Flame Suit On - Another Rolling Road Day

[SR71]

Rob,

Any engine is tunable...just depends how much you want to spend. But the cost:benefit equation for ~10hp more than the claimed publicity doesn't float my boat at the moment...

DTM cars making 460hp from 4 litres, 997 GT3's making 435hp from 3.8 litres demonstrate there is margin...115hp/litre is about the limit...means ~480hp ought to be possible from the 4.2...

I leave that project to MRC.



P_G,

http://pics.tdiclub.com/data/517/Intake ... eaning.pdf

(Check out page 19 for how much build-up there might be...)

&

http://www.myturbodiesel.com/1000q_how_ ... remove.htm

The car might run "fine" even with that amount of build-up. My A3 did except for a slight hunt at idle of ~100rpm and some clues when you plugged in VAGCOM.

Albeit these images relate to EGR build-up but the point is you'll never know what the state of your inlet is like unless you crack it open.

As for your curves, the absolute values are only half the story.

For instance, your peak torque comes 2000rpm too early as alluded too...

I have to say, your curve looks suspiciously like Rob's car with just the non-res Miltek cat-back. The performance is slightly better than his car - his original torque curve dipped below 300 ftlbs a number of times...

But his car was up to 25 ftlbs down on my stock car and like RI_RS4 says, at the top end he was running ~5 degrees less advance, probably equivalent to ~10 ftlbs of torque at the points beyond 5500 rpm.

That said it ultimately ran 390hp versus my 388hp...

Unfortunately, and I don't really understand why, but I suspect your exhaust is responsible to some extent.

You have to believe there is some funky aerodynamics going on in this engine.

[RI_RS4]

if the engine is misfiring or 'knocking' you'll get a check light, or at least codes stored...

the fact that it's making rated torque at lower rpm's, and dropping at higher, imo, indicates air flow issues...
could it be deposit related? perhaps...

Incorrect. A misfire is not knocking. The engine is always looking for knock with sensors on both banks. It uses this to adjust timing. Timing advance is most critical at high engine torque, with very minute changes causing major torque variations. In all cases that I've seen, lack of the torque boost at 5500 rpm is due to increased timing <beep>, and has nothing to do with airflow. This can be measured on the street with VAG, and is not related to airflow. SilverRS4 has seen the same issue.

[RI_RS4]

Thing is, I use mine on a daily basis and it is motorway commuting so a high degree of airflow and I suspectthat the build up may not be as dramatic as people think. Sure, there will still be deposits but with that much air passing through I wonder if it won't have the chance to accumulatre as mush as say for instance, a car that does a stop start commute or is used for short bursts / weekend toy?

You can have carbon buildup on the valves that does not seriously disrupt airflow, but does cause pre-ignition (detonation), requiring the ECU to pull timing.

[pippyrips]

SR71,

I hear you, I'm not sure I would pay full whack for the work but remember 10bhp over claimed figures actually meant a 40bhp increase for me as the car didn't produce the number in the first place!

[P_G]

It may well be that the x-pipe does make the appreciable difference and perhaps to the negative overall. Like said the cost to benefit ratio for de carbonising is non existent for me at this stage, happy enough to have 396bhp, a mucky inlet manifold and a few thousand £ in my pocket at present that perhaps 400+ bhp and be broke!

I was personally using the Dastek road as a starting mark for all future work that I do so it will be interesting to see how various additions affect the overall picture.

[ArthurPE]

if the engine is misfiring or 'knocking' you'll get a check light, or at least codes stored...

the fact that it's making rated torque at lower rpm's, and dropping at higher, imo, indicates air flow issues...
could it be deposit related? perhaps...

Incorrect. A misfire is not knocking. The engine is always looking for knock with sensors on both banks. It uses this to adjust timing. Timing advance is most critical at high engine torque, with very minute changes causing major torque variations. In all cases that I've seen, lack of the torque boost at 5500 rpm is due to increased timing <beep>, and has nothing to do with airflow. This can be measured on the street with VAG, and is not related to airflow. SilverRS4 has seen the same issue.

wrong:
OBDII records misfires...per cylinder and multiple...
as do all modern ECU's...
yes, the ONSET of knock or detonation is used to adjust (<beep>) timing as a SAFETY, not primary control variable, the map does that...but beyond a certain value, it is recorded...because that means if it is bumping up against that safety, there is an issue...

a 'minute' (degrees) timing change will not result in 'major' torque reduction (>10-20% would be 'major')

I still say you will never get full power on a dyno...
when Audi engine dynos the car they PRESSURIZE the intake plenum with a std velocity pressure...

a car will never make full power without load, load means moving down the road....

there is nothing wrong with his car, as borne out by his timed runs...

isn't anyone the least bit curious how he 'gained' 40 HP (the other guy gained 50)?

it may be retarding power, and cost a 1 or 2% power, buts it's probably due to the traction control torque limiting, etc., not deposits...

as I showed the deposits, even if 30% of the lift, still allow a larger anulus area than the valve seat opening, therefore they can not be the limiting factor...

P1325 Cyl. 1 Knock Control Limit Attained
P1326 Cyl. 2 Knock Control Limit Attained
P1327 Cyl. 3 Knock Control Limit Attained
P1328 Cyl. 4 Knock Control Limit Attained
P1329 Cyl. 5 Knock Control Limit Attained
P1330 Cyl. 6 Knock Control Limit Attained

P1340 Multiple Cylinder Misfire During Start
P1341 Multiple Cylinder Misfire With Fuel Cut-off
P1342 Misfire During Start Cylinder 1
P1343 Misfire Cylinder 1 With Fuel Cut-off
P1344 Misfire During Start Cylinder 2
P1345 Misfire Cylinder 2 With Fuel Cut-off
P1346 Misfire During Start Cylinder 3
P1347 Misfire Cylinder 3 With Fuel Cut-off
P1348 Misfire During Start Cylinder 4
P1349 Misfire Cylinder 4 With Fuel Cut-off
P1350 Misfire During Start Cylinder 5
P1351 Misfire Cylinder 5 With Fuel Cut-off
P1352 Misfire During Start Cylinder 6
P1353 Misfire Cylinder 6 With Fuel Cut-off
P1354 Misfire During Start Cylinder 7
P1355 Misfire Cylinder 7 With Fuel Cut-off
P1356 Misfire During Start Cylinder 8

[ArthurPE]

I would check the air box flap and the intake runner flap(s)

[S2tuner]

ArthurPE: your whole theory about knock is COMPLETELY wrong. I can assure you, you can go to your nearest and cheapest gas station, fill your RS4 up with 87 octane fuel, thrash the car, you'll hear it knock or ping, BUT you won't get a fault code, unless it pinged to the point where it's probably just about to destroy the engine. Oh and you won't see a single CEL because of this, NOT A SINGLE ONE.

Maybe you'll listen to someone who spends his life his head burried into ECU code, knock sensing strategies and routines if you don't listen to a fellow american B7 RS4 owner (RI_RS4, who was more than right to try to correct you).

[S2tuner]

isn't anyone the least bit curious how he 'gained' 40 HP (the other guy gained 50)?

my explanation is simple: the Dastek dyno (whilst not my favorite) measures driveline losses, the Dyno Dynamics (whilst very accurate for wheel HP, tractive effort and very repeatable) does not, it just guesstimates them out of a pre-recorded losses curve. Put 2" wider tires on a 4WD car putting out say 400wHP on a DD and dyno it again, you'll get the same 400wHP and the same estimated losses in shootout mode. Put the same car before/after on a dyno that measures driveline losses, and you'll see your driveline losses going up with the wider tires.

Simple as that, although I'll continue to remain doubtful about the B7 RS4s making their factory rated HP. As it has been said before, even if it is just airflow (or lack thereof), then how do you explain that a stock GT3 doesn't need 400,000 bandaids in order to put out its factory rated 415 PS at the crank on virtually any dyno, provided it has decent fuel in it?

[ArthurPE]

ArthurPE: your whole theory about knock is COMPLETELY wrong. I can assure you, you can go to your nearest and cheapest gas station, fill your RS4 up with 87 octane fuel, thrash the car, you'll hear it knock or ping, BUT you won't get a fault code, unless it pinged to the point where it's probably just about to destroy the engine. Oh and you won't see a single CEL because of this, NOT A SINGLE ONE.

Maybe you'll listen to someone who spends his life his head burried into ECU code, knock sensing strategies and routines if you don't listen to a fellow american B7 RS4 owner (RI_RS4, who was more than right to try to correct you).

I've got codes with bad gas...
both misfire and 'knock'...

why would fouled valves cause detonation?
they wouldn't, fouled combustion chambers or piston tops may, but not the valves...

please capitalize American

[ArthurPE]

isn't anyone the least bit curious how he 'gained' 40 HP (the other guy gained 50)?

my explanation is simple: the Dastek dyno (whilst not my favorite) measures driveline losses, the Dyno Dynamics (whilst very accurate for wheel HP, tractive effort and very repeatable) does not, it just guesstimates them out of a pre-recorded losses curve. Put 2" wider tires on a 4WD car putting out say 400wHP on a DD and dyno it again, you'll get the same 400wHP and the same estimated losses in shootout mode. Put the same car before/after on a dyno that measures driveline losses, and you'll see your driveline losses going up with the wider tires.

Simple as that, although I'll continue to remain doubtful about the B7 RS4s making their factory rated HP. As it has been said before, even if it is just airflow (or lack thereof), then how do you explain that a stock GT3 doesn't need 400,000 bandaids in order to put out its factory rated 415 PS at the crank on virtually any dyno, provided it has decent fuel in it?

the Dastek has higher measurement resolution in every catagory, including such variables as wheel speed...far more accurate
the repeatable for the 2 runs? <1%

so as I contended, the DD FW numbers are bogus, essentially worthless, especially when 'converted' thru dubious means to FW...

if the 40 HP was all attributed to the cf, guess what? ALL the cars in the previous test made ~rated HP when the correction factor is adjusted...

this dyno cf ~302 to 396 ~ 31%, the DD ~ 20%, or a 50% difference...
so a 370 on that machine, using the Dastek cf becomes 407

[P_G]

although I'll continue to remain doubtful about the B7 RS4s making their factory rated HP. As it has been said before, even if it is just airflow (or lack thereof), then how do you explain that a stock GT3 doesn't need 400,000 bandaids in order to put out its factory rated 415 PS at the crank on virtually any dyno, provided it has decent fuel in it?

Because the GT3 has a far more simplistic drive system and not the Quattro + ESP system that the RS4, R8, S8 and RS6 has, all of which suffer the same fate as our RS4's in not producing the power on dyno's?

[Dom81]

please capitalize American

If we're getting petty, us English prefer capitalise...

Latin root (capitellum) so we like -ise. Of course if you'd asked S2tuner to "emphasize American" then I'd be with you - Greek root (phasis) and all that

[SR71]

The behaviour of P_G's car beyond 5500rpm is nothing to do with the dyno.

Both my car and Rob's car showed up the difference at SRR, albeit on different days. Andy's car generated exactly the same curves as my car at SRR to within 1hp.

I have to say Camberley Audi have been super dealing with my case.

But as I (and they) have always maintained, Audi UK &/or the factory will only be inclined to act, like they did with the DRC, if people stop acquiescing to a design that is frankly, unacceptable in a £55K performance vehicle, and query it.

If Dyson made a vacuum cleaner like our CCV system, he'd be penniless.

Forget about the power issue...as a result of the eco-nazis, the automotive industry is presently stuck with "immature" EGR/FSI technology and we are paying the price for the design short-cuts...

You/we may be surprised at the consumer clout we have...

Out of interest, the 997 GT3 might not drive a couple of extra diffs, but it has both SC and TC. I have no idea of the comparable efficiency of Porsche drive-trains versus Audi's, but the only difference should relate to the magnitude of the corresponding losses in a 4WD versus 2WD car?

[ArthurPE]

MAHA has a white paper with special proceedures for testing Audi's
their numbers are always >400HP, and they also measure losses...

losses can be measured a couple of ways: inertial (non driven) and when driven (loaded), which will be more accurate...
the losses on a MAHA are typically ~105-110 HP, on this dyno (inertial) ~95, add 10 HP to these numbers (396 + 12 ~ 408) and you are getting very close to rated HP...factor in the air flow and you're there...

the 'droop' in torque could be:
air flow
dyno correction
stability/traction systems, torque retardation/limitation

most likely a combination
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