Internal vs external wastegate... which is better?
 

In the sloooow process of turboing my 3.2 and am using a standard K27 HF and exteranal WG at .6 bar. However, looking at newer turbos/ systems, internal wastegates seems stardard. Love the external WG for 'cool' factor and sound, but is it 'old' tech? How exactly do you vary the spring rate on the external WG? Is there any advantage? Thanks

I was always under the impression the external was the norm in these cars.

In order to vary the spring rate, you just buy one at the rate you want and replace the old one. Or you can just buy the lowest rate / cut the old one, and run a boost controller.

OOPS, i meant to say, how do you vary the boost pressure on the INTERNAL wastgates.

Internal or integral, W/Gs are very cost effective methods of getting the job done however their adjustment and flow capability are closely tailored and not something you want for your project.
The external W/G is best for you.

That is easy, I have done it MANY times...you have to disconnect the rod to the diaphram, cut it and re-thread it, so it opens later -or - install an inline boost controller to fool the wastegate (I have used Manual Boost Controllers, with great results).

Yasin

Thanks guys. I have seen a lot of guys using Internal WG turbos on TT aftermarket systems, but none for the 930. So the only advantage is of an internal WG turbo is the elimination of a dump pipe and more closely tailoring of the wastegate parameters to a particular turbo?

Most are just upgrading the twin integral W/G turbos the factory installed. The factory went this route because twin tubos like these are cheaper and lighter. Two integral W/G modern turbos are cheaper than the installed cost of the old tech single turbo with external W/G found on the previous 964(5) 3.6L single turbo motor.

The only advantage to an internal wastegate is that it's cheap, and *maybe* easier to plumb.

But it's undesireable because it causes a lot of flow resistance due to all the post-turbine turbulence. So if you want big power & efficiency, you want an external WG. Ideally you want the WG to dump to atmosphere (which is pretty darn easy to plumb!) but OEMs can't design that way for emissions reasons. For emissions, you'd route the WG outlet it back into the exhaust stream, preferably at least 1+ foot downstream.

So there's little controversy; external is better.

...at least that's what the experts tell me...

Internals suck unless you are going to run it on an intended aplication- e.g 16G on mitsubishi etc and even then you get boost creep. If you are modifing boost levels or plumbing or anything like that, I would just stick with external. Some of the performance based internal (integral) gates are ok I guess, but why bother when the money you save on the wastegate is going to be snatched away by the price of the turbo.