PaulW

...not too much boost, what would it do? Increase the torque/HP numbers to close to 400 each? I don't think you would want to push it more than that.....even if you got 375 HP, it would be a monster and could last long.

pw

Audis or VWs 4Life

Didnt hohenester build an S8 a while back with a twin turbo? (pre RS6 era)

mclarenm8d

relative to stock fuel injection system, we already know we can push 300 hp with the A8 and the S8 system works 360 hp.

Then, it's just a matter of what RPM that HP level occurs - lower RPM, more torque.

Smaller turbos will spool up quick as well, the 4.2 will get those things kicking quicker than the 2.7 or the single-turbo 1.8.

Just armchair engineering, I've thought that simply going with two of the "built a million of 'em" 1.8T's turbos might be the ticket. The single turbo on our old 1.8T was pretty cool when we chipped the car, I'm thinking the displacement would take out some of the hysterics (1.8 single, 3.6 twin, applied to a 4.2).

But these are just thoughts Paul. I'm time and resource limited now relative to putting my money where my mouth is.

Jkay

A one word, dismissive reply never suits anyone; least of all the person trying to make a point.

mclarenm8d

mapping to knowns on my old 300ZX TT -

3 liters
Stock turbos ~ 300HP at 9psi
Stock intercooler

Chipped
Stock turbos ~ 400HP at 14psi
Stock intercooler
Improved intake and exhaust

On the 4.2 liter, just being simplistic, we would probably want to stay at 6 psi to keep the costs down (heat control, head gaskets, pistons, blah blah blah). Just rule o' thumb kinds o' stuff.

So, applying the 300's turbos and keeping things VERY simple:

Stock config - 3liters/4.2liters, 300hp -> ~6.5 psi (my leap here is air flow relative to engine displacement).

This would results in a 4.2 have much more torque. HP curve would be pretty interesting, stay flat at 300HP from 3000 to 6000 RPM. We could probably figure that own out as well.

My summary is that this could be done with old, readily available, cheap parts. One would need a cheap donor car that one wouldn't be scared of destroying and access to someone that can do the plumbing (plenty of ad hoc turbo shops in Chicagoland).

skiwi

you'd overspin those puppies.

the k04 might work (2 used on the rs4), but again could easily overspin. a 4.2 @7k rpms pushes a lot more air than a 2.7.

you'd want to use rs6 manifolds obviously, as that would be the best engineering solution (i.e. tightly integrated units, closely situated etc), which would lead you down the same turbo route as that car.

the other issue would be tranny, you'd most likely have to uprate it aka the rs6 5hp24a unit. from memory, they are only "lifed" for 430nm.

mclarenm8d

Excellent point !!! Thanks Dave.

cuatrokoop

A company over in Europe did, yes. Wasn't just for the S8 though...

greenie

Paul I love that front end! Does Ill. require a front plate? LOL

cuatrokoop

Big difference. An electric pump is likely just an after-run pump. Audi started doing that with the 10vt's in mid-1985 with the water cooled turbo introduction on the KH code right before the MC was released. Pretty sure the KW code (Sport quattro) had the same sort of deal when it was intro'd for what, 1984? But, you should know that (wasn't your urq powered by an RR code? I can't remember from the olden-days of the Q-List).

Even the 30v non-turbo V6's have after-run pumps and many non-turbo Audis have heavier duty cooling systems (larger radiator, larger oil cooler, etc). The 2.3L 20v's came with a 2nd radiator standard, and no turbo.

Dual IC's just make more sense from a packaging standpoint on a factory V engine, not from a thermodynamics standpoint.

Just something to think about ;-)