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10-14-2019, 02:51 PM | #1 |
Scooby Newbie
Member#: 434904
Join Date: Nov 2015
Location: Spokane, WA
Vehicle:2002 Impreza WRX WRB |
G25-660 Daily/autox bugeye build.
So after a predictable EJ205 failure during an Autocross late in 2018 I decided to build my 20002 WRX centered around Garrett's G25-660. The goal was to make a mid-range response monster with 400whp on pump gas that could be a locally competitive car but still driven to the track and work. I feel that I have accomplished that with this build and I've been super impressed with this turbo. The build, fabrication and tuning has all been done by me and/or friends except for the engine machining and assembly which was done by Gibson Performance in Spokane WA. Also a shoutout to both Fishhead performance and Tier 1 performance for the use of their dynos at various stages of the build.
Highlights. - Dyno numbers - 397 whp at 7000 rpm and 345 ftlbs peak. The torque is above 300ftlbs from 4200-7000rpm. Dyno Dynamics (Stock STi is 215whp) On pump gas, 20psi and 11.9 AFR, 55F ambient temp, 2073 ft above sea level. - Turbo system - Garrett G25-660 0.72 AR, custom rotated kit, Tial 38mm EWG, custom air to water (A2W) intercooler top mounted, cobb 3 port boost solenoid. - Fuel system - ID 1300cc injectors, Aeromotive 340lph pump, stock tank, Cosworth fuel rails plumbed in series, stock lines from tank to filter and then -6 AN after that, Fuel lab regulator. - Exhaust system - AFE 4-1 twisted headers (same as MAPerformance), Custom 2.5" upipe with a Y for the EWG, recirculated EWG to the downpipe, custom stainless 3" exhaust with a vibrant 18" resonator and magnaflow 14" muffler. - Short Block - EJ257 with stock crank, Manley turbo tuff I beam rods, Mahle powerpak 99.5mm/ 4032 low expansion alloy, Killer bee oil pan and pickup. - Heads - EJ257 heads with a die grinder port and polish by me, GSC S1 cams, ferrea springs, ferrea stainless valves stock size. - Controls - Megasquirt MS3Pro based plug-n-play unit for 02 wrx, some custom integration and extra sensors by me, LC2 wideband O2 at stock rear O2 location. - Drivetrain - 03 JDM 6 speed non DCCD w/3.90 final drive, R160 rear diff w/cusco LSD, DSS single piece aluminum driveshaft, DSS front OE replacement axles, stock rear axles, ACT 6 puck clutch w/sprung hub, ACT street lite flywheel. - Brakes - 4pot/2pot conversion, EBC yellow pads and GD rotors, ABS delete, Wilwood bias valve. - Suspension - Feal 441+ 1 way adjustable custom valved coilovers w/ spherical top mounts, bushings, lockdown bolts, STI control arms, Whiteline sway bars, Greddy Strut tower braces, the usual autocross stuff. I have some tidying up left to do, it's been a bit of a thrash to get it ready before the end of season for testing; so this winter will be busy. Plans are to do a few more handling mods to tighten it up, Perrin PSRS, Delrin bushings, upgraded trailing arms and lateral links, solid subframe bushings. And I'll probably end up putting in some kind of cage. Half or full I am undecided but I have friend who won't ride with me until I let him cage it, lol. Unfortunately I can't go to bigger brakes without losing the ability to run my street and winter wheels; the car needs better brakes for the punishment I put it through. Some pics are here, I'll post more pictures and more detail of the individual systems soon. Currently not utilizing AVCS, however that will come soon and fill in that curve a bit more. G25-660 vs. VF24 Progress shot of the engine layout
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Last edited by tsrapophis; 10-14-2019 at 02:59 PM. |
10-14-2019, 03:26 PM | #2 |
Scooby Specialist
Member#: 111755
Join Date: Apr 2006
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that dyno is intense. making power all the way to 7k!!!
nice wheel and tire choice. looks like u went up a size. what are you doing for Engine management? are you running carberry? |
10-14-2019, 03:34 PM | #3 | |
Scooby Newbie
Member#: 434904
Join Date: Nov 2015
Location: Spokane, WA
Vehicle:2002 Impreza WRX WRB |
Quote:
Running a Megasquirt MS3pro based setup. It's from their PNP lineup but I have had to make a lot of changes to it's original configuration. Love it so far though. Launch control is aggressive! |
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10-14-2019, 06:13 PM | #4 |
Scooby Newbie
Member#: 434904
Join Date: Nov 2015
Location: Spokane, WA
Vehicle:2002 Impreza WRX WRB |
Head porting detail.
I used a long nosed die grinder with a couple different size and shape rotary files to do the bulk of the material removal. Afterwards everything was smoothed out with a couple stages of sand paper flapper wheels. 80 and 160 I believe. All the pictures are progress pieces. I didn't get any finished pics. On the intake ports I port matched to the intake gasket, knife edged the divider and then carefully smoothed the transition on the back side of the valve seats. afterwards I polished everything until smooth, but not with the goal of enlargement. Above is a bit of before and after on the valve seats pretty rough stuff on brand new subaru castings. On the exhaust side, similar port match and valve seat smoothing procedure. I also paid extra attention to the rear most ports on cylinders 2 & 4. The rear most ports in the heads had quite a big kink in them compared to the nice and straight shots of the rest. So I took a decent amount of material out of the inside of the curve to try and reduce the backpressure. |
10-17-2019, 08:33 AM | #5 |
Scooby Guru
Member#: 158864
Join Date: Sep 2007
Location: Aussieland
Vehicle:2003 SOHC destroker |
So I just saw this from another thread. How come you didn't up the redline? and I presume you kept the 2.0L capacity? Also curious as to why just 20psi, was it way out of efficiency past it or did you just feel like that was enough?
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10-17-2019, 01:53 PM | #6 |
Scooby Newbie
Member#: 434904
Join Date: Nov 2015
Location: Spokane, WA
Vehicle:2002 Impreza WRX WRB |
Its a 2.5L and the redline is 7500, It was a miscommunication with the dyno operator. Its still right in the meat of the efficiency but as I'm chasing the dream of "reliable 400hp" I didn't want to lean on it more than I needed to after I achieved my hp goal. It already feels stupid fast with the turbo response and torque band. Next year I'll set it up with flex fuel and tune on ethanol for some big numbers but it's not high on my priority list. E85 is kind of scarce around here so I'll have to buy a barrel of Thunderbolt when I want to do that.
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10-18-2019, 01:49 AM | #7 |
Scooby Guru
Member#: 158864
Join Date: Sep 2007
Location: Aussieland
Vehicle:2003 SOHC destroker |
Gotcha. got a spool plot? very interested to compare to the old gtx3067
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10-18-2019, 02:44 AM | #8 |
Scooby Specialist
Member#: 29292
Join Date: Nov 2002
Chapter/Region:
SCIC
Location: Orange County CA
Vehicle:2004 WRX wagon silver |
are you running avcs?
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10-18-2019, 04:39 PM | #9 |
Scooby Newbie
Member#: 434904
Join Date: Nov 2015
Location: Spokane, WA
Vehicle:2002 Impreza WRX WRB |
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10-18-2019, 04:42 PM | #10 |
Scooby Newbie
Member#: 434904
Join Date: Nov 2015
Location: Spokane, WA
Vehicle:2002 Impreza WRX WRB |
I am not running avcs yet. I've been having a difficult time figuring out how to make the factory hall effect sensors work with my MS3. I only recently learned that the factory sensors switch polarity at random, which my ecu is not equipped to handle. Once I get over that hurdle I'll be able to start using AVCS and then I'll post another dyno plot.
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10-22-2019, 07:58 AM | #11 |
Scooby Newbie
Member#: 428946
Join Date: Aug 2015
Vehicle:2008 JDM WRX |
Hey man thanks for the info
Your max boost is 20psi and hitting 20psi @ 4500rpm ? |
10-23-2019, 04:45 PM | #12 |
Scooby Newbie
Member#: 434904
Join Date: Nov 2015
Location: Spokane, WA
Vehicle:2002 Impreza WRX WRB |
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10-23-2019, 09:03 PM | #13 |
Scooby Newbie
Member#: 428946
Join Date: Aug 2015
Vehicle:2008 JDM WRX |
Cool.
I have a 2.0L 4EAT max RPM 7000 My dream turbo is the G25 660 I was wondering if I should go for the 0.49 T25 A/R or the 0.72 Vband A/R.. Not sure if the 0.49 A/R would be too small tho |
10-24-2019, 12:34 PM | #14 |
Scooby Specialist
Member#: 29292
Join Date: Nov 2002
Chapter/Region:
SCIC
Location: Orange County CA
Vehicle:2004 WRX wagon silver |
i think think the 49 might be okay since youare not really going for ultimate power. if you want a better flowing turbo maybe the 550 would be a better choice.
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10-24-2019, 12:54 PM | #15 |
Scooby Newbie
Member#: 428946
Join Date: Aug 2015
Vehicle:2008 JDM WRX |
Thanks!
I kinda want something in between. Good power and good spool. Hence maybe the 660 with the .49 a/r What do you mean 550 is a "better flowing turbo" ? You mean that in comparison to the 660 ? |
10-25-2019, 11:19 PM | #16 |
Scooby Newbie
Member#: 428946
Join Date: Aug 2015
Vehicle:2008 JDM WRX |
Oh perhaps you mean that the 550 is a better spooling turbo than the 660?
I'm kinda looking more towards the 660 as I would like a little more headroom |
10-27-2019, 11:57 AM | #17 | |
Scooby Specialist
Member#: 459799
Join Date: Dec 2016
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G25-660 Daily/autox bugeye build.
Quote:
I would highly suggest steering away from the t25 .49a/r. You will end up with increased back pressure for very little gain. Overall EJ’s need to breathe to really shine the better the turbine flow the easier it is for the engine to breathe and make power. I gather that you want good spool, but I firmly believe that the .72 G25-660 would be the optimal setup for you; even with an EJ20. Good spool and should continue making power through redline even if redline is bumped up. |
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10-27-2019, 07:13 PM | #18 | |
Scooby Specialist
Member#: 29292
Join Date: Nov 2002
Chapter/Region:
SCIC
Location: Orange County CA
Vehicle:2004 WRX wagon silver |
Quote:
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10-27-2019, 07:18 PM | #19 | |
Scooby Specialist
Member#: 29292
Join Date: Nov 2002
Chapter/Region:
SCIC
Location: Orange County CA
Vehicle:2004 WRX wagon silver |
Quote:
Since your car is an auto it will be a dog til you hit 4000 or a little later with th 660. once again, youre not going to be happy going of r ulitmate power but you want something that is drivable. especially with an auto and that is why I suggested the smaller 550 with a larger turbine rather than a 660 with a smaller turbine housing also im assuming you have a usdm not a jdm running avcs is that right? |
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10-28-2019, 12:12 AM | #20 |
Scooby Specialist
Member#: 459799
Join Date: Dec 2016
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G25-660 Daily/autox bugeye build.
Yes. Good thing there isn’t much boost lost between shifts.... spool becomes less of an issue. Sluggish initially in first gear maybe? Still beats a manual running into the limiter and trying to go to second if we are talking all out pace. Might feel less exciting, but I’d bet it would move along nicely. |
10-28-2019, 02:13 AM | #21 | |
Scooby Newbie
Member#: 428946
Join Date: Aug 2015
Vehicle:2008 JDM WRX |
Quote:
I was also thinking of shooting for the .72 as it's in the middle of the .49 and .92 However my redline cannot be changed as it's limited by the TCU. Redline will always stay at 7000rpm |
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10-28-2019, 02:15 AM | #22 | |
Scooby Newbie
Member#: 428946
Join Date: Aug 2015
Vehicle:2008 JDM WRX |
Quote:
It has Dual AVCS. U20 heads. If I were to purchase Aftmkt cams, it would be the same part number as the 2008+ USDM STI |
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07-06-2020, 12:38 PM | #23 |
Scooby Newbie
Member#: 434904
Join Date: Nov 2015
Location: Spokane, WA
Vehicle:2002 Impreza WRX WRB |
Update, Went to the drag strip and ran some back to back 12.3's@115mph. pump gas + octane booster, street tires, 21psi of boost pressure. Best 60' was 1.7, datalogs show that my A2W intercooler is undersized for the horsepower, IAT's got up to 174. I have my megasquirt ECU programmed to progressively pull timing starting at 145 so I went through the traps with 9 degrees of ignition timing rather than the 13.5 I usually run.
To address this I am going to do 3 things. 1.) design and have built a custom intercooler using a Garrett A2W 750hp core, currently my 450hp china special is just not cutting it. I would go with their 1000hp core to be safe but I still want it top mounted and there are space constraints. I am fairly certain this is the issue, I have upgraded the intercooler pump and not seen any improvements in the rate of heat soak. I do not have a thermocouple in the intercooler coolant loop but to the touch it does not reflect the temps I'm seeing on my IAT's. 2.) Replace intake manifold with the 2005 NA impreza manifold. I've done some rough volume calcs and the 2002 WRX manifold I'm using is very small for the EJ257 I'm running. It's been great for response but the NA manifold has a better design IMO. I will also be converting to drive by wire (DBW) and moving the throttle body to the inlet of my W2A intercooler. This will allow me to directly bolt the intercooler to the intake manifold and gives me extra space to fit the larger intercooler. My concern with this is that I will increase lag. I did some rough calcs for intake manifold volume before and after these changes and I will go from a Intake manifold/engine displacement ratio of 0.91 currently to 1.45 with the new setup. Although this is a big jump, my current setup is very skewed towards response over power and so the new ratio should put me in a very normal range. 3.) Add and datalog a Turbo speed sensor. From initial turbo sizing calcs I am fairly sure that I am pushing this turbo into an inefficient zone for the low pressure ratio I'm running on pump gas. I may limit my RPM shorter if I am drastically overworking the turbo above say 7200rpm. |
07-07-2020, 01:22 PM | #24 | |
Scooby Specialist
Member#: 29292
Join Date: Nov 2002
Chapter/Region:
SCIC
Location: Orange County CA
Vehicle:2004 WRX wagon silver |
Quote:
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07-07-2020, 04:19 PM | #25 |
Scooby Newbie
Member#: 434904
Join Date: Nov 2015
Location: Spokane, WA
Vehicle:2002 Impreza WRX WRB |
Yes, The whole turbo kit is custom built by a friend. The idea was to be able to keep a top mounted intercooler so the charge piping was a short. Heres a couple from during the build.
https://photos.app.goo.gl/pDcUA7ogPw9Yj3pk9 https://photos.app.goo.gl/oj3QVTVh8MXZvQkG6 |
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