S8 and R8 V10 engines

[RS2_Russ]

Does anyone know what the differences are between the S8 V10 and R8 V10?

Looking at the obvious specs they look mighty similar.

From

2009 Audi R8 Spyder specs, specifications, tech specs - 2 door 5.2 litre (5204 cc) V10 525.2 PS, 6 speed manual

and

2005 Audi S8 5.2 FSI quattro specs, specifications, tech specs - 4 door 5.2 litre (5204 cc) V10 450.2 PS, 6 speed automatic

BOTH have the same:

Bore × stroke 84.50 mm × 92.80 mm

3.33 in × 3.65 in

Cylinders V-10 in 90.0° vee

Displacement 5.2 litre 5204 cc (317.568 cu in)

4 valves per cylinder 40 valves in total

Compression ratio 12.50:1

Fuel system direct petrol injection

Bore/stroke ratio 0.91

Unitary capacity 520.4 cc/cylinder

The R8 is dry-sumped and has 525.2 PS (518 bhp) (386.3 kW) @ 8000 rpm

with 530.0 Nm (391 ft·lb) (54 kgm) @ 6500 rpm

The S8 is wet-sumped and has 450.2 PS (444 bhp) (331.1 kW) @ 7000 rpm

with 540.0 Nm (398 ft·lb) (55.1 kgm) @ 3500 rpm

Apart from tuning, anyone know why they're so different? :confused:

Tell you what else is amazing if true: The R8 has a Drag coefficient of 0.37 (which is middling), but the S8 has a Drag coefficient of 0.286, which is amazingly low! So low that even with 15% larger frontal area it has a 15% lower Cd x A.

Russ

[PsYcHe]

could well be different bits inside, also the r8 revs to 8000 so you would get a chunk more bhp that way

[cruiser647]

It's the way they want the engine to behave in each car. That's the only real difference.

An S8 owner is 'less' likely to rev the thing to 8K, and due to the weight, will need to extra torque produced lower in the range.

Just my 2p!