RS2 on 4x2 dyno

[R-TECH]

Hy friends, my name is Eduardo ,and I need help from friends about dynamometers and audi rs2
we are working on a RS2 project and now is time to tune the engine, but I not have any 4x4 dyno close to me , only 4x2 dyno, because that I ask if is possible put this machine on a 4x2 dyno suspending the rear wheel or maybe turn off the rear differential?

Below have some detail about this project.

• Bullseye S366 Turbocharger
• Modified cylinder Head flow 129cm intake and 104cfm exaust @10'' 10mm.
• Dbillas camshaft 269 x 269 x 11,9mm x 112 lobe
• Custom made Race intake manifold large plenum with 70mm TBI
• 5x deka4 60lbs fuel injector on primary and 5x 160lbs on secundary
• fuel used is alcool (etanol)
• motor displacement is 2350cc ( 5x 83 x 86,4mm)
• the exaust is 3'' Stainless steel
• tubular Race Stainless steel exaust header
• HKS 50mm wastegate
• Forjed 144mm Scat rods and forjed 83mm Ross pistons
• Haltech sport 2000 ecu
• Custom made Steel block guard on main caps

Thanks in advance

Eduardo Guilhon
JJ-Competition
electronics specialist

[S2central.net]

'turning off' the rear differential isnt something you can do with a switch... its an all mechanical 4WD quattro system (except for electric circuit to engage rear diff lock but that doesnt help you here) on S2/RS2. AFAIK - there is no easy way to fool the transmission into running FWD.

I heard of stories where a broken rear driveshaft on quattro results in ZERO torque delivery to any wheel such is the weird mechanical science inside the torsen centre diff. As I understand it - there is a limit of approx 70-30 difference in torque that can be accomodated by the centre diff.

You are looking at major gearbox fun and games to achieve this on a 2WD road... or lift out the engine and place it on a pure engine dyno.

[Zoig]

Or fit a 2wd gearbox for the dyno run.

[Dan]

I heard of stories where a broken rear driveshaft on quattro results in ZERO torque delivery to any wheel such is the weird mechanical science inside the torsen centre diff. As I understand it - there is a limit of approx 70-30 difference in torque that can be accomodated by the centre diff.

The theory, as I understand, is that the diff can provide up to 3 times the torque going to one end as the other.

Assuming the rear end is off and therefore spinning freely, there is zero resistance, zero load and therefore zero torque.

0 times 0 is zero, so even if 3 times more is sent to the front...

This same effect happens on ice - the trick used there is to use the handbrake to provide some resistance to the free-spinning rear... which then also allows torque to the front (0 * 3 => 1 * 3).

If one provided resistance to the rear wheels, I'm guessing that would allow the fronts to spin BUT - then a) the dyno would be off since some torque would be sapped trying to turn the rears and b) I'm sure doing this at full load would probably break something, either diff or otherwise.

In other words, I've just commented on how you're up sh*t creek, before throwing a broken, useless paddle in your rough direction.