from what i have read the ea82 has a 92 mm bore. and an ej18 is obviously 1.8 liters.

 

according to other reading the ej18 bore is the same as the 20 and the 22

 

do ea82 turbo pistons swap in? what would compression ratios be.

 

if the ea82t is 7.7:1, and carb is 8.5, and spfi is 9.0(or is it 9.5) then...

 

what would be the compression ratios of a normak ej18, an ej22, and whatever various WRX motors there are.

 

and head interchangeability?

 

basically the idea in mind is to put an ej18 turbo in an rx as if it were the normal ej retrofit with stock wrx or mild aftermarket parts.

Miles,

NASIOC has some really good documented EJ18 turbo builds.

http://www.wac.addr.com/auto/obs/turbo/ejcalcs.html

is a good reference point for EJ hybrid motors and compression ratios.

This is a Comp Calculator that I made using excel. It’s a nice reference point taking some of the data from the above site and playing with it until it worked.

These are not real world numbers and some of the head/block setups may not bolt together.

I am not sure of the benefits of putting EA82 pistons into an EJ18 motor. Most people on NASIOC do the EJ22 head swap to lower compression. One drawback with using the EJ18 block is that there is no knock sensor. It might be possible to use an EJ22 harness/CPU and put a knock sensor onto the EJ18 block. Most people don’t bother and rely on emanage or other types of engine control to keep things working.

One drawback with using the EJ18 block is that there is no knock sensor.

here's what i did - get a knock sensor equipped (most are) EJ22 intake manifold that bolts to the EJ18 block. it was easy, on the EJ18 the knock sensor boss is there...and it was already drilled...and i think it was even tapped on mine....i did it a couple weeks ago and can't quite remember.

ej20* pistons and ea82 pistons share the same bore size but different connecting rod rist pin location and diameter of wrist pin....I can tell u for sure that ej18 pistons are smaller than ea82 pistons..

Kaz

EJ18 runs an 89mm bore, not 92mmm.....

ok, the ej22 head swap sounds like the answer. thank you

Here's a link to a Subiesport build, where they added a turbo to an EJ18.

 

http://mag.subiesport.com/index.php?option=com_content&task=view&id=108&Itemid=59&limit=1&limitstart=0

ok, the ej22 head swap sounds like the answer. thank you

 

what parts do you have available to you? the prev owner of my outback did the motor build as a "budget build" with extra parts he had. but it's a ej25 block, which I think has fitment issues in EA? bodies?

So why do you want to have a ej18 turbo.. Why don't run a ej20??

So why do you want to have a ej18 turbo.. Why don't run a ej20??

the EJ18 is easy to find and cheap. EJ20 is not. EJ18's can be bought for next to nothing.