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Old 03-23-2010, 05:45 PM   #1
snowflowmfg
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Smile VF34 on my 07 WRX - yes I am beating the dead horse.

Ok, so the urge for some more getup and go on my car is starting to get the best of me and I just spend about an hour just searching through here trying to research some more on the subject. Anyways, I know this has been brought up many times, but i'm going to try to be very specific and get some good answers.

I have an 07 WRX. STi tmic, catless tbe, and a walbro. Currently on a cobb ots stg2 map. Going to have it dynotuned when turbo is installed and a RA tranny this summer.

My Goal: I want to be somewhere in the vicinity of 300whp, BUT what I want most of all is to retain as much quick spool and street drivability as possible!!! I don't drag or autox or anything like that. Just daily drive and I want as little lag as possible and lots of usable power. Don't really care too much about that little bit of extra ooomph at 7000rpm and don't want to change out injectors either.

Now, I know that a vf39/43 is easy to get and cheaper blah blah blah, but the 34 has the ball bearing design and supposedly quicker spool. However, I want to know if the 34 will give me noticeable better results towards having quick spool and good usable power my 2.5L?

So is the 34 going to be more worthwhile on the 2.5L or are the 43 and 34 going to both get me pretty equal results. Does the 34 have noticeably quicker spool than a 43?

TIA,
Dan
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Old 03-23-2010, 10:36 PM   #2
jakedown
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i have a monster td04 wich is ported and polished and also had the clipped turbine wheel all done by deadbolt, let me know if you intrested it in. This is a grest turbo for daily driving it has almsot no lag
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Old 03-23-2010, 11:11 PM   #3
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i would think it's kinda hard hitting 300 whp on the stock injectors! i'm pretty sure the increase in turbo lag with the vf34 will be noticeable but some wrapped headers, up pipe and a bar and plate IC might help a bit!
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Old 03-24-2010, 02:22 AM   #4
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Originally Posted by jakedown View Post
i have a monster td04 wich is ported and polished and also had the clipped turbine wheel all done by deadbolt, let me know if you intrested it in. This is a grest turbo for daily driving it has almsot no lag
Not looking for a td04

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Originally Posted by cenzoSTI View Post
i would think it's kinda hard hitting 300 whp on the stock injectors! i'm pretty sure the increase in turbo lag with the vf34 will be noticeable but some wrapped headers, up pipe and a bar and plate IC might help a bit!
Would it be hard?

I'm comparing the vf43 to the 34, you know this right? So are you saying that the 34 is slower spooling than a 43? I'm pretty sure it's the other way around.
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Old 03-24-2010, 02:27 AM   #5
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if you wanna get max outta small vf34, 39, 43 turbos, get bigger injectors, a better tmic than sti one, and a walbro. talk to your tuner
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Old 03-24-2010, 03:03 AM   #6
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Originally Posted by bzbuzz View Post
if you wanna get max outta small vf34, 39, 43 turbos, get bigger injectors, a better tmic than sti one, and a walbro. talk to your tuner
Not looking to max. Looking to maintain spool and driveability > huge top end power.
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Old 03-24-2010, 04:22 AM   #7
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Originally Posted by snowflowmfg View Post
Not looking to max. Looking to maintain spool and driveability > huge top end power.
I wouldn't worry too much about spool with a VF43 (even less so with a VF34). The key is to use a 3-port boost solenoid and to get it tuned properly. I was in the exact same situation as you with my 06 WRX. I drove around for 3 or 4 months at stage 2 level with the stock TD04 and the stock boost solenoid. I wasn't very impressed with power delivery. It's abrupt and peaky as you've probably found out. The TD04 is always on boil but it cannot stay on line for very long, it's just a flash of power.
After moving to a VF43 and a 3-port boost solenoid I can tell you that this is definitely the turbo the car should have had from the factory. The 3-port boost solenoid in interrupt mode helps a lot with spool on the VF43 and the car feels as strong down low as a TD04 with the stock 2-port boost solenoid. It's also very clear that the VF43 works more efficiently that the TD04, I see less boost below 3K RPM and yet the engine clearly makes more power than with the TD04. After 3K RPM, the VF43 just trumps the TD04. And you don't have to push it hard either, 16~16.5 PSI is plenty enough IMO.

PS: Stock injectors will pretty much max out by redline with a VF43. This is especially true with CA 91 gas and a STI TMIC since we have to target 10.8~11 AFRs to be on the safe side.

Last edited by neg_matnik; 03-24-2010 at 04:32 AM.
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Old 03-24-2010, 10:12 AM   #8
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i had a vf34 on my wrx 07 and yes it will do what you want it to do
it made 315 wp with about the same setup. at the end of the day you can ask opinions and every body has them. but i think the vf34 was amazing i only regret was i didn't have enough for a vf22
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Old 03-24-2010, 11:44 AM   #9
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Originally Posted by neg_matnik View Post
I wouldn't worry too much about spool with a VF43 (even less so with a VF34). The key is to use a 3-port boost solenoid and to get it tuned properly. I was in the exact same situation as you with my 06 WRX. I drove around for 3 or 4 months at stage 2 level with the stock TD04 and the stock boost solenoid. I wasn't very impressed with power delivery. It's abrupt and peaky as you've probably found out. The TD04 is always on boil but it cannot stay on line for very long, it's just a flash of power.
After moving to a VF43 and a 3-port boost solenoid I can tell you that this is definitely the turbo the car should have had from the factory. The 3-port boost solenoid in interrupt mode helps a lot with spool on the VF43 and the car feels as strong down low as a TD04 with the stock 2-port boost solenoid. It's also very clear that the VF43 works more efficiently that the TD04, I see less boost below 3K RPM and yet the engine clearly makes more power than with the TD04. After 3K RPM, the VF43 just trumps the TD04. And you don't have to push it hard either, 16~16.5 PSI is plenty enough IMO.

PS: Stock injectors will pretty much max out by redline with a VF43. This is especially true with CA 91 gas and a STI TMIC since we have to target 10.8~11 AFRs to be on the safe side.
I see. Thank you for actually giving me a good answer (nasioc ). I see you're in the bay. Who did your tune? I was planning on going to Paul @ Db Tuned. Next choice would have been ed @ eq or gst.

You on i-club?

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Originally Posted by lobolusk View Post
i had a vf34 on my wrx 07 and yes it will do what you want it to do
it made 315 wp with about the same setup. at the end of the day you can ask opinions and every body has them. but i think the vf34 was amazing i only regret was i didn't have enough for a vf22

Thank you. Finally a real answer. Sounds good. What were the other supporting mods you ran that I don't have? Injectors? How was spool?
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Old 03-24-2010, 02:52 PM   #10
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Originally Posted by cenzoSTI View Post
i would think it's kinda hard hitting 300 whp on the stock injectors! i'm pretty sure the increase in turbo lag with the vf34 will be noticeable but some wrapped headers, up pipe and a bar and plate IC might help a bit!
The 06+ wrx has the ~same size injectors as an sti (cant remember if its 550 vs 565). Also, there wont be much lag from a vf34 on an ej25 as a vf34 is the same as a vf39, except ball bearing vs thrust bearing. I never noticed lag with vf39 on my sti. With the fpgreen on my car, its a bit more noticeable.
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Old 03-24-2010, 04:01 PM   #11
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The 06+ wrx has the ~same size injectors as an sti (cant remember if its 550 vs 565). Also, there wont be much lag from a vf34 on an ej25 as a vf34 is the same as a vf39, except ball bearing vs thrust bearing. I never noticed lag with vf39 on my sti. With the fpgreen on my car, its a bit more noticeable.
Any idea of how much less lag a vf34 will have than a vf39/43?
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Old 03-24-2010, 09:43 PM   #12
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Quote:
Originally Posted by snowflowmfg View Post
I see. Thank you for actually giving me a good answer (nasioc ). I see you're in the bay. Who did your tune? I was planning on going to Paul @ Db Tuned. Next choice would have been ed @ eq or gst.

You on i-club?[...]
I simply bought an XPT Stage 3 tune and I have slightly modified it to accommodate a GrimmSpeed BCS. I also bought a wideband O2 sensor to keep AFR/fueling in check. Thanks to the wideband O2 I've realized that stock injectors are pretty close to maxing out with the VF43 at redline (especially if AFR target is 11.0 and below).
I'm not on i-club but I'll check it out.
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Old 03-24-2010, 10:01 PM   #13
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I've got a VF43, sti tmic, AP2 protune and all the other standards that go with this setup. Good setup for around 300whp and it spools up very quick but it does lose power around 5K rpms. Which ever way you go I think VF43/39/34 RA gears are overkill IMO.
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Old 03-25-2010, 12:18 AM   #14
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Any idea of how much less lag a vf34 will have than a vf39/43?
Gonna depend on the tune and supporting mods.
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Old 03-25-2010, 12:21 AM   #15
snowflowmfg
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Gonna depend on the tune and supporting mods.
Well I listed my supporting mods. wrx blue injectors, walbro, sti tmic, catless tbe....

How much on average quicker would I spool? How much faster is it possible for me to spool one?
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