Here is a interesting post I found on iwsti.com. It may not be fact in the end but its a very good post on the differences between these two turbo's physically since they are not documented much...
It doesnt say anything about the wheel diameter/ compressor etc. So power levels between the two are not documented in the post. Nevertheless, the physical differences look identical... -tode




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 VF39 is on the left, VF43 on the right. 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.


taken from http://www.iwsti.com/forums/engine-p...hs-busted.html -tode