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Old 03-01-2012, 11:00 AM   #1
DrnknZag
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Default VF series upgrade from VF34? Maybe twin scroll....

Well, the seals on my VF34 are finally starting to go so I'm turbo shopping again, but I don't know what to look at. I'm extremely happy with my current setup in terms of power and daily drivability.

For reference, here's my dyno stats:
-298.7hp @ 5350rpm
-323.9tq @ 3500rpm
-max boost 17.1psi at ~3500rpm
-Domtuned on stock injectors (hence the 17psi)



So what I loved about this setup was the quick spool (which probably could have been tuned to hit a bit quicker too) and the low end torque. I'd love to find a new setup that would also spool quickly and give me that lower end torque I love. It wouldn't mind picking up a bit of HP on the upper end too, and I will have larger injectors so I can bring the boost up. 310-320whp would be cool, but I don't really NEED it, I'm pretty content with right around 300 like it is right now.

I've started looking at a possible twin scroll setuup, like a 36 or 37. This would definitely give me the unique factor that I liked with the VF34, but cost will obviously be a bit higher and I'll lose part of that boxer rumble. I should get the quick spool, but how does the top end compare to the 34?

Two other options I've looked at are the VF22 and VF48. I know I'd get a bit more lag out of the 22, but the top end would be nicer for sure. What about the 48? I've read a bunch of threads comparing the 48 to other VF turbos, but a lot of the info is contradicting and I feel like there is a bunch of misinformation out there. They seem to be pretty well suited for the 2.5L....

For all those IHI haters who say any VF series is too small for the 2.5L, save it for another thread. My Stealthwagon build is driven by mostly OEM parts and I intend to keep it that way. No 16G/18G/20G/Green at this point.

Anyway, thanks in advance.
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Old 03-01-2012, 11:05 AM   #2
LBell05STI
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Overall goals power wise? Or are a driveability, I want spool at x rpm driver? (Like me)
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Old 03-01-2012, 01:25 PM   #3
teiva-boy
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a larger 16g/HTA/XT on a 2.5 is a great turbo, especially over a vf34/48. Shame you're so set on OEM.
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Old 03-01-2012, 01:39 PM   #4
DrnknZag
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Quote:
Originally Posted by LBell05STI
Overall goals power wise? Or are a driveability, I want spool at x rpm driver? (Like me)
If I had to name some goals, I'd say quick spool (full boost ~3500rpm at least) and over 300whp, which is close to where I am now. I just don't want to downgrade from the 34. It must be street-able, with good low end torque.

Quote:
Originally Posted by teiva-boy
a larger 16g/HTA/XT on a 2.5 is a great turbo, especially over a vf34/48. Shame you're so set on OEM.
At this point and time, I'm sticking with OEM. My stock block has 95k miles and I don't want to put too much additional strain on it while it is my daily driver. Once it's not my everyday car, the block will be built and a bigger turbo will be in the works.
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Old 03-01-2012, 02:02 PM   #5
WMCCook29
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While I appreciate your desire to stay with an OE turbo, any turbo that's an upgrade from your current one will put more stress on your motor. Doesn't matter if it's IHI, MHI, Garrett, etc.
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Old 03-01-2012, 02:25 PM   #6
DrnknZag
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Quote:
Originally Posted by WMCCook29
While I appreciate your desire to stay with an OE turbo, any turbo that's an upgrade from your current one will put more stress on your motor. Doesn't matter if it's IHI, MHI, Garrett, etc.
True, and I obviously could run a 16G/18G tuned down a little bit to stay in a "safer" zone. I do feel more comfortable with a VF series turbo, knowing somewhat where they're limits are. I know I probably won't tune for much higher than 19-20psi.
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Old 03-01-2012, 03:12 PM   #7
LBell05STI
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The oem turbos may have awesome driveability, but the HUGE torque spike that you get with a small frame turbo in such a short rpm range is more stressful than having more power spread over the whole powerband. In the 1.8t world rods were snapping on stock KO3s because they would make 300+ wtq at 2800-3000 rpms and such a huge load at one time that the rods couldn't handle it.
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Old 03-02-2012, 12:05 PM   #8
DrnknZag
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^^True, but I'm not looking for a face crushing torque hit, especially with my stock bottom end. I'm just looking for something that's similar to my torque curve on my VF34.

A local guy is selling an HTA68, but I feel I don't have the supporting mods to let it breathe properly. I still have the stock turbo inlet and an STi TMIC. I'm not looking to upgrade these parts at the moment. That's another big reason why I'm limiting myself to a VF series turbo at this point too.
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Old 03-02-2012, 07:33 PM   #9
LBell05STI
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Drnkn it will still run effeciently without all the supporting mods, but be choked uptop. you will make the same powerband but wont be able to utilize its full capability.
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Old 03-04-2012, 06:17 PM   #10
Joshwrx04
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i have a vf22 with the p20 exhaust housing on my sti, domtuned. i love it, lil bit of lag but makes up for it up top
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Old 06-23-2012, 10:24 AM   #11
westey2109
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Im considering a vf34 with a p20 exhaust housing myself, i really want to know how a vf34 compares to a vf48 though. Like spool rates and power deliver etc. I have a 04 fit so i don't want to go over 300whp so i don't need to get forged interals
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