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i have ej205 block off from 02 wrx and ej20g heads off from BC.
can i mount ej20g head on to ej205 block?

Yes. But if the heads are from a BC (Legacy/Liberty) your compression will be low. I'm not 100% on what your compression ratio will be, but the chamber on those heads is noticably larger than the WRX heads.

IIRC, you will need to use the EJ20G crank sprocket to get the proper timing signal to the early ECU.

thanks!

I'm going to bump this thread because I'm doing the same thing right now (got a running block for free) and I have a few questions:

Headgaskets. What should I use? EJ205 ones?

Management. Will a EJ20G ECU power me just fine on low boost with a VF39? Or should I just buy another RobTune? I know it drops compression so I'm just wondering what's best..

Crossover pipe. Will me EJ20G pipe work with the 205 block?



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Which type 20g heads do you have?

Early HLA heads


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I forget the combustion chamber volume on those offhand, assuming you mean the legacy 20g. I'd use ej205 head gaskets even with those you'll have a fairly low compression ratio, sub 8:1.

robertpaige wrote: Management. Will a EJ20G ECU power me just fine on low boost with a VF39? Or should I just buy another RobTune? I know it drops compression so I'm just wondering what's best..

Crossover pipe. Will me EJ20G pipe work with the 205 block?



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HG: I'd double-check the 20G head's layout as the 205 may not line up well. Since the block is open-deck it's not as tough to match if it's the 22T's closed-deck? Bratman probably knows.....or Phyrra should, too.

(For my '96 EJ22e w/EJ22T heads I had to use a 22T HG as the NA version blocked the head's ports.)

EM: If you can verify the CR, Rob can make you a low CR tune - as he has one avl. for the EJ22T/DOHC combo that is about 7.5:1...that is Best, IMHO. But the EJ20G ECU will work if you don't have/want to spend the $$. Assuming you have the 440 injectors.

X-over pipe: The 205's have the Oil Cooler, which may interfere w/the pipe? A 205 X-over should be avl from NASIOC cheap....although shipping may be $$.

From another post on here - Legacy RS EJ20G heads - HLA?



GL,
Td

It's actually a Ver 1 closed deck 20g (that blew). I'll have to get some info on the cc volume. I have an oil cooler so the headers should be fine. And If Rob can make me a low CR tune I'll run 550's.


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Tangent/related...do WE (LC comm.) know if the Subaru closed decks all use the same port 'arrangement' - coolant/oil jackets? Meaning the HG from a 2.2T closed-deck would match a 2.0G closed-deck, except for the cylinder bore being wrong, and therefore not interchangeable?

wtdash wrote:Tangent/related...do WE (LC comm.) know if the Subaru closed decks all use the same port 'arrangement' - coolant/oil jackets? Meaning the HG from a 2.2T closed-deck would match a 2.0G closed-deck, except for the cylinder bore being wrong, and therefore not interchangeable?

I used ej22t HGs on my 2.0 block with the wrx ej20g heads for a few years.


I agree with using the ej205 head gaskets if they don't block holes in the heads. Since the ej205 pistons don't protrude the deck, you'd be better off gaining a little compression with their thinner gaskets.

Impreza 20g heads have 49cc combustion chambers, ej205 gaskets will leave you right at 8:1 compression.

So, 205 gaskets will keep 8:1 ratio?


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robertpaige wrote:So, 205 gaskets will keep 8:1 ratio?


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Sounds like you're saying you have Legacy ej20g heads. The compression with the ej205 gaskets will be below 8:1

Edit: Marnix's compression ratio chart says an ej205 block with the ej205 gasket and legacy ej20g heads makes 7.3:1. Swap those heads for wrx ej20g and it's 7.9x:1 with ej20g/ej22t (aka 1.37mm) gaskets, or 8.3:1 with ej205 (.80mm) gaskets.

Okay, so 7:3:1. I'll see what Rob can cook me up. Or I'll go ESL and have it tuned. But I really like the RobTune awhole lot.


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