I've spent quite a bit of time researching turbo upgrade options and wanted to get your educated opinions for my daily driven 05 FXT
4EAT.
I feel it is very important to differentiate this thread from the others comparing these turbos, because it is
4EAT specific. A few hundred RPM difference can easily be adjusted for using a clutch pedal on a MT, but with an Automatic trans, it is much more important to match the turbo to the trans.
Like most people, I'm looking for bolt-on mods. I do not want to mod my transmission. Maybe Cobb will release 4EAT TCU tuning support like they have talked about, that would be great but until then - I think my trans is going to remain stock. (I believe with a 3200rpm stall speed)
I would like to have safe, streetable, semi-MPG friendly power so i can decide if I want horrible mileage or good mileage on a road trip with my right foot. So I'd prefer to stick to
stock injectors.
Supporting mods:
STI TMIC
STI Hood scoop
Walbro Fuel Pump
STI Catless Uppipe
Cobb Catted Downpipe
STI CatBack Exhaust
INJECTORS STOCK STI/FXT
3 Options
(data from
Subaru Turbo List - Newbies & FAQs - NASIOC)
IHI VF39 - 400-450?cfm at 18psi 250-325whp
Full boost between 3000-3500rpms.
IHI VF34 - 460cfm at 18psi, 250-325whp
Full boost between 3000-3500rpms. May spool faster than 39 due to roller bearing.
Evo3 16G - 575cfm, 275-375whp
Full boost between 3200-3700rpms.
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Is there a strong argument for or against these turbos for a
4EAT equipped FXT?
I don't see too much performance difference with the 34 to justify the additional cost over a 39. It seems that you'd either go with a 39 or step up to an Evo3 16G rather than paying the premium for a 34, unless you got a really good deal on it.
The faster spool of the VF39 and VF34 are great, but the Evo3 16G is pretty close with more upside. I've read claims of Evo316G's hitting full boost below 3k rpm, but I don't know if that is true.
Other than spool and output potential, are there other pros/cons I am missing when paired with a 4EAT driving in the real world? I'm speculating boost creep will be a non-issue with my catted downpipe.
Note - I may post this on Nasioc as well, since there are a lot of 4EAT owners there.
In a Nutshell....
What is the best turbo to use on a 4EAT Suby with STI/FXT injectors (upgraded pump) that provides loads of power with the best daily driver experience?