Audi A8 1.2 E-TDI luxury fuel sipper
 

Now Tuneko/me have already proven on the lupo that you can improve 33% of the best fuel efficiency car up to date. This next project will show that you dont need to get the smallest car and strip its interior to get good fuel consumption figures.

Details: Audi - A8 - Audi A8 2.5 TDI Quattro (D2 Facelift 2) - Spritmonitor.de

At the moment best Audi A8 D2 driver gets that kind of fuel consumption figures and I have again bold plans to half those levels. In this project I try to keep all the necessary gadgets working and it still look pretty much the same.

Biggest mod will be engine which will be moved from my red lupo to this audi. It already makes 120 hp, but next target is 144hp from 1.2 TDI engine. That aint gonna be fast enough for me so car will get also huge electric motor to assist in accelerations.

Current setup and best results of this car:
- 1.2 TDI with 120 hp and 285 NM
- 1749V garret turbo
- Big intercooler
- 6 speed manual front wheel drive gearbox
- Weigth 1470 kg with full tank
- Yamaha R1000 radiator no fan
- power steering
- 205/70R15 tires
- smooth underside
- Grill block
- A4 B6 front brakes and suspension components
- Weight of the car 1470 kg with full tank

Best fuel consumption
3.92 L/100 km
59.97 mpg (US)
71.97 mpg (Imp)
80% at 100 km/h speed
15% at 90 km/h
and 5% in the city
cars onboard computers avg speed was 88km/h.

Acceleration 60-120 km/h -> 10.5 seconds

Some last calculations about the coming fuel consumption figures, looks promising. http://ecomodder.com/forum/tool-aero...ToStep=5-200-5

https://scontent-arn2-1.xx.fbcdn.net...ef&oe=57870C8D

https://scontent-arn2-1.xx.fbcdn.net...8b&oe=579765EA

A 1.2 diesel in an A8?

Insane.

I look forward to it. :D

Subscribing as I also dreamed about a smaller Audi engine in Hermann...

If the latest 2.0 140 TDI unit is good enough for the latest A6 (which weighs pretty much the same as the A8 of that generation) then a 1.2 making 144 would be good enough too but maybe with far better MPG.

This is more or less what VAG is planning but maybe 5-10 years ahead IMHO. I can see a 3cyl 1.0 TDI being the norm and a 4 cyl 1.6 TDI being for premium models circa 2020.

And I just bought a 2.7 V6 TDI... :rolleyes:

What about the AWD drive train, will you use it, split it or replace it completely?

A setup where the Lupo engine and tranny drives the fronts and the electromotor drives the rear through the current drive shaft may be possible.

Following.

144 hp for 1400 kg seems overpowered to me. I would cut at least one cylinder out. :D

Subscribed, this will be nice :D

Subscribed :)

Very cool indeed.

Nuts! - but will follow with interest....

Any updates or plans on this ?

Project is officially started ;).

https://fbcdn-sphotos-b-a.akamaihd.n...69323931_n.jpg

Weight of those 15" wheels 5.8 kg per piece.

Aerodynamic & rolling resistance, power & MPG calculator - EcoModder.com

Rough calculations of the project first with only diesel powertrain.
On lupo 3l you can reach 3 liters at 100 km/h speed with 1.2 TDI.
Lupo weights 950 kg with driver and A8 target weight 1500 kg = 36,7% difference in weight every 10% increase is 2-4% on highway --> max 14,7% higher fuel consumption
Lupo 3l CdA 0,29*2,0=0,58 Audi A8 modded 0,23*2,2=0,506 = A8 is 12,7% better so 12,7% less fuel consumption on highway speeds

That means I should try to keep the gear ratios pretty close to same as in my Lupo 3l gearbox. That is one reason behind that I will first test 195/65R15 tires. Other is weight savings and ofcourse the frontal area gets smaller.

Errr .... the online wheel shops that I checked, give 16" as the smallest wheels on the A8 (up to 10/2002 - and17" after that).

Are you sure the 15" will fit ?

Sure they will fit but propably not with stock brakes. Lighter car needs smaller brakes...

In that case ... :cool:


If you need any help with translations (Dutch / French / German) when searching for an A8 in Europe, just let me know.

What I am looking for is:
- Audi A8 D2 2.5 TDI with manual transmission- must have
- Price between 1000-2500€ from europe. (Engine failure ones for 1000€)
- Miles does not matter as car is rebuild mostly.
- Outer body panels should be in mint condition so not crashed cars that arent repaired properly
- Learher interior
- Preferred color silver

Wow! The car must be really light... there is nothing to it! :D

Though call ...

Autoscout

You will also gain with the better rolling resistance of 15" tires.

0950 kg / Cr 0,0079 / CdA 0,580 = 9,91 hp at 90 km/h
1500 kg / Cr 0,0066 / CdA 0,506 = 9,77 hp at 90 km/h

It can only be better at higher speed with better CdA.

Do you know how it's possible to fit smaller brakes and pass the inspection? Just asking 'cos I need to do the same thing soon..

Will you be fitting the electric motor as part of the propshaft?

EV system still needs R&D work before can be released/revealed. Rear axle driveshafts from 4wd version is one option.

Yes my budget is tight. I am trying to get one for under 4000€ when its registered to finland. there is one manual at the moment in finland which price is 4900€, but it has been in finland winter salt from 2005-. So underside of the car is not mint. Also it has some other issues cost money to fix.

I drive 80-90% on highway so weight is not that big enemy as you might think.

+1 - round town though it's a millstone round your neck - literally... :(

Any progress ? If no A8s available how about using an A6 instead ;)

It's really impressive how light-duty Diesels evolved quickly.

No progress as there is no money to buy the car. Last year I paid myself 0€ salary during whole year... So in short its not easy to make money by making fuel efficient products to market with tiny budget even the ideas and execution are world class...

Anyway there is hope of better as Ziptie plug patent went through and more patents will follow. At the moment all my money is spent to get first plastic injected plugs ready for sales. So A8 project will not start sooner than I have the plugs.

A6 wont work as those will rust.

Have you never lurked about building your own full-size sedan from scratch?

Good news I have my own A8. First fuel consumption test showed 6.1l/100km @ 95 km/h actual avg speed. Real drive speed avg was 100 km/h. Car has now 18" wheels which increased the fuel consumption a lot.

https://fbcdn-sphotos-f-a.akamaihd.n...72973975_n.jpg

More pictures of the car can be found again at my facebook pages:
https://www.facebook.com/media/set/?...1&notif_t=like

https://www.youtube.com/watch?v=YDUb...ature=youtu.be

Own DIY car projects will come but it takes big money which I dont have at the moment.

Congrats Vekke. Going to be fun to follow what you can do with that one :)

That 2.5TDI is actually not a bad engine, but it might be cool to see how the tiny 3-banger is gonna fare into the A8.

Glad you've got hold of an A8. They're still very handsome-looking cars. Unfortunately I don't think we got a diesel of any kind in that generation in the UK, and an A6 of similar age doesn't appeal quite as much.

Well my 2.5 fuel pump circuit board already broke so the engine swap will begin ASAP. Cost to repair the pump about 1000€. Tried already to replace the transistor and that did not work...

very interesting.

somewhere in one post you write about differetn 16 in wheels weights.

i rememmber c5 wheels 5.5 kg, am i wrong?

The Citroën C5 wheels were 15" and ~4kg, I have those on my Peugeot for summer.
Ultralight 15" wheels for Citroën/Peugeot owners

I believe that there may also be ligtweight 16's for the Citroën C3, but I haven't investigated it.

http://ecomodder.com/forum/showthrea...ist-27498.html

I found the post with the list and answered myself about what light wheels to put in a vw golf mkiv platforma car.
I did already some theoretical calculations about how much improvements in acceleration I will get and it seems that aerodynamics is the way to go. weight reduction seems to be better in traction on bumpy road and in ride confort other to affect fuel consumption (we are talking about not very heavy tyre+wheels with very big inertial moment). maybe important in city, drag racing and racing.

do you measured any noticebale decrease in fuel consumption between lightwheels and stock on road?

Project is still alive and well.

At the moment weigth reduction BOM shows 1448 kg so already weigth has dropped nicely.

Lupo engine is at place and work continues with exhaust piping, altenator belt to add air condiotioner and power steering unit. Also starter motor need to be installed.

Hopefully this beast will be alive during next weekend as electrical wiring process begins
https://fbcdn-sphotos-e-a.akamaihd.n...5269f88a9b5e70

More pictures again here

So power steering will be belt-driven? Why not use electric PS?

Yes belt driven at first stage anyway. First target is to get car on the road with that 1.2 TDI. There are million mods long list what will be done and tested...

I have made some calculations based and cd targets and BSFC map.
https://fbcdn-sphotos-d-a.akamaihd.n...e8fdf169b33d2b
Looking good I dont need very low drag to reach that 3 liter target that means I migth not even have to make a "boattail" to the car to get there.

Is the old 2.5 TDI a V6? The V6 2.5 TDI engine is what a local mechanic considers to be a nightmare to work on. As soon as you fix something, something else doesn't work. Change a valve cover gasket, and it might leak after two weaks, even if he uses a Victor Reinz gasket. He is convinced the French designed it, and he hates working on French cars. I don't really have anything against the French, but their cars could be easier to work on.

On the bright side, he says that they run great and are a good engine until the problems start.

Could you take a better picture of the engine bay? I'd love to see how small the 1.2 tdi engine looks in that big car. :-D

I'd also love to see a peek of your BOM.

Cant wait for the car to hit the streets. Your background research seems thorough.