Subaru Impreza GC8 & RS Forum & Community banner
41 - 60 of 80 Posts

·
Experimenter
Tubaru Pickup
Joined
·
3,914 Posts
ive put the ej25 pentroof heads on 2.2 blocks twice. Both times they failed, second still failing, after about 5k miles do to ringlands. Using both 93 octane and E85, both boosted in thevlow to mid 20psi range. I dont think the failures are mushroom related, but just shear abuse and high timing to an old engine.Pentroof ej20g heads would br ideal for my application but i dont have any. im not shure what advantage deshrouding S20 heads would have but many have done it
 

·
Registered
The subaru of many acronyms
Joined
·
1,919 Posts
Since you still seem pretty confident in your ej22 hybrid, ill pit my stock 9:1 compression ej20 against yours on 93 pump gas. since you seem to focus most your despise towards the 9:1 comp ej20s.
 

·
Experimenter
Tubaru Pickup
Joined
·
3,914 Posts
who me? my ej22 isnt seein much boost these days, just gettin me buy til i put a 97 ej25 block in there for a 9:1 turbo 2.5
 

·
Registered
1998 Subaru Legacy GT Limited
Joined
·
236 Posts
Discussion Starter · #44 ·
ive put the ej25 pentroof heads on 2.2 blocks twice. Both times they failed, second still failing, after about 5k miles do to ringlands. Using both 93 octane and E85, both boosted in thevlow to mid 20psi range. I dont think the failures are mushroom related, but just shear abuse and high timing to an old engine. Pentroof ej20g heads would br ideal for my application but i dont have any. im not shure what advantage deshrouding S20 heads would have but many have done it
The mushroom chambers are doing it, and here is why. During the combustion cycle, the heat builds up in those particular spots and the heat doesn't stop building until the engine is off and cooled. Where does the collected heat go when the engine is off? It is absorbed into those particular spots.

The heat can't escape at higher rpm, it just spins in place, rotating and rotating until the engine comes to a stop and it has a chance to dissipate into the aluminum head and that part of the sleeve. As you can imagine, the heat is intense enough that the engine failed, in the exact same way. Twice.

Since you still seem pretty confident in your ej22 hybrid, ill pit my stock 9:1 compression ej20 against yours on 93 pump gas. since you seem to focus most your despise towards the 9:1 comp ej20s.
EJ22 hybrid with your heads at 9:1 compression ratio on 93? I'd be a fool not to bet on it in the twisties, even closed deck against closed deck. Straights, that EJ20 would probably win, but it wouldn't be by much. But 9:1 is suicide for any EJ that doesn't have the proper gas, tuning, and breathing.

Ideal compression ratio for that gasoline is 8.5:1, unless you live in a place at higher atmosphere, then you'd have to spike the compression ratio to make any sort of power.
 

·
Registered
1998 Subaru Legacy GT Limited
Joined
·
236 Posts
Discussion Starter · #45 · (Edited)
To answer any confusion on the non-STi EJ20K, it is actually an EJ20G (Common G), and should be treated as such. Subaru had annoying applications of certain engines that were stated as something, but were really something else. EJ20G is also the very first nomenclature that Subaru gave it when it was first created, so any Phase 1 EJ that was spun off of it can correctly be considered a product of the original EJ20G line.
 

·
aka arangov3
Do noffin Foz
Joined
·
2,802 Posts
The EJ22T block is pretty much a bored early EJ20G block, which is the same used in the early RA's. These blocks, though probably not as strong as the early RA's, have not yet been proven weaker.
I don't think you can bore out a 20g to get to 2.2L without stroking it so idk how true this is but I'm just nobody
 

·
Registered
1998 Subaru Legacy GT Limited
Joined
·
236 Posts
Discussion Starter · #47 ·
I don't think you can bore out a 20g to get to 2.2L without stroking it so idk how true this is but I'm just nobody
It can be done. Even though it has a closed deck, it still has sleeves, just like the EJ22T. Boring it to 97mm would effectively make it an EJ22T block. Stroking it via EJ25 crank would make it a 2.1L, or an "EJ21", which is also a thing to do.
 

·
aka arangov3
Do noffin Foz
Joined
·
2,802 Posts
IDK if you can afford to bore that much out of a 2.0 I don't think it would be withing the specs from the FSM. lets get back on topic remember I'm nobody but a fly on the wall
 

·
Registered
1998 Subaru Legacy GT Limited
Joined
·
236 Posts
Discussion Starter · #49 · (Edited)
IDK if you can afford to bore that much out of a 2.0 I don't think it would be withing the specs from the FSM. lets get back on topic remember I'm nobody but a fly on the wall
You shouldn't bore an EJ20 out that much. If you wanted 2.2 from an EJ20, you could use an EJ25 crank and bore the sleeves out to 93mm. That'll bring you close enough to call it a 2.2L. Or you can get an actual 2.2L block.
 

·
Registered
The subaru of many acronyms
Joined
·
1,919 Posts
Not technically bored out to the 97mm. More like sleeves to 97mm they cast the block then machine the walls out to the desired thickness. Building the ej22g/t block they reduce the thickness of the aluminum supporting cylinder walls for the thin sleeve, it's nowhere as thin as a 25, but a slight amount. The ver10+ ej207 actually came from the ej257 casting, but instead of having sleeves with a 99.5mm bore they have a 92mm bore. This is why they take those block for srt usa stage rally/ rally cross cars and cram 40+ psi down they're throat with 10:1cr.
 

·
Registered
The subaru of many acronyms
Joined
·
1,919 Posts
And low compression ratio with boost is more of a safety net for cars with "dumb" ecus that have to fit a majority of different environments and fuel qualitys. Modern cars have much more sophisticated ecus that can precisely control and adapt to boost and high compression boosted engine properly. The 2015 wrx Fa20 has a static cr higher than the NA ej251 at 10.6:1 and it pushes 15-20 psi out of its little turbo on pump gas. I tune my slightly higher comp turbo ej20 to the environment and fuel it regularly sees and the extra torque and response is well worth the extra time spent refining the map.
 

·
Registered
1998 Subaru Legacy GT Limited
Joined
·
236 Posts
Discussion Starter · #53 · (Edited)
And low compression ratio with boost is more of a safety net for cars with "dumb" ecus that have to fit a majority of different environments and fuel qualitys.
Subaru has always used a "self-learning and adjusting" ECU of some kind, but there are limits to what some of those ECU's can do. This holds especially true for the older models. Those aggressive ECU's were still blowing up 8:1 engines, but a piggyback or a standalone usually solved that problem by the tuner reeling in the timing to ideal levels.

Modern cars have much more sophisticated ecus that can precisely control and adapt to boost and high compression boosted engine properly. The 2015 wrx Fa20 has a static cr higher than the NA ej251 at 10.6:1 and it pushes 15-20 psi out of its little turbo on pump gas.
The FA series can't be compared to any EJ because the heads have direct fuel injection, as opposed to the manifold injector type of the older and lesser tech EJ's. This allows it far greater room of control by said adaptable ECU's, since it can tune before the fuel even gets to the chamber.

I tune my slightly higher comp turbo ej20 to the environment and fuel it regularly sees and the extra torque and response is well worth the extra time spent refining the map.
Subaru does this for it's ECU's as well, but unlike the aftermarket tuners, it programs its ECU's for certain things, then leaves them like that for certain markets, often times causing aftermarket tuners to figure out a way to get around the programming to get the engines in their sweet spots.

While I feel privileged to know this now I know for the most part all ej motors come from similar design but I am finding it difficult to believe that subaru just increase the bore and that's it.
They don't bore them out. EJ20's and EJ22's are cast similarly with different sleeve boring.
 

·
Registered
1998 Subaru Legacy GT Limited
Joined
·
236 Posts
Discussion Starter · #54 · (Edited)
Not technically bored out to the 97mm. More like sleeves to 97mm they cast the block then machine the walls out to the desired thickness. Building the ej22g/t block they reduce the thickness of the aluminum supporting cylinder walls for the thin sleeve, it's nowhere as thin as a 25, but a slight amount. The ver10+ ej207 actually came from the ej257 casting, but instead of having sleeves with a 99.5mm bore they have a 92mm bore. This is why they take those block for srt usa stage rally/ rally cross cars and cram 40+ psi down they're throat with 10:1cr.
The EJ22T was created with a far different, older method than the EJ22G. As a result, it is denser, heavier, and thus stronger than any of the late period EJ20's or EJ22's. This being the case, it is definitely one of the strongest, but at the trade off of being a bit more difficult to cool off. The EJ22T was created as a 96.9mm from the start. It also has iron liners, like the EJ22E's.
 

·
Registered
1998 Subaru Legacy GT Limited
Joined
·
236 Posts
Discussion Starter · #55 ·
/\ Thanks. Do you have the ej20k non sti specs? Those are the cams and heads I run with my 257 block (modded combustion chambers)
EJ20G Cam Specs:
Intake opens 8° BDTC.
Intake closes 52° ABDC.
Exhaust opens 52° BBDC.
Exhaust closes 8° ATDC.
Overlap 16°.

Common G = non-STi K. They are the same. The STi K is a monster in comparison.
 

·
Experimenter
Tubaru Pickup
Joined
·
3,914 Posts
And low compression ratio with boost is more of a safety net for cars with "dumb" ecus that have to fit a majority of different environments and fuel qualitys. Modern cars have much more sophisticated ecus that can precisely control and adapt to boost and high compression boosted engine properly. The 2015 wrx Fa20 has a static cr higher than the NA ej251 at 10.6:1 and it pushes 15-20 psi out of its little turbo on pump gas. I tune my slightly higher comp turbo ej20 to the environment and fuel it regularly sees and the extra torque and response is well worth the extra time spent refining the map.
I beelive this is all possible due to direct injection. Its hard to knock when the fuel isnt injected until it's ignited, and then still being injected while its burning.
 

·
Registered
1998 Subaru Legacy GT Limited
Joined
·
236 Posts
Discussion Starter · #57 ·
EJ20D Cam Specs.

Intake opens 6°/4° BDTC
Intake closes 54°/56° ABDC
Exhaust opens 66°/36° BBDC
Exhaust closes 24°/16° ATDC
Overlap 30°/20°

In case anyone doesn't know, EJ20D's came in 1st Gen Legacies in Japan and are outwardly similar to old school EJ20G/EJ25D's, but have higher compression ratios. However, that exhaust cam is amazingly bad for boost, it would seem. The intake cam is about spot-on the same as the STi 20G cam, which means that the swapping of exhaust cams between heads is a lot more important if you want to boost or stay N/A.
 

·
Registered
13 RAV4,'00 RS SRP,'00 S10
Joined
·
74 Posts
Since you live so close to me maybe I'll have you build me an engine I can run in my RS. I'm always willing to learn, but all these specs jumble together for me in my head. Since Subaru has a habit of renaming things that already existed it is hard to keep track of. You must have notebooks full of information to just be typing it all out now.
 
41 - 60 of 80 Posts
Top