is a factory fit.  Due to lack of visability I couldn't find the engine temperature sender, where is it?
Michael's point about the water cooling only being part of the overall problem is a very valid one.
Nice drawing Michael but the whole area of aerodynamics and the airflow under the car and around the engine bay really deserves a topic of its own, this is an area where the cars could be improved.

If by engine temp sender you mean water temp sender, its situated in the thermostat housing next to the distributer.... look for the hoses.. you cant miss it :)

Nice drawing, Michal

The source for air cooling is the rear of the car, which generates a decent amount of vacuum at increasing speeds. This vacuum sucks out our from the engine compartment, and because of the heat shield fitted on the 2.2, the air will be drawn in from the top of the engine.

But have you looked down your engine compartment, lately? ;)
The air can't really get up in front of the engine, there's simply too much obstructing the air flow: Airbox, carburettor(s), manifold, starter, coolant hoses.

No I'm quite convinced that the airflow passes under the engine (adding to the cooling effect of the oil pan), and up on the back. The yellow zone.

The S-spoiler adds seriously to the vacuum effect by the way, by increasing the vacuum on the rear. It also adds downforce on the rear end, so it has multiple functions. An airflow meter in the channels under the boot should show it.

I agree with Macaroni that the tuning work Hennes did was obviously not good enough - they have messed something up, ignition or carburation, or both. The overheating of the engine in the first place should have caused the red warning light to turn on. The fact that it literally blows the cylinder should really raise a concern. Someone wasn't thinking here. Even if the engine was 100% only water cooled, it shouldn't be happening this way if something was wrong - the piston would be expected to break first from wear, and the head gasket of course. Not the block.

Michal, you still run the original carubrettors. These Solex'es are known to wear out in the bearings on the throttle shaft, which are brass - not ball bearings like Weber DCOE's. This wear will eventually cause a serious vacuum leak - and as Macaroni points out this could be the source of the problem. You may have already, but I suggest that you check your carburettors for indications of wear. It's impossible to measure a vacuum leak on only one cylinder using an exhaust gas tester, but if you buy four of Gunson colortune plugs, then you might be able to see a difference in mixture over the cylinders. What are the plugs looking like now that you have been driving the car for some time?

- Anders 8)

Hm, I though, that the small piece of GFK ( maybe 100 x 40 cm) which is under the car is sending the air right into the small space between engine and the chassis


Which control lamp is for overheating? I think that I don't have it on my dashboard.


I drove cca 4500 kms and all plugs are looking very nice  :D no, they are orange, we say brickly orange, and it seems to be good. I think that my carbs are in excellent condition. Engine is running like Japan one, follows the throttle pedal immediately and pull the car like joung bull, starting when is cold in first second... I think it can not be better! And I am happy for that!!!

This is only fitted on German spec cars, mine for example doens't have it. We had a discussion about it some time back on the mailing list. I think it was required by TÜV to improve cooling of the fuel tank.

Remember that the engine room cooling is vacuum driven off the rear of the car, not by pressure under the car (which there shouldn't be).


I was talking metaphorical... if I had had my engine tuned and it blew up after only 5000 km, I would be very worried about the job done.


Sounds like you have a perfect car, Michal - I understand your happiness and pride!

- Anders 8)

No, the GRP panel under the fuel tank, was to protect it.  A TUV requirement.

As for the heat in the cast iron exhaust manifold verses a stainless tubular exhaust, the cast iron manifold retains it's heat for longer and I believe does more damage.  You only have to feel how quickly a s.s tubular manifold cools after switching off, compared to a cast iron one.  There is more air circulation around it, and even though mine is slightly closer to the boot than the cast iron one was, the boot does not get quite as hot inside.

Finally, anyone that fits a tuned exhaust manifold in place of the original cast iron manifold must richen the fuel system otherwise it will run too weak. (owing to better gas flow)  I found no need to change my static timing and I would not recommend more advance as you will also get more at the higher revs, which combined with a weak mixture can be lethal to the engine.  Weak mixtures cause more internal heat which can damage the engine.  However, I have heard many people running Murena on 95 octane low-leaded fuel which is also not correct.  The Murena, especially tuned, requires 98 octane (i.e. super low-leaded) because pre-ignition and detonation are closely linked and detonation will blow holes in pistons!  One tip here, is that many forget to put a few drops of oil down the centre of the distributor under the rotor arm every 7500 km.  This oils the advance weight mechanisms at the base of the distributor, and I have seen these seized up.  This was a common service item when we had contacts that needed regular checking but since changing to electronic distributors, people forget...

I have run a Murena 2.2 from new (1983) and tuned it myself with Holbay cam, 4 into 1 s.s exhaust system and Weber 34 DMTR (which replaced a worn out Solex 34CIC).  It produces 145 bhp and returns around 35 mpg average (worst usually 28 mpg best 40 mpg although I do have the high 5th gear) and I generally like to drive fast on the open road!!  I have not had any cooling problems with mine, even in bad traffic for long periods in London on really hot days.

Provided the cooling system is in good condition the Murena is no more prone to problems than any other car, but these are now 25 years old and many have not had the systems overhauled which is what really causes problems.  I have replaced radiators on other peoples 2.2 Murena and you would be surprised how heavy the old ones were compared to the new ones.  This is due to build up of 'silt' inside over a long period of time, and it reduces the cooling capability.  After fitting the new radiator, it is noticeable immediately how much cooler the system ran.  If your radiator is older than say, 10 years, it is about time it was changed.  Thermostats and radiator switches are also not changed often enough considering the important job they do, and how little they cost.

Hi Roy

Your your valuable input on this subject is very much appreciated!

Regarding ignition, I have been referring to Des Hammils book on the subject of tuning distributor ignition systems. He points out that it is important to get the static idle advance correct AS WELL as the total advance. I understand that total advance is a dangerous thing to play with, but with care it should be possible to go beoynd the factory numbers. As Hammil points out, the car manufacturer had to ensure that the car would be able to run on many different kinds of conditions (including fuel octane numbers) - we can be more careful. I think you agree on this, Roy?

Macaroni had his dizzy set up for something around 35 degrees total advance with a professional tuner, which is a safe number according to Des Hammils suggestions for hemispherical combustion chambers. If we look at the ignition maps at http://www.technikhomepage.de/kfz/elektrik/verteiler.html (http://www.technikhomepage.de/kfz/elektrik/verteiler.html) (which I have verified to be according to the workshop manual, whether they are according to actualy distributors I don't know of course), we will find that the total centrifugal advance on the 2.2 dizzy is 13 degrees (cam), corresponding to 26 degrees on the crank.

Thus with an unmodified dizzy, we can go up to 14 degrees static ignition and still be within the 35 degrees total advance. Whether that is safe to do with a given engine on a given fuel type will have to be carefully verified of course - Hammil discusses fast road cars as well as racers, and while pinking and even a bit of detonation may be okay on the latter (where people tend to rebuild their engines routinely), I think most Murena owners will be playing the safe game. I know, I will :D

Hammil gives instructions for limiting the total advance of the distributor, though. It is a relatively simple mechanical modification. The difficult part is to get the tuning right - and you will always be "on your own" when you start modifying things. It's not a thing you "just" do.

Hammil claims that a 290-300 degree cam like the Holbay should run about 12-16 degrees static advance, depending on the actual engine. The 2.2 Murena engine may require less? Increasing the idle above 1000 rpm will however increase the effecitve idle advance (by simple centrifugal advance), so it may not be necessary to advance it at all on a given setup, but that's another story.

Thanks for the tip of lubricating the distributor - that was a service item I would have missed! It is extremely valuable to have this kind of advice passed on from an experienced person like you.

As always, your input is extremely valued, Roy.

- Anders 8)

PS: Your performance numbers on the Holbay cam with the single carburettor setup should impress a few people. With that cam, I beleive that the exhaust manifold is much more important to its performance than the inlet.

Yes but unless you start modifying the distributor, one has a direct bearing on the other.  Most people are not going to start modifying distributors and owing to liability legislation I would only recommend the manufacturers specs.  If you change the static timing position you change the overall advance too.  For most people the static advance is 10 degrees BTDC and the distributor will add up to another 24 degrees with throttle and higher revs. giving 34 degrees total advance, which is close enough to that 35 degrees limit.

The other problem is getting accurate figures.  The only figures I have seen for the 2.2 were actually for the Tagora version of the 2.2 (code 9N2) not the Murena 2.2 (code X5N2) which has a different distributor with 'altered timing characteristics' according to the publicity.  I have written to Bosch stating the two different distributor numbers and asking if they can supply details of the actual differences but so far have not received any reply.

Without these details, all you can do is try one on a rolling road, and check it's setup and even tune it ideally for that specific car, but as mass produced cars all tend to be slightly different it is not safe to assume what you do to one is good for all.  In fact setting up a car on a rolling road is usually the best way to get the ideal for any particular car and can often benefit all round.  However, as you say, fuel also varies and you have to allow a little for that with a road car.

This is possibly why some peolpe claim they can run a 2.2 Murena on normal low-leaded (95 octane) when I have found mine will simply not run on it.  It must have 98 octane to run properly.  A little pre-ignition (pinking) may be acceptable occasionally but detonation - never!  Since most cannot distinquish between the two it is best to have neither.



I had a kit car in last week with a Triumph Vitesse (6 cyl. 2 litre) engine in it, and the distributor was rusty and seized through lack of oil, so the advance could not work, so it reminded me that people have forgotten about this important item!



That was a good example of setting up on a rolling road to get the best for that particular engine but it was also a few years ago when we had proper (leaded) fuel!  I don't know what it is now.

Actually both manifolds are important as shown by another club member who did not have the cooling system plumbed in to the downdraught inlet manifold, and the car was not pleasant to drive during the warming up phase; but the tuned exhaust certainly is more important with a modified cam.