I think the starting question is...WHY do you want to replace/build the block before going with an STI turbo?

 

Strength and reliability.

Is there any way to swap in an Ej207 block and keep my usdm 205 heads and ecu?
I do not want a 2.5 or avcs.

 

Yeah you can do that fine. Just need to make sure the heads are matched to flow correctly to the block (may not be an issue like it is with a 2.5L)

I'd just start with a compression test on your current 2.0L block. If it's holding fine within spec, no need to spend a ton of extra money for a block swap. You're not exactly pushing a ton of power with any VF series turbo. The stock 2.0L if healthy, will handle a VF** perfectly fine (properly tuned and with necessary fuel upgrades of course).

 

I would just really hate if I spend over $1000 on an Sti Vf turbo, Sti tmic, injectors, fuel pump etc, flash the stage 3 map and blow my ej205 within a year.

What exactly is better about the ej207 than the ej205? Just the semi closed deck? Rods?
I read that the 2004-05 ej205 had a better oiling crank than the earlier 205, like the 207 crank?
Are the 205 pistons as strong as the 207 pistons? I do not want an increase in compression or displacement, but a little confused here :S

 

Supposedly the Ej205 has 8.0:1 Cr, as well as the Ej207 with 8:1 cr. But, they have different heads, correct?

Will my 2005 usdm Wrx ej205 heads on an ej207 v7 block raise, or lower the compression? Or would it somehow stay the same even though the heads are different?

Has anybody here run a v7 ej207 and usdm ej205 heads?

 

But unless you have an unhealthy engine to begin with or you beat the ever living piss out of it, you won't blow your engine within a year if you're just running a VF30/VF34/VF39/VF43/VF48.

All honesty though, I'd skip an OTS map and STI TMIC and go with a protune of some sort and a good aftermarket TMIC such as Processwest. You'll get better cooling efficiency out of that, and you will ensure the tune is working specifically better for your car.

I believe the ej207 heads are different in that they have AVCS, depending on which year/version STI they came off of. I don't recall when they began utilizing that technology. But in the grand scheme of things, it won't make all that much difference with a 0.1 increase in compression. You could probably utilize a thicker headgasket to offset that anyway. The difference between a semi-closed and an open deck block at your potential power levels also won't make a difference. The open deck 2.0L block is plenty stout.

I don't know enough about the internals to tell you which is better, but I do know enough to say that you don't have to worry about spending all that money to put in a different block, when the block you have will be fine (as long as it checks out with a compression or leakdown test, like I mentioned).

 

I understand that people have run vf3x turbos at around 300hp/tq on a completely stock ej205, and still going strong, which is cool as hell. But, I still want another block. Maybe to throw in "before stage 3", or possibly keep in my garage untill it's needed.

Just wondering if anyone know's if/how the compression will change, and also trying to find others that have put the ej207 block under their usdm ej205 heads. I'm not looking to MAKE more power with the new block, I just want a block that can hold way more power than I have.

 

To reiterate, the more power you build your engine to handle, the less reliable it will be. If you're worried about reliability, first thing you need to do is stay away from ****ty OTS maps and get a real tune.

 

This is silly.

The main strength of the EJ207 motor over the EJ205 IS the heads. The bottom-end is stronger, but you can just build the EJ205 block.

Other than that, the physical blocks are very similar in strength.

I really think you ought to do a bit more research.