2002 Audi allroad mod thread.

[fjasper]

I figured I'd stake out a little space on the inter-webs for my effort to improve the gas mileage on my big car. My goal is to get it to a reliable 25mpg.

I have coroplast sitting in the garage, and the pizza pans are supposed to show up later today. I read the first chapter of Aerodynamics of Road Vehicles last night, so I'm pretty much an expert on airflow now.

"Sylvio", my allroad, has a 2.7 biturbo and a 6-speed manual transmission. Up to this point, the only thing I've done is alter my driving style, air up the tires, lower it about 1/2" (It has an adjustable self-leveling air suspension), and run 0w-30 synthetic oil.

Over the course of the last 6 months, I've averaged 19.1 (EPA combined: 16 ) according to the trip computer. It's not perfect, but it can be calibrated (one more thing I need to get around to doing) since I have the software on my laptop to talk to the ECU.

It has big mirrors. Has anyone had success with the rearview camera idea? I'm leaning toward just putting some small convex mirrors on it for "blind spot" visibility, since I'm not made of money.

[fjasper]

I'll put up a picture or two once I get my post count up. It has a very nice lower engine cover complete with NACA ducts to direct air to specific components, but it (they, actually, there are two) only covers the first third of the belly. There are some vestigial deflectors that look like they could be enlarged to smooth airflow around the front tires.

Audi did a lot of work managing the airflow on the front of the car. It has baffles controlling airflow through the radiator and intercoolers and covers over the engine to hold in heat after it's shut off. Grill block seems like an obvious first step, but I want to find a way to monitor the temperature of the turbos so I can tell if they get significantly warmer. Pyrometer?

The fender flares (and wheels, for that matter) look like they were specially designed to create drag, so I'll have to figure out what to do about them. I think the back ones might make a good place to start a boat-tail taper.

One question I have is this: Would it likely be helpful to direct cooling air so that it exits through the front wheel wells? It's easy to make the air from the intercoolers exit from the front of the front wheel openings.

[fjasper]

Initial pics, with specially installed micro-vortex generators blanketing the entire vehicle (frost & dirt).

[Hubert Farnsworth]

A thermometer, and or thermocouples could be used if you had some, unless there are already egt temperature sensors you can take readings off of on the ECM in order to determine the relative effect of the aero mods on the temperature of the turbocharger and other under hood components

[fjasper]

It does have an EGT sensor for each side. I'll have to find the measuring block number so I can monitor them. I'm also thinking about the temperature of the housing and particularly the oil seals.

Apparently an aftermarket chip can be programmed to lower the boost limit.

I just thought of something else to do: get one of those little radiator fin tools to get the pebbles out of the condenser/radiator and straighten the fins.

[euromodder]

The roofracks (especially the transverse carriers) are already gone, I hope ?

The ridge on the front bumper cover may save your paintwork, but it isn't going to help your fuel economy.

Removing the mudguards aft of the wheels will help a bit.

Exhausting air through the wheel wells may very well work against you rather than improving your mpg .
Then again, it is being done (by BMW, IIRC) to lower the drag, but they have the slight advantage of a wind tunnel to test how and where to exhaust the air.

[fjasper]

The roofracks are off...I usually take them off as soon as I'm hauling whatever I'm hauling. Noisy, draggy and theftable.

I'm trying to decide if the mudflaps could be used to attach fairings behind the wheels. They have a pretty anti-aerodynamic shape, though, concave on the front to grab the air.

The thing on the hood produces a big airflow separation, and kicks the airflow up, reducing snow, etc. on the windshield, but it also makes a big reverse flow covering most of the hood. It's a winter-only item.

I was hoping there would be some easy rule of thumb when it came to airflow in/out of the wheel wells. I guess when I get some other stuff done maybe I'll have to try some A-B-A trials.

[fjasper]

Well, here it is two and a half years later...and I haven't done much on the car. I did get some lighter wheels (by 12 lbs each) and some narrower tires (215s vice 225s) that save another 4lbs each. And a window-screen lower grill semi-block to reduce airflow and prevent sand & pebbles from getting to the AC condenser & radiator.

I'm nervous about reducing airflow through the engine compartment too much, what with the two very hot and very expensive little turbochargers that live in there.

Then today, I was supposed to be replacing the rear main seal in one of the Miatas. So suddenly playing with cardboard looked like the better option. I put together a little Kamm and a fairing behind the fender flares.

The pictures were taken in the dark...I had to use some extreme measures to make the Kamm visible, but the lines drawn on the first picture follow the profile pretty faithfully. Maybe in daylight I'll get some better pictures.

Next step should probably be some sort of tuft testing. If I can figure out how to mount a camera back there, I'll try that. The weirdly light pattern on the Kamm is some housepaint I drizzled on with the hopes that the airflow would move it around when I took a test drive. Instead it just dried in place.

[Arragonis]

Looks quite good, just subbing as I'm in a similar road boat, albeit Diesel powered.

How do the turbos like the 0w oil ?

[fjasper]

Hard to tell. I did notice a little more engine noise than with heavier oil. I sent in a sample of the Mobil for analysis, and they said it was pretty much worn out (additives depleted and viscosity dropping) at 5,000 miles. I switched over to (what's sold in the US as) Shell Rotella T6 5w40 heavy-duty engine oil. It's a synthetic marketed toward big trucks. After 5,000 miles I sent in a sample, and it was in much better shape-they recommended trying a 7,500 mile interval. It's less expensive than the Mobil to boot. I don't think it's on the VW/Audi list of 502.xxx approved oils, though, so it's probably not appropriate for use during the warranty period.

I'm envious of your TDi, I've thought about trying to get an engine and transmission sent over for a conversion. Even a 6th gear from a TDi seems like it would help, but they want $900 for a pair of gears here.