legacycentral bbs

I know this had been discusses a little bit last year, but want to know if anyone here has actually run this set up. I know that it will run around an 11.5:1 CR and have it from a reputible source that with 91 octane gas it will be right around 210hp at the crank. Anyone have comments, especially someone who is running this (Thawa, that means please don't link in 5 threads you find on a search as I have already searched and read the historical info! )

We are probably going to do this for a bit either way. I have a buddy with a project car and we want to play around while we build an NA Cobb EJ25 to run in the car long term...

I would think the power gain due to the compression ratio change alone would be limited to 10% at the very most, you are talking about a 27% gain there...

are some of these gains being attributed to better breathing, because I thought it was the other way around

Also I would think 11.5 compression would want 93-94 octane gas, unless perfectly controlled with a custom fuel map

We will be running this on premium. And the hp number I listed assumes that it is running a CAI and full header back exhaust, so yes better breathing. Lastly, I have always been told around 1-3% more power per .1 of CR bump so those kinds of gains are mathematically possible...

The "rule of thumb" numbers I've heard from engine builders, and clandestine SCCA head-shavers who shall remain nameless has been 4-7% per POINT of CR change, with the higher end of that range more often quoted.

as with all mods the proof is in the doing, and dyno-ing. I'd still bet on 10% due to CR change alone

professor wrote:The "rule of thumb" numbers I've heard from engine builders, and clandestine SCCA head-shavers who shall remain nameless has been 4-7% per POINT of CR change, with the higher end of that range more often quoted.

as with all mods the proof is in the doing, and dyno-ing. I'd still bet on 10% due to CR change alone

Yeah, I cut what the racers tell me in half and if I get more, then I am happy. If you believed half of what they tell you a 2.0l car has 1 MILLION hp. It is kind of like the doctor. If you tell him you have 3 drinks a day, he assumes it is actually 6..

We will likely run this car on a dyno just for kicks. We have a local AWD dyno that charges $75 for 3 runs.

there is a guy on the 2.5RS board that did it.

his screen name is b-o-b-s

he did it last winter i believe. as of sept. it was running strong still.

he said it had alot of bottom end pull.

wouldn't it be better to shave the 2.5 heads, and fit a thinner gasket if possible ? I don't know the specifics of how much can be safely shaved but it usually takes very little to up the CR by a full point. The 2.5 heads must have bigger valves and a higher breathing capacity.

The 2.5l heads aren't free. Like I said, this is a temporary build. We have a 1.8l Impreza that we are building a full blown NA EJ25 project(like the one in my RS). But that will take us a few months and we have a spare EJ25 block and all the 2.2l top end and want to play around. I have a thing for Frankensubbies.

Plus if I had a spare set of EJ25 heads to play with, they would go on my EJ22E block (8.6:1 CR) and be boosted to 15-16psi to see if it will blow up. I am actually acquiring a '93 SS without a motor that is a candidate for that. MY ghetto garage doubles as a mad scientist lab....muhahaha

you know me too well matt

the thing about shaving the heads is, if you shave too much your manifolds wont fit.

I think this is a great idea. Lemme know how it turns out.

The only thing, you'll be limited by the SOHC setup and antiquated headflow design. You might have 11.5:1 CR, but I doubt you'll be able to go much over 7k, unless you do some crazy stuff to the heads...

this type of a build isnt about revs its about torque at the low RPM range.

the guy on the rs club said it pulls very hard. a little better than a ej25 in the 1st 3 gears.

i was gonna do this in my FWD but am buying a turbo car instead. my brother may do this or he may just put a whole ej25 in it he hasnt decided yet.

exactly what Greg said. This isn't a rev til you puke build. It is a torquey build. And everyone likes to poo poo the 2.2l heads, but they are not poorly flowing heads. They don't flow like the EJ25 heads, but it is all relative. We hope to have this car running by Monday, so I will post back with our initial impressions next week...

And Subyluvr, if you really think that SOHC heads on a boxer is an issue, you should read this:
http://www.wrxforum.com/cgi-bin/ultimat ... 917#000000
These are not Hondas. SOHC is not a liabilty on a boxer engine and the final engine we put into this project (as well as the engine in my 2.5RS) are SOHC...

This progressing quite well. The heads look almost brand new, we go them sooo clean. The block is about 75% assembled and we are waiting for cams from Delta to drop in there for some more power. I will try and post some pics next week after i get back from thanxgiving...

wow, i'm VERY interested in this buildup. being a former honda guy, i LOVE NA setups. please post as much as you can about it.

i'm curious to know what makes it a 2.5L versus the 2.2? is it in the stroke, bore?

i can't even imagine what a high CR boxer would sound like with i/h/e and big cams

you WILL need to run 92/93 octane and a programmable fuel/timing system to get it to run right.

there is a guy on rsclub using a stock ej25 ecu to get it running but i have been told a ej22 one will work too.

We are using a chipped ECU from an 1.8l. The "chipping" was done by Al, formerly of Torque Chip (he left the country) and he raised the redline to 7500rpm. The 1.8 ECU has different timing maps that make it run much better up top than either an EJ25 or EJ22 ECU would allow.

Xephyr,(yes the one and the same) has a '94 wagon with an EJ25 in it that he is using 272 duration HKS STi V3 cams on the same Al prepped 1.8l ECU. It is dead until 4500rpms, but then snaps your neck all the way to 7500rpm. It is like the damned thing has a v-tec in it. It probably has more HP than my RS, but lacks the torque curve that my car has, so my car is faster even though his is 300lbs lighter...

greg donovan wrote: ↑Thu Nov 18, 2004 3:52 pm this type of a build isnt about revs its about torque at the low RPM range.

the guy on the rs club said it pulls very hard. a little better than a ej25 in the 1st 3 gears.

i was gonna do this in my FWD but am buying a turbo car instead. my brother may do this or he may just put a whole ej25 in it he hasnt decided yet.

Update to this engine. The old 2.2 is currently still in stock form and now lives on as the heart of our 97 coupe NA4wd rally car!

Nice!