Valves- carboning up

[PetrolDave]

As an esteemed member of this forum, your view that rolling road results are unreliable has been noted. But it is a reference point with not so many variables.

Sims, you need to catch up with the last 3 years of discussion on this forum regarding rolling road testing of the B7 RS4.

Not only are there the variables due to poor operator of the rolling road (leading to totally inaccurate transmision loss figures), but also the operation of the RS4 ECU software limits the throttle valve opening in some gears.

IMHO, and that of many other members it appears, use of a rolling road to establish absolute figures for an RS4 is akin to witchcraft. A rolling road is very useful to establish the delta due to changes made to a particular car, but not to determine absolute figures.

The 30-100 figure is far less error prone, especially when several runs are averaged, than a rolling road figure - and relys on nothing more than O-level Physics to verify it's efficacy.

[ArthurPE]

Sims, you need to catch up with the last 3 years of discussion on this forum regarding rolling road testing of the B7 RS4.

Not only are there the variables due to poor operator of the rolling road (leading to totally inaccurate transmision loss figures), but also the operation of the RS4 ECU software limits the throttle valve opening in some gears.

IMHO, and that of many other members it appears, use of a rolling road to establish absolute figures for an RS4 is akin to witchcraft. A rolling road is very useful to establish the delta due to changes made to a particular car, but not to determine absolute figures.

The 30-100 figure is far less error prone, especially when several runs are averaged, than a rolling road figure - and relys on nothing more than O-level Physics to verify it's efficacy.

bravo, spot on

as Dave noted there is a place for both
a dyno is good to track changes with an individual car...
and even then, better be same set-up, dyno, operator, etc., or all bets are off...

imo, a timed run is a much better metric for an entire class of cars...especially when used to compare it to factory (and media) testing figures...pretty sure that is why most mags do timed runs vs dyno charts

[HYFR]

Further MRC Tuning have an open day on April 17/18th and will be conducting rolling road tests. Hopefully there will be some B7 RS4's there. It would be helpful if some (if not all) of those people conduct the 3k to 8k test immediately after the rolling road results. Perhaps with the use of a Vag-Com, and on the same stretch of road.

Im the only B7 attending AFAIK

Im travelling up with a convoy including a couple of C6's, both tuned I think.... that gonna be scary !

[RS6chris!]

do some 3rd gear, 3000-8000 rpm runs using the OBC
if ~8 sec, you are in good shape, actually better becuase a stock car runs ~8.4

Right..

Done this today as follows>>

1st run....8.2
2nd run.....8.4
3rd run....8.4
4th run....8.1....although i wasnt to good on the button!!

Car standard using the onboard lap timer for reference.

I know not the most scientific tests but there or thereabouts.

Arthur comments????[/quote]




Heres my results from earlier in the thread.

[HYFR]

I defo buy into the 3-8k RPM test...im a believer

I did it ages ago and got rubbish times, but this was when I had EPC issues, which when resolved by Audi, I had my 5k rpm BOOST back and now I can do 8sec times

and all that with 73k on the clock....imagine how much carbon is in there!

[ArthurPE]

Done this today as follows>>
1st run....8.2
2nd run.....8.4
3rd run....8.4
4th run....8.1....although i wasnt to good on the button!!
Car standard using the onboard lap timer for reference.
I know not the most scientific tests but there or thereabouts.

Arthur comments????



Heres my results from earlier in the thread.

imo, your car is peforming to spec...(I have you in the database already, 1/4 tank, etc. )...we tend to look at the worst runs, but imo, the fastest are equally telling..

were your valves ever cleaned?

I wish we could do some unrestricted GPS verified top speed runs
now THAT would tell us something!

[ArthurPE]

I defo buy into the 3-8k RPM test...im a believer

I did it ages ago and got rubbish times, but this was when I had EPC issues, which when resolved by Audi, I had my 5k rpm BOOST back and now I can do 8sec times

and all that with 73k on the clock....imagine how much carbon is in there!

considering the mileage, your car is strong...
I'd like to see some times on your car after the valves were 'cleaned'
does anyone really think he's going to go better than 8 flat?

[sonny]

Will weather effect the 3-8k test, such as the likes of a head wind, a tail wind would surly give a 'quicker' time?

[ArthurPE]

Will weather effect the 3-8k test, such as the likes of a head wind, a tail wind would surly give a 'quicker' time?

marginally...

aero really doesn't become a significant factor until >120 mph or so...
and then it's exponential...

obviously it depends on magnitude...100 mph wind, some, a 20 mph, probably none...

it's easy to calculate the force (pressure x area) of wind...

(vel (ft/min)/4005)^2 = p (in wc)
let's say 20 mph wind (pretty strong and exactly parallel with travel) or 29 ft/sec or 1760 ft/min
p (in wc) = 0.19 in wc or 1 lb/ft^2...
if we assume the area to be 24 ft^2, total added force (thrust) ~ 24 lbs

compared to the driving thrust of the engine ~ 240 lb ft (after losses) x 4.11 x 1.52 / 1.08 ft ~ 1390 lb...

wind force added 'thrust' ~ 24/1390 ~ 1.7%, hardly anything 7 HP or so...
10 mph, only 6 lb of added 'thrust'!! <2 HP

[2manytoys]

I think Sims was suggesting that the cars go on the Dyno, and lets say one is 20hp down or whatever, then do a timed run and see what the difference is.

Arthur, have you timed 6000 to 8000. How long does that take (assuming you are flat stick from 3000)

Mal
Team Carbon

[SR71]

What I find bizarre is that I guarantee you that if I'd posted up a picture of a non-FSI engine years ago before they became mainstream and the internals of this non-FSI engine were covered in s**t, everyone would have said "What the hell's up with that engine?"

I mean, as one particular poster has been keen to tell us, diesels have been used for years without suffering from deposition issues? (My own experience with diesels with EGR does not support this conclusion)

Now suddenly FSI is mainstream, and an engine covering its internals in s**t is OK.

What??????

We know what causes the deposition but that doesn't make it OK IMHO.

We've got ~2% due to wind, ~2% due to incline, ~2% due to measurement error etc etc. so there is ~25hp right there...

The 3-8K test is a crude test - as crude as a dyno IMO - especially without using VAGCOM and must be resulting in a lot of owners running into their rev limiters if they're doing the test properly.

To my knowledge, are me and Rob still the only ones who have run "dirty" and "clean" B7 RS4's side by side on the same day, same tarmac, same ambient conditions, the day the car came out of MRC?

Granted Rob's car had been ported at the same time, but anyone care to guess the results (even though I've stated them before)?

Billy's "Time Attack" times continue to demonstrate the advantages of his setup.

Whilst I tend to agree with PetrolDave, the observations of those who work with the dynos day in day out is that many Audis do make the stated claims (or better) on a chassis dyno, but the B7 does not.

I'll be at MRC on the 17th.

Should be a fantastic event.

[ArthurPE]

I never said deisels didn't have deposits...just the opposite, they do, but yet suffer no performance loss due to them...
just like the RS4...

what causes the deposits? I'd like to know....

and I gurantee if pics weren't posted no one would even know they exist...
because they sure as heck wouldn't feel a performance loss, lol

[ArthurPE]

SportAuto supertest:
36 to 96 using all gears (same speed range as 3k to 8k in 3rd) 8.1 sec, the average 3rd gear data is 8.2-8.3...
from 72 mph to 96 (6k to 8k) is 4.3 sec (in our test a bit longer, maybe 4.4 sec) if you were down 10% HP your time would increase ~20% or 0.9 sec (1 sec in our test)
instead of running 8.3, you'ld be running >9.3 sec...no one has done that, even in 108f temps...

this test provides far more meaningful data than a dyno...that is why all magazines use timed tests and races aren't run on dyno, but rather a timed interval....

[SR71]

Arthur,

I absolutely agree with you that those cars which were running deficits of 50+hp were not experiencing this loss as a result of carbon deposition. That is ludicrous. I have never suggested otherwise.

It is a shame though, that in these cases it often took Audi a while to diagnose what seems to be a common occurence, namely, namely corrosion of the airbox flap solenoid which has a huge affect on the airflow at high rpm. I think Camberley were the first to sort this out?

But for me, the problem with the road tests are that for seeking to ascertain whether there is a performance delta due to deposition, the errors associated with the test are of the same order of magnitude as the effect you are trying to measure.

We are trying to ascertain an affect that IMO is no greater than 2-5% at the very greatest.

So the delta is ~0.2-0.4 secs against a "clean" car.

I suspect that even using VAGCOM, this type of test will not deliver conclusive results, especially bearing in mind how quick deposits seems to return.

I'm curious....are Porsche DI engines experiencing deposition?

Are Lexus DI engines experiencing deposition?

Are BMW DI engines experiencing deposition?

If so, what is the suggestion?

If not, what is the suggestion?

[Terry1948]

I think that that arthurs test may have a lot of variables but at the end of the day it is a real world test something that average drivers can achieve from their cars. I see this issue much the same as hifi people start listening to the performance of their equipment and forget to enjoy the music. How can records sound better than a cd? I have been guilty of all these crimes I have learnt that once I have bought something never look at prices in other shops you will always find it cheaper and spoil your day. SR71 is correct in saying that carbon is not good and we used to decoke the engines because performance = clean engines, ported , gass flowed & blueprinted etc,etc.