Why are dyno numbers for a A4 lower unlocked than locked. How much more are they when you lock the conv. Just curious, Thanks!

 

Depends on the holding capacity and efficiency of the converter. A stock converter has a coupling point of around 2000 rpm. That means it will be locked up as good as it can be by 2000 rpm. A Vig 3600 has a coupling point closer to 5000 rpm. That means anything below 5000 rpm, the Vig 3600 will be using it stator to multiply torque (which is why you'll see higher torque readings at lower rpm compared to manual trannies), but anything above the coupling point will be at the mercy of how efficient the holding capacity of the converter is.

At 6000 rpm, a 300mm stock converter may lose only 10-15 rwhp unlocked vs. locked, but a 245mm Vig 3600 may lose 30 rwhp vs stock. Although that may sound bad, the Vig 3600 makes 50-80 more rwtq than stock at 3000-4000 rpm. This is why the aftermarket converters allow the car to launch so hard. Just don't expect big dyno numbers until you get past the coupling point (which varies on every converter).

 

Thanks, I wondered why my numbers where lower unlocked verse locked by 30-40rwhp N/A and 50-65rwhp on spray! Thanks!

What I don`t understand is MTI dyno`s with it locked and we left it unlocked at G-force.

 

Locked naturally puts more heat/stress on the tranny and converter. I dynoed mine unlocked and the #s are in the sig. If it wouldve been locked it wouldve prolly be 20rwhp more since the converter wouldnt be "slipping" when its locked. Personally I see no need to do it locked unless you are purely looking to put down big dyno #s.

 

Last time my rig was dynoed it made 6rwhp more locked vs unlocked.
Stock 4L60 with deep pan, tranny cooler and SY3500 converter??? who woulda guessed.