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Old 02-01-2014, 11:09 PM   #1
spyrule
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Join Date: Sep 2009
Chapter/Region: E. Canada
Location: Ottawa, Canada
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2006 Impreza 2.5i
Crystal Grey

Default N/A Engine build questions...

Ok,

So I'm doing some research and I have a few questions... but first the details:

06 2.5i (4EAT)

I do NOT plan on turbo'ing this car (maaaaaybe a SC if I could find one cheap, but otherwise, strictly N/A). So I'm planning to build with N/A in mind.

Things I already have, but have not installed:
OBS header with High Flow Cat (not yet installed)
Frankenstein Intake (not installed)

Why:
I've got an oil-leak between the block and the transmission bell, only under acceleration. plus I'm about 20k short of needing to do my timing belt. I'm gonna have to pull the block to fix the oil leak (assuming it's not a HG leak).


Initial plan:
So I'm thinking I'll buy a shortblock, put in some improved N/A heads, faster cams, good HG and Gates timing belt, lightened crank pulley, IPT High-Stall TQ, 4EAT Shift kit.

Unfortunately, I do not have access to a garage to do the work myself, so I'd need to be able to give it all to a local mechanic and have it done.

Obviously, I'd like to keep this build simple, to the point, and not complicated (as much as possible).

I'm thinking TWE Stage 2 Cams with TWE Valve Spring/Titanium Retainer kit for the heads...

As for pistons, I have no clue, as I am only starting my research.

I'm thinking of maybe going higher compression pistons (maybe TWE Race N/A pistons 12.5:1 but with maybe Turbo HG to bring down the compression...) to get a little more power, but I'm not sure if this is such a good idea.

Your thoughts/suggestions are very much welcome.

Also: Please don't tell me to sell the car and buy a WRX... With the engine going, I would, but it's just not worth much on the resale side as it is.
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Last edited by spyrule; 02-01-2014 at 11:16 PM.
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Old 02-02-2014, 06:14 PM   #2
MoreChuChu
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Default

I don't recommend doing any builds on the N/A engines, because the power gained even with tens of thousands of dollars invested is still miniscule. If you can't live without it though, there's no replacement for displacement (except boost).

Seriously though, unless you've had a catastrophic failure, a new shortblock won't be necessary. Just cams, pistons, and some head work. That's all you really can do to these N/A engines.

Again, don't expect much.
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Old 02-02-2014, 07:09 PM   #3
spyrule
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Crystal Grey

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No, I fully realize that my gains will be minimal at best (I'm hoping 20-30HP), but since I'll be doing an engine refresh, I expect to be somewhat better then a 9 year old engine (whatever my HP is now at this point).
I'm short of having a catastrophic failure, but I wouldn't be surprised if something major occurs in the next 3-6 months. The car has been exhibiting some odd issues, not to mention the oil leak that I cannot find the source (other then it seems like it's coming from between the engine block and the transmission housing bell).
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Old 02-02-2014, 07:19 PM   #4
Paul
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Oil leak is proly the rear main seal. I also suggest you do NOT build the motor. Replace the seal and move on.

You will spend THOUSANDS of dollars for only 20-30hp and thats best case scenario. Worst case would be you spending all that money then having a issue after the rebuild....do some searching and you'll realize that happens often around here and not worth the risk IMO
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Old 02-04-2014, 12:20 AM   #5
spyrule
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Default

So, if that's the case... which of the two options would you do:

Swap in a JDM N/A v9 block (unsure of the milage):

or, brand new OEM EJ25 N/A shortblock, and TWE Cams & spring kit in my existing heads (price diff is ~$800 more than the JDM swap).
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Old 02-04-2014, 07:56 AM   #6
atomicfire
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Take the engine out, re-seal it, clean it up, put in cams if you really want, and put it back in. Even if you rebuild it with high-compression pistons, headwork, cams, all that and assuming all of the labor was free so you would only spend about $1400 on parts, you would only end up with a ~10hp difference and you would still get murdered by a stock WRX.
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Old 02-04-2014, 09:10 AM   #7
spyrule
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Crystal Grey

Default

I'm not really caring about comparing it to a WRX/STi... I KNOW those will be faster. Yes, I'd like to make this as torque as possible only for auto-x reasons, but that's for my own fun, not for actual competition.

This is currently my DD, and since I'd get nothing for it without an engine, I'd rather swap it to a good reliability state, maybe with a little more power or tq (or really just faster revs is fine too). THEN drive it until the body dies. I'll own this car outright in 2 months, so thats why I'd rather keep it then junk/toss it, and start over for payments (I have money, but it's all going into a house in the next year or so).
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Old 02-04-2014, 11:36 AM   #8
Paul
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Twin Scroll 2.5XTR EJ207

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Quote:
Originally Posted by spyrule View Post
So, if that's the case... which of the two options would you do:

Swap in a JDM N/A v9 block (unsure of the milage):

or, brand new OEM EJ25 N/A shortblock, and TWE Cams & spring kit in my existing heads (price diff is ~$800 more than the JDM swap).
neither..lol

Re-seal and move on. Theres nothing wrong with your motor other than a leak. If you want more power throw some cams in.


Quote:
Originally Posted by atomicfire View Post
Take the engine out, re-seal it, clean it up, put in cams if you really want, and put it back in. Even if you rebuild it with high-compression pistons, headwork, cams, all that and assuming all of the labor was free so you would only spend about $1400 on parts, you would only end up with a ~10hp difference and you would still get murdered by a stock WRX.
+2!!
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Old 07-24-2014, 02:39 PM   #9
scrambled beezer
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My 05 is doing all of the above and i am in the exact same boat as you.

- almost 10 year old subie (driven like an angry teenager behind the wheel)
- oil leak at bell housing
- exhibiting odd behavior mostly lagging on hills (slight reduced torque and power)
- 207K miles and due for timing belt at 220K

Debating either pull and reseal my engine swap a new clutch in and plunk it back in the hole.

Or get a JY engine and do the following - reseal, timing belt, water pump, thermostat, stage 1 or stage 2 cams, clutch swap, engine swap.

Swap - time reduced for my daily driver by doing the JY engine.

What odd behavior is yours exhibiting?
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Old 07-24-2014, 03:06 PM   #10
spyrule
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Member#: 222703
Join Date: Sep 2009
Chapter/Region: E. Canada
Location: Ottawa, Canada
Vehicle:
2006 Impreza 2.5i
Crystal Grey

Default N/A Engine build questions...

No odd behavior besides the annoying oil leak. At this point i should mention that i got offered a trade-in deal that put me $500 above a repair-sell value, so ive traded for a 2015 wrx...
Which im still waiting for delivery.



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Last edited by spyrule; 07-24-2014 at 03:13 PM.
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Old 08-10-2014, 07:27 AM   #11
spyrule
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Member#: 222703
Join Date: Sep 2009
Chapter/Region: E. Canada
Location: Ottawa, Canada
Vehicle:
2006 Impreza 2.5i
Crystal Grey

Default

So nix the trade in... 😡, back to getting the car completely repaired.


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