2002 Audi allroad mod thread.

[fjasper]

I replaced the coolant-temp switch that controls the after-run coolant pump and radiator fans (circulates coolant through the turbos and runs the electric radiator fans slowly to circulate air through the engine compartment after engine shutdown) with one that closes at a lower temperature.

Before the conversion, the pump almost never ran. Now it runs for a minute or two after almost every shutdown. I noticed after the switch that the coolant temp doesn't rise after shutdown. Previously if I restarted the car after a few minutes, the coolant temp would be higher than operating temperature. Now it stays at operating temperature.

[fjasper]

I'll pull off the ram-air snorkel to warm up the intake air, at least for winter. The computer's reaction to excessive intake or exhaust temperatures is to cool the system with extra fuel. Better than cooking the turbos, I guess, but it's kind of disconcerting to see the single-digit mpg numbers when it's making boost. Better aerodynamics should help it stay out of this range by reducing engine load.

[Arragonis]

I have no mods yet - it is away at an Audi bodyshop just now having a whole new tailgate fitted as the original one was rusting from the inside (I sneakily think they repaired it from a bump and it didn't take).

I kind of thought having it in standard form would be better that grill blocks etc. for this event as I'm still in shock that they repaired it under warranty - +1 for Audi, top people.

On the other hand I agree that Audi parts are very spendy, as is the level of work required if anything does go wrong - timing chains for example means engine out (they are at the back of the engine bay) and about two thousand quid but luckily mine has had the mod to stop timing chain noise and excess wear / stretch.

Mine is a conventional Auto (no DSG, no Multi-Chronic) which is the main sapper of MPG for me as I drive mostly in town. On a longer run I can get it into the mid or late 40s (imp) but as I posted the real MPG is lower by about 10-20%. At 70 in top the engine is doing under 2.5K RPM.

Around town (day to day) I get about 30-35 every day which is below "EPA" (ECE here) but I like to compare my record against the ECE "Urban" figure which is 27 MPG - mainly so I feel better...

I do have plans to start taking out and examining pipes in the induction system and check for carbon build up and if the swirl flaps are working - there is an updated kit available. I also plan a plug in tuning box rather than a remap so I can go back to standard if / when needed. I also plan an EGR delete which a few UK based TDI V6 owners have done to some benefit in terms of smooth running and MPG.

Being honest though given it is a 140 MPH Auto AWD machine, getting mid-30s out if it around town seems pretty decent.

I look forward to your aero mods.

[fjasper]

Fairings rough-cut from coroplast. I've learned that managing the direction of the grain is important. That's why the Kamm-back is made of 5 pieces. You can tell I'm getting more sophisticated, because these are held together with clear packaging tape instead of duct tape.



I'm thinking of doing a partial under cover, but since this is my winter car, I don't like aluminum. I was going to use soffit siding:



but they're using magnesium chloride on the roads here now, and it seems like it makes aluminum practically dissolve while you watch. I saw some black plastic sheet at the used building supply place that felt like it wouldn't get brittle, maybe I'll try that. Melamine/formica countertop material seems like it would have a good combination of flexibility and strength (and it comes in pretty colors), but it doesn't seem very impact-resistant. I guess it heat-forms well, though. Maybe I could glue it to coroplast to make it tougher.

I'd like to end up with fender fairings that look kind of like the Audi quattro, but not tapering in at the bottom as much as these:



Or like these:



Come to think of it, maybe I should just get the blue car...

[fjasper]

I got out on the highway with the cardboard mods the other day, and I think they helped. I was getting about 19mpg with the fairing on, before the tape started to fail.

I stopped, pulled off the fairings (carefully enough to avoid damaging them) and got back on the road. I resumed the cruise control at the same speed (about 135km/h) and was getting between 16.5 and 17. Not an A-B-A controlled test, but the road stays level (actually slightly uphill as it follows the river) and the wind wasn't blowing, so I think it's indicative, if not definitive.

I know, it's a shocking waste of fermented dinosaur blood, but I was in a hurry to get to an interview. And I made it with one minute to spare. I drove 60 mph all the way home to make up for it.

[fjasper]

Next thing, I suppose, is to figure out how to tuft-test the whole back of the car. I saw a GM SUV on the highway a while back (maybe a Buick Enclave?) and it was pretty clear from the pattern of dirt on the tailgate that there was a donut-shaped vortex behind the car. That seems like a good way to extend the effective taper of the rear of the vehicle. Sounds like it's time to spend an evening with Hucho's book.

[Arragonis]

Originally Posted by fjasper

I know, it's a shocking waste of fermented dinosaur blood, but I was in a hurry to get to an interview. And I made it with one minute to spare. I drove 60 mph all the way home to make up for it.

60 is a bit speedy for me I duck behind a truck and cruise at 55 or if I strike MPG gold and follow a Morrisons supermarket truck (limited to 52) then I follow those.

[fjasper]

He-he-he...I guess I was raised in the west of the US, where anything under 70mph is considered slow. That's what most of the semi trucks run on the freeway, and I've noticed that quite a few of them seem to be hypermiling a little. Slowing on inclines, even short ones, and speeding up on the declines.

Some pictures...I fitted the coroplast, and have started adding extruded polystyrene foam to the Kamm so I can shape it all. I'm thinking next will be plaster, since it's easy to build up and sand down, and also cheap.

Fender flares are just taped on without significant adjustment yet. I think they show some promise, though.

[fjasper]

Ok, so I was doing some reading:

http://publications.lib.chalmers.se/...366/177366.pdf

and it has this picture:



which makes it look like vortex reduction behind a wagon calls for increasing downward component of flow coming off the roof. And my fairing looks like it would do the opposite. Hmmmm. Maybe if I split the flow from under the car and direct it up and away from the centerline?

[fjasper]

Crap. Cut myself. I should really be more careful.

Meanwhile, the project is on pause...