V8 power loss

[mattwchappell]

Heard that Audi are being taken to court over the power loss in there engine. sure the guy said that it was in a new R8. Anyone heard anything else???

[Dom81]

Power loss, or insufficient power from the start?

[drcarrera]

I thinks it's more to do with the power output being way below their quoted figures.

[MikeD]

As proved by who? I am talking to Audi service in germany about the lack of power from the B7, but they have answered me everytime with more loop holes than you would belive, 1st they said that a dyno plot is no good as it would not have enough cool air to get peak power, then they picked holes in the dyno its self, then they trierd to say the car had not been serviced by an audi dealer ( as it is still pending to have its first service?????????, but has had an oil change and a warraty work done by main dealer , so you tell me) still working on it, if I get any info I will post it.

[tartan_rob]

This is a dead easy one. Audi take an engine off the production line and stick it on a Dyno at the flywheel. Job done either way.

[mattwchappell]

Put the car on the rollers and all transmission and drive train etc is accounted for ????
My car was still running in at 387 Horse as a standard model. Which i am told is good ???
With CATS and Milltek system + re-map only pushing 417 Horse

[S4INT]

387 not a bad figure for these engines, some have been way below that. Mine dyno'd at 395bhp, which is one of the highest standard outputs I've heard of. Still pi$$ poor though.

[mattwchappell]

Yep !! the bets of the previous sessions was only 369 ??????????????

[Lancia]

This is a dead easy one. Audi take an engine off the production line and stick it on a Dyno at the flywheel. Job done either way.

Tartan Rob has the best solution right there.
I wouldnt trust a chasis dyno whatsoever.
I wouldnt blame Audi for picking the holes in them!
My car measured 292HPATW. To get the right power output thats 30% drive train loss. Now Im not sure what mode the dyno was in. Didnt check my tyre pressures, how much had the operator tied the car down. Your measuring traction effort so all this comes into play along with other factors previously mentioned. I have taken the car back the next day and get a reading 10% different to that.

Saying all this the car still runs 12.9 down the quarter. Only tried that once.

Chassis Dynos are POINTLESS. Short of Audi taking your car back to the factory pulling your engine out and sticking it on the engine dyno theres no way that you can pove the engine is not putting out the power.

[graemep]

Some interesting reading in this thread here:

http://www.rs246.com/index.php?name=PNp ... torder=asc

[ARSEY4]

This is a tricky area untill someone takes their engine out and tests it you will never know as there seems to be too much movement in the the conversion to make it reliable.
Personally all I can say is that my car feels fine and very fast. Sometimes in hot weather it feels as if it hs lost the edge but generally it meets my expectations and I have to say that I test drove an rs4 before buying and was happy with the test cars feel. Having said that I would feel mighty peed off if my car wa infact no more powerful than an s4 or s5.
Just out of interest what is the actual difference between our engines and s5 engines, is it just the ecu or have we got some different internals?

[Marcus-RS4]

I dont think there is much the same between them internally, apart from the cubic inch lol

Here are the differences for those that might think that the RS4 engine has only a few minor "tuning" differences. These come from the Audi 4.2-liter V8 FSI Engine Self-study Program

The main technical differences between the base engine and the high-revving engine lie in the following:

* Crankshaft/connecting rods/pistons
* Timing gear
* Cylinder head
* Oil supply
* Engine cooling
* Intake path
* Exhaust system
* Engine management


The cylinder crankcase of the high-revving engine was machined to higher specifications due to the higher stresses in this component. To minimize warping of the cylinder manifolds, the crankcase is honed under stress. For this purpose, a honing template is attached to the crankcase before the honing process in order to simulate the warping of the bolted-on cylinder manifold.

Modifications to High-revving Engine
At very high engine speeds, axial vibration occurs due to the unbalance in the single-mass damper. This can cause the crankshaft to break.

To avoid this vibration, a dual-mass damper without unbalance is employed in the high-revving engine. To compensate for unwanted engine vibration, heavy metal inserts are integrated in the first and eighth crank journals by way of unbalance.

Connecting Rod
Cracked connecting rods made of 36MnVS4 are used in the basic engine, while the conventionally split connecting rods in the RS4 engine are made of 34CrNiMo8, for strength.

In addition, the geometry and tolerances of the
connecting rods were reduced on the high revving version of the 4.2L V8 FSI engine.

Bearing journals diameter: 54 mm
Bearing bushings: 1.4 mm thick, 15.25 mm wide
Length of bushing: 0.20 mm diameter rolled
Connecting rod length: 154 mm

Piston
For strength reasons, forged pistons with a slightly higher weight than conventional pistons, are used. Both engines have the same piston geometry.
Piston weight without rings: approximately 290 g (10 oz)
Piston pin: 0.20 mm x 0.11.5 mm x 40 mm

High-revving Engine

* 3/8" simplex sleeve-type chains are used here. Their advantage is their reduced wear and higher stress resistance at high engine speeds. In this case the idler gears have 38 and 19 teeth. The camshaft sprockets have 25 teeth.


Different Features of the High-revving Engine

* To match the higher engine power output and RPM, the following cylinder head components were modified:
* Intake ports are charge optimized (based on larger cross-sections)
* Intake valves are chrome-plated hollow stem valves (for weight reduction)
* Valve springs are made of a material with higher tensile strength and also have higher spring force
* To meet the higher fuel requirements, the injectors are designed for higher flow rates.
* Roller rocker arms are more robustly designed, with peened rollers for higher strength
* Camshafts have different timings and larger opening lengths
* Intake valve opening angle 230 crank angle degrees
* Exhaust valve opening angle 220 crank angle degrees
* The lifters were adapted from the 3.2L V6 engine found in the TT and A3. They have a larger ball stroke which, in the course of testing, proved advantageous for the high-revving engine (with regard to the inflation of the hydraulic valve clearance compensation element).
* The cylinder head has a modified water jacket which circulates coolant to the area between the intake port and the injector, thereby reducing the temperatures in the cylinder head combustion chamber plate.
* Due to a modified camshaft drive reduction ratio, the camshaft adjuster has 25 teeth for the chain drive, as opposed to 30 teeth in the basic engine.

In the more highly stressed high-revving engine, an additional oil-air heat exchanger is used to minimize the oil temperature even at high engine load. This additional heat exchanger is operated in parallel with the heat exchanger via a thermostat.

Audi RS4 Sump
A reliable supply of oil in all driving situations is critical, especially in a sports car such as the RS4. The oil supply system in the high-revving engine was designed for racing applications in which it is subjected to lateral
acceleration of up to 1.4 g. To ensure this, the sump in the RS4 has an additional system of flaps.

Design
Four flaps, whose axis of rotation is parallel to the longitudinal axis of vehicle, are arranged inside a housing. Each of the flaps opens toward the inside of the intake end of the oil pump.

Function
When the vehicle is cornering, the oil flows inside the sump toward the outside of the corner. The two flaps facing the outside of the corner close and hold the oil in the sump intake. At the same time, the two flaps facing the inside of the
corner open to allow additional oil to flow into the intake. This ensures a sufficient supply of oil to the oil pump.

The intake system of the RS4 engine was designed with emphasis on maximum flow control. Pressure loss is minimized by a large cross-sectional areas in the Mass Air Flow (MAF) Sensor G70 and air intake pipe in combination with a 90 mm diameter throttle valve.

To ensure a sufficient supply of air to the engine at high RPM, the power flap in the air filter is opened at engine speeds higher than 5000 RPM and at road speeds higher than 200 kph.
The power flap is opened and closed by a vacuum
actuator which is map-controlled by the ECM via the Intake Air Switch-Over Valve N335.

The sand cast aluminum (should be magnesium) intake manifold was designed specifically to match the sporty characteristic of the engine. In contrast to the basic engine, maximum torque is produced at higher engine RPM. At this engine speed, the intake manifold changeover valve would be switched to the short path for higher power output.

Spark Plugs
In contrast to the Audi Q7, spark plugs with a higher heatrating (colder plugs)* are used because the RS4 engine is subjected to higher thermal stresses.
* applies to NGK spark plugs

Injectors
Due to the higher fuel demand and the shorter window of time available for injection at very high engine speeds, the RS4 engine is fitted with larger injectors than the Audi Q7 engine.

[GardinerG]

I guess this is why you can get an MTM supercharger for the S5 and not the RS4?

[SR71]

MikeD is trying to make progress with this debate...

My take on the matter is that the performance figures the car spits out at the track, or via VAGCOM (see t_urbo's experience - 4.2 sec 0-60!) are commensurate with a "quick" car.

My GTechPro RR spits out a figure of nigh on 300 net horse power which is not quite the same as wheel horse power and it runs 13.0's for the 1/4 trapping at ~110mph.

The 0-100mph figure is a little higher than you'd expect because you need to shift at ~98mph to avoid the limiter but with a 996TT running 8.9 for the same yardstick, the B7 RS4 is only tenth's away from that....

Whatever your stats on the dyno, you have to be pleased if you can hang with a 996TT, a car which, new, cost almost twice as much and is a serious icon in the business of performance vehicles...

Drive your car against others cars you think are "quick", see how you fare, and forget about the numbers you see at the shop...

VMAX is a great event for this kind of thing...judging relative performance...

I have to go one day!

[scoobyc]

sorry if going off topic a bit but not sure i agree with the above about hanging with a 996 turbo and where you get the tenths of difference between them? If you use 0-90mph so you remove the shift mentioned above and use autocars figures the rs4 is 8.7s and the turbo 7.4, that to me, at this level is a big difference. This is just stats of course (statisitcs are like mini skirts - very nice to look at but they only cover up the important stuff - as said by an aberdeen football manager!) and having owned both, the turbo is definately that much quicker and in real life situations probably more, eg if you haven't got the revs up on the rs4 the turbo will pull out a very large gap very quickly. I'm not slagging the rs4 here, but to me its not that close to a turbo. If you have a look on one of the american forums (audiworld and 6 speedonline) you'll see loads about both and lots of people that have had both and i don't think i've ever heard anyone say they could hang with a turbo in an rs4.
ps good going with the 13.0's for the 1/4!