Flame Suit On - Another Rolling Road Day

[pippyrips]

Well done guys, I guess this helps to prove what some have been saying, you shouldn't read too much into them!

It also proves that the engine is also pretty tunable for a n/a one.

[P_G]

Managed to get my graph uploaded....

[ArthurPE]

looks good, very consistent...

look at the ramp rate...the other runs were 10 and 15...not sure if they are the same units...

the car looks starved for air >6000 rpm...
the curve looks identical to the factory curve up until then...
your 90% T point is ~7200 rpm
the factories is 7600

Torque
factory... P_G
4000 RPM
300...304

5000
311...302

6000
314...305

7000
298...283

7500
288...271

factory peak is 5500, yours ~3600
my guess, fans can't supply enough air...

consider: let's say the total intake area is 1 ft^2
at 30 mph ~ 2,640 CFM (just for the intake)
at 60 mph, 5,280
at 100 (4th gear >6000 rpm) ...8800 CFM

can't pressurize the plenum...a bit of boost
velocity pressure ~ 100 MPH ~5" WC ~ 0.17 psi of 'boost'

[caldy]

Way above my head - but it would account for the fact that my 'inlet system' is considerably modified from stock and that this is significantly responsible for increased power. I need to do some VagCom runs of airflow to see what is going on.

[pippyrips]

Caldy, when you do mine peaks at around 180g/s with a steady increase all the way up. From memory it peaked at around 165g/s before the manifold work.

[Gazzer68]

Not seen mine over 150g/s

[pippyrips]

What mileage have you done Gazzer? That's low compared to the other cars I have seen.

[Gazzer68]

36k

[RI_RS4]

looks good, very consistent...

look at the ramp rate...the other runs were 10 and 15...not sure if they are the same units...

the car looks starved for air >6000 rpm...
the curve looks identical to the factory curve up until then...
your 90% T point is ~7200 rpm
the factories is 7600

Torque
factory... P_G
4000 RPM
300...304

5000
311...302

6000
314...305

7000
298...283

7500
288...271

factory peak is 5500, yours ~3600
my guess, fans can't supply enough air...

consider: let's say the total intake area is 1 ft^2
at 30 mph ~ 2,640 CFM (just for the intake)
at 60 mph, 5,280
at 100 (4th gear >6000 rpm) ...8800 CFM

can't pressurize the plenum...a bit of boost
velocity pressure ~ 100 MPH ~5" WC ~ 0.17 psi of 'boost'

This is typical of the engine when timing is being retarded. I've seen this many times on the dyno and VAG runs. If you run full throttle and monitor timing if you're making full power you'll see on a few degrees of <beep>. When the torque bump at 5500 is not there, it's indicative of 5 to 10 degrees of timing pull.

[P_G]

So you think my car's timing is out? It is going in for it's MOT on Monday so I may ask them to look at this if that is the consensus. It has done 50k miles after all so may happen.

[RI_RS4]

Timing pull is done automatically by the ECU in response to knock. Sometimes it is due to valve or combustion chamber deposits.

[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...

[P_G]

It will either be car related airflow or the amount of air fed into the car by the fan, I will maybe ask them to do the VAG-com vacuum airbox flap test.

[pippyrips]

I know when SR71 & myself did some data logging with vagcom prior to the modding I've had done my timing was retarded more than his, and he had better FATS times as a result, even though I had a more consistant flow of air going in. Neither car showed any fault codes.

At 50k you just know what the state of your inlet/valves will be. It could be a number of things but your air flow with definately be affected by the buildup which you will have higher up the rev range.

[P_G]

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?