Originally Posted by Fabrik8
Clutch slip is bullshit. If the clutch was slipping at a certain torque, it would plateau at the same point as the torque rose back up. There is no indication that that is happening at all. I'm guessing the ECU is cutting power when it senses an overboost condition or something along those lines, like you're saying. I've heard some interesting things about VW ECUs trying to regulate boost in wierd ways once the engine has some mods to it, so this is probably a reflection of that. Modern ECUs kinda suck because they try to do fault correction every time they see something the least bit different from stock.
It would be nice to see some sensor data, I'd like to see the throttle position and manifold pressure during that dip.
The second peak is a little stranger, it looks like the ECU is doing some boost control, the turbo is probably running out of flow around that area. They have a crazy smoothing factor on that graph, it's probably hiding some interesting info.
Is it a Dynapack? Tire slip really would be fun to see then..
My responce was almost exactly the same as what you just said, just without the graphic. If a clutch is slipping, it's doing it at a certain torque number. Like you said, it won't slip at 200lbft at 4000rpms and then miraculously grab again at 200lbft and 5000 rpms.
I think the line at the top of the graph after the torque peak could be clutch slip. It slips at a certain RPM and then plateaus after that. The owner of the car did say his clutch slipped so I'll buy it at the topof the powerband.
BTW, this is on a VR6 turbo. It's not a stock turbo car so the ECU is playing no part in boost control other than closing the throttle momentarily if the ECU calculates a too rapid torque increase.
I'd really like to find a dyno plot of clutch slip so I can post it up in there and shut Rich up.
This is the thread on VWVortex just for reference:
http://forums.vwvortex.com/zerothread?id=2682521
Also, this is the dyno plot on the car that EIP did themselves. Notice the VERY slight dip in power at the same RPM. If you dyno the car immediately following an ECU reset, the powerband will be very smooth. It takes a few miles of driving for the ECU to "learn" and then the ECU starts adapting all of these "safety measures" which ends up with the HUGE power loss at ~4000rpms that the other dyno plot shows.
Originally Posted by Corey
If that is a chart from EIP's dyno then it is not a dynapack.
That's not from EIP's dyno. Here's the car on the dynapack:
The dyno plot I just posted is from EIPs dyno.