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On The Road to 425WHP

7226 Views 78 Replies 17 Participants Last post by  zax
So I am just starting to be happy with the few exterior and interior mods that I have done to my 17 WRX. Want to start putting some money into the engine. What I would like the end results to be is somewhere in the ball park of 425WHP. I know this a very stereotypical number for most WRX owners but the heart wants what the heart wants. I am not terribly familiar with hands on engine modification, however luckily I work at a dealership with a certified Subaru tech to help me work on my upgrades and mods.

Basically I don't want to get too ahead of myself by modifying a part of the engine to a certain point that it would be causing damage to it due to a powerful aftermarket part vs. the stock parts. I have heard that yes, of course the Cobb AP is the GO-TO first modification to do. However I was under the impression that the engine should already have some aftermarket performance parts on it so a dyno shop can tune it to a certain tune with the AP. Like I said I am new to this so I am sure somethings that I mention won't be 100% accurate.


In either event, what I pretty much looking for from the kind people of ClubWRX is a few suggestions, maybe even a list of which modifications I should do first or in a certain order of which mods to do. Anything is really helpful but of course I am not trying to break the bank right off the bat. Maybe like a few hundred dollar parts that add a noticeable difference... Wasn't sure if there was already a forum for this or one similar to it. Like I said, anything helps!

Thanks!:wiggles:
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To get close to that number you will need a bigger turbo.
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You will not see noticeable difference in performance with a few hundred bucks dumped in. I would start off with a tune first, then a exhaust, then intake, Ect. Work your way to the bigger mods and see if you still like the car or need more power. A lot of people just see numbers and say I want that and then the car handles differently than they wanted and its a waste of money and time. IMO.
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i think you shouldnt worry about chasing a number, but research and add mods that will give you satisfactory power. as you outgrow the current mod or hp number, move onto the next. a typical engine mod sequence that many do can look something like this:

intake + tune
downpipe + tune
aftermarket top mount, fuel pump, electronic boost control solenoid, + tune
up pipe and/or wastegate and/or headers + tune

thereafter youre looking at larger turbo and/or internals + tune

with all this said, you cant neglect the complementary parts in and out the engine that may need to happen in order to support said desires [of gains]. mods to consider in the chain of command include:

mounts of all sorts, air/oil separator, gauges, hoses of all sorts, suspension, brakes, tires and many other items.

again, take your time. avoid chasing a number. be smart and enjoy the car responsibly.

someone correct me if needed.
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You will want a built motor, built transmission and better rear diff.

This will not be a cheap endeavor.

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^ This, close thread.

Folks could produce a list, but you will not come close to that number with basic "stage" mods.
You will not see noticeable difference in performance with a few hundred bucks dumped in. .
Well I wasn't saying that I only wanted to put a couple hundred into it. I meant like a couple hundred each part. I just don't want to be spending hundreds almost thousands a piece for certain parts. You know what I mean? I hope this makes more sense. But thanks for the other recommendations.
i think you shouldnt worry about chasing a number, but research and add mods that will give you satisfactory power. as you outgrow the current mod or hp number, move onto the next. a typical engine mod sequence that many do can look something like this:

intake + tune
downpipe + tune
aftermarket top mount, fuel pump, electronic boost control solenoid, + tune
up pipe and/or wastegate and/or headers + tune
Thank you! That was actually really helpful. I will definitely look into those. I am kind of drawn because I sorta am chasing that 425 but sorta not. It's what I would love to have but if I end up being not far off and still really enjoy the ride of it, I think I'll be just as happy.
A reasonable list:

COBB AP
CAI (if noise is desired)
TGV delete
EGR delete
TBE
IAG AOS
pro-tune
http://www.clubwrx.net/forums/tuning-electronic-engine-management/134366509-dyno-faq.html

Call the shop that will be doing the custom ECU calibration. Tell them you have a 2017 WRX and ask them how to get to "425whp" on their dyno.
Didn't Cobb keep their AW torque numbers down because in the long run the FA20 internals wouldn't be able to hold over 350tq?

"is likely that the connecting rods will prove to be the long-term weak spot for modified FA20DIT cars"

Unless OP makes high HP low torque?


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A reasonable list:

COBB AP
CAI (if noise is desired)
TGV delete
EGR delete
TBE
IAG AOS
pro-tune

Am I correct that the only things on that list that actually add hp are the downpipe and tune?
mjmwrx said:
Am I correct that the only things on that list that actually add hp are the downpipe and tune?
No
There was a thread on the other forum by someone like mishmoto, or ETS maybe Cobb where they were around 430 hp on a 15. I'm sure it can be done, but at what price, and what longevity I don't know.

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Which others add hp and how much

CAI and TGV deletes will increase power output as well.. how much depends on several factors, but the TGV deletes alone should provide a good boost in power.
So is it safe to say that intake & AP are a good start? Im not looking to get the 400 horses out of it soon. Im trying to crawl before I can walk. Wanna start by doing a few changes, add a noticeable amount of power, make sure it still drives the way I desire, and go from there by adding and upgrading as time goes on.
CAI and TGV deletes will increase power output as well.. how much depends on several factors, but the TGV deletes alone should provide a good boost in power.
Run straight E85 on top of these mods and get there faster


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Last I saw e85 was torching the HPFP and there wasn't a e85 capable pump yet. That may have changed, but it would help for sure. The more I read about the e85 and talk to my local shop the more I think that's my future plan, but the station close to me that sold it stopped carrying it from lack of use. So availability is always a factor.

I would personally go with the downpipe first with the ap. If you can swing a dyno tune at that time with the turbo back and AP purchase you would get the best results for power. The intake will get you some, and give that induction sound a lot of folks are after.

I haven't really seen anyone mention they have nuked a gear box yet, however the more torque you make the higher the likely hood a bad shift or a hard launch can grenade a gear, or drivrline component.

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The fundamental challenge with the new FA20 motors is the failure mode. With the older EJ25x, you could run 400whp+ on most dynos and it may or may not fail. However, if it did fail, the failure mode would most certainly be the pistons. In most cases, the block could be salvaged as well as the heads, rods, and crank.

With the FA20, it might hold 400whp for a while, or it might not. But if it fails, the failure mode is usually the rods which is far more catastrophic. You might need to replace the entire motor from block to heads. It's this reason the FA20 should absolutely be built preemptively.

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