DDK - Die Deutschen Klassiker

Having a problem with the 2.4T in my 356. When the oil returns to the tank it is frothing considerably. The thinking is the problem might lie with the tube size that leads to the oil cooler which is an aftermarket type and/or the oil lines themselves. It is early days for this engine to be running but I was just wondering if any of you learned gentlemen have ever experienced this problem with your engines??

Have you over filled the oil perhaps ? The crank will froth the oil if the level is too high.

Not sure if this is relevant..
I have a race car with a 3.2 flat 6 in it.
It has a 13 litre dray sump tank with a screw on cap and when running you can see the oil from the engine coming into the tank top section. The oil is a bit frothy, but it is designed for the return oil flow to go down the side of the circular sump tank before it drops to the tank bottom.
This swirl contact allows the bubbles in the return oil to dissipate so neat oil get to the hose that is sucking the sump oil to the engine pump.

Maybe this is what happens in the irregular dry sump tank of your car and all is well!

Yes, I was going to point to tank design too as a possible cause - assume it is was purpose built rather than a stock 911 one fitted in the wing? I had two made over the years, one for the front, one rear, and both had baffles built in (effectively shelves with holes in them if that makes sense) that slows down the oil and takes the air out as it settles to the bottom.

HTH

The 911 oil tanks have a mesh inside to catch and separate the frothing.

Yes, same principle and works well.