head swap sohc to 2.5L sohc

Heads, valves, pistons, rods, crankshaft, etc...

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x2hawt4ux
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head swap sohc to 2.5L sohc

Post by x2hawt4ux »

ok so it may sound weird but i got an offer from a friend to buy his heads and intake mani and everything else i might need off of his 2005 legacy 2.5i. its the n/a 2.5 not the 2.5gt. he says i should see a significant power increase as these are much better flowing heads. i know the dohc 2.5gt version heads would be better, but he said i can have what ever i need for only $150. i looked on msn autos and the 2005 legacy 2.5i has 168hp stock na. i know our cars, according to msn autos, comes stock with 160 turbo. this would all be going on to a 22t with a 16g. the 2.5i heads are top feed and i have some 470cc topfeed injectors that im pretty sure would work. i curently have 440's. what do you guys think.

thanks in advance
92 turbo legacy: RWD W58 SWAP, td04, 3"tbe, mbc, fmic, wrx brakes/hubs, wrx seats, welded 4.11, fcd, drift steering wheel, Drifting Stickers
Legacy777
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Re: head swap sohc to 2.5L sohc

Post by Legacy777 »

That's not really going to be your best option. The 2.5i heads are non-turbo heads and do not have the opening for oil & coolant fed to the turbo, nor do they have the turbo oil return line. Also, the 2.5i heads have EGR on them, and you would not be able to run the 2.2t intake manifold.

There is a certain limit to the "legos" theory with Subarus. If you stay roughly in the same genera of age, things are pretty interchangable. Once you start making large leaps, there's a bit more differences.

Also, just because there's more hp, that doesn't really mean squat. The turbo legacy made around 180 ft-lbs of torque stock. I believe that's going to be much better than the 2.5i.
Josh

surrealmirage.com/subaru
1990 Legacy (AWD, 6MT, & EJ22T Swap)
2020 Outback Limted XT

If you need to get a hold of me please email me rather then pm
x2hawt4ux
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Posts: 170
Joined: Sat Jun 26, 2010 11:07 pm
Location: Bellingham, Wa

Re: head swap sohc to 2.5L sohc

Post by x2hawt4ux »

you are right about the torque. id i was to make oil lines and run the 2.5i manifold. do you think i would see an improvement over what i have now?
92 turbo legacy: RWD W58 SWAP, td04, 3"tbe, mbc, fmic, wrx brakes/hubs, wrx seats, welded 4.11, fcd, drift steering wheel, Drifting Stickers
Legacy777
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Re: head swap sohc to 2.5L sohc

Post by Legacy777 »

To be honest....not really. You will run into issues getting the electrical to work and any gains will be marginal if anything. These heads may be restrictive, but there are options you can do to get good power out of them. I was making near 300 chp and over 300 ft-lbs of torque on the stock heads & cams.

If you have an intercooler and are running more boost to the point where the stock ECU can manage it, the next step is to upgrade to better engine management. The best bang for your buck and really the only "good" option IMO is to go with a Rob tune EJ20G ECU. You put in the yellow top injectors, run the JECS MAF, and swap in the new ECU. It doesn't get much easier than that.
Josh

surrealmirage.com/subaru
1990 Legacy (AWD, 6MT, & EJ22T Swap)
2020 Outback Limted XT

If you need to get a hold of me please email me rather then pm
Mister Anderson
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Re: head swap sohc to 2.5L sohc

Post by Mister Anderson »

Legacy777 wrote:To be honest....not really. You will run into issues getting the electrical to work and any gains will be marginal if anything. These heads may be restrictive, but there are options you can do to get good power out of them. I was making near 300 chp and over 300 ft-lbs of torque on the stock heads & cams.

If you have an intercooler and are running more boost to the point where the stock ECU can manage it, the next step is to upgrade to better engine management. The best bang for your buck and really the only "good" option IMO is to go with a Rob tune EJ20G ECU. You put in the yellow top injectors, run the JECS MAF, and swap in the new ECU. It doesn't get much easier than that.

Where would one find a rob tune ECU?



NVM I found his thread
91 black SS 5 speed (Canadian).... Closed deck EJ20G, fully built, V5/6 sti ra drivetrain, haltech stand-alone
93 silver TW 5 speed... rebuilt 22T with 20G heads, wrx ra drivetrain, otherwise stock.
73 kazen red VW bus riviera camper
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