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Old 01-22-2011, 08:27 PM   #1
Scooby Newbie
Member#: 269045
Join Date: Jan 2011
Default 06/07 Impreza 2.5i build compatibility questions/suggestions?

I currently drive a '96 Legacy Wagon but I'm planning on buying an 06-07, possibly 08-09 Impreza 2.5i in the future.

I want to do an engine build-up to gain a bit of power but more than anything to have fun building up the engine from a bare block. I realize "tuning" an impreza 2.5i isn't the most rewarding in terms of power-per-dollar, but again I just enjoy wrenching and I still want something that can be my daily driver with a little autocross on the side. The way I'm going about this project is a little different though... I'm not going to be doing this build in the normal fashion of buying the car then tearing the engine down and doing the work...

I should have a free EJ251 short block in the near future that has some rod knock, so my plan is to start with the engine, disassemble the short block and swap in some new rods or tend to the problem one. Add some used heads and get the cams ground, then maybe a lightweight flywheel or just lightweight pullies and of course replacing all of the seals and gaskets as I go.

Once I have the engine built up I'll start looking for an Impreza then swap the engines, add headers/exhaust and a tune and sell the removed long block.

The main advantage I see to doing it this way is that I won't have a car sitting in my garage without an engine needing payments and insurance while I take my time wrenching.

So on to my questions as I'm not as familiar with the new gens of Imprezas:

-If I build an engine up with an older set of heads (non-avcs), will it swap into a newer Impreza (06-09) without any problems? From what I have read you can disconnect the avcs solenoid on the newer cars and it doesn't affect much other than a slight power loss above whatever the rpm is that the solenoid activates.

-I've read that delta 1000 cam grinds don't do much, and that delta 2000 cam grinds throw codes, whats the word on the 1500 grind? I'm leaning towards the 2000 grind, but that'll probably mean new valve springs and what else?

-Suggestions for pistons/block work?

-What else should I do while I've got the engine torn apart, and are there any major flaws you can see in my plan?

Thanks in advance, I'm really looking forward to this project!

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Old 01-23-2011, 12:28 AM   #2
Scooby Newbie
Member#: 219094
Join Date: Aug 2009
Chapter/Region: MWSOC
07 95L-RS Rally
custom OBS paint


go with higher compresion pistons, and maybe a stronger ballanced rotating assembly, wiseco pistons are great, and can special make anything you want, nothing crazy if its DD.. and set it up for e85, its just 30% bigger injector and a 255 walbro pump, make more power, and burn cooler. rev it out to 7500 rpm, and get a 10mm oil pump from any turbo for oiling security.

the 06+ have variable valve timing, so the computer will look for that, might just take an open source tune to get rid of that.

if your going with delta cams, ship them your heads, and spend a few mins on the phone and explain what you want, and your build and they can custom grind your cams, maybe a "2300", or "1900" would work best, and nothing against rallitek, but they sell delta cams, at a mark up over what you can get direct..

this may sound like a bit of work, and lots of $$ but build it rite the first time and be happy. i am building a similar motor, more on the race side, with a 257 block, and running E98 race fule...
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