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I'm thinking about buying a new 2017 STI. I'd really like it to make more power but would not want to have to worry about something going wrong since the warranty will obviously be compromised. So if I wanted 400 wheel horsepower or more what's the best safest route and how much would it cost?

I know all the basic parts evolved when tuning these cars for more power. But I want reliable power. So aside from all the bolt-ons like downpipe, upgraded fuel pump, exhaust, injectors, blah blah blah etc etc.

For reliability would it be necessary for forged pistons and a closed deck block? Or would the pistons be good enough? And what would the typical cost be for 400hp? I know for 300hp to the wheels stage 2 it's about $2900..
 

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If you don't mind me asking, why not buy an Evo X?

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Discussion Starter · #3 ·
Well i never liked the style of the Evo and there being discontinued. Plus the last year one the interior is horrible. Even tho the engine stock pistons are a weak link in the Subaru the drive train is way better then the Evo.
 

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Well i never liked the style of the Evo and there being discontinued. Plus the last year one the interior is horrible. Even tho the engine stock pistons are a weak link in the Subaru the drive train is way better then the Evo.
You will spend far less money making the Evo fast. End of story.

I don't understand you.

First you want a car that is fast enough to run mid 12s in the quarter. When I explain to you that there are far better cars than the STI for drag racing, you get defensive. Now you're asking about 400whp which will put you into the 11s if tuned on some dynos. If you like the STI, why not just buy it instead of asking all these damn questions?

If you truly are torn, please consider listening to the logic here.

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Discussion Starter · #5 ·
First off i ask all the "Dam questions " because i like to learn and hear different opinions and approaches! Why do you get so angry? Second i dont like Evo's as ive already stated! Third a lot of the questions i ask are because i want to know the safest route to mod and best route because i know it will void the warranty. And lastly i only talk about straight line track times as a reference for acceleration performance. I will never drag race the car. So it has nothing to do with drag racing whatsoever. Maybe since i cant get any clarity on the best way to make bigger power out of a new STI reliably i might just day screw it and go buy a $39,995 727 horsepower Mustang GT out of Ohio. Screw it. .. Actually ill go with the 670hp option and get the 3 year warranty. Id rather a fast AWD Subaru but getting advise is like pulling teeth with this crowd!!!!!
 

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If you want 400whp, here:

  • ID1000 Injectors
  • Walbro 255lph pump
  • GTX3572R rotated manifold turbo
  • ETS FMIC
  • EWG
  • Killer-B ELH + rotated EWG UP (does this exist yet?)
  • E85 flex-fuel kit
  • Tuning solution (obviously)
  • TGV deletes
  • Parallel fuel rail mod
  • IAG fuel damper kit
  • IAG AOS
  • Snow performance Water/Meth injection (you'll need all the det-resistance you can get)
  • Catless DP
  • Speed-density conversion
  • Killer-B Oil pan, baffles, and pickup (you'll need the extra oil capacity for cooler oil temps)

That should make 400whp on most dynos. The motor may last 100,000 miles or 1,000 miles. At these BMEPs, the motor could go at any minute.

Sure, you could build the motor for another $8,000-10,000 and it MIGHT last another 50k miles, but built motors rarely last as long as stock OEM motors.

At the end of the day, you might have an Impreza that cost you $65,000 and resells for $25,000. Or you could have a $40,000 Camaro SS (with 400+whp mind you) that resells for $38,000.
 
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If you want 400whp, here:


ID1000 Injectors
Walbro 255lph pump
GTX3572R rotated manifold turbo
ETS FMIC
EWG
Killer-B ELH + rotated EWG UP (does this exist yet?)
E85 flex-fuel kit
Tuning solution (obviously)
TGV deletes
Parallel fuel rail mod
IAG fuel damper kit
IAG AOS
Snow performance Water/Meth injection (you'll need all the det-resistance you can get)
Catless DP
Speed-density conversion
Killer-B Oil pan, baffles, and pickup (you'll need the extra oil capacity for cooler oil temps)

That should make 400whp on most dynos. The motor may last 100,000 miles or 1,000 miles. At these BMEPs, the motor could go at any minute.

Sure, you could build the motor for another $8,000-10,000 and it MIGHT last another 50k miles, but built motors rarely last as long as stock OEM motors.

At the end of the day, you might have an Impreza that cost you $65,000 and resells for $25,000. Or you could have a $40,000 Camaro SS (with 400+whp mind you) that resells for $38,000.

Qft. You'd basically buy a 40k new car and have to replace half the parts.
 

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1) I think you maybe reading "anger" in-to Zax posts. There may be some frustration there but I don't read any anger.


2) Getting answers may seem like "pulling teeth" to you.. but that is most likely because you don't quite understand that your questions are not as simple as you seem to imagine them to be.


3) I would direct you to off be reading Defiant Autospeed's post on NASIOC: Public Service Announcement "I Want 400WHP!..."



Good luck. :)
 

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If you want 400whp, here:

ID1000 Injectors
Walbro 255lph pump
GTX3572R rotated manifold turbo
ETS FMIC
EWG
Killer-B ELH + rotated EWG UP (does this exist yet?)
E85 flex-fuel kit
Tuning solution (obviously)
TGV deletes
Parallel fuel rail mod
IAG fuel damper kit
IAG AOS
Snow performance Water/Meth injection (you'll need all the det-resistance you can get)
Catless DP
Speed-density conversion
Killer-B Oil pan, baffles, and pickup (you'll need the extra oil capacity for cooler oil temps)

That should make 400whp on most dynos. The motor may last 100,000 miles or 1,000 miles. At these BMEPs, the motor could go at any minute.

Sure, you could build the motor for another $8,000-10,000 and it MIGHT last another 50k miles, but built motors rarely last as long as stock OEM motors.

At the end of the day, you might have an Impreza that cost you $65,000 and resells for $25,000. Or you could have a $40,000 Camaro SS (with 400+whp mind you) that resells for $38,000.

Of course while this set up will net 400WHP on most dynos, one would be still be quite foolish to not also upgrade any number of other things that will not last long with a doubling of stock power.

So plan on spending a fricking crap ton more money to get so-called DD "reliability" and you will likely never be able to get any of that money back out of it should you need to in a private sale (trade in will not even be an option as no dealer would touch it with a 100 foot pole).


Good luck slaying the reliable 400whp daily driver Subaru windmill, Don. lol


:)
 

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Some reputable builders like IAG offer what they call a "drop-in piston" program that strengthens the primary failure point of the EJ257.

They take a brand new OEM engine and replace the OEM pistons with a set of forged aluminum pistons leaving the rest of the rotating assembly alone. The crankshaft and rods are quite strong from the factory, so this setup MIGHT make a reliable 400whp motor feasible. Or it may not. The benefit to this program is that block does not need to be split open. A program like this requires an almost new motor with factory cross-hatching since a bore-hone isn't practical with the rotating assembly in place.

This program typically costs between $2500-3000 so it is much cheaper than a full rebuild. If you want to do this properly, look for shops that will do a "Hot torque plate" piston installation whereby a plate is torqued to the block and the block is heated before the piston is installed. This process significantly reduces clearance-related failures.

If you value the life of your block, stay away from 2618 alloy pistons. These slugs will make short work of your OEM ductile iron sleeves. For a light build, 4032 pistons are far more practical. Good luck.
 

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Define reliable.. by my definition (in an OEM sense), any modern engine should last at least 200k miles under normal conditions without needing any major repairs. By that definition it doesn't matter how much money you spend, you will never have a reliable 400whp Subaru engine.
 

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Regardless, the 4B11T is a much better platform for reliable power compared to the EJ257.

Both motors can support similar torque in OEM form, but the 4B11T will produce approx. 15-20% more power for a give torque output.
 

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Discussion Starter · #13 ·
Well its sounding like its not a good idea to try and increase the power in the STI. I love the car and the idea of having performance and AWD. But it may be sounding like it wont be enough performance. I get mixed signals because theres so many different opinions on this subject. Even when you look up opinions from tuners and builders advice like Crawford out in California and other reputable places they talk like the weakest link and problem really isn't the EJ motor at all. They say the real issue and cause of failer in these engines is people buying online tunes or taking it to a tuner that really isn't good at tuning these cars. And when that happens the EJ motor does not run right because it either runs lean or has knock and other issues which cause the rings to fail. According to them if its done right and the ECU is tuned right it will last as long as a stock engine!
 

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Well its sounding like its not a good idea to try and increase the power in the STI. I love the car and the idea of having performance and AWD. But it may be sounding like it wont be enough performance. I get mixed signals because theres so many different opinions on this subject. Even when you look up opinions from tuners and builders advice like Crawford out in California and other reputable places they talk like the weakest link and problem really isn't the EJ motor at all. They say the real issue and cause of failer in these engines is people buying online tunes or taking it to a tuner that really isn't good at tuning these cars. And when that happens the EJ motor does not run right because it either runs lean or has knock and other issues which cause the rings to fail. According to them if its done right and the ECU is tuned right it will last as long as a stock engine!
They want your business. Where are you located man?
 

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Discussion Starter · #19 ·
Im an hour from Evans tunning. They have good reviews. They said for a stage 2 and pro tune it would be around $2,900. But that would only give me 300hp to the wheels and 345tq. According to them. I get any deeper in the conversation at the time to go beyond that. They said it would be reliable with that.
 
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