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Author Topic: What is EWP?  (Read 16344 times)
macaroni
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« Reply #15 on: May 07, 2007, 11:17:46 pm »

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.
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Anders Dinsen
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« Reply #16 on: May 08, 2007, 05:47:28 am »

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

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.

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

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

- Anders Cool
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Will Falconer
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« Reply #17 on: May 08, 2007, 10:07:22 am »

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
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Anders Dinsen
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« Reply #18 on: May 08, 2007, 10:42:24 am »

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.
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michaltalbot
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« Reply #19 on: May 08, 2007, 12:06:22 pm »

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 Smiley
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macaroni
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« Reply #20 on: May 08, 2007, 12:39:57 pm »

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.

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michaltalbot
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« Reply #21 on: May 08, 2007, 12:40:16 pm »

Well, don't laugh too much to me  Grin Grin Grin



Question is, how is cooled the yellow zone?
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michaltalbot
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« Reply #22 on: May 08, 2007, 12:45:00 pm »

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.



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!  Wink
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macaroni
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« Reply #23 on: May 08, 2007, 01:20:44 pm »

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
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gizmo
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« Reply #24 on: May 08, 2007, 01:40:30 pm »

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.

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krede
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« Reply #25 on: May 08, 2007, 04:58:11 pm »

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 Smiley
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Anders Dinsen
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« Reply #26 on: May 08, 2007, 10:00:13 pm »

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? Wink
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 Cool
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michaltalbot
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« Reply #27 on: May 08, 2007, 10:42:52 pm »


But have you looked down your engine compartment, lately? Wink
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.

- Anders Cool

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


The overheating of the engine in the first place should have caused the red warning light to turn on.

- Anders Cool

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


What are the plugs looking like now that you have been driving the car for some time?

- Anders Cool

I drove cca 4500 kms and all plugs are looking very nice  Cheesy 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!!!
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« Reply #28 on: May 09, 2007, 08:53:40 am »

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

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).

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

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.

Quote
I think it can not be better! And I am happy for that!!!

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

- Anders Cool
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roy4matra
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« Reply #29 on: May 10, 2007, 10:38:51 pm »

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

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.

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.
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