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Old 09-15-2010, 02:53 PM   #1
Bishj275
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Default 2005 Vs. 2007 SOHC????

Anyone have any idea how much hp and tourqe differences there is between 2005 forester SOHC and a 2007 Impreza SOHC with AVLS? Do you all think that the gains from the 2007 out wiegh the cost of getting a few more wires added to my wireing harness???
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Old 09-15-2010, 03:07 PM   #2
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In short... no.

It's not even a 10hp difference at the flywheel. By the time you factor in drivetrane loss you've got 5 or 6hp to the wheels... which is nothing.
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Old 09-15-2010, 03:22 PM   #3
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Thats what i figured, i can proably get that much by getting my cams re profiled in the 2005.... anyone else has some input??? im looking for opinions
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Old 09-15-2010, 04:31 PM   #4
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Quote:
Originally Posted by Bishj275 View Post
Thats what i figured, i can proably get that much by getting my cams re profiled in the 2005.... anyone else has some input??? im looking for opinions
The 10 HP difference is between the switchover the SAE Net HP ratings. Correct me if my timeframe is wrong, but that means the actual difference in power is a bit larger.

The 10HP is from AVLS, which can only be used with an 06+ ECU. So unless you're planning on swapping the ECU, and deal with the pains of rewiring (whether or not you swap the ECU) you will have no benefit of AVLS on an 05 car.

However, from what I understand, once you start getting past intake/header and start tuning and looking into cams, AVLS becomes a big help.
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Old 09-15-2010, 04:50 PM   #5
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Originally Posted by formula91 View Post
The 10 HP difference is between the switchover the SAE Net HP ratings. Correct me if my timeframe is wrong, but that means the actual difference in power is a bit larger.
Interesting... hadn't considered that but it is a good point.

The new SAE certification standards went into effect 2005, but manufacturers weren't required to test by that standard yet. Switching over was all voluntary.

It all depends on when Subaru switched to the "new" standard. It also depends on if the older 2.5 would gain or lose power under the new standards.

Does anyone happen to know when that was done?

Speaking from my knowledge of GM's Ecotec engines, adding variable valve timing was good for about 20hp at the flywheel.

Last edited by RaineMan; 09-15-2010 at 04:59 PM.
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Old 09-15-2010, 09:18 PM   #6
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Well i am running a stand alone ECU, and was told that it can be wired to run the AVLS, However i just bought the 2005 Forester 2.5X engine, it is rated for 173 hp but i dont have the head ache of messin with the AVLS now. Anyone have the actaul hp rateing of the AVLS engine to make me kick myself in the @$$.....????
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Old 09-15-2010, 09:45 PM   #7
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From my knowledge, Subaru switched to EL headers for the n/a motors in 07. Atleast that is what happened with the 2.5i Legacys.
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Old 09-15-2010, 10:34 PM   #8
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i think they switched to el in 06
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Old 09-16-2010, 01:24 AM   #9
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Originally Posted by olsen726 View Post
i think they switched to el in 06
I can second 173 BHP and the switch to EL in 06. Also they did decide to use the new HP ratings in 2006, I remember this fully because they decided to increase the power of the STi that year, but it only ended up being "5" because they lost a bit through numbers in the switchover.

I remember the EL switchover because a bunch of you 2.5i lamers were complaining about how much it sounded like a Civic. I kid... I kid... sort of. lol
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Old 09-16-2010, 09:32 AM   #10
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Quote:
Originally Posted by RBP2.5i View Post
From my knowledge, Subaru switched to EL headers for the n/a motors in 07. Atleast that is what happened with the 2.5i Legacys.
\

THEY HAVE ALWAYS BEEN EL (well very close but NEVER UEL)
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Old 09-16-2010, 09:38 AM   #11
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I can second 173 BHP and the switch to EL in 06. Also they did decide to use the new HP ratings in 2006, I remember this fully because they decided to increase the power of the STi that year, but it only ended up being "5" because they lost a bit through numbers in the switchover.

I remember the EL switchover because a bunch of you 2.5i lamers were complaining about how much it sounded like a Civic. I kid... I kid... sort of. lol
The increase in Crank HP was due to the addition of the AVLS and a reworking of the internals. The The current stock manifold configuration changed to fit the relocation of the water pump, the new internals which resulted in a new oil pan, SOA aiming for higher emissions ratings meaning they moved the primary cat closer to the exhaust ports.

All these could not be achieved with the old style EL manifold if you swap the CBE on any EJ251 or Ej253 it will sound like any other import. The only N/A Subarus with a mostly UEL are 95 and older N/As
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Old 09-16-2010, 01:29 PM   #12
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\

THEY HAVE ALWAYS BEEN EL (well very close but NEVER UEL)

my 06 wraps around the passanger side.
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Old 09-17-2010, 08:14 AM   #13
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Quote:
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my 06 wraps around the passanger side.
Yes and the 05's went down the drivers side...that's one of the reasons why it's such a pain in the ass to do a header install on our cars
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Old 09-17-2010, 10:46 AM   #14
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Originally Posted by bmobs06 View Post
my 06 wraps around the passanger side.
Yes the same as my 2008 Legacy 2.5i but those primary length are as follows (both passenger sides are 25" the driver sides are 21" and 19" all @ 1.625" dia)
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Old 09-17-2010, 10:52 AM   #15
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Originally Posted by flightwatch View Post
Yes and the 05's went down the drivers side...that's one of the reasons why it's such a pain in the ass to do a header install on our cars
Yeah major limiting factor is the cat and its placement T 3 axis graph would best depict it: X-O2 reading Y-Values that are acceptable Z- Temp of catalyst

The temperature isn't a value in any table in the ECU but it plays into how the cat converts gases. HOTTER better Colder No bueno move the stock cat back 20 inches it will be 30 degrees cooler and still converting quite well but not per the rear sensor table values range in the ECU.

This is why the best fix is to "tune" for the rear O2 which is nothing more than an annoyance Get some logs to see what is actual, then adjust table values to accept the readings.
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Old 09-17-2010, 12:45 PM   #16
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Quote:
Originally Posted by GEE-OTTO View Post
THEY HAVE ALWAYS BEEN EL (well very close but NEVER UEL)
Quote:
Originally Posted by GEE-OTTO View Post
Yes the same as my 2008 Legacy 2.5i but those primary length are as follows (both passenger sides are 25" the driver sides are 21" and 19" all @ 1.625" dia)
So that in your opinion is not UEL? That's a 25% difference in primary lengths - in other words, that's unequal length.

Last edited by Patrick Olsen; 09-17-2010 at 01:06 PM.
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Old 09-18-2010, 04:12 AM   #17
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Technically, any non-zero length difference is going to be UEL. The thing is, the 97-05 header is every bit as UEL or EL (take your pick) as the 06+ header. When people call one EL and the other UEL, it's just stupid. What really changed is the style. The older header was basically a 4>2>1 style header with extremely short primaries. The new header is basically a 4>1 style header with longer primaries and a close-coupled cat. The differences in power and the shape of the power band come from the design type and the primary length, not UEL-ness vs EL-ness.

The total power difference comes from the different header, different cams, AVLS, and the different pistons. Frankly, none of that is as good as you could get aftermarket. Keep your 2005 motor, get a Techworks Engineering 4-2-1 High Output header, keep your stock cat, get a set of Delta 1000 Grind cams, make a hybrid intake, get a tune, and be happy.

Or spend like a 10th of that on suspension and be even faster.
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Old 09-19-2010, 12:47 PM   #18
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Cams got AVLS and our intake manifold was inlarged from what I have noted..along with EL headers and no my car doesn't sound like a Civic in no way way to deep to be a Honda. Also 06+ share similar rods and crank as the wrx well all three share the same crank. AVLS from my understanding is due to the cam profile could be wrong but has nothing to do electronically,,they sure do make a difference when boosted I'll tell you that for sure.
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Old 09-19-2010, 03:26 PM   #19
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Quote:
Originally Posted by VIsubi View Post
our intake manifold was inlarged
That happened in 05.

Quote:
EL headers
The 06 headers are no more EL than the headers from 05. We just covered this in another post recently.

Quote:
Also 06+ share similar rods and crank as the wrx
All modern 2.5L EJ engines share the same crank. The RS/2.5i has unique rods that are significantly longer than the turbo rods.
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Old 09-20-2010, 12:28 AM   #20
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Quote:
Originally Posted by VIsubi View Post
AVLS from my understanding is due to the cam profile could be wrong but has nothing to do electronically,,...
The AVLS is variable lift, which does affect the cam profile. It's actuated by a solenoid valve, so electronics is definitely involved.
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Old 09-20-2010, 02:05 AM   #21
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Be sure to check out the research I assisted with on the function of AVLS. It doesn't behave like people think it does.
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Old 09-20-2010, 08:47 AM   #22
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Yeah, I was just reading that yesterday. I was at sea when you guys had originally posted it, so I had missed it. Pretty interesting.
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Old 09-20-2010, 07:03 PM   #23
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I can feel it engage at around 4,000 rpm ever time seems heads start to flow alot better around there. As for intake manifold looks alot different than the 05 but I guess runners are the same. Rods stroke seem about the same. If longer the rpm redline is reduced but thought that was due to rev limiter adjustment and or valving.
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Old 09-20-2010, 08:31 PM   #24
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Quote:
Originally Posted by VIsubi View Post
I can feel it engage at around 4,000 rpm ever time seems heads start to flow alot better around there.
You are wrong, as you are almost every time you open your mouth. The AVLS crossover happens barely off idle. The change you feel around 4kRPM is partially the CL->OL transition and partially hitting the efficiency region of the cam profile.
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Old 09-20-2010, 08:49 PM   #25
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Quote:
Originally Posted by VIsubi View Post
I can feel it engage at around 4,000 rpm ever [sic] time ...
Actually, you can't. Read this (which is what williaty was referring to before).

Quote:
Originally Posted by VIsubi View Post
As for intake manifold looks alot [sic] different than the 05 but I guess runners are the same.
Here's an '05 2.5RS from over on rs25.com:


Here's an '06 2.5i also from rs25.com:


Ignoring the CAI, which part looks "alot [sic] different"? (I'll give you a hint - no part looks different, because they're the same exact intake manifold.)

Quote:
Originally Posted by VIsubi View Post
Rods stroke seem about the same.
Did you base that on looking at the engine or how it feels or what?

Quote:
Originally Posted by VIsubi View Post
If longer the rpm redline is reduced but thought that was due to rev limiter adjustment and or valving.
Double . There just might be something to what williaty said about you opening your mouth!

Last edited by Patrick Olsen; 01-23-2015 at 12:50 PM.
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