Heat management in engine bay

[Chris_D]

Anyone done any heat-management mods?
It's obvious that a lot of heat-induced wear&tear, degradation and mechanical failures take place in and around the engine bay of an e85 M54 engined zed and my leaky cam cover gasket is a testament to that fact- it was literally baked hard! I'm keeping an eye on the rearmost 2 coils too as these will be subject to higher temps than the forward ones.

As i plan to get another 100k miles from this car i'm thinking about some minor mods to bring in more cool fresh air to the engine bay and also maybe either contain heat sources or vent/expel the hot air somehow.
Thinking about channeling some cool air to the rear of the engine bay via a front iinlet somewhere and directed towards the rear of the engine, maybe zircotec coating the exhaust headers or cutting some vents into either the bonnet or wings.

Plenty of time for r&d over the winter months however in time for its 'ring debut next year.
Any experiences, mods, tips?

 

[Yorkie Z]

I'd personally start with this https://www.ebay.co.uk/itm/152033093783

 

[Chris_D]

I'd personally start with this https://www.ebay.co.uk/itm/152033093783

eww seriously? i was thinking of something a little more discrete...

 

[cj10jeeper]

I think you're wasting your time and money on a stock engine.
These cars (and most others) are designed to run all day in 40-50c environments

Even if you do manage to get significantly more air under the bonnet, then that could be at the detriment of air flow through the rad

Incidentally I do run extra engine cooling on my Jeep but that's a powerful electric bonnet mounted extractor fan on the bonnet and a second electric rad fan in front of the rad to supplement the viscous fan. The Jeep does however often operate on full throttle at <5 mph...

 

[Chris_D]

I think you're wasting your time and money on a stock engine.
These cars (and most others) are designed to run all day in 40-50c environments

Even if you do manage to get significantly more air under the bonnet, then that could be at the detriment of air flow through the rad ...

OK, great to have an opinion cj but due to the physical evidence that there are obvious design flaws and exceptions when it comes to heat management in the engine bay of an E85 - as observed with the very common cam cover gasket failure occurrence as well as numerous accounts of bank2 failed coils etc, I've decided to go ahead and 'waste time and money' on exploring and implementing some minor modifications in order to avoid repeat occurrences. Operational longevity of engine components is the project goal here, not engine overheating mitigation, such as in your jeep. :wink:

airflow through the rad obviously won't be compromised, with an alternative inlet being constructed/found somewhere near the lower grill intake at either side where the 2 blanked portions are, then sufficiently ducted to the rear of the engine bay somehow.
venting will also be explored if it doesn't become too expensive as obviously hot air buildup is not being extracted from anywhere other than the bottom of the engine bay.
i have a friend who runs a ceramic coating company here in holland and have previously implemented a heat-reduction solution for the headers on a mk1 atom with his assistance, so budget-willing i'll also be exploring this as an option on the zed.

 

[cj10jeeper]

Your call Chris and if money no issue then coating or wrapping the exhaust manifold will help. I suspect your Atom had very specific reasons to cool the manifold and not to do with under bonnet temp

In terms of airflow, it's simple dynamics that if you push significantly more air under the bonnet via other routes then less will flow through the rad. All to do with pressure differential.

 

[Yorkie Z]

I'd personally start with this https://www.ebay.co.uk/itm/152033093783

eww seriously? i was thinking of something a little more discrete...
image.jpeg

 

[Smartbear]

Hi, I'd start by logging the existing engine bay temps in the areas you're concerned with at the top & rear of the engine-that way you will know if any mods are making any noteworthy difference
Rob

 

[Highlander]

I recall owners ceramic coating the exhaust manifolds on the Rover engined TVR's to reduce under bonnet temps and from my own experience it certainly ran very hot with significent heat soak into the passenger compartment.I never coated the manifolds on mine but remember it being noted that it helped with under bonnet temps but the exhaust heat soaked out further down the system.....the cat if fitted on these TVR's was inside the compartment behind the rad(not the best but ran nice and hot for efficiency).If sat in traffic/slow moving traffic in my Chimaera the gear lever & handbrake lever(both alloy) would get very hot.
I'm thinking along the lines of you coating the manifold in your car and the exhaust heat moving down the pipework to "escape" further down the system which might heat something adjacent up which is not designed to cope with higher temps.
Would it also be worth investigating if you could put extra vents into the engine undertray to promote a throughflow although you wouldn't want to dump too much "extra" air under the car but any "extra" air you introduce under the bonnet has to escape somehow!!........will be an interesting bit of research & development.

 

[GuidoK]

I have a ceramic coated exhaust manifold. But they are stainless headers and give off much more heat than the stock headers (due to the much larger surface area and thinner walls). I had them coated both for heat given off (burning wires and engine mounts in its vicinity) and to keep the exhaust gas flow hotter due to having also different style (ceramic) cats (my car needs a test drive to heat up to pass MOT emissions, idling wont do).
For the stock manifolds this is hardly an issue, but SS headers can give up 2-4 times as much heat.


Imho its not a design flaw that the engine runs too hot. It's controlled by the thermostat and the ecu. The heat level that the engine runs on is its designed operating temperature. Forcing cool air in will only result in the thermostat opening less, to try and maintain the heat in the engine to up to its designed spec. In our climate its very unlikely that your engine is acutally overheating.
Running the engine forceably under its optimal running temperature will cause powerloss, efficiency loss, less mpg, more emissions, and argueably a shorter life span. Every instruction manual warns about not giving full throttle/revs if the engine is not up to that temperature.
If you manage to cool down the engine that much, you'd be driving in that state all the time.
Insulating your manifolds cant hurt because that is an 'outside heat source' (heat already left the engine) but I wouldnt tamper with the engine's running temperature.

The design flaw is the materials used on the parts that fail due to heat. So its not the engine running too hot, but that gaskets/coils are made out of materials that cant stand the nominal engine operating temperature over time.
So the best way to solve that is to get/make parts out of material that are up to that nominal operating temperature.
So try and get cam cover gaskets out of a different rubber compound instead of the used NBR (at least I think its NBR) and maybe get coils from another manufacturer that uses a better coil wire insuating laquer.

Whats the company your friend is running?

 

[Chris_D]

interesting theory and yep, ceramic coating of the manifold and exhaust system, maybe right along to the muffler is an idea atm. venting and hot air expulsion also ideas.

Imho its not a design flaw that the engine runs too hot. It's controlled by the thermostat and the ecu. The heat level that the engine runs on is its designed operating temperature. Forcing cool air in will only result in the thermostat opening less, to try and maintain the heat in the engine to up to its designed spec. In our climate its very unlikely that your engine is acutally overheating.
Running the engine forceably under its optimal running temperature will cause powerloss, efficiency loss, less mpg, more emissions, and argueably a shorter life span. Every instruction manual warns about not giving full throttle/revs if the engine is not up to that temperature.
If you manage to cool down the engine that much, you'd be driving in that state all the time.
Insulating your manifolds cant hurt because that is an 'outside heat source' (heat already left the engine) but I wouldnt tamper with the engine's running temperature.

The design flaw is the materials used on the parts that fail due to heat. So its not the engine running too hot, but that gaskets/coils are made out of materials that cant stand the nominal engine operating temperature over time.
So the best way to solve that is to get/make parts out of material that are up to that nominal operating temperature.
So try and get cam cover gaskets out of a different rubber compound instead of the used NBR (at least I think its NBR) and maybe get coils from another manufacturer that uses a better coil wire insuating laquer.

Whats the company your friend is running?

was hoping you would chime in Guido
The idea is not to lower the engine's operating temperature by any means as I understand how critical this is for many reasons. More the idea is to dissipate the ambient heat created around the rear of the engine bay with an ultimate goal of reducing heat-induced damage to engine components and as you suggested it could be better to focus on the materials that the gasket and coils are manufactured from perhaps. Interesting. I laso suspect the residual heat buildup around the manifold could lead to premature o2 sensor failures located on that side.
the company is Saedt near amsterdam and they do all sorts of machine revisions and repairs. I first sub-contracted the company years ago to ceramic coat some turbine blades and housings for a project i was working on and got to know Jeroen quite well.

 

[Chris_D]

Hi, I'd start by logging the existing engine bay temps in the areas you're concerned with at the top & rear of the engine-that way you will know if any mods are making any noteworthy difference
Rob

good idea rob

 

[john-e89]

Demon tweeks do a range of exhaust manifold wraps ranging from £20 to £150 Chris, a cheap starting point. Click on performance, then on the left hand side click on engine bay parts and accessories, the wraps pop up there.

 

[GuidoK]

More the idea is to dissipate the ambient heat created around the rear of the engine bay with an ultimate goal of reducing heat-induced damage to engine components and as you suggested it could be better to focus on the materials that the gasket and coils are manufactured from perhaps. Interesting. I laso suspect the residual heat buildup around the manifold could lead to premature o2 sensor failures located on that side.

I dont know about o2 sensor failures. I think the sensors get the heat directly from the manifold so I dont think there is any cooling possible. Also the o2 sensors must work on a high temperature (about 800degC), they even have their own heater core build in.
From what I know the common thing to fail on o2 sensors is that heater core. Also you always get warned with o2 sensors that they cant stand cold shock. Thats one of the reasons they have that heatercore. So giving them extra cooling isnt a good idea I think.

The only thing I think you could reduce is maybe heat coming off the manifold that hardens the valve cover gasket on the bottom. But I doubt that is a real issue: that gasket already gets hot from the cylinder head and on top of the manifold sit small heatshields to shield that heat from the manifold.
Usually underbonnet heat is limited for performance reasons. So that either the engine is running too hot (something you can monitor with an obd2 reader) or that the inlet sucks in hot air. But the z4 gets its air form outside.
The only fix in terms of parts you can do is swap the thermostat housing for an aluminium one (there is an aftermarket aluminium m54 thermostat housing). But cracked thermostat housings is more a m52/e36 issue than it is a m54 issue I think.
As for other parts that have heat issues, I can only think of the valve cover gasket and the coils.
For coils there are manufacturers that have different designs (Ignition projecs, okada), but these are expensive and there is no telling if they stand the heat better. Different doesnt mean better in this case, they are made for performance issues, not heat issues.

I think if you swap the coils and gasket every 50k miles you're way ahead of any problems to come. Thats about £150 in parts I think if you shop on ebay.
Thats a cost of 0,003ct/mile, so £3 per 1000 miles.

In the end gaskets are a maintenance item. And coils appantly too. Just like water pumps, thermostats etc.
Everything made from rubber is called perishables in the automotive restoring world.

 

[Marius]

Intake temperatures on the track don't go higher then 30°c. Better go and work on brakes because they are complete shite on all bmw's

 

[Chris_D]

More the idea is to dissipate the ambient heat created around the rear of the engine bay with an ultimate goal of reducing heat-induced damage to engine components and as you suggested it could be better to focus on the materials that the gasket and coils are manufactured from perhaps. Interesting. I laso suspect the residual heat buildup around the manifold could lead to premature o2 sensor failures located on that side.

I dont know about o2 sensor failures. I think the sensors get the heat directly from the manifold so I dont think there is any cooling possible. Also the o2 sensors must work on a high temperature (about 800degC), they even have their own heater core build in.
From what I know the common thing to fail on o2 sensors is that heater core. Also you always get warned with o2 sensors that they cant stand cold shock. Thats one of the reasons they have that heatercore. So giving them extra cooling isnt a good idea I think.

The only thing I think you could reduce is maybe heat coming off the manifold that hardens the valve cover gasket on the bottom. But I doubt that is a real issue: that gasket already gets hot from the cylinder head and on top of the manifold sit small heatshields to shield that heat from the manifold.
Usually underbonnet heat is limited for performance reasons. So that either the engine is running too hot (something you can monitor with an obd2 reader) or that the inlet sucks in hot air. But the z4 gets its air form outside.
The only fix in terms of parts you can do is swap the thermostat housing for an aluminium one (there is an aftermarket aluminium m54 thermostat housing). But cracked thermostat housings is more a m52/e36 issue than it is a m54 issue I think.
As for other parts that have heat issues, I can only think of the valve cover gasket and the coils.
For coils there are manufacturers that have different designs (Ignition projecs, okada), but these are expensive and there is no telling if they stand the heat better. Different doesnt mean better in this case, they are made for performance issues, not heat issues.

I think if you swap the coils and gasket every 50k miles you're way ahead of any problems to come. Thats about £150 in parts I think if you shop on ebay.
Thats a cost of 0,003ct/mile, so £3 per 1000 miles.

In the end gaskets are a maintenance item. And coils appantly too. Just like water pumps, thermostats etc.
Everything made from rubber is called perishables in the automotive restoring world.

thanks guido! invaluable and considered insight as usual!
i think a cost/benefit analysis, or in this case a faff/benefit analysis would probably conclude that there isn't much that would be effective to do in the way of heat dissipation - just replace the maintainable items ahead of failure as you say.

the other driver for thinking about this was that back in summer i noticed the temp needle travelling eastwards just a bit, wheras normally it should be pointing straight up all the time.
i'll be swapping in a new waterpump and thermostat as a matter of course along with a slightly leaky oil filter housing gasket but i'm presuming i will only be able to tell if the new pump/stat is a benefit when the warmer weather arrives.
went all the way to Posbank and back from Vleuten today and the the needle stayed constant straight up the whole time, so no worries in the colder weather.
any thoughts on temp fluctuations in warm weather with normal, relaxed driving?

 

[Smartbear]

I think the temp gauge doesn't accurately display temperature variations, it's coded to display "normal" unless something major happens & it ignores small variations that occur normally with differing weather/traffic jams etc.
Rob

 

[Chris_D]

I think the temp gauge doesn't accurately display temperature variations, it's coded to display "normal" unless something major happens & it ignores small variations that occur normally with differing weather/traffic jams etc.
Rob

I thought it was purely derived from coolant temp?

 

[Ewazix]

I think the temp gauge doesn't accurately display temperature variations, it's coded to display "normal" unless something major happens & it ignores small variations that occur normally with differing weather/traffic jams etc.
Rob

Yes the coolant dash temp' gauge will sit dead centre normal anywhere between 75 and 113 deg C (i.e. normal operating range) which explains the way the engine can appear to warm up so quickly and doesn't rise or fall as the fans kick in I suppose.

 

[GuidoK]

Yes that meter is a so called dampened meter. Not so useful if you ask me as it gives no actual readings. But reassuring for most drivers.
But it gives no good information for fault tracing/diagnose.
OBD2 reader coolant temp should be accurate I think.