nossisnave

A brief search on Wikipedia and a Jag forum says it is the same. Maybe ZF underreported the max torque by a large order of magnitude

silverd2

W12 wasn't introduced on USA models until 2005...D3 A8 with the ZF 6hp I believe. Failures of the 6 series are rare as I understand it.

nossisnave

Right the 6hp24 failures do seem quite rare, too bad the 2003 D2 didn't have the 6hp in it. The D2 W12 in Europe apparently had the same 5hp24a as the 4.2 A8 tho.

Seems the 5hp24a failure is not so much about increased power output than it is that stupid O-ring failing. Am I right in reaching this conclusion?

BrianC72gt

If I were going to cobble together a supercharger system, I'd either lower the compression or plan to run it on E85.

I like this: http://caddyinfo.com/wordpress/cadil...deas-motorama/

So, for $800 or less, I'd get a brand new STS-V MP 122 supercharger/manifold/laminova core assembly on e-bay. http://r.ebay.com/3MtRBp The two banks of intake runners on the blower assembly are narrower side to side, but longer front to back than on the 4.2 in the A8. Carefully cut the intake runners off as they are cast into the supercharger assembly. The cast aluminum assembly is also tricky to weld to.



Then sit the trimmed blower down in the valley where your Intake manifold assembly once resided - square it, level it, and align the snout pulley with your lower drive pulley (we'll get to that in a second). Then lay a flat slab of 3/4 plate on top--maybe 14" wide by 20 or so long. Make cut outs for blower output from the center, and 4 holes on either side to feed the intake runners. This would be the slice of meat in between the supercharger/intercooler sandwich. Then weld 8 new short runners to this plate and 8 injector bosses. This way the whole assembly will be as low as possible.

Intake runner material: http://www.rossmachineracing.com/ovaltube.html

Fab up additional support for the cast blower housing to handle the weight and turning forces since you cut off the runners, you don't just want the few top down bolts supporting it. Also, you'd probably fab up a 1/2" adapter plate for the stock Throttle body, or see if the electronic Caddy one (a little larger than a stock D2)will work. It is included with the manifold assembly.

Then I'd get a 6.5" pulley from these guys for $100 (6.5 is the stock STS-V pulley size)

https://lightningforceperformance.co...r-pulley-ring/

Then a 6" diameter x 2" tall piece of 6061 aluminum solid bar stock and turn it down on a lathe to mount the additional pulley directly in front of and tight to the harmonic damper pulley using the 8 bolts on the damper pulley. Make sure your lathe jaws can handle 6" stock of course..

I'd probably also want to pick up an SVT pulley tensioner assembly and adapt the **** out of it. Gonna have to trim the radiator fan shroud a smidge...maybe relocate a fan.

Assuming you get all that fabbed up, lined up and fitting - which is HUGE - then the plumbing for the Air to water intercooler, coolant pump, and cooling fan is trivial. The beauty is, now you've got a proper 8 rib belt running your blower and the ability to dial up the boost with another $100 quick change lower pulley. It also makes the system easier to remove for any reason...cough cough emissions testing cough cough.

Now, if you have to pass emissions, then I'd get an AEM F/IC8, rather than a stand-alone ECU.
http://www.aemelectronics.com/univer...ll-sensors-632

and the correct oversized injectors....

...and a wideband O2 sensor setup to tune and monitor it...

and get a spare ECU to cannibalize for the female connector and a wiring harness connector from car-parts.com to create a plug and play wiring harness. That way you could properly fuel and time the beast on boost and hide all of this bad behavior from the stock ECU and not throw codes. Making up a plug-in harness adapter would also make the surgery easily reversible...if say...you had to go pass a CA smog check once every two years.

Still not sure if it would fit under the hood...may need to cut two lengthwise slits and tig weld in some patches to create a powerdome type bulge.

While you're at it, do a 01E six speed conversion (swap to a 4.1 S8 rear on the A8) and add in the lower long legged 6th gear from a euro only TDI box. Speaking of the S8 v A8, I believe the S8 engine has forged rods while the A8 does not.

Throw in big brakes first though - make sure you can slow fast before you go fast. Upgrade your D@ Facelift to D3 brakes: http://forums.quattroworld.com/a8/msgs/85769.phtml

I still have more questions than answers, but that's how I'd do it. Also, I don't think the AEM piggyback will support flex fuel. That's a shame because the sensor to sniff the fuel can be had for about $200. You need to flow nearly twice as much E-85 as regular gasoline for the same amount of combustion.

http://www.zeitronix.com/Products/ECA/ECA2.shtml

Plus a $150 flex-fuel compatible fuel pump. http://www.aemelectronics.com/e85-hi...ter-inlet-1348

That way you could run modest boost on pump gas, then automatically dial it up to insane levels dynamically using E-85 or straight E-100. The sniffer returns a 0-5 volt signal depending on the gas/ethanol ratio in the fuel. Double the injector size again though if you intend to run E fuels.

I'm confident you could run the stock high compression safely on E-85...but I think premium pump gas alone at 11:1 compression ratio might be too dangerous...maybe at low boost...but then what's the point.

The other option is to have Cometic make you some custom fat head gaskets to lower compression a bit and run it on regular gas...PITA though...pulling heads...new headbolts...may as well get ARP studs...and on and on...

Target 12lbs of boost and 450 to 500 hp...oh...and a metric ton of time talent and money.

nossisnave

BrianC72gt, I like the way you think. Very interesting write up, this may become a part of my L sooner rather than later