RS4 B7 Stated Power claim of 420ps MKII

[ArthurPE]

northernpar...GREAT post, thank you for taking the time, very informative...I'd like to pick your brain some time (weird expression, is it not? lol)

[northernpar]

I could be way off the mark with my theory/thoughts but if you take my car for example, 22k miles and never had the inlet manifold off in fact the car is standard and has only been serviced once as per the variable service schedule (notwithstanding the first service). On a given day I jump in and the car drives like a rocket, the very next day I jump in and it doesn't. It's still fast but it doesn't have the punch at 5k and above. Now I know that the 'ass dyno' is probably the least scientific of methods but the difference is noticeable. If there are carbon deposits on the valves/intakes (and I'm sure there are) then this would have a constant effect so there must be some other variable coming into play. Fuel type the same, same altitude, same roads, ambient temperature roughly the same but the car performing different.

I first started thinking about the MAF and it's affects but this soon turned to the other sensors. However even the measurement errors in these should be fairly constant/predictable unless there is a genuine faulty sensor which is producing a random error effect. Now I know from previous posts that others have experienced the same day-to-day changes in car performance without being able to determine why which took my thoughts away from the sensors and towards the other moving parts that could have significant impact on engine performance. Hence the focus on the inlet vanes, power flap and associated controls.

As I say I could be heading down the proverbial rabbit hole with this one but the theory is plausible and one, with some thought and planning, that could be checked without necessarily resorting to lifting the manifold. However, I need to take a closer look at those parts of the system and quite frankly between a hectic work and home schedule (not to mention the deplorable weather of late) I have not found the time to investigate further.

From the level of interest and quality of posts on this subject my thoughts were that collectively we would stand a better chance of digging a little further and either proving or disproving these systems as the culprits. Either way it would be of benefit.

[ArthurPE]

honestly, you may be onto something...
when changing my air filter I noticed that the box flap is very 'sticky', it binds...I wondred if the actuator hung up at times?
I greased the pivot points and the flap circumference, a bit better, but still tight...perhaps weather may expand/contract the pieces, and reduce/enlarge the gap?

maybe some other mechanism affecting the inlet flaps?
maybe traction control limiting torque? dampness, cold hard tires, etc.

you hit the preverbial nail: deposits would have a constantly deteriorating effect if the mechanism people believe responsible for their power loss was valid, ie, occlusion of the air flow path...

I could be way off the mark with my theory/thoughts but if you take my car for example, 22k miles and never had the inlet manifold off in fact the car is standard and has only been serviced once as per the variable service schedule (notwithstanding the first service). On a given day I jump in and the car drives like a rocket, the very next day I jump in and it doesn't. It's still fast but it doesn't have the punch at 5k and above. Now I know that the 'ass dyno' is probably the least scientific of methods but the difference is noticeable. If there are carbon deposits on the valves/intakes (and I'm sure there are) then this would have a constant effect so there must be some other variable coming into play. Fuel type the same, same altitude, same roads, ambient temperature roughly the same but the car performing different.

I first started thinking about the MAF and it's affects but this soon turned to the other sensors. However even the measurement errors in these should be fairly constant/predictable unless there is a genuine faulty sensor which is producing a random error effect. Now I know from previous posts that others have experienced the same day-to-day changes in car performance without being able to determine why which took my thoughts away from the sensors and towards the other moving parts that could have significant impact on engine performance. Hence the focus on the inlet vanes, power flap and associated controls.

As I say I could be heading down the proverbial rabbit hole with this one but the theory is plausible and one, with some thought and planning, that could be checked without necessarily resorting to lifting the manifold. However, I need to take a closer look at those parts of the system and quite frankly between a hectic work and home schedule (not to mention the deplorable weather of late) I have not found the time to investigate further.

From the level of interest and quality of posts on this subject my thoughts were that collectively we would stand a better chance of digging a little further and either proving or disproving these systems as the culprits. Either way it would be of benefit.

[HYFR]

Right now, my car does not have a power issue

do you mean it doesnt 'feel'down on power, or have you have it measured?


mines going on a dyno on the 17th....mine doesnt feel like it has a power issue, bit im not expecting 414bhp!

[sonny]

I noticed that the box flap is very 'sticky', it binds...I wondred if the actuator hung up at times?
I greased the pivot points and the flap circumference

This is a quarterly (every 3 months) check procedure for me, the first time I serviced the flap it was very stiff. now it opens a lot smoothly. I recommend doing this if you have not already done so, esp on higher mileage examples.

[scaghead]

i have found this very interesting to read,and some excellent thoughts expressed..and imo from what i have read on this forum in the last 18 months or so most peoples lack of power isuues are air /vacuum system related.

[sonny]

Right now, my car does not have a power issue

do you mean it doesnt 'feel'down on power, or have you have it measured?


mines going on a dyno on the 17th....mine doesnt feel like it has a power issue, bit im not expecting 414bhp!

I put mine on the rollers last month and made 385bhp, did not post it up as it was not a appropriate time to post it in regards to "other" on going threads. however its just a baseline to measure deviation for my own personal test.

[HYFR]

I noticed that the box flap is very 'sticky', it binds...I wondred if the actuator hung up at times?
I greased the pivot points and the flap circumference

This is a quarterly (every 3 months) check procedure for me, the first time I serviced the flap it was very stiff. now it opens a lot smoothly. I recommend doing this if you have not already done so, esp on higher mileage examples.

how can you check it sonny? easily?

[PetrolDave]

mines going on a dyno on the 17th....mine doesnt feel like it has a power issue, bit im not expecting 414bhp!

Be aware that there are so many variables in extrapolating between wheel power & torque and engine power and torque that taking absolute dyno figures as "true" is questionable.

However, if you have previous results from the SAME dyno, then using it to compare how your car has changed is valuable information.

Dyno readings have been another emotive subject on here, I must admit to some trepidation at raising the issue...

[sonny]

Located in front of the air box at the bottom, when you will need to remove the air filter, yes its easy. putting the air-box back together is a bit challenging I found lol

[RS6chris!]

Any chance someone could post some details or pics of how to access the "flaps" ??? If you pardon the expression!!! lol

Sorry guys just trying to add a bit of humour to a forum thats getting more and more negative by the day.

[scottie1979]

However, I have a background in gas turbine design .

northernpar what is it you do? Im involved in the IGT field supplying spares and replacement parts - was also a previously a casting engineer manufacturing blades and vanes for the turbine section.

[northernpar]

Any chance someone could post some details or pics of how to access the "flaps" ??? If you pardon the expression!!! lol

Sorry guys just trying to add a bit of humour to a forum thats getting more and more negative by the day.

A couple of bottles of wine usually helps!

[northernpar]

northernpar what is it you do? Im involved in the IGT field supplying spares and replacement parts - was also a previously a casting engineer manufacturing blades and vanes for the turbine section.

Currently an operations manager for a Canadian oil & gas company but spent 12 years of my career within the industrial gas turbine dvision of Rolls-Royce. Been a while since I got my hands dirty with a turbine (around 7-8 years) but for the latter part with Rolls-Royce I was working within the design team on fuel control systems for RB-211 and Avon engines both conventional combustion and dry low emissions (DLE) variants plus got some exposure to the Trent DLE package. Was employed out of Ohio but travelled and spent some time in Ansty near Coventry before moving up to Aberdeen.

[ArthurPE]

I noticed that the box flap is very 'sticky', it binds...I wondred if the actuator hung up at times?
I greased the pivot points and the flap circumference

This is a quarterly (every 3 months) check procedure for me, the first time I serviced the flap it was very stiff. now it opens a lot smoothly. I recommend doing this if you have not already done so, esp on higher mileage examples.

how can you check it sonny? easily?

I did it by removing the airbox cover and air filter, you can then reach it easily...if you have access to a Audi service computer it's function can be tested...but you still may want to grease it