Rad blind experiment

[Dieselman]

Originally Posted by MBManInKen

Surely there must be good design reasons for engineers to design grilles and airflows into the engine compartment the way they do? And good reasons why they don't blank the rear side of the grille (partially) off?

If the airflow takes heat away, then what happens to that heat now?

I think it's one size fits all with most manufacturers and a grille is a design feature as opposed to an engineering one, there are cars with no bonnet grille and they don't overheat.

Consider the same grille is used for a 250kw AMG and a 100kw diesel. The AMG wastes approximately 70% of input energy as heat the diesel approximately 60%. There is about another 5% loss in noise and some of the heat goes down the exhaust so say 50% and 35% wasted as underbonnet heat.
So to achieve outputs of 250kw and 100kw we need a cooling capacity of something like 500kw for the AMG and 120kw for the diesel.

Both have the same size cooling intakes..does that make engineering sense.?

The thermostat is creating a restriction to try to keep the engine warm, the amount of air would overcool it without that.
Maybe a better method would be to restrict the intake air and use electric water pumps, which are already planned for cars in the next few years, and have no thermostat.

[MBManInKen]

Originally Posted by Dieselman

I think it's one size fits all
[...]
Both have the same size cooling intakes..does that make engineering sense.?

No, it does not and that is a very good point.

[DieselE]

I agree that the cooling intakes are the same across the range but does anyone know if the radiators are the same size?

[Adam230K]

Diesel, i'm guessing your soul-purpose of doing this is to reduce drag, and to be honest with you, i've thought about blocking up the gaps i have on my bumper under the bonnet to reduce drag... does the 210 have considerably large gaps on the bumper? or would this make no difference?

[st13phil]

Originally Posted by Dieselman

iirc The old BMW 525TD has such an automated blind.

The latest incarnation of the 3-series with the Efficient Dynamics package certainly has an automatic set of vanes as a rad blind.

[230K]

Originally Posted by Adam230K

i've thought about blocking up the gaps i have on my bumper under the bonnet to reduce drag...

If you are chatting about your C230K, blocking the holes in the bumper just below the numberplatewill reduce airflow to your intercooler. You would get a reduction in power as a result.... I would imagine you wouldnt want that

230k

[del320]

If it worked well 80 years ago on this...



(thermostaticallly controlled radiator shutters)

and was indispensible 50 years ago on this...



then I'm sure this handcrafted effort will work just as well here...

[Dieselman]

Originally Posted by DieselE

I agree that the cooling intakes are the same across the range but does anyone know if the radiators are the same size?

Possibly not, but the one on this car is full size but it would appear it doesn't need to be as they never get too hot even without a fan.

If the radiators are different sizes all that would mean is that the greater amount of wasted heat will make the engine bay hotter and would require more airflow, but that same amount of airflow isn't required for the lesser wasting engines but isn't altered as manufactured.

I've just got back from a motorway drive and can say the car is definitely more stable when passing lorries, you just don't notice them at all now whereas they would push the car around a bit with their wake.

One observation is that the EGT temperatures tend to rise a little when stationary after driving then fall back to normal. This is probably due to radiated heat keeping the exhaust manifold warmer for a while.
The water temperature is no warmer than normal.

[Dieselman]

Originally Posted by Adam230K

Diesel, i'm guessing your soul-purpose of doing this is to reduce drag, and to be honest with you, i've thought about blocking up the gaps i have on my bumper under the bonnet to reduce drag... does the 210 have considerably large gaps on the bumper? or would this make no difference?

As 230k says, don't block the under grille because of the intercooler, but also because that's in a very high pressure, stagnant air area so works very well without creating much drag. The bonnet grille is in an area of faster moving airstream and causes more drag.

You could always try it but beware if you drive your car hard it will require lots of cooling air as it has to dissipate about 250kw of heat, mines only ever going to need about 170kw due to higher thermal efficiency.

[poisas]

me and my father are blocking same way as you doo, every winter, what i got from it ? only about 15% faster engine warm up=some economy but still even with cover engine is cooling down if i drive 120km/h @3000rpm to 70C

[Dieselman]

Originally Posted by poisas

still even with cover engine is cooling down if i drive 120km/h @3000rpm to 70C

OM605 / 606 engines tend to run at about 75c even with an 80c thermostat fitted.

I suspect what happens is that with the blind fitted the thermostat opens up more so allows more water to flow round the radiator, hence still keeps cool.
In one respect this is a good thing as it reduces the pumping effort due to a closed thermostat.

How much of the rad is blocked off and have you ensured the engine air intake is still exposed to fresh air.

[Dieselman]

Originally Posted by del320

then I'm sure this handcrafted effort will work just as well here...

Hmm, not quite sure how to take that Del, but for experimenting I just used what came to hand. I needed the barrel to use as a storage box so just used the side I cut off for this. It fits tight up against the back of the grille so seals pretty well in that area.

Anyway...I like free mods...all the more satisfying when they work..

I've got more barrels, do you want a piece..??

[banditdave]

ive followed your lead DM and blanked off, with aluminium foil, half of both grills on this astra i'm now driving, there isn't a temperature gauge on the instruments and ive no idea what temp the engine's been running at but the heater is now much better, so its stopping like that until the weather improves, cheers

[maddog]

It shouldnt make much difference to how quickly the car warms up because the thermostat if closed shouldnt allow significant flow through the radiator

I know most modern cars are over-cooled but that shouldnt make a difference if the thermostat is working correctly , I fitted a massive alloy radiator to my Skyline last summer , made no difference to the running temp but when pushing the car hard the temperature remains more stable and comes down faster

There should be no need for a blind on an modern motor car, not in the UK anyway sounds like someone has been watching Ice Road truckers where the purpose of the blinds is to INCREASE underbonnet temps to prevent damage to electrics.

Cue the "I've fitted a starting handle to my car" and "Where can i buy wire spoked wheels for my E class " threads

[lynall]

Quick google reveals e300td 97 on rad core size 640x490x40 same core size as my 430, site didnt list e55 and i was to lazy to look any further .

I remember running no viscous fan on my tdi discos, std basic car was okay but next disco with air con rad cooling was border line, next one (3rd) was an auto and once viscous removed started to overheat and also suffered from heat soak after a motorway run quite badly especially in the summer and the kenlowe fan couldnt cut the mustard.

Last one td5 famous for head gasket failures (plastic head dowels ) i alway ran the std set u,p but with a larger intercooler the viscous fan cut in quite a bit more frequently so obviously air flow was more restricted.



Lynall