Rolling road Results

[mdm]

I also had a fluttering gauge and it was a goodun, i never did get to the bottom of it, and i checked every thing!
Where abouts do you get it? at peak boost and high rpm?

if and when it does it just coming into boost say about 0.3 of a bar and jumps to 1 bar.

[terrybullwon]

if and when it does it just coming into boost say about 0.3 of a bar and jumps to 1 bar.

Mine was only under high load and high boost, from say 4k onward...

The gauges are pretty simple, i doubt it would be at fault maybe worth checking your vacuum lines and line at the ecu/gauge feed

[Acidburn]

Do you get any noises from under the bonnet like a whooshing noise etc as you might have a boost leak if its not going up as high as it should be.

Mine had a slight one and meant that sometimes I was getting full othertimes not enough etc.

I'm not sure if andyp has got any boost test kits in stock again but good idea to get one and test it considering the price.

[terrybullwon]

Do you get any noises from under the bonnet like a whooshing noise etc as you might have a boost leak if its not going up as high as it should be.

Mine had a slight one and meant that sometimes I was getting full othertimes not enough etc.

I'm not sure if andyp has got any boost test kits in stock again but good idea to get one and test it considering the price.

Newsh had the same problem as me iirc, mine would flutter from 1.5bar-1.55bar very very small like 1psi.

definitely not a leak but something amiss

[Acidburn]

hmmm bit wierd as if it was a aby with something like a homefries on then i'd have said it would have been common as both andy caseys and david (s2driveruks) have done that and a couple of others as well.

[terrybullwon]

hmmm bit wierd as if it was a aby with something like a homefries on then i'd have said it would have been common as both andy caseys and david (s2driveruks) have done that and a couple of others as well.

Think John had it fixed by Mihnea changing the map

But sure it could be a leak, mine was not though and thats for sure

[Rusty]

Looks like the low boost map. The torque is the same as mine did with the MRC low boost map. 262bhp and 289ftlbs sounds about right for that map on a standard car. Some new sparks, a boost leak test and a new air filter might help but you're not going to get to 280 on that map without a decent exhaust.

Do a search for my posts about rolling road results, I've had 3 done in the last few months wih different specs.

Did you have the Air Fuel ratio measured as this is the a good indication of how well things are running.

My boost gauge also flickers after having the MRC map fitted, must be a funny with the WGFV... Even does it on mine now with a Homefries.

[newsh]

I'm pretty sure the fluttering is the WGFV pulsing the boost (although, strangely, it doesn't always do it..) I've ordered a special T piece which is supposed to smooth out the response of the boost gauge will let you know how it goes
This map has the same sort of curve I had when I first had mine dynoed, its holding back just after the torque peak, you can see this in both curves, could be a misfire a small leak a dodgy PCV system or a soft maf hose. Its a bit of a classic misfire or holding back curve though, seen a lot like it before.

[mdm]

Looks like the low boost map. The torque is the same as mine did with the MRC low boost map. 262bhp and 289ftlbs sounds about right for that map on a standard car. Some new sparks, a boost leak test and a new air filter might help but you're not going to get to 280 on that map without a decent exhaust..

It was definitely the hi boost chips, i know this cause i fitted the low ones first and they were no were near as strong.

Did you have the Air Fuel ratio measured as this is the a good indication of how well things are running.

No, it was a rolling road day so 2 power runs were just done. however i do have a wideband sitting in the garage, so i think i'm going to fit it.

One question though is, will the ecu run off the narrow band feed from my wideband?

My boost gauge also flickers after having the MRC map fitted, must be a funny with the WGFV... Even does it on mine now with a Homefries

I fitted the gauge before i chipped the car and it did it then hence the reason i thought it was the gauge, also as far as I'm aware you can't though the car.


Next step i think is a pressure test. i have a feeling there is an air leak because i'm averaging 16.8mpg although some of this is driving around town.

[Rusty]

AFRs will indicate a boost leak.

Boost is related to load so you'll only see 1.5+ on a steep hill at 3k in 5th/6th.

Let us know how you get on.

[dan_b]

if your MPG is down to 16 I'd suspect a lambda on the way out - are you getting any other symptoms? On constant throttle do you get a slight surge then hesitation sensation, or any unusually extra pops from the exhaust?

[EspenW]

Should be a set of RS2 readings to show power loss against transmission
POH!!! Dam! and fitzy http://www.s2forum.com/forum/showthr...t=rolling+road

Something seems weird with that RS2 reading. 300bhp at he wheels should mean quite a bit more than the quoted 350hp at the flywheel. Quattros lose more then 15% through the drivetrain (25% is often quoted), even though the percentage decreases with increasing power, due to the loss figure being part constant and part power dependent.
Was this power at the wheels or at the hubs (Rototest/Dynapack)?
Note: the B7 RS4's normally produce approx 315bhp at the wheels and they are quoted at 420 at the flywheel (even though this is most likey overrated).

[Pirvu Eugen]

goood point EspenW! I have dinoed my car after the MRC generic chip for the 3B engine and i get 235 HP they say at the Flyweel but with the ~ transmision loss i am very close with the 276 claim power. I am sure that my readings were at the wheels not flywheel.
How they can get from rolling the flywheel power? if they dont know the actual power loss in transmision?
I am sure that my car has the claimed 276hp at the flyweel! Is much more fast than the oem setup 218hp. They have done some mystakes in the dyno.
Maibe is your problem also!
Hope this helps!
Eugen

[EspenW]

The only way to measure true crank hp is to lift the engine from the car and test it on an engine dyno according to the given standards for such testing.
What is measured on a chassis dyno (rolling road) is power produced at the wheels, flywheel power is then (gues)stimated. A coastdown run will tell us something about the rolling resistance, and how much power the drivetrain saps when unloaded, and rolling in the reverse direction. Problem is that during the power run, the drivetrain is not unloaded, and it runs in the opposite direction. Some losses are constant, while other are load dependent, some losses are highest at mid load, while others peak at max load. in addition,to make things even worse, the SAE and DIN dyno correction standards (compensates for altitude, temperature, barometric pressure and humidity) do not apply for waste gate controlled turbo cars...
Chassis dynos should be used for tuning and gauging gains from mods and not as an accurate indicator of flywheel power, or even wheel power, as numbers will vary wildly from one dyno to another. Turbo magazine got numbers ranging from 228hp to 265 hp (at the wheels) on different dynos with the same car, on the same day:

http://www.turbomagazine.com/tech/0306tur_turbo_magazine_dyno_dash/index.html

More info:

http://www.caranddriver.com/article.asp?section_id=4&article_id=8020&page_number=1

[Greg_S]

I never realised it didnt apply for wastegate controlled cars, what is the reason for it?