Cross Reference chart

[chevyman1968]

Hey guys,

I found this chart for cross checking different head and block set ups for Subarus. It shows the compression ratios for the different head/block combinations.

http://www.b4et.com/docs/cr_matrix.pdf

Enjoy!

[Wiscon_Mark]

Nice!

Added to the N/A engine threads of note.

[harrymaneuvers]

It doensnt mention the head volume for the Phase 2 2.2L heads... anybody know what it is? Either way it looks like my compression on the EJ251/EJ22 motor is between 10.4 and 11.4 to 1. :)

[86bratman]

Yeah, ej222 heads are 50cc just like the ej251.

[harrymaneuvers]

Um... excuse my ignorance here but then how does that make a high compression motor if the heads are the same size as the stock EJ251 heads?

[decke48]

according to the interwebs 97 ej22 are 41cc head 12cc piston
http://web.archive.org/web/200902282103 ... calcs.html (http://web.archive.org/web/20090228210321/http://wac.addr.com/auto/obs/turbo/ejcalcs.html)

[86bratman]

phase 1 ej22e is 42cc, so is the ej18. The phase 2 ej222 is 50cc. The ej18 and ej222 heads are both expected to have smaller combustion chambers than their larger counterparts, but they do not.

[decke48]

ok well according to the 50cc head and lets say 12cc piston dish. on a EJ251 block and EJ222 heads with .56mm thick 102mm bore HG your looking at 11.18:1 ratio
same thing with ej22e heads your looking at 12.97:1 ratio

[86bratman]

I'm still looking for the official specs, I've seen them but it's been quite a while and I didn't care to bookmark the page. But here's a quote from Jay Storm.


If anyone is looking for EJ22/25 hybrid headgaskets, I have a pair of Cometic "MLX" series gaskets that I won't be using. Why not you may wonder? Well, I learned something yesterday.

The phase II EJ222 (with internal headbolts) is exactly the same as an EJ251 head, except for the exhaust port being siamesed into the singleport we all know and love(to hate). The combustion chamber is the same, the valve placement and sizes are the same and the coolant passages are the same. If you put that hybrid gasket on, which has the phase I EJ22E coolant passages, they will not match at all on the upper portion of the cylinders.

Thank goodness my contact at Cometic happened to have a set of standard EJ251 gaskets hanging in his garage, so I can get this HCF back together today.

Another note, it won't be a HCF at all......the combustion chambers are the same, so all things being equal, it'll just have a more restrictive exhaust. :(


Jay

[chevyman1968]

Yeah, I found the chart when look at compression ratios. I am putting my ej25d heads on ej251 block. My heads are 46cc and according to the chart I am supposed to get a 10.4-10.9 to 1 ratio. Although I did get my heads decked the last time I had them at the machine shop. I am planning on using cometic ej251 headgaskets. The thinnest ones they sell. I think they are .026 once torqued down. Idk what that will get me as far as compression ratio.

[86bratman]

It really depends on how much was taken off the heads. I'd guess at least 11:1

[chevyman1968]

So, I would have to use 89 or up then wouldn't I? I don't really want to use higher octane gas unless I absolutely have to.

[86bratman]

I'd recommend it.