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Old 06-24-2008, 10:24 AM   #1
Defiant Autospeed
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Default VF39 and VF43 directly compared!

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.
HOWEVER
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)


Thoughts?

Last edited by Defiant Autospeed; 06-24-2008 at 10:57 AM.
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Old 06-24-2008, 10:39 AM   #2
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OMFG.... THANXXXX for this.

+1234567890123456789012345678901234567890 KUDOS!

+1 for sticky.
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Old 06-24-2008, 10:46 AM   #3
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You got them mixed in the first pic. 39 on the left and 43 on the right.
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Old 06-24-2008, 10:47 AM   #4
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Yeah I did..
Fixing it right now.

The rest of the pics are correct (were to begin with, just making sure that is clear )

Also removed the double pic
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Old 06-24-2008, 10:47 AM   #5
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Well if this is in fact true props to all those that have sold their VF43s for a higher price because it's a "better" turbo.
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Old 06-24-2008, 10:49 AM   #6
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Have a 48 laying around?
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Old 06-24-2008, 10:56 AM   #7
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Quote:
Originally Posted by Clark_Kent View Post
Well if this is in fact true props to all those that have sold their VF43s for a higher price because it's a "better" turbo.
Well, in all fairness, the 43s probably had lower milage on them. We know that at least, the differences in the pics are true. Getting the housing off the VF43 will tell the story on the hot side wheel comparison. I will get comparison pics there as well.

Quote:
Originally Posted by fullerton View Post
Have a 48 laying around?
Not yet, Im sure I will get my hands on one at some point. I have been doing a decent bit of porting turbos lately, so the chances of me having a 48 and either a 39 or a 43 at the same time are decent. I will get pics when I have one.
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Old 06-25-2008, 10:48 PM   #8
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Quote:
Originally Posted by Defiant Autospeed View Post
Well, in all fairness, the 43s probably had lower milage on them. We know that at least, the differences in the pics are true. Getting the housing off the VF43 will tell the story on the hot side wheel comparison. I will get comparison pics there as well.


Not yet, Im sure I will get my hands on one at some point. I have been doing a decent bit of porting turbos lately, so the chances of me having a 48 and either a 39 or a 43 at the same time are decent. I will get pics when I have one.
If im going to be buying a VF43 from the subaru... should i just buy the VF48?

i heard their the same price...
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Old 06-26-2008, 12:56 AM   #9
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Quote:
Originally Posted by RSbullet View Post
If im going to be buying a VF43 from the subaru... should i just buy the VF48?

i heard their the same price...
You should skip both and do either a 16G or an 18G. The 39 and 43 are every bit equal to a 16G, and an 18G is definately larger than a 48. IHI turbos are decidedly inferior to the mitsu based turbos, so if you are buying one, just get something worthy to begin with. Never chose an IHI turbo if you have other options. Not that they are garbage, but comparatively, they kind of are. They are nowhere near as efficient, they spool quite slowly for their size, they are sluggish to respond for their size, and they taper off more than the should up top.
The 16G is, as the VF39/43/48, too small for the 2.5L motor, at the smallest, an EVOIII 16G, if not at least an 18G should be the smallest turbo you would consider. A TD05-18G 8cm (with a proper compressor housing, not the tiny one some builders are using to push cheap turbos out the door, they just dont perform the same) is an excellent match for someone who wants a turbo upgrade but doesnt want huge power.

Last edited by Defiant Autospeed; 06-26-2008 at 01:02 AM.
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Old 06-24-2008, 12:08 PM   #10
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Thanks!
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Old 06-24-2008, 01:39 PM   #11
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nice information.... now im waiting for hot side/inside pics...
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Old 06-24-2008, 01:43 PM   #12
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I really can't tell in the pics but could you put a micrometer on that wastegate flapper and tell us if there is any difference between the two? Also, if there is anything else different or special about the wastegate internal dimensions or shape.

Thanks for this thread, good work.
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Old 06-24-2008, 02:09 PM   #13
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I will get a caliper in the holes when I get the apart. I am out the door to go do it in about 5 minutes.
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Old 06-24-2008, 03:11 PM   #14
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awesome.!
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Old 06-24-2008, 04:15 PM   #15
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Thanks I figured this would be usefull info, or at least interesting.

I have been nauseated all day, tossing the cookies easily once an hour, so I havent been able to get out to it yet.
This pretty much stinks :bleh:
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Old 06-24-2008, 10:15 PM   #16
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sweet! thanks for taking time to do this.
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Old 06-24-2008, 10:30 PM   #17
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i thought the only difference was the 43 doesnt have boost creep issues.
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Old 06-24-2008, 11:48 PM   #18
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Quote:
Originally Posted by grex07 View Post
i thought the only difference was the 43 doesnt have boost creep issues.
Actually, the 43 dose have boost creep issues so that's why you need to get them ported out, found that out the hard way, but it did not cost me much thanks to my shop.
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Old 06-25-2008, 09:00 AM   #19
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Actually, the 43 dose have boost creep issues so that's why you need to get them ported out, found that out the hard way, but it did not cost me much thanks to my shop.

Yeah if its an IHI you can count on a good chance it will creep on the 2.5. They are just not quite as good of a design as the mitsu based turbos. Even then, the mitsu turbos can creep. I am of the opinion that creep isnt as much an issue caused by that, but caused by the hot side being too small for the engine itself. Here is why I say this.

-From what I have seen, TD06s creep less than TD05s
-8CM housings creep less than 7cm. Most 8cms dont creep. It seems like maybe not most 7cms, but a lot, do creep. You definately stand FAR less chance it will creep on an 8cm housing than a 7cm.
-2.0L wrx motors dont have anywhere near the instances of creep.<which points at the turbo being more properly matched.
-the way a 16G "feels" on a 2.0L, is the way an 18G "feels" on a 2.5L This is a compressor difference obviously, but as far as "this is what it feels like it should have come with", that is a decent comparison. That tells me that they are more properly matched to those motors.



People also need to understand that porting the turbo doesnt only benefit you by reducing creep. It wildly changes the spool and response characteristics of the turbo. This isnt as much of an issue on the 2.5L as it is on the 2.0L, which needs all the help it can get in that dept, but its still a big difference between how fast a ported turbo is than a non ported turbo. Moral of the story there is that ANY stock location turbo benefits from porting. Even a TD06-20G 8cm, will perform a good bit better if properly ported.

Last edited by Defiant Autospeed; 06-25-2008 at 09:23 AM.
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Old 06-26-2008, 04:12 AM   #20
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Quote:
Originally Posted by Defiant Autospeed View Post


People also need to understand that porting the turbo doesnt only benefit you by reducing creep. It wildly changes the spool and response characteristics of the turbo. This isnt as much of an issue on the 2.5L as it is on the 2.0L, which needs all the help it can get in that dept, but its still a big difference between how fast a ported turbo is than a non ported turbo. Moral of the story there is that ANY stock location turbo benefits from porting. Even a TD06-20G 8cm, will perform a good bit better if properly ported.
where do you feel the most gains can be had from porting? exhaust outlet and inlet?

is porting the compressor inlet and outlet worthwhile?
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Old 06-24-2008, 10:27 PM   #21
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Great info!!! Deff Sticky!!
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Old 06-24-2008, 10:57 PM   #22
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Looks like the 39 is addicted to Torco
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Old 06-25-2008, 12:11 AM   #23
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Thanks alot dude, you are awesome! So many questions can be answered by looking at this thread.
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Old 06-25-2008, 10:37 AM   #24
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Nice write up! Thanks for the info!!
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Old 06-25-2008, 11:55 AM   #25
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good info ...thank you!
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