2.2 heads on a 2.5, and vice versa..

where did that thread go?

what are the pros/cons of putting 2.2 heads on a 2.5

and pros/ cons of putting 2.5 heads on a 2.2?

[Okin DaVanh]

I think the later has been done. 2.2 with 2.5 heads.... frankenmotor style, but the twin cam cam into question as well as some other emissions stuff. Reason was attempting this last I knew. Don't know if you want to ask him tho. :smt002


Shoot Chuck a PM and see if he can give you a heads up.

[jey]

2.5 heads flow really well, especially the SOHC heads.
2.2 heads are restrictive, especially the single-port variety.
Can't see any performance reason to run 2.2 heads on a 2.5 shortblock, unless you already have a regular EJ22 and are looking for an upgrade in displacement or changing the compression ratio.
Hybrid setups in general can produce interesting compression ratios - good for NA builds (high compression) or turbo builds (low compression)

[Scimitar]

Grafton put 2.2 heads on a 2.5 in his build thread (https://sl-i.net/FORUM/viewtopic.php?f=11&t=19394). I thought it was a pretty interesting setup.

[Baddog]

We are looking to swap the Dual Port EJ25 heads to my Single Port EJ22. And he will be using a 95's EJ22 Dual Port Heads on his 2.5 (and then my single ports would go onto the 95). We were looking to see what kind of power gains (if any) we would get. I know the Dual Port 2.2 Heads on the EJ25 does give it a good boost in power.

But what about the Dual Port 2.5 Heads on the 2.2?

[Grafton]

We are looking to swap the Dual Port EJ25 heads to my Single Port EJ22. And he will be using a 95's EJ22 Dual Port Heads on his 2.5 (and then my single ports would go onto the 95). We were looking to see what kind of power gains (if any) we would get. I know the Dual Port 2.2 Heads on the EJ25 does give it a good boost in power.

But what about the Dual Port 2.5 Heads on the 2.2?

first are the ej25 heads DOHC or SOHC?

swapping heads also involves swapping intake manifolds, both of you need to take that into consideration.

and 2.5 heads on a 2.2 will drop the compression way down close to 8:1 extremely low for na aka going to suck to drive, 8:1 is more of a "high boost" compression ratio

DOHC on the 2.5

i'll have both full engines so swapping things wont be a big deal i think

[Baddog]

We are looking to swap the Dual Port EJ25 heads to my Single Port EJ22. And he will be using a 95's EJ22 Dual Port Heads on his 2.5 (and then my single ports would go onto the 95). We were looking to see what kind of power gains (if any) we would get. I know the Dual Port 2.2 Heads on the EJ25 does give it a good boost in power.

But what about the Dual Port 2.5 Heads on the 2.2?

first are the ej25 heads DOHC or SOHC?

swapping heads also involves swapping intake manifolds, both of you need to take that into consideration.

and 2.5 heads on a 2.2 will drop the compression way down close to 8:1 extremely low for na aka going to suck to drive, 8:1 is more of a "high boost" compression ratio

Anything I can do to keep the compression around the same? I would like to do a turbo build but it will probably cost 1,500 to do that. My EJ22 has 165k on it.

[StatGSR]

i think some of this information needs to get straitened out. a full 2.5 will always be a better and more capable motor than a 2.2head 2.5 block high comp Frankenstein engine. if your car came with a 2.5 it is never worth swapping to 2.2 heads.

the franken motor works as a great upgrade for those that have a car that came 2.2 and and want to bump the power, but don't want to deal with wiring. if you already have a 2.5 and want more power, just get cams, pistons, thinner headgasket, and you should end up with a better motor than a 2.2/2.5 high comp frankenmotor.


as for a 2.5 heads on a 2.2 block. what you get there is a drop in compression that if you kept it NA would be a huge piece of crap. would be great if you where looking to boost, as you would get a lower compression engine with better flowing heads.


Also, dual port 2.2 heads do not flow better than 2.2 single port heads. in fact single ports have larger valves on either the exhaust or intake side. dual ports just open you to the world of super sweet headers.

thats all i got for now.

so really no good will come from the 2.2 heads on my 2.5 block?

even with grinded cams and the heads ported and polished?

[StatGSR]

I'm not necessarily saying that (it could make more power than a stock 2.5). What I'm saying is that you would be better of with 2.5 heads with cams, and a port and polish.

[Baddog]

In that case zeus gimmie your 2.2's dual port exhaust :O

thats what im thinkin

[Baddog]

And then you can put my single ports on your 2.2 :O

[Grafton]

statgsr has got it right except the valves bit

the single and dual ports call for the same part number for the valves, the 2.2T heads had a 1mm smaller valves... and after looking at the single port heads that came out of my motor the exhaust path is really contorted

[jey]

Anything I can do to keep the compression around the same? I would like to do a turbo build but it will probably cost 1,500 to do that. My EJ22 has 165k on it.

You can mess with thinner/thicker head gaskets to some extent to get the compression ratio you're looking for.

[StatGSR]

^ doesn't that botch the timing on a subaru to some extent?

[Grafton]

Anything I can do to keep the compression around the same? I would like to do a turbo build but it will probably cost 1,500 to do that. My EJ22 has 165k on it.

You can mess with thinner/thicker head gaskets to some extent to get the compression ratio you're looking for.
the difference between NA head gaskets and STi head gaskets (.054"/.021") is worth around .4-.6 to the ratio

my build would've been ~11.5:1 if i would've went with .040" head gaskets going to .027" jumped me by .5 to 12:1


^ doesn't that botch the timing on a subaru to some extent?
if you go past the limits on milling the heads and block yeah it advances one side and retards the other but you can fix it with adjustable idlers but when adjusting via headgasket you need to maintain a proper quench distance, that's why i went with a .027" thick head gasket to get an ideal quench zone

[4n70n1n0]

In that case zeus gimmie your 2.2's dual port exhaust :O
:smt006
I have a set of Stage 2 Delta Cams if your interested :grin:

[Baddog]

In that case zeus gimmie your 2.2's dual port exhaust :O
:smt006
I have a set of Stage 2 Delta Cams if your interested :grin:

I saw your thread from sometime ago. Did you still have those heads as well? Or were they just the exhaust ports? I forget.

In that case zeus gimmie your 2.2's dual port exhaust :O
:smt006
I have a set of Stage 2 Delta Cams if your interested :grin:

stage 2 is...?

i may develop an intrest...

[Reason]

Justin you have a 2.5 correct? Maybe you should talk to Ken at Delta cam and see what he can do. Aren't you kind of close to his shop?