Lower grille blocking for fuel economy gains

dj_efk

A2OC Donor
United-Kingdom
In THIS POST @gills shared the study that was undertaken on improving the A2’s air drag co-efficient factor and knocked up a lower grille block as a result of the findings showing this made one of the biggest differences.

Has anyone else come up with a solution that doesn’t involve cable ties? Whatvmaterials did you use and any comments on lessons learned?
 
^^ this. There are masks available here with a warning not to use them above 0C. The block that's shown in the thread seems to help but covering the whole thing is suboptimal IMO.
I did do the same thing with correx a few years back and have a spare lower grill as a result. It fell apart after a couple of years with the abuse from the snow / salt hitting it at speed.
 
Remember the intercooler and radiators need fresh air.

This is obviously a very good point! I added cut-outs for the intercooler on the off-side and a smaller one for the external temp sensor on the near-side. Quite a lot of cooling air goes in from the gap underneath the service flap and when I checked the water temp (using OBD11) on one of the 30+C days last summer, it was still not going much above 90C, so I think the radiator was still getting sufficient air flow. Interestingly, in the cold weather last week, there was still enough cold air getting to the engine bay for the temp gauge to struggle to reach 90C.

I think the best option for a grill block would be one made out of shaped ABS plastic, held in place by a number of spring clips which gripped the original grill. It would be easy to install/remove, look original and not require any modification to the car.
 
Remember the intercooler and radiators need fresh air.
Re: the intercooler, if you see the link and look carefully, Gills has left a space for air to enter the intercooler unimpeded.

Re: the radiator, I think the diesel is so efficient that you’d only need to worry about possible overheating in the height of summer - so perhaps the solution I’m looking for to be safe is to have something that can fairly easily be removed / reinstalled with the seasons?

it would be good if it didn’t look totally naff also!

EDIT, I see you’ve already replied @gills - that sounds perfect - Any ideas how I could get one made?
 
Could you get another center grille and modify the horizontal bars to rotate them to close off parts of the grille. In the same way as the interior vents work?
 
I admire the quest for fuel efficiency improvements however my only real question is how much are you going to gain by this level of effort and cost?

I’d just take the rear seats out and drive it like a minivan, I feel you’d get the same result for no cost or effort and it’ll make it faster. Clearly not in the spirit your intending but in Colin Chapmans words (Lotus) “add lightness” ?
 
I admire the quest for fuel efficiency improvements however my only real question is how much are you going to gain by this level of effort and cost?

I’d just take the rear seats out and drive it like a minivan, I feel you’d get the same result for no cost or effort and it’ll make it faster. Clearly not in the spirit your intending but in Colin Chapmans words (Lotus) “add lightness” ?
Sorry to be a pedant but the correct quote is “simplify, then add lightness” which is probably even more fitting @Jeetesh. I tend to agree with you here, the marginal gain would be dwarfed by losing the rear seats or not using the lovely heated seats he has. But then I suspect it is more as a point of interest or challenge for @dj_efk rather than a cost saving/money making exercise?
 
Sorry to be a pedant but the correct quote is “simplify, then add lightness” which is probably even more fitting @Jeetesh. I tend to agree with you here, the marginal gain would be dwarfed by losing the rear seats or not using the lovely heated seats he has. But then I suspect it is more as a point of interest or challenge for @dj_efk rather than a cost saving/money making exercise?
Yeah, aware of the actual quote as I’m a massive Lotus & Elise fan however comparing an A2 to an Elise is somewhat strange to me as I couldn’t ever call an A2 simple, so I deliberately left that bit out.

I love stuff like this though and it the ‘James May’ in me/us that makes this interesting. I might however have started with a 1.2 tdi though and then see how you could improve on Audi’s efforts...... now that would be a challenge.
 
Yeah, aware of the actual quote as I’m a massive Lotus & Elise fan however comparing an A2 to an Elise is somewhat strange to me as I couldn’t ever call an A2 simple, so I deliberately left that bit out.

I love stuff like this though and it the ‘James May’ in me/us that makes this interesting. I might however have started with a 1.2 tdi though and then see how you could improve on Audi’s efforts...... now that would be a challenge.
I’ve just said exactly that on the thread running parallel to this one that @vaderstep has posted. He’s in Norway so LHD a bonus!
On Elise/A2 similarities, I think that similarities definitely exist. Both ahead of their time, classic designs and actually both under rated (s1 Elise’s finally seeing values starting to creep up) They also both steer beautifully and do the jobs they were created for without equal or compromise.
 
I’ve just said exactly that on the thread running parallel to this one that @vaderstep has posted. He’s in Norway so LHD a bonus!
On Elise/A2 similarities, I think that similarities definitely exist. Both ahead of their time, classic designs and actually both under rated (s1 Elise’s finally seeing values starting to creep up) They also both steer beautifully and do the jobs they were created for without equal or compromise.
....was hoping one of you would say something really nice about the Elise/340R frame work and in particular the innovative glue process.. since it impressed 9 other brands enough to buy rights use it too.... ? ? ??
 
@Erlingtheelder and @Jeetesh you're both right in ways - yes it’s a challenge and a (potentially silly) point of interest. I am not looking to spend much money however, call it an additional / extra aeromod over the what Audi did: we know that a fairly decent gain in drag reduction is there to be had, I don’t want to compromise on using my rear / heated front seats on occasion.

As stated before, I accept there are no economical win-back arguments to be made, I just want Audrey to chug along at the national limit using as little fuel as possible.

I thought the suggestion of clips on a sheet of plastic sounded cost-effective and sensible, wondered if anyone else had done something similar,
 
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Without wanting to take this too far off topic, I have an Elise S1 an Audi A2. Had the Elise 17years, been my daily drive then trackday toy and now occasional Sprint/Hillclimb car.

Having worked on my "proejct" A2 for the couple of months I do see similarities. The A2 has so much thinking in it, way more than just an aluminium car the packaging and designed in simplicity (of parts) is significant. The other week I was under on some mechanical refurb and said to myslef "They weren't messing about" which was i think looking at how the front suspension is mounted. There is a surprising lack of steel in the A2 in places where im sure the easy route would have been a big strong heavy lump of metal.

I have been contributing to some of those threads and do keep talking about very marginal gains. Back to this thread I wouldnt blank anything because Audi put a lot of thouht into this car an if it was safe to do, they would have done it. One example is the front of the early cars had a flat "access pannel" for a smooth shape. Later cars had a bit more of a fake grille IMO to appease conservative buyers who think cars should have grilles (same issue today re electric cars). My advice is for day-to-day-driving if Audi diddnt do it dont do it, for racing or hyper modding, fine as people accept risks/compromise. Personally the A2 is perfect as it left the factory.
 
I didn't read whole thread but I made blanket which goes behind the grill in the bumper from cardboard-plastic and it covers only the radiators not intercooler which is on the right side of the car (if I am not mistaken). It wasn't super efficient for engine to warm up rapidly faster but it did some work. I forgot to remove it in spring and during town traffic driving in 17°C. My coolant started to go little bit crazy - like 105-110°C but I catched it at right moment with heating fully on.
 
See this a lot in colder countries, purely to help the engine get to temp and stay there, as with -20 to -40c outside even with perfectly working thermostat temperature just doesn't go up, less for aerodynamics and more for efficiency of engine running at temperature/heating cabin etc.

would imagine one could put together some type of closing/opening flap system or re-use one from more recent cars with a button in cabin, but doubt it'd be worth the trouble personally, though mesh behind the plastic cover for bottom of bumper might do good, considering how bombarded my radiator looks.
 
At the risk of another thread swerve, picking up on the points above about similarities between A2s and Elises, I full agree with the thoroughness of the thinking that's gone into much of the A2's execution. It's lovely to see, and the more you look the clearer it becomes why Audi made no money on the project (although you have to wonder whether they went into it with their eyes wide open; they're not fools, and there were probably other objectives than making pots of money).
However, and I'm donning my anti-angry-reply armour now, I think the three cylinder diesel engine is a disaster. It's the worst example of additive engineering that I can think of, exactly the opposite of the "simplify and then add lightness" ethos. What the specification objectives for the engine were, I have no idea, but if you think of the thought process as:
- let's make a three-cylinder diesel engine; that's a nice simplifying step
- oh dear, that now shakes like a mad thing
- I know, let's add not one, but two balancer shafts
- that makes the engine very tall now, having a major impact on the scuttle height and therefore overall vehicle height
- and the weight of the balancer shafts is significant
- and just to reverse-gild the lily, we'll add a dual-mass flywheel, which is heavier than a single mass and has a short in-service life
- invoke the Magnuss Magnussen principle (I've started so I'll finish)
- so we now have a very slightly shorter but very tall, very heavy, maintenance-demanding engine, albeit one that when looked after lasts forever.

So now install that into a lovely lightweight aluminium bodyshell that you've spent gazillions on the development of, and it's all so out of balance you have to stick a ~22kg iron bar inside the rear bumper to even things out. Anyone with any engineering sense about them would have stopped at about step 4 above, at the concept review stage, and said, you know what, this isn't working. A lightweight, better balanced four cylinder diesel, perhaps liberally constructed out of aluminium, natch, would have been a better bet. The tensile forces the block sees (not handled well by ally castings) can be handled by through-bolting, à la Rover K-series. If you're desperate to make it short, either squeeze up a standard in-line four (chain drive for cams, long stroke, narrow bore) or do a very narrow angle V4 like Lancia or lop a cylinder off VW's own V5.

So I can see the integrity of the concept of the whole car in the petrol versions, but it seriously lost its way in the diesels. That said, I do love my TDi 90 so the imperfect package has managed to overcome my purist objections.

That's my fourpence worth.

All the best to y'all. Here's to the approaching summer.

Mike
 
However, and I'm donning my anti-angry-reply armour now, I think the three cylinder diesel engine is a disaster. It's the worst example of additive engineering that I can think of, exactly the opposite of the "simplify and then add lightness" ethos.

I think the A2 suffered from having to choose from the available VAG power units at the time. I think the 1.0L TSI 3 cylinder petrol would have been a fantastic engine for it, had it been around at the time - light, powerful, torquey & economical.
 
having driven one in both this Octavia and the previous one, I agree; i get 5l/100 on the office run in the warm and it's fast enough, thanks, with a decent 6-speed box. Shame it won't fit the A2, being too tall...
 
...
- I know, let's add not one, but two balancer shafts
- that makes the engine very tall now, having a major impact on the scuttle height and therefore overall vehicle height
- and the weight of the balancer shafts is significant
- and just to reverse-gild the lily, we'll add a dual-mass flywheel, which is heavier than a single mass and has a short in-service life

- so we now have a very slightly shorter but very tall, very heavy, maintenance-demanding engine, albeit one that when looked after lasts forever.
...
The fact is that height of the engine is same as 1.9 TDI. Balancer shafts have to be added in pairs in 3cyl engines because of counterbalancing. Dual mass flywheel has been added to not torsion oscilations affect the gearbox. I am thinking what is maintenance demanding on this specific engine? Just change regularly correct oil, filters and timing belt...

...
- invoke the Magnuss Magnussen principle (I've started so I'll finish)
...
That's the German thinking. They do always like that.

...
A lightweight, better balanced four cylinder diesel, perhaps liberally constructed out of aluminium, natch, would have been a better bet.
...
Remember price this car had brand new and it used engine that was common to whole A04 platform and used lots of parts from it's bigger brother 1.9. Then add costs of development of completely new aluminium engine and the result would be price that nobody would ever buy that ;)
 
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