Ercoupe Posted January 20, 2016 Share Posted January 20, 2016 Hello all, I wonder how many first post start as mine does...Help..? I have a 05 Baja that has a low end knock so I found an 05 Outback engine on Craigslist and promptly bought it... Do you know where this is going? I got the engine home and discovered the single exhaust port (California emission EJ259) as opposed to the dual port that I needed. So,,, my question to the experienced Subaru folks is this, will EJ251 heads work with an EJ295 short block and pistons? I either have to sell it and find another or transfer my current heads to the EJ259. Any help is greatly appreciated... Thanks.. Ken Quote Link to comment Share on other sites More sharing options...
86BRATMAN Posted January 21, 2016 Share Posted January 21, 2016 The head won't work, the 04 and 05 pzev motors have a unique piston design with large domed segments. These pistons would make full contact with the heads. Best option is to resell the engine and purchase another, being more careful to check it out before you hand over money. Quote Link to comment Share on other sites More sharing options...
ccrinc Posted January 21, 2016 Share Posted January 21, 2016 ^^^This.^^^ Emily 1 Quote Link to comment Share on other sites More sharing options...
idosubaru Posted January 21, 2016 Share Posted January 21, 2016 bolt the Baja intake manifold onto the new engine and call it done? Quote Link to comment Share on other sites More sharing options...
Ercoupe Posted January 24, 2016 Author Share Posted January 24, 2016 I was very tempted to go for the install but I was able to sell the engine after 1 day on Craigslist. The only concern I had was the restricted exhaust flow if I installed it dressed with the correct intake manifold...K Quote Link to comment Share on other sites More sharing options...
stangman69 Posted February 10, 2017 Share Posted February 10, 2017 My first post too... What if you have an EJ259 and it puked a rod. Would my EJ259 head/intake/etc. fit onto a non-259 short block? I get the -259 block can't be matched with non-259 heads (piston to valve contact due to domed -259 pistons). It would seem to fit but I'd give up a bit of compression maybe due to non-domed pistons and a domed-piston head... Can't seem to find many EJ259 donors. Others are much more common. No wonder the first poster sold his on CL in less than a day... I'm seeing EJ20 JDM motors pretty frequently. What about swapping one of those in place of the EJ259? Guess I'd need a different ECU and different exhaust too, right? Anything else? This car is just too good to junk... Thanks, Nate Quote Link to comment Share on other sites More sharing options...
stangman69 Posted February 14, 2017 Share Posted February 14, 2017 Preference would be to put in a JDM EJ25 motor or at least keep the short block and swap on my EJ259 heads and intake/exhaust manifolds... Quote Link to comment Share on other sites More sharing options...
86BRATMAN Posted February 14, 2017 Share Posted February 14, 2017 I don't know the exact volume of the ej259 heads, but I would guess you'd be looking at mid 9's:1 compression with the 251 shortblock. So it wouldn't really be a big drop in compression. If you can find one reasonably priced I'd go that route. Quote Link to comment Share on other sites More sharing options...
iriejedi Posted June 4, 2017 Share Posted June 4, 2017 (edited) On this topic I'm curious if an 04 short block will work with 09 heads. My 09 is a knocker and I have access to an 04 short block that busted a timing belt and most likely trashed the heads. Edited June 4, 2017 by iriejedi 1 Quote Link to comment Share on other sites More sharing options...
05Pzev Posted May 30, 2019 Share Posted May 30, 2019 (edited) Sorry this is old but does anyone know if we can put any of the forged piston offerings in an EJ259 motor (actually 2005 California emissions) and end up with a 9-10:1 CR? Assuming we can get CR correct by picking the right piston dish, do I still need to worry about valve contact? My goal is a forged bottom end for my supercharged EJ259. Edited May 30, 2019 by 05Pzev Quote Link to comment Share on other sites More sharing options...
FerGloyale Posted May 31, 2019 Share Posted May 31, 2019 put the EJ251/3 pistons in the EJ259 block. throw a new set of rings on while yer at it. Use the EJ251 heads. done Quote Link to comment Share on other sites More sharing options...
05Pzev Posted May 31, 2019 Share Posted May 31, 2019 On 1/20/2016 at 8:51 PM, 86BRATMAN said: The head won't work, the 04 and 05 pzev motors have a unique piston design with large domed segments. These pistons would make full contact with the heads. Best option is to resell the engine and purchase another, being more careful to check it out before you hand over money. Are you sure that they are domed and not dished? They look like they have negative , not positive volume to me. Quote Link to comment Share on other sites More sharing options...
1197sts Posted March 15, 2021 Share Posted March 15, 2021 I have a similar situation, I am working on a 2004 Outback with an EJ259 that threw a rod, so the lower end is toast. I would like to install a EJ251 lower end and use the 259 heads. Will this work? Swapping pistons is not an option as the original 259 lower end is not usable and I don't have any other 259 pistons, and using 251 heads is not an option due to the single port exhaust. I have seen people speculate that it would be reduced compression but not much, can anyone verify that? One other question, when an EJ blows a rod, the oil system is contaminated. If I completely disassemble the head and clean out the oil passages in the head and the inside of the cam is it likely to be usable, does it usually do much damage to the cam bearing journals? Light enough damage a little scotch brite will do the trick? Quote Link to comment Share on other sites More sharing options...
ocei77 Posted March 15, 2021 Share Posted March 15, 2021 This may help; O. EJ_cr_matrix (1) (3).pdf 1 Quote Link to comment Share on other sites More sharing options...
el_freddo Posted March 19, 2021 Share Posted March 19, 2021 I doubt a thrown rod would contaminate the oil system unless the issues started some time before the rod let go. Youd want to know what signs of the rod letting go we’re there before the big event - knocking noises for example. Cheers Bennie 1 Quote Link to comment Share on other sites More sharing options...
1197sts Posted March 21, 2021 Share Posted March 21, 2021 Thanks el freddo, I have disassembled a couple of 251 heads in the past and there were some light scratches on the cam journals and cam itself. I think these can be cleaned up and reused no problem, but just wanted to see what others experiences are. On my 259 project, in addition to the original with a broken rod, I have sourced a core engine, it was running when pulled, low compression on #1 and #3. No rod knock according to the previous owner. I am probably going to harvest only the pistons and heads from this engine, so I should be good. BTW, I enjoy trying to determine what caused the failure on the blown engine. It was low on coolant, had oil everywhere including all over the bottom of the cross member, its is hard to say, but it may have had headgaskets leaking badly and finally ran low enough on oil that it fried the rod bearing. In addition to that is also high mileage, so the net effect of having a 7mm oil pump may have finally kicked in. Quote Link to comment Share on other sites More sharing options...
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