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Old 09-17-2004, 06:12 PM   #1
t3hWIT
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Lightbulb High Compression Frankenstein

Maybe I'm onto something. Maybe I'm stupid. But i was looking over a chart of specs of all the subaru engines built, 91 and up. I was looking at the different sizes of things and their compression. I also remember somebody comparing these cars to lego blocks. So i was thinking maybe I(or someone else) could build a high compression motor with stock parts or aftermarket parts made to fit the stock vehicles. I personally think that it would be cool to build a powerful NA motor over a period of time, and someday swap it into my Prezza. Or like I said, maybe I'm just stupid. But hey, at least I dod something constructive during study hall.

the list of parts and reasons are as follows:

My stock engine is the NA EJ22, just for reference. If I would ever do this, it would be a second engine, but i want to keep to the 2.2 block.

Because of the above, the first part is:
MY91-94 EJ22T block. its built sturdier than the NA, or so im told.

The following is a choice of the 2, but i dunno which would be better:
MY98 EJ25 DOHC cylinder head (cuz its dohc)
OR
MY00-04 EJ25 SOHC cylinder head (boasts higher compression)

I also dont know about the following. I dont know if they will fit(prob not), of it they'll help me with power or anything but...:
MY98-04 connecting rods and crankshaft. If they dont work, id go with the EJ22 or EJ22T rods and shaft.

MY97-98 EJ22 pistons (higher compression, and they'll fit)

finally...
MY97-98 SOHC EJ22 head gasket. (higher compression than the dohc gasket)

I'd like to stick to better than OEM parts on stuff, including the other stuff, such as clevite bearings and arp bolts/studs

my questions are:

Will it all fit?

What kind of compression would be expected?

What about engine magement?

Sohc head or dohc head?

Would it start?

Any other suggestions?

One more thing... am I freakin nuts?

-shaun

Last edited by t3hWIT; 09-21-2006 at 01:06 PM.
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Old 09-17-2004, 06:24 PM   #2
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I think the best thing you could do is get all the stats of all the parts you are considering using and take it to an engine builder. Have a little chat with them and see what they think.
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Old 09-17-2004, 08:39 PM   #3
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Talking

Quote:
Originally Posted by Tim Sanderson
I think the best thing you could do is get all the stats of all the parts you are considering using and take it to an engine builder. Have a little chat with them and see what they think.
ah no man. that takes all the fun outta it.

not being an ass here but if i was gonna spend that much money, id just turbo the thing. theres a twin turbo kit out there. and this HC thing is junkyard parts.
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Old 11-13-2013, 02:58 PM   #4
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Originally Posted by t3hWIT View Post
ah no man. that takes all the fun outta it.

not being an ass here but if i was gonna spend that much money, id just turbo the thing. theres a twin turbo kit out there. and this HC thing is junkyard parts.

EXACTLY!!!! i have the $ to do an NA build with 11.5:1 compression pistons, cams, intake and more but i decided that by the time I finish the build with costs and tuning, i an 3/4s of the way to a wrecked useable driveline STI swap. so why at that point would i want to do a na build when the stock sTi would smoke it? sure 220-240 whp sounds cool in NA, but then your maxed out. stock STi is 240-250 range and with a small tune and nothing more, you can make an extra 30-40hp crank or 15-20 wheel power before you touch it it other than tuning. always passed na then.

my costs estimated for a decent NA build is $4500 for the engine assembly done. a wrecked STI is $5k-$6500 depending on damage and milage.

do the math.

you do an NA build because you want to be different and have extra $.
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Old 11-13-2013, 03:28 PM   #5
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Originally Posted by oscarmayer View Post
EXACTLY!!!! i have the $ to do an NA build with 11.5:1 compression pistons, cams, intake and more but i decided that by the time I finish the build with costs and tuning, i an 3/4s of the way to a wrecked useable driveline STI swap. so why at that point would i want to do a na build when the stock sTi would smoke it? sure 220-240 whp sounds cool in NA, but then your maxed out. stock STi is 240-250 range and with a small tune and nothing more, you can make an extra 30-40hp crank or 15-20 wheel power before you touch it it other than tuning. always passed na then.

my costs estimated for a decent NA build is $4500 for the engine assembly done. a wrecked STI is $5k-$6500 depending on damage and milage.

do the math.

you do an NA build because you want to be different and have extra $.
And you can buy a WRX with a blown 2.0 bottom end for $1500 and swap in an ej22e bottom end for a hundred bucks. To each his own.

I like many others suck at saving money, so saving 5k for a 1 in a 1000 insurance right off is out of reach. I did however have a couple half good engines laying around and a part number for a cometic head gasket set. I now have the torque i need to save 20 minutes a day commuting by lane jumping before the tunnel. And can still afford my raceland coilovers.
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Old 09-17-2004, 08:45 PM   #6
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and i live in central Pa, aka Penntucky. the closest thing to an engine builder we have is the neighborhood mechanic, or some guy at AAP who'll gather the parts together. The biggest thing in tuning around here is slapping a big ol aluminum wing, stick on hood scoops, chrome exhaust tips, and APC spinner wheel covers. I'm interested in performance and teaching these tuner wannabes a lesson in real cars. But since I'm one of the few and proud, i dont have access to this stuff. just junkyards. ugh... i hate this region...
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Old 11-05-2017, 12:05 AM   #7
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Originally Posted by t3hWIT View Post
and i live in central Pa, aka Penntucky. the closest thing to an engine builder we have is the neighborhood mechanic, or some guy at AAP who'll gather the parts together. The biggest thing in tuning around here is slapping a big ol aluminum wing, stick on hood scoops, chrome exhaust tips, and APC spinner wheel covers. I'm interested in performance and teaching these tuner wannabes a lesson in real cars. But since I'm one of the few and proud, i dont have access to this stuff. just junkyards. ugh... i hate this region...
***128514;***128514; that's incredibly true...
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Old 09-17-2004, 09:02 PM   #8
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Maybe you misunderstood, If you get the copies of the service manuals you can have a nice reference for all the parts you are considering using. I did'nt suggest that you go get all the parts and mickey mouse around with them.

Have at it and good luck. Like to see what you come up with.
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Old 09-17-2004, 09:19 PM   #9
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Quote:
Originally Posted by mi_cistemz_loudr

Any other suggestions?
-shaun
Paeco Industries!
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Old 09-17-2004, 10:00 PM   #10
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Quote:
Originally Posted by mi_cistemz_loudr
Any other suggestions?
Get the toughest block and pistons on the list, combine that with the best flowing heads, and then let the machine shop deck the block to give you the compression ratio you desire. Either that or go the custom piston route.
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Old 09-17-2004, 10:47 PM   #11
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get as close to 13:1 compression as possible..
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Old 10-02-2005, 02:35 PM   #12
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Quote:
Originally Posted by BoostdScubaru
get as close to 13:1 compression as possible..

If you are going to build a real n/a beast then you should shoot for
14:1 - 16:1
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Old 10-02-2005, 09:16 PM   #13
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Quote:
Originally Posted by 02Toyowrx
If you are going to build a real n/a beast then you should shoot for
14:1 - 16:1

And just WHAT kind of fuel would you run in a 16:1 motor, as is sure wouldn't be pump gas
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Old 10-03-2005, 12:40 PM   #14
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Originally Posted by huck369
And just WHAT kind of fuel would you run in a 16:1 motor, as is sure wouldn't be pump gas
Diesel
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Old 10-03-2005, 11:33 AM   #15
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Quote:
Originally Posted by 02Toyowrx
If you are going to build a real n/a beast then you should shoot for
14:1 - 16:1
Right. I guess you missed the press release last week for the 300chp 2.5RS? 11.2:1 CR...

And did you even bother to read the whole thread? This isn't about building race cars. This is about low cost streetable performance gains for people who didn't get the gift of a 2.5l engine from the factory...
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Old 10-16-2009, 01:38 PM   #16
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Originally Posted by BoostdScubaru View Post
get as close to 13:1 compression as possible..
That way you'll never have a chance to afford fuel for the thing...
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Old 01-03-2013, 12:11 PM   #17
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Originally Posted by BoostdScubaru View Post
get as close to 13:1 compression as possible..
Have fun running race gas.
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Old 09-17-2004, 10:56 PM   #18
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Quote:
Originally Posted by redwagon
Get the toughest block and pistons on the list, combine that with the best flowing heads, and then let the machine shop deck the block to give you the compression ratio you desire. Either that or go the custom piston route.
Decking the block too much will cause problems with the crank and cam sensors. It would be better to have pistons made.
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Old 09-17-2004, 10:49 PM   #19
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Whilst your on the point of mixing and matchingI"ve often wondered about this combination.
EJ25 block for maximum bore capacity
EJ20 crank , shorter stroke better rpm capacity
custom long rods - improve rod ratio by having the taller ej25 block and the short stroke ej20 crank. The long rod combination improves rpm capacity.
Overall capacity will still be close to 2.5L (about 2.4L I think).
I really dont think the strength of the block is an issue after all turbo motors are putting out much higher hp's than n/a would ever be capable of and whens the last time you heard of a block failing?
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Old 09-17-2004, 10:59 PM   #20
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Quote:
Originally Posted by bugeyes
Whilst your on the point of mixing and matchingI"ve often wondered about this combination.
EJ25 block for maximum bore capacity
EJ20 crank , shorter stroke better rpm capacity
custom long rods - improve rod ratio by having the taller ej25 block and the short stroke ej20 crank. The long rod combination improves rpm capacity.
Overall capacity will still be close to 2.5L (about 2.4L I think).
I really dont think the strength of the block is an issue after all turbo motors are putting out much higher hp's than n/a would ever be capable of and whens the last time you heard of a block failing?
I don't think they fail so much as flex and cause head gasket failure. I like your ideas though, A rod ratio of 1.8 or more would be nice. Not sure on the crank though, I think the n/a 2.2 are'nt forged.
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Old 09-18-2004, 01:59 AM   #21
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do what i amp planning:

phase II ej25 shortblock with the older dual port ej22 heads and the thick ej25 gasket. should get you right around 11.5:1. any higher and you would need to possibly add a piggyback to retard the ignition timing or add water injection or find a way to increase the fuel or all of the above.
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Old 11-17-2004, 04:16 PM   #22
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Quote:
Originally Posted by greg donovan
do what i amp planning:

phase II ej25 shortblock with the older dual port ej22 heads and the thick ej25 gasket. should get you right around 11.5:1. any higher and you would need to possibly add a piggyback to retard the ignition timing or add water injection or find a way to increase the fuel or all of the above.
I know back in the day, there were a couple of people on this board running this set up. Anyone still out there with this? I have some specific questions about doing this...
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Old 02-29-2016, 11:23 PM   #23
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do what i amp planning:

phase II ej25 shortblock with the older dual port ej22 heads and the thick ej25 gasket. should get you right around 11.5:1. any higher and you would need to possibly add a piggyback to retard the ignition timing or add water injection or find a way to increase the fuel or all of the above.
Having done just this, and swapping the 2.5 ecm in the 96 containing the Frankenbork, I'm wondering if you have experienced a flat spot between 60-95% throttle. I have, and It's bugging the hell out of me. I would start my own thread, but I cannot, having not met the reply quota.
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Old 03-02-2016, 02:27 PM   #24
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Originally Posted by Grombal View Post
Having done just this, and swapping the 2.5 ecm in the 96 containing the Frankenbork, I'm wondering if you have experienced a flat spot between 60-95% throttle. I have, and It's bugging the hell out of me. I would start my own thread, but I cannot, having not met the reply quota.
Today, I stuck a cheap aftermarket air-filter on it. The mid-range and top end gained a bit more TQ and responsiveness that I could feel. I has to be better than the paper OEM filter. The head is ported. Before the intake, I noticed the car pulls better at about 70% than it does at 100%, according to the wide-band, its going a bit rich up there at WOT, like 12.5:1 witch isn't horrible, I also have deleted cats, and modified exhaust, if you have a bad cat, it can do weird things like that, they tend to rattle around and them block restriction when you floor it. Cams are the next big mod, I'm going to try and send my spare set of cams off to be welded/reground, this will make a huge difference in top end from what I've read.

I will post the dyno sheet when i have it, and video I'm hoping will show my wide-band
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Old 05-02-2016, 11:10 AM   #25
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Quote:
Originally Posted by greg donovan View Post
do what i amp planning:

phase II ej25 shortblock with the older dual port ej22 heads and the thick ej25 gasket. should get you right around 11.5:1. any higher and you would need to possibly add a piggyback to retard the ignition timing or add water injection or find a way to increase the fuel or all of the above.
I have a question...why not use a turbo short block 2.5 with 2.2 heads and keep compression reasonable? especially if the short block in question had the forged pistons the sti uses and the better rods and crank? With any luck you would keep compression down in the 9-10:1 range and have something you could actually run real world fuel in and still have a froggy little motor. Any thoughts?
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