pseudo SI Drive for BK w/ EJ20.fuel effecient=>Agressive

[LunchBox04V]

Ok guys and gals, I have made some choices, and have decided on swap an EJ20 into my BK ('99 Legacy Wagon L), and going for the deep sleeper look. However, it is my nature to do some in depth research. So, I have started with my first concept questions.

(This would be a dialy driver, nothing crazy, just some snap)

1.) Would it be possible to get a programable ECU (Hydra, AEM, etc.) that could have a switch in the cabin that could switch between a low boost MAP to a power oriented MAP?
*I have to believe that it is totally possible with a programable unit, but I thought that I would run the question past you folks.
*Any Stand Alone ECU's that you floks like let me know. I hear a lot of people are using the Hydra......

2.) Has anyone tried running and EJ20 close to N/A EJ25 or EJ22 power numbers to save fuel?
*I thought that reducing the boost on the EJ20 could save fuel, after all more air (more boost) would mean more fuel(mpg down). Somthing like 5psi or even less, aiming for 140-160 hp at the crank. I don't know if this would cause choking (compressor stall) in the stock turbo, or surge (I can never keep them correct which is which).

3.) Slightly different question, but while I have your attention.....What are the opinions on a water-air intercooler?
*Either from the JDM EJ20's, or an aftermarket. I would like to keep the non-scooped hood on the car (see picture). With a water-air intercooler, and the stock hood cause overly hot intake temperatures, and for that matter overly hot underhood temperatures in general due to reduced air flow? Or would it just be better to go with a stock GT hood (scooped) and just run a standard air-air intercooler (I thought that stock WRX air-air would not fit, plus I have a whiteline strut bar.)?

http://memimage.cardomain.com/member_images/1/web/2581000-2581999/2581248_14_full.jpg

Notes:
1.) Again this would be the daily driver, so nothing crazy in the mod department. That is no GT55 and no Front mounts IC's.
2.) The idea is to be a sleeper. No major exterior mods. That is 2005 WRX scoop, body kits, etc.
3.) The car does have a Whiteline Front Strut tower bar.
4.) If I am just nuts say so! lol :lol:
5.) It would be a full drivline swap too. Forgot that earlier. lol

That is all I can think of now. It will be a slow project, but it should be fun![/img]

[Huffer]

Here's the thing. If you have the right turbo, the right EM and the right tune, you will be as fuel efficient as your stock Legacy was. It's all about power delivery.

However - the issue is with the type of fuel you'll be using. Typically, you're running 91 octane on a stock WRX/Legacy GT boosted motor. Now with a few simple mods like an up+downpipe, intake and exhaust, plus the right tune, the factory ECU will improve the powerband, turbo spool up will be more responsive and the torque band will rise and flatten out.

All that means you will still have the same kind of NA response under 3000rpm but more power - which is still useful.

If you get the right balance of components, you can still pull 27+mpg on the highway. Plenty of people have achieved it.

Face it - you will always pay a little more for fuel because you are buying a higher grade.

Intercoolers - water/air ICs are fine to use - in fact in some cases they make more sense. The early Legacy RS engines (BC/BF chassis codes) used water/air ICs. Frankly, I would run an AWIC over a FMIC. However, a FMIC is preferable for a lot of people simply because it's simple. There's no fluid to exchange, you just route some piping. And with the flat four layout, you just throw one on top and run some tubing.

There is also nothing to say that you couldn't use a TMIC-sized FMIC and still have it stealthily mounted in the bumper - flip the intake manifold and you'd have shorter run pipe to make up for the drop in pressure that a FMIC usually induces.

One other thing to consider is this:

Going full standalone EM with a variable valve turbocharger as found on the Acura RDX... it changes diameter depending on throttle position so as to maximise efficiency and response.

[LunchBox04V]

Huffer thanks for the info. I totally forgot about flipping the intake. I guess that any tune would have a partial throttle map(duh). LOL funny that you mention a VG turbo. I was thinking about that. Let me think about that one.

[rougeben83]

Cobb AP, Utec have switches for different map settings.

AWIC is possible, you need to source a heat exchanger (some have used AC condenser, I was going to use a Mustang Cobra unit before I sold my setup). Use a Centriflo pup pump (used for commercial applications, RV's, etc) and wire it up.

A good FMIC setup will only drop 1-2psi though. Throttle response is what suffers.

[jg09]

You could run water/methanol injection and keep your lower octane fuel. Modified Magazine got 550 hp or so out of an EVO after turning up the boost super high (close to 30 p.s.i. IIRC). They ran it on 91 octane pump gas at that pressure with no problem. They just had to put in a different ignition to handle the motor's new found output.

[sexystover]

looking forward to how this goes because i plan to do the same in my BG, one question though, does the ej20 motor from a USDM wrx bolt up to a 5spd from a BG/bk?

[Huffer]

looking forward to how this goes because i plan to do the same in my BG, one question though, does the ej20 motor from a USDM wrx bolt up to a 5spd from a BG/bk?

yes.

[rougeben83]

as far as MPG is concerned...as long as you stay out of boost, you can get good mileage out of a turbo.

Ex. all highway, long distance trip, I averaged 25mpg.

If I'm :twisted: I average 17mpg. :wink:

[LunchBox04V]

Now don't hold your breath folks. This is going to be a slow project. I want to get all the info, then all the parts and do this right the first time. I am just starting the first phase, amassing the information. I plan to start getting parts around Feb-March. Install will happen a few months after that.
I did a little research on the VG turbo. Very nifty piece of tech. I don't know if it would be the best option, but I am still looking around at ideas. Maybe a different A/R on the Compressor, and the Turbine side. I am just looking at different ideas.
As far as ideas, I think that switching from a high MPG mode, to a High power mode might be hard. However, using a boost controller might be the best idea.
I would entertain any ideas though! Let them fly. A stand alone would be able to control the VG turbo, and different MAP's etc. So I guess I don't know the details. However starting with a rebuild of the trany and the bottom and top end of the EJ20 will be a definite start. lol

[chuckthefuk]

1) ecu

From what I'v seen with AEM / Hyrdra both are Computer programmable. Thus you must connect your computer your EMS through serial port and change the MAPS manually. It is possible to run a *script* that will change it on the fly through windows, but regardless theres no simple way of switching maps.

I'll give you some good news. I have a buddy with a GC8 V5 swap FMIC hyrda etc..

Before he got his hyrda. He running Sunoco 94 octane he was getting 550+ KM per tank. After his hyrda hes been getting much lower fuel economy due to higher boost, +600cc injectors etc..

With my stock EJ25D w/ new head gasket, seals, water pump, timing belt, etc and weight reduction + A/C delete I might be able to hit 550 km on a tank.. Average for me and some what aggressive driving is 480 km

I know everyones fuel consumption is different but we are all in the same range.

2) 227 @ 12-13 psi is what a stock ej20 runs.. You want to run 5 psi? I understand you want some snap but thats a tad low. 9-10 I can understand.
Theres psi/power calculators just search google.

3) Airflow / Coolers

If you want the stock hood setup with a TMIC its a very tight fit. Your better off running a FMIC behind your grilled bumper and spacing you hood w/ no hood rubber seal. In addition a FMIC will allow more turbo choices since you don't have to worry about the direction the turbo is clocked.

Also your strut bar isn't an issue

https://sl-i.net/FORUM/images/imported/2008/10/bc7JPG-2.jpg

- Chuck

[LunchBox04V]

Thanks for the insight Chuck.

Low psi EJ20 (3-5psi):
*Thought of that as a way of limiting boost, thus limiting my foot. lol A boost controller would be able to do that easy enough. I guess I was thinking that limiting the boost to 5psi or less would help strech the gallon.

I think that you guys are right with the FMIC. The right combo will have little psi loss. However, I would rather have the good throttle responce. Again this is going to be a daily driver. Target max at the crank *for now* is 300 hp. I know everone gets the itch for more, but that will keep me safe for now. lol If I want to go EJ257 later, and GT30R I can do that later. haha

I am really thinking that keeping it simple is a good idea. No VG turbo. Just a good hybrid turbo, with a responsive A/R would be nice. I would rather have hot 3-5000RPM band, than a flat out max hp. This is why I am thinking air-water IC. Not much IC hose to run, and would fit under the current hood. I think......

Oh, and the front strut bar. Can I turn it to have the bend go toward the firewall? Right now it goes to the front of the car.
http://memimage.cardomain.com/member_images/1/web/2581000-2581999/2581248_2_full.jpg

Well, the saga continues....... Some coilovers will be the first thing to go on the Wagacy once I get the money('04 STi Teins :grin: ). Never heard that line before right guys! haha

[Huffer]

You can flip that bar.

Look into a turbo with a properly balance shaft and lightweight blades. Newer ones have titanium blades for efficiency. They cost $$$.

Just forget low boost - it's pointless on a car that has lower compression pistons. Forget it. It is easier to adjust your driving style than to try to mod around it. You are far more adaptable than your ECU will be.

[rougeben83]

Thanks for the insight Chuck.

Low psi EJ20 (3-5psi):
*Thought of that as a way of limiting boost, thus limiting my foot. lol A boost controller would be able to do that easy enough. I guess I was thinking that limiting the boost to 5psi or less would help strech the gallon.

I think that you guys are right with the FMIC. The right combo will have little psi loss. However, I would rather have the good throttle responce. Again this is going to be a daily driver. Target max at the crank *for now* is 300 hp. I know everone gets the itch for more, but that will keep me safe for now. lol If I want to go EJ257 later, and GT30R I can do that later. haha


Have you read what I posted? You can get a UTEC with a map selector SWITCH on the dash to run up to 4 different maps if you want to. Boost can be modified via the electronic boost solenoid - in fact that's what its there for; you can limit it up the wastegate spring if you want to (8psi) if you're using a TD04 or have it bleed vacuum to whatever boost you want.

I think you're over thinking this problem. Plenty of WRX owners have had to deal with fuel consumption before; solutions are out there, its up to you to do some reading on what your options are.

[BigLooga1]

In my opinion,

no fancy shmancy maps and stuff, just drop in a WRX engine and be light with your foot. Besides the WRX engine will never get the MPG that the N/A 2.5 is getting, it's all about powa!

EDIT! Oh yhea, get a hood with a scoop, they were stock those years and non-turbo, it will still be a sleeper.

[LunchBox04V]

The more research I do the happier that I think I will be with a simple setup. Nothing to wild with switching MAP, though I am going to look into the UTEC. I am going to start looking at some turbo options. I had not heard of titanium blades. I was thinking ball-bearing and ceramic. Same size a the stock IHI or *SLIGHTLY* bigger. Again, looking for low lag, and fast spool. Has anyone messed with different that stock A/R's? I know that a lot can be done with lag and power with the A/R.
Thanks again for all the responce and help. Like I said this a little way off, but I wanted to start gather ideas now, so there are less problems in the future!
Oh, and on the low boost idea. I think that I am favoring a boost controller (a must no matter what) and setting it lower. And a light foot. I have been squeezing 35.5 out of the ol' girl now!

[rougeben83]

Gotta pay to play. If youre that concerned with gas mileage, keep that car stock...(and buy a WRX for power) :lol:

[LunchBox04V]

Oh I'm not that concerned! lol I was just trying to streck it a little bit. That's all. haha

[LunchBox04V]

Hell, I just might go for this level....... :lol:

http://videos.streetfire.net/video/Subaru-speedo-build-20G_103601.htm

Ah, I can dream.

[kunchris]

Done the same thing to my BG swaped a BC5 RS RA motor ej20G closed deck with AWIC very effective and stealthy check my build

[ouch1011]

Keep in mind that with a WRX engine, you are dropping the compression ratio considerably. Lower compression means that it won't burn the air fuel mixture as efficiently so you will get a drop in fuel economy right off the bat from that. And as rougeben said and I want to reiterate, 3-5 psi boost is probably not even going to be possible unless you swap out the wastegate actuator for one with a lighter spring. There is a limit to how you can go with your boost setting and odds are it is higher than 3-5psi, because a spring that light would tend to flutter under pressure. Boost controllers can only adjust up from what the wastegate spring is set at, so if the wastegate spring is calibrated for 8psi, that is absolutely as low as you can get the boost to be without using some other means of boost control (pretty much your right foot). Besides, 3-5psi on a low compression EJ20 is probably not even going to get you to stock EJ25D power output.

The beauty of turbocharged engines is that you can choose when you want to have gobs of power and when you want to have efficiency, and its all up to how far you bury your right foot.