Modifying the front grille for increased air flow - pros & cons

[tigger73]

I've been toying with doing this for a while and as I'm about to install an S3 intercooler into the Tig I'll have the front end off.

So my question is in relation to the lower grille which has half of it blocked off (see pic below). The top section is blanked off whereas the lower section is open. Just wondering about removing the top "blanking" and having air flow through the whole lower grille. Is there any issues with doing this? Plus side is better cooling but wondering if it's going to cause me any issues.

[tigger73]

OK so I might be answerig my own question here but on further research I've found there's a few Ford models with active grilles - little stepper motors which open and close off the grille.

Theory goes that having the grille closed helps to warm up the car quicker to get to operating temps and also helps with fuel economy by reducing aero drag. However having the grille open obviously assists with cooling so there's a trade-off.

Given I can only have 1 fixed position, do I stuff up my aero for extra cooling or not?

[team_v]

I would say go for the extra cooling.
The tig is brutal on aero anyway so it isn't going to add much more loss.

[tigger73]

I would say go for the extra cooling.
The tig is brutal on aero anyway so it isn't going to add much more loss.

Hahaha yes I probably won't stuff up the aero much more


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[zei20t]

I rekon you can stuff up the aero.

the whole reason why things are blocked off are to force the air to move through certain parts of the car. generally for maximum velocity at cruising speeds.

if you mess with that and push air where its not really needed, you may go backwards and not get enough air flow through the radiator / AC condenser etc.

[BrettD]

hmm good answer VW fanatic..as my question was going to be, "Why is it there in the first place?"

[tigger73]

I rekon you can stuff up the aero.

the whole reason why things are blocked off are to force the air to move through certain parts of the car. generally for maximum velocity at cruising speeds.

if you mess with that and push air where its not really needed, you may go backwards and not get enough air flow through the radiator / AC condenser etc.

Yeah which is why I asked the question. Just want to find out if anyone has done this sort of thing before and if they experienced these sorts of issues.

[zei20t]

only one way to find out

if those black panels unclip or come out somehow. just remove them and see how it goes. but PLEASE monitor water and oil temps, especially over summer.

[tigger73]

only one way to find out

if those black panels unclip or come out somehow. just remove them and see how it goes. but PLEASE monitor water and oil temps, especially over summer.

Yeah the panel unclips - had it out when I installed the fly screen.

Do you reckon I should do wind tunnel tests on a rolling road for before/after comparison too?

Maybe I'll just run it and have a look at fuel consumption...


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[zei20t]

why not try both? I would imagine a wind tunnel is harder to test. unless you have one, or access to one?

[tigger73]

why not try both? I would imagine a wind tunnel is harder to test. unless you have one, or access to one?

I was joking about the rolling road wind tunnel test. There are very few full-sized rolling road wind tunnels in existence and I don't think there even is one in Australia. It's what the F1 guys use when they want to sort things on their car.... I think my Tig is a way away from needing wind tunnel testing.

So I think I'll just do the mod and then monitor it with my Autopolar FIS+

[zei20t]

I thought you might have worked at a University or something, and had access to one

[tigger73]

I thought you might have worked at a University or something, and had access to one

Unis may have a scale version with a fixed road but full size rolling road is massively expensive. For one you need to have huge fans to push a large volume of air at constant speed over the entire car surface. And then match air velocity with road speed. And keep all temperatures and pressures stable.

So it's a large, complex and very expensive machine.

I was hoping someone may have done something similar before and be able to tell me if it was going to work or if I was going to stuff things up.... Without using a wind tunnel of course.


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[zei20t]

be easier to just get a wind tunnel

[tigger73]

Well after all that I pulled off the front bumper/grille on the weekend to install some new mesh and found that behind the blocked off section of grille there's a big chunk of polystyrene.




I'm not sure what to do about it so I left it. It's probably there for impact resistance I imagine.

Here's the full grille treatment: