AAN Compression Test – Acceptable Specifications

AAN Compression Test – Acceptable Specifications

The acceptable “Compression Pressures” are:

Specified Value: 9.0 to 13.0 Bar (131 to 189 psi) (ED: 1 BAR = about 14.5 psig)
Wear Limit: 7.0 Bar (102 psi)
Maximum permissible pressure difference between individual cylinders: 3.0 Bar (44 psi)

I do not like to see more then 10%– but that is me and does not mean that your engine might have unacceptable leakage. Perform a leak down test and see if it can be determined where the leak is coming from. If you hear it out of the CC breather or oil fill then you may have ring wear. With the hard cylinder coating and the ring design these days, I have found that cylinder leakage is not as common.

More often you hear it out of the exhaust or intake. Have a friend go back to the exhaust tip if you run it again to take a listen.

If it is the valve seating (I assume you did this at TDC) you may simply have carbon build up and a good tank of BG44 may improve your readings.

Contributors: Mark T / Dave F

The Audi RS 5 Coupé – the beauty of power

Classic elegance and awesome power – the Audi RS 5 Coupé


INGOLSTADT, Germany, Apr 13, 2010  –  A classically elegant coupe with a breathtakingly powerful engine: Audi is introducing the RS 5 Coupé. The high-revving 4.2-liter V8 pumps out a hefty 331 kW (450 hp), yet uses fuel extremely efficiently. Like all of the high- performance models from Audi, the RS 5 Coupé delivers its power to the road via all four wheels. A new evolutionary stage of quattro permanent all- wheel drive is also debuting here.

The Audi RS 5 Coupé uses a high-revving, normally aspirated V8 displacing 4,163 cc. This engine is closely related to the V10 that powers the R8 high- performance sports car. The 4.2 FSI delivers 331 kW (450 hp) at 8,250 rpm, with the peak torque of 430 Nm (317.15 lb-ft) available between 4,000 and 6,000 rpm. The sonorous V8 catapults the two-door model from 0 to 100 km/h (0 to 62.14 mph) in 4.6 seconds on its way to an electronically governed top speed of 250 km/h (155.34 mph). Audi can increase that to 280 km/h (173.98 mph) upon request.

The normally aspirated engine consumes just 10.8 liters of fuel per 100 kilometers (21.78 US mpg) on average – far less than its key competitors. This impressive figure is due to the combination of technologies from the Audi modular efficiency platform, which also includes a recuperation system.

With its high efficiency and its long top gear, the standard seven-speed S tronic also contributes to the good fuel economy. Drivers can let the lightning-fast dual- clutch transmission shift automatically or change gears themselves using the selector lever or with paddles on the steering wheel.

Like all RS models, the RS 5 Coupé also applies its power to the road with quattro permanent all-wheel drive. Audi is using a new development stage of the center differential called the crown-gear center differential.

Very compact and lightweight, it can widely vary the distribution of torque between the front and rear axles, with up to 70 percent flowing to the front or as much as 85 percent to the rear, if necessary. The default 40:60 ratio of the rear- biased configuration ensures sporty handling.

The crown-gear center differential works together with the likewise new torque vectoring system, which acts on all four wheels. If the load on the inside wheel is reduced too much while the car is being driven dynamically, that wheel is braked slightly before it can begin to slip. Audi offers the sport differential as a complementary option that actively distributes the power between the rear wheels.

The chassis of the RS 5 Coupé is tautly tuned, lowering the body 20 millimeter