N/A Build Plan suggestions please

[Smitty911]

I'm not a Subaru guy at this point, but still a Factory Five fan.

I didn't get the Cobra, because size 13 feet with street tennis shoes didn't fit. Hopefully they will in the 818.

Now I'm thinking about a N/A build, I like nice linear power output. I'm thinking 2.5 but which years? I've read the '06-'07 has better brakes and tranny, true?

I'll have the motor freshened up and add all the bolt on stuff (Cams, Headers, Intake, etc. etc.) before it goes into the car. I read the thread on Subaru site for around 200 to the wheels. That should be good for starters, but long term adding a turbo.

So what does this early version of a N/A motor need to be able to add a Turbo (Still will be looking for linear power - If Possible) down stream.

Thanks, I'd like to start sourcing some parts to get cleaned, plated/coated before I need them.

Smitty

[riptide motorsport]

I'll follow this closly as I'm in the same boat......good tread.

[StatGSR]

You don't want to do an NA build then do a Turbo build they do not work together in fact one is basically the opposite of the the other.. If your really looking for reliable Turbo power, you do not want to use an originally NA motor to get it. If you decide to go to a from a NA engine to a Turbo engine, then I recommend you swap engines, or be prepared to break several NA engines by throwing a Turbo on it....

[shinn497]

According the phyrra, the first generation legacy gt motors could be turbo'd. These are also possible donors, but check his thread to make sure.

[Silvertop]

I'm not a Subaru guy at this point, but still a Factory Five fan.

I didn't get the Cobra, because size 13 feet with street tennis shoes didn't fit. Hopefully they will in the 818.

Now I'm thinking about a N/A build, I like nice linear power output. I'm thinking 2.5 but which years? I've read the '06-'07 has better brakes and tranny, true?

I'll have the motor freshened up and add all the bolt on stuff (Cams, Headers, Intake, etc. etc.) before it goes into the car. I read the thread on Subaru site for around 200 to the wheels. That should be good for starters, but long term adding a turbo.

So what does this early version of a N/A motor need to be able to add a Turbo (Still will be looking for linear power - If Possible) down stream.

Thanks, I'd like to start sourcing some parts to get cleaned, plated/coated before I need them.
the engine.
Smitty

From everything I've read in this forum -- The comparatively weaker earlier transmissions really shouldn't be a problem unless you are planning on extracting huge sacks of horsepower from your engine -- well above 300--, so you probably needn't worry too much about that issue.

I'm probably going to go NA as well, unless I find a really good deal on a WRX donor -- so I'll be looking for an '02-07 Impreza RS 2.5 donor car in order to achieve the most compatibility. Probably an '02 or '03 with a damaged body but sound mechanical components in order to keep the donor car costs affordable. Then the same route you talk about with cams, intake and other bolt-ons being part of the equation. And an ECU tune.

I know it is possible to turbo an NA motor -- but I kind of agree with other responders that this is probably not the best way to go. Better to use an engine with components in it that were originally meant for turbocharging.

[Smitty911]

Ok, so a '02 - '07 Impreza RS. There isn't one year that has better "parts" ie - Brakes, tranny, half-shafts, seats, Gas by wire, ECU, Gear ratio, etc. etc.?

I'm assuming that a Turbo motor is similar in build to a Blown motor. Lower Compression, different cam profile?

So staying with a stock compression ration for the "main" motor components means changing cams and adding Turbo system. If you have to build custom piping and inter-cooled options than your really not talking about a huge undertaking.

My initial thoughts are Bone stock, get her running and drive for the good months (in Cali that's 9 months out of the year). First year winter project, yank the motor and get it re-built and ECU Tuned. Looking for at least 175 at the wheels. This is based on riding in a 160 Flywheel Horse powered Porsche 914, which was HUGE Fun.

Depending on how the rebuild performs, it may never see a turbo, but if I get to used to the power to quickly, it will have to stepped up.

Smitty

[Xusia]

According to PhyrraM's thread, you can add a turbo to the early motors, but you are limited to the parts bin - including the turbos - from those early years.

From what I understand, if you plan to go NA first, then either add a turbo or swap for a turbo engine later, you'll want to use a WRX wiring harness to start off with. Otherwise you'll need to swap the wiring harness later, because apparently the NA wiring harness can't support the turbo.

[305mouse]

The compression in the turbo motors is lower than that in the N/A motors. I would not turbo a late model N/A motor, ie 02-07 or newer. I guess you could pull the heads and put on a thicker head gasket to slove that. I would turbo an older 2.2 engine with the closed deck block. In conjunction with everything else needed, you would have to run oil line and from the turbo, unless you went with a turbo that didn't use a serperate oil feed.

[Oppenheimer]

If your N/A goal is about power delivery (as opposed to just saving donor costs), and you want more power than can feasibly be generated from the 2.5 RS, what about a blower? Does anyone make such a kit for Subies?

I know there are some here that want to solve this equation by getting the flat 6 to fit, which would be cool if that is a realistic option. If its not, might a blown flat-four be a suitable alternative?

[Smitty911]

Blower could be nice not the crazy Turbo hit. I worked with a guy whos dad is the Ownre and designer of Hampton Blowers. Check them out. He called about getting a setup for my Porsche 914. They have a smaller one ready for a 2.0ish motor.

Might have to check that out.

Smitty

[StatGSR]

According the phyrra, the first generation legacy gt motors could be turbo'd. These are also possible donors, but check his thread to make sure.

there were no first gen GTs, they were all SOHC NA 2.2s or SOHC Turbo 2.2s (ej22t closed deck), First gen models included L, LS, LSi, and SS




According to PhyrraM's thread, you can add a turbo to the early motors, but you are limited to the parts bin - including the turbos - from those early years.



well you can turbo any engine... and no you are not limited to any sort of "parts bin" atleast not mechanically, electrical is a differant beast.



I would turbo an older 2.2 engine with the closed deck block.

the old 2.2 with the closed deck block was already a turbo motor (found in the old Legacys SS), All 2.2 NA engines are open deck



Blower could be nice

A few blower builds have been done, most are homebrew with old eatons, but there is a company in austrailia that makes a centrifugal kit for the 2.5rs. I think somebody might be making a Rotrex kit these days too (they are my favorite).

[Xusia]

PhyrraM did specifically state the limiting factor when dealing with the older motors was electrical. Sorry I wasn't specific enough for you! LOL :)

[PhyrraM]

PhyrraM did specifically state the limiting factor when dealing with the older motors was electrical. Sorry I wasn't specific enough for you! LOL :)

Specifically, sometime about 2000-2002 the cam and crank timing signals and pickups changed. The crank wheel can be swapped between the two, but the cam sprockets cannot. (So any block can be considered for any build, however heads must be compatable with the chosen ECU/harness). There are also specifics on the throttle position sensors that would need attention, but usually work themselves out because only certain intake manifolds fit certain heads.

[NonProfit]

A few blower builds have been done, most are homebrew with old eatons, but there is a company in austrailia that makes a centrifugal kit for the 2.5rs.

The Raptor Superchargers (http://www.raptorsc.com.au/models.php?id=6) look sweet but are not cheap. One guy took the unconventional approach of mating up an Eaton M90 from a T-Bird to his '06 Impreza over a long weekend. This guy has some skilz and ended up spending a mere $460 (http://www.rs25.com/forums/f7/106812-spuds-definition-ghetto-rigged-m90-supercharger-build-thread-lotsa-pics-4.html#post1687684) (+$7 in spray paint.).
9045

It's an interesting, if not long-winded read (http://www.rs25.com/forums/f7/t106812-spuds-definition-ghetto-rigged-m90-supercharger-build-thread-lotsa-pics.html). At one point he ran out of O2 and, not wanting to stop the progress, fired up the BBQ to get the job done.
9046

[StatGSR]

yea, there are also several side mount eaton M62 builds out there like the picture below

http://i131.photobucket.com/albums/p310/anothernord/IMG_3605.jpg
http://i131.photobucket.com/albums/p310/anothernord/IMG_3467.jpg

[Smitty911]

So it appears that just purchasing a Side Hit Suby N/A Impresa 5 speed makes the most sense.

Yank the motor, rebuild short block, send heads and intake to Extrude Hone, rebuild heads, add headers, cams,etc. and should net close to 200ish.

That's where I'm leaning - is there a favorite year for Impreza's?

Smitty

[StatGSR]

I would recommend one new enough to have the SOHC 2.5.

[Smitty911]

I would recommend one new enough to have the SOHC 2.5.

Thanks, seems like there are quite a few that have been totaled by Insurance companies; from hail damage to front end hits.

I'll track down what year. But why the SOHC?

Smitty

[PhyrraM]

....to front end hits.
.......But why the SOHC?

Smitty

Be careful of front hits. The 'engine in front of the wheels' layout of the Subaru, combined with a timing belt, makes the motor more likely to be damaged in a front hit. If the timing covers are damaged, check for signs of collateral damage. Even on non-interferance motors, if the valve is open from cam position, the piston can smack it if the belt gets wiped out.

The switch from DOHC to SOHC (on the 2.5 N/A) was 2000 (1999 for the Impreza). The SOHC is simply a more modern, better flowing design.

[projectrally]

All the NA 2.5L motors were SOHC. DOHC was reserved for turbo motors only. That changed with the newest generation,but displacement also dropped to 2.0L, as did power.

For the 2002 - 2007 MY impreza, there's very little difference in years. The car received a very modest power output change of about 2hp in 2005 or 2006, but I'm not sure if that was due to an engine recalibration or a revised testing method. Either way, it was a minimal bump, and not worth narrowing your search. Everything else that you'd want for the 818 swap were unchanged during the model years.

The SOHC motor makes decent power and great torque. Compared to the 2.0 turbo in the 02 - 05 WRX, the 2.5L NA motor is much torquier off the line and easier to live with around town. My guess is that this would be perfect in the 818 if you were looking for a really affordable build. That said, if you're planning to turbo the car later, you'll spend less money in the long run looking for a nice 06-07 WRX with the 2.5 turbo motor. Power output isn't much changed from the 2.0, but the power delivery is much more linear. Still feels like a turbo motor, but much more drivable.

Likewise, adding power to the 2.5 NA motor is a prohibitively spendy proposition to get anywhere near 200hp, at least in terms of buying a WRX as a donor. Not trying to talk you out of the NA build...

[Smitty911]

Be careful of front hits. The 'engine in front of the wheels' layout of the Subaru, combined with a timing belt, makes the motor more likely to be damaged in a front hit. If the timing covers are damaged, check for signs of collateral damage. Even on non-interferance motors, if the valve is open from cam position, the piston can smack it if the belt gets wiped out.

The switch from DOHC to SOHC (on the 2.5 N/A) was 2000 (1999 for the Impreza). The SOHC is simply a more modern, better flowing design.

Front ends, seems I've seen mostly straight on impacts, of course I'd want to ensure the motor never had contact from the collision. I like to find a side punched or rear ended one. For the 2002-2007 there are probably enough running ones around to make it a non-issue.

Thanks for the info.

Smitty

[StatGSR]

All the NA 2.5L motors were SOHC. DOHC was reserved for turbo motors only. That changed with the newest generation,but displacement also dropped to 2.0L, as did power.

wrong... the first NA 2.5s were all DOHC, it can be found in all second gen legacys, the 98 2.5rs, as well as the 98 foresters.... the NA DOHC is the EJ25D



I'll track down what year.


anyway, i would go with the EJ251 which is the the SOHC that also uses a MAP sensor insted of a MAF sensor... i hate MAFs... it is found in the following
Usage:

Impreza 2.5RS, 2.5TS 00-04 (US)
Impreza Outback Sport 02-04 (US)
Forester 00-04 (US)
Legacy 00-04 (US)
Outback 00-04 (US)
Baja 03-05 (US)

[Silvertop]

. ...........The SOHC is simply a more modern, better flowing design.

And less expensive to tweak with hotter cams by about half (only two cams to replace instead of four)!

[StatGSR]

And less expensive to tweak with hotter cams by about half (only two cams to replace instead of four)!

This! i never said it our loud, but that is one of the other great reasons to use the SOHC 2.5.

[wjfawb0]

I ran a 2005 STI into a ditch at 25mph a couple years ago, and it ended up totaling the car. The core support took out the timing belt at several thousand RPM. The STI headlight assemblies were quoted at ~$800 each, and as you can imagine about everything on an STI is outrageous when priced by subaru.

[metalmaker12]

The impreza 2.5 with a set of forged pistons with 12:5:1 compression and a stand alone ecu or reprogramed stock ecu would get you like 220hp and be what you want. Problem is it has no turbo future. If you want both you keep the impreza stock and build it turbo later.

[StatGSR]

The impreza 2.5 with a set of forged pistons with 12:5:1 compression and a stand alone ecu or reprogramed stock ecu would get you like 220hp and be what you want. Problem is it has no turbo future. If you want both you keep the impreza stock and build it turbo later.

^ a build like that is going to cost you 3-4K so i would recommend knowing if you want to go turbo or not before doing a NA build out.

[Smitty911]

^ a build like that is going to cost you 3-4K so i would recommend knowing if you want to go turbo or not before doing a NA build out.

I could live without the turbo, if the motor is actually putting out some power.

Do you really need the 12:5-1 Compression ration? I live in SoCal, 91 octane is all we get. Although an E85 is opening on the corner from work.

Smitty

[projectrally]

wrong... the first NA 2.5s were all DOHC, it can be found in all second gen legacys, the 98 2.5rs, as well as the 98 foresters....

I know. I used to own a DOHC 2.5rs. I should have qualified my answer: all 2.5 NA motors during the accepted 2002-2007 single car donor range are SOHC.

[shinn497]

Thanks, seems like there are quite a few that have been totaled by Insurance companies; from hail damage to front end hits.

I'll track down what year. But why the SOHC?

Smitty

Where would you find these?

[BrandonDrums]

Where would you find these?

Here's one site for starters
http://www.salvageworld.net

For more, just google search "salvage title cars" or any variation there of and click away. Really there are only a couple good salvage title auction sites but I don't know them by hand.

[leetfade]

Most people have already covered it, but the last thing you want to do is do an N/A build then go turbo. However, if you are looking for a drop-in to run for now (won't be 200whp) then that's fine, but look at changing pistons, head gasket to lower compression for turbo down the road. Add a proper turbo cam to increase air-flow in the head (different cam profile than N/A cams) and then start worrying about the transmission. ;-)

Agree with BrandonDrums. Find those insurance auction sites. I already have a friend watching a totalled 07 WRX with all rear-end / roll-over damage. No use to most, but the interior and engine bay look unscathed!

[Smitty911]

Where would you find these?

One I found a couple nights ago. https://www.iaai.com/ They are in several states, Private Purchase on some cars, Broker needed on others. WRX I've seen for 2,500.00 side punched.

Smitty

[leetfade]

That's the one I use. ;)

[Smitty911]

Is it just me or am I stupid?

Looking around for information on a N/A 2.5 motor lead me to read up on cams.

One Tuner (not to me named) had Stage 1, 2 and 3 level Cams for the SOHC motor.

Stage One $430
Stage Two $480ish
Stage Three $1300

I have trouble believing there is Three times as much material to remove (opposite in fact) which would require the HUGE jump in price.
I have trouble believing there is Three times as much R&D to change the profile a smidge.
I have trouble believing the Stage Two sells at a 10 to 1 ratio to get a better price from the actual grinder.

Can someone explain why the huge difference in Price for the same thing with a slightly different profile?

Thanks

Smitty

[StatGSR]

If your talking about delta cams or another regrinder, they probably have to weld metal onto the cam to get the stage three profile, vs just grinding down the base circle of the lobe to get the profile. that or the stage three comes from an all new blank cam

[Evan78]

Just post a link to the product page. I don't so a reason to not name them, it's an honest question and there shouldn't be a reason for defensiveness on the part of the manufacturer. They could just say "because we feel like charging $1300" and there wouldn't be anything wrong with that.

[Smitty911]

Just post a link to the product page. I don't so a reason to not name them, it's an honest question and there shouldn't be a reason for defensiveness on the part of the manufacturer. They could just say "because we feel like charging $1300" and there wouldn't be anything wrong with that.

You maybe assuming a level of maturity that may or may not exist with the Manufacturer, it's been my experiance that when questions, I get the it is what it is attitude and if I don't like it, I don't have to buy it.

Be that as it may here is the link.

http://www.techworkseng.com/Products/Subaru_Engine_Cams.htm

In correction my above statement the SOHC is only double.

Looks like I'll be putting a spread sheet together and posting it for review.

Smitty

[StatGSR]

^ I see, also i dont see a stage one offering from tech works for the SOHC on that page.

in any case be sure to talk to delta cams, I'm pretty sure their prices are better, and they are vary popular in the subaru community. They even have their own forum that you can use to ask them questions.