I have been meaning to post these for a while.
SO, I have a VF43 and a VF39 here to be ported, both in great shape, so I thought these would be perfect for comparison, to discover a few things, and to my suprise, dispell a couple myths.
SO here they are
The VF43 is on the right, VF39 on the left. Think that the VF39 compressor housing looks slightly beefier? It is. Its not a huge difference, but its definately bigger. Notice that the compressor wheels look identical? Having seen so many IHIs apart, I can tell you that I would bet my life on them being the exact same wheel.
What does this mean? That they are identical turbos when it comes to the compressor section, if anything, the VF39 compressor would be slightly better.
VF43 closer pic
VF39 closer pic
Back side pics, again, VF43 on left, VF39 on right.
Identical size hot wheel outlet. Wheels look identical. I have a pic of the VF39 wheel with the housing off, I will be disassembling the VF43 today, and as long as I can get the hot housing off (many MANY VF43s are seized together and simply cannot be split) I will get pics to directly compare the two wheels to confirm if they are in fact the same hot wheel.
Side by side on their side. The angle isnt the best, but the hot sides are identical size wise. There are some VERY slight differences in shape, but not any that would make a power output difference.
Here is a closer pic of the VF39 hot side
Here is a closer pic of the VF43 hot side
So I have to say, there is no way that either of these turbos will make a measureable difference in power from one to the other.
The VF39 cracks pretty often, and in 99% of cases, it doesnt change the performance in any way.
The VF43 also cracks, not as often, but it DOES crack in the same place.
I will stick my finger in and see if I can feel any thickness or shape differences inside the inlet of the hot side, to see if maybe the 43 is thicker or something in the area that typically cracks. Looking in there, it doesnt look any different.
This confirms my suspicion that the reason the 07 STI makes a decent bit more power on the stock turbo, is due to the changes in the motor itself. At least that is what I have always thought, and now believe even more firmly. From what I have seen, the 07 STI seems to make a bit more on every turbo. I could be wrong there. I just seem to have noticed that.
Anyway, this isnt meant to start an arguement as to one being more power producing than the other. I just wanted to share my findings, and I havent seen side by side pics. (maybe they are out there? I didnt see them)