Hi TT - Thanks for entering into this debate/discussion.
Now you should well-know me by now that I'm up for a good
fight debate, even a mass one!
Firstly I would like you to understand that I'm really not taking the pi$$ in any of this discussion - I really am that ignorant when it comes to some aspects of the subject!
OK - but I suppose your extreme levels of enthusiasm tend to be so high, that they appear (to me, anyway) to very much overshadow any areas of weakness of knowledge on a particular subject. And I don't mean that as a dig in any way, more of just an observation, which I sometimes have difficulty seeing through - if you get my drift?
And neither am I trying to score points to look good winning a debate. I will concede certain points and doubtless remain unconvinced on others and attempt to identify points where we may indeed be in agreement, even if we don't realise it at the time!
Yup, I'm fully with you on that. I personally don't give a flying fig weather others agree with me or not - as long as I, and all the other forum members, are free to "put our point of veiw" down on the forum (and without being unreasonably moderated), then I'm as happy as Larry. If others want to agree, or disagree with me - is not really important!
Also, to establish that we are talking about the same subject - I am talking about the 'factory' version partially open grills and not any homemade all-open version done by a crazy yankee teenager armed with a dremel in his backyard.
OK, and so was I. But I also wanted to illustrate the extremes of the subject, and I think it is important that we do. Afterall, Robin, just like you have modified your Golf as a "whole", it can aslo be stated that you have modified individual "components" of the said whole Golf. Some peeps may fit the hot climes grilles without any tampering, whereas others will get the hacksaw, hammer, and hot glue gun to them!
However, I think for you (or anyone else) to "narrow down" or restrict the subject to a certain level of open-ness in the grilles is not really appropriate. I would see that as a similar approach, using CF as an example, of saying something like "we can only call carbon fibre products carbon fibre, if they are 100% black". I'm sure Hurdy would throw his teddy out of the cot if someone tried to state is silver CF bonnet and mirror caps wern't CF!
So regarding these grilles, we must respect that even the smallest openings, as on the pre-production ones, which had the rough equivalent of just 4 "open" hexagons were deemed to have an effect on air flow, and were therefore binned by VW.
Finally, lets not look at these with one eye closed.
Whilst the "hot climes" official ones have the right one closed (in front of the screenwash), the left one is very much open, and can potentially flow a very large volume of air. However, more importantly, where these have been retro-fitted to a car which doesn't have the additional rad, and therefore no "restrictor" to the airflow, this grille will have a massive effect on starving, or diverting air from other critial areas, such as the lower and upper central grilles, which have effectively four sucessive planes of resistance (1st the air con condensor, 2nd the intercooler, 3rd the main coolant radiator, and 4th the cooling fans and shrouds). Air, just like water, or other liquids, is a fluid - and when flowing, will take the path of least resistance. Try this as an example - get a garden watering can, attach the sprinkler rose to the spout, then fill it with water. Now turn it upside down. How much water comes out of the rose, and how fast - and how much comes out of the BFO hole which you filled up under the tap from.
It seems we are agreed that we don't actually know what any adverse effects of 'open' (only partially, remember please) may be, but you are convinced based on your expert knowledge that there will be a disadvantage. Perhaps where I differ is whether that disadvantage is enough to be worth being concerned about.
Not really. I am 100% positive that these open fog grilles cause a "disadvantage". Where we probably both agree though, is that none of us knows for certain
categorically and exactly what components are disadvantaged, and more crucially,
by how much.
However, based on my studies, and using basic physics and engineering principles - I can put my hand on my heart, and state that I strongly believe that certain components WILL be affect. I can also clarify that this is my personal opinion, and try to help the "doubters" with some examples (the watering can, and I'll try to think of more). What I can not do is quantifiy my thoughts and opinions, because (a) I don't work at Wolfsburg, and (b) I've never properly studied "Computational Fluid Dynamics" or CFD. If there is anybody reading this forum who has expertise in (a) or (b), then I am 100% certain that my concerns and opinions would categorically agreed with. If you've never heard of CFD, Google it - and you will hopefully agree that I'm not waffling or BSing.
Regarding screenwash disadvantages, I concede to the wind chill factor. However, in discussing the 'partially' open grill version, the air flow or wind is completely blocked on that side, so I think it's reasonable to discount the potential effects on screenwash as being a problem. I agree that the typical yankee totally open version could freeze their body fluids!
OK the wind-chill is settled -good!
Regarding the "closed" right one (infront of the screenwash), then yes, you may have a point on that very specific instance, however, as I state above, I need to consider ALL versions (from the pre-production, to the "hot climes", to not only the yanks but also some UK peeps on ukmkivs.net and GolfMk5.com who have opened up their right one), and also include both right and left grilles.
As stated above though, partially open or fully open grilles make no difference. A hole is a hole, and no matter what size, air (and fluids in general) will still flow through it. The only thing which changes in accordnce to the size is the volume. Carburettor jets are one example. Or try the watering can - but this time with a different experiment. Fill the watering can up to a certain level - say 5 litres. Now put the sprinkler rose on the end of the spout. Now go and water your dafodils, using only the sprinkler rose, and time how long it takes to empty. Repeat the experiment with the same 5 litres, but this time, remove the sprinkler rose, and water the daffs through the open pipe (where the rose pushes on to) and time how much quicker the can empties. So that will prove that big holes or small - the same volume of fluids can still pass - irrespective of size of hole.
Now, onto my second concern of your above paragraph - about the flow being blocked on the rear. That just isn't true. Open your bonnet, (with the engine off and cold, I hasten to add) and from inside the engine compartment, from the top, put your hand/arm down beween the battery and the left headlamp. You should be able to get your hand all the way down, and actually touch the rear of the fog lamp - and even tap some SOS morse code on the rear of the fog grille. For the right side, the same free flow is there, but because of the large washer bottle, you can't actually get your hand down there (unless you are ET, with weird skinny arms!
). This "airflow" can pass extremely freely through the engine compartment, and exit underneath the bulkhead/firewall - so this particular point is a complete non-starter!
. . . to be continued (due to me waffling on and exceding the 10k character limit)
