First attempt at a lower grill block
 

A couple of weeks ago I came across a sheet of plastic, that I thought would be perfect for a grill block. So whilst doing a filter and oil change I decided to take the time to make it.

The first thing that struck me was that I worked out what corroplast was - up until yesturday I assumed that it was some kind of branded plastic, then it dawned on me . . . corrogated plastic, exactly what I had found.

Anyways after measuring the grill by eye and hand spans I cut a piece out and then cut out some ventilations holes and cable tie holes.

It turned out to be a little narrow but here it is infront of the grill
http://i132.photobucket.com/albums/q...Y/DSC_0111.jpg

And then fitted behind the grill (the reflection of the plate was messing up the flash from my phone)
http://i132.photobucket.com/albums/q...Y/DSC_0116.jpg

I'll be interested in seeing the car in the light, I was expecting the block to be really visible and that I would have to paint the block, but whilst in the garage it wasn't very noticeable at all.

I am already thinking about the next version, mainly smaller cut-outs for the air, but for the prototype I would rather keep the holes on the bigger side and not risk over heating.

Longer term I am considering making several grill blocks one for every season, or perhaps an adjustable block.

Hi i had a similar problem with my grill block. When we had a rogue high of 35c instead of usual 20c my engine got very warm so had to remove by roadside to prevent super overheat. So adjustable venting is something i have thought about but not come up with a practical solution yet.

The slots you have are fairly narrow - this will seal them off (effectively) above a certain speed. I would try doing a block that has a single opening. And if you can, prevent air that comes through the opening from not going through the radiator. Because, stock opening are often so over sized, they let lots of air escape - which adds drag for nothing.

What doe the upper opening look like? Block that off completely first, before doing anything about the lower opening has a positive effect, without affecting the cooling. The lower opening is more effective, typically.

The upper block in its prototype form is some pipe insulation wedged into the gaps.

Unfortunately the car got a little too warm today so I will have to revise the design.

Whilst on the motor way / main roads (generally above 60 km/h) it was fine, but at slower speeds it got very warm very fast.

My idea with quite a few slots was to spread the air over the radiator so that there wouldn't be any hot spots.

I have now found a sheet of black corrplast so I was planning to re-make the upper grill block, in the meantime the lower block will have to be re-thought.

I'm thinking perhaps two or three slots that go horizontally from one side to the other.

I decided to leave it for a few more drives to see generally what happens.

I made some notes from my drive on tuesday, my temp gauge looks something like this one whereby it just says normal.
http://i778.photobucket.com/albums/y...n/100_2079.jpg

Outside temp about 22 degrees C
Motorway driving into the wind about 80 km/h the temp needle was on R
Single lane road with the wind behind me between 70 and 80 km/h the needle was on M
Driving at about 20 - 30 km/h the needle was on A.
Pre grill temp was almost always on N

My feeling is that the grill block is deforming whilst at speed and I was driving into the wind, and thusly allowed alot more air in, hence the lower temperature.

I normally dont do any city driving, but due to the sensitivity of the Zetec engine I would prefer to keep it on the cooler side, right now my aim is to keep the engine around R and no higher than M.

First I will remake the upper grill block, then the next step will be to make a new lower grill block, I'm thinking two slots running almost the entire width of the block, and see what the outcome of that is.

What does the space between the intake grills and the radiator look like? Are there gaps where air can "escape"?

I would do a total block on the upper grill, and work your way down to a single opening in the lower block that keeps the fan from coming on most of the time, and keeps it from needing the fan for very long.

You also might benefit a LOT from a ScanGauge or an Ultra Gauge; both for the temperature and for the mileage, as well.

A bit of a holy grail item for many around here.

I'm certainly taking your suggestions on board, you are of much help.

I would love a scan gauge (or similar) but I haven't had any luck with the OBD port, the car has one, but it Europe they became mandatory around 2000 or 2001, my car is 98, and Ford stopped with the escort in 2000. Some escorts will communicate and some wont, even with Ford software.

I am considering an MPGuino but I'm not so good with electrics, I did come across a chap in eastern Europe who was selling them prebuilt. But first I need to sit down and look at the wiring diagrams of the car to see what wires I could tap into.

I have been considering a vent such as this

http://i.ebayimg.com/00/s/MTYwMFgxNj...Uy8eZ/$_58.JPG

I was considering having two or three then I could manually open them before setting off (thinking about where I'm going, the ambient temp, route, etc).

I'm sure that a bonnet release type cable could be routed from inside the car to the vents to allow adjustment whilst driving.

vena contracta
 

The drag of a flat plate opening will be akin to a flat plate (Cd 1.11),with massive flow separation which actually chokes off the airflow within the passageway,(known in fluid mechanics as a vena-contracta entry loss) worse than with the cuboid (far left) below
http://i1271.photobucket.com/albums/...ad2/12-061.jpg
Even with a sharp-edged pipe opening we get the vena contracta loss (the yellow regions of turbulence are choking down the flow)
http://i1271.photobucket.com/albums/...Untitled32.jpg
If the inlet is bell-mouthed (like inside the throat of a carburetor's venturi) the loss is completely eliminated,leading to the most aerodynamically-efficient inlet.
http://i1271.photobucket.com/albums/...titled3351.jpg