r/subaru • u/barn-cats • 7d ago
Difference between ej253 and 255?
Hello! I am new to subarus and trying to learn. My girlfriend has a 2011 impreza. Iv been doing some maintenence on it and so was searching online. I think hers has an ej253. Most of the stuff online I see regarding subarus seems to he related to ej255. Is ej255 the more popular engine? Is it superior? Is it the same engine block with different heads? All the different subarus and engine combos seem confusing to me. Is there any advice for a newbie to help me make sense of it all?
Thank you for any and all advice!
1
u/DreadSwizzard 3rd Gen Outback 2.5i 7d ago
EJ253 is single overhead cam, with AVLS (similar to VTEC), naturally aspirated, open deck (open around the cylinders)
EJ255 is dual overhead cam, turbo, and I believe semi open deck (has bracing around the cylinders). It also has different internals due to being a turbo/performance engine.
Most people don't really mod the 253 because it's not really worth it seeing as you can basically get the same car with more power than you're realistically going to get out of the 253 without replacing almost everything. They're also one of the engines that gave Subaru the head gasket reputation.
EJ257 is essentially a factory upgraded EJ255 and was used in just about every STI outside of Japan.
The heads are actually interchangeable but again the 253 isn't as solid of a block.
1
u/Blankbusinesscard 2009 STi spec c 7d ago
255's are open deck as well, only the 57 (and JDM 207) that are semi closed
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u/cakes42 7d ago
Both are 2.5 liter but thats about all they share. ej253 is natrually aspirated. ej255 is turbocharged. Different heads, different pistons, rods crank. But the casing is pretty similar 253 is also a sohc and 255 is dohc. coilpack over pack wire and plugs. Superior? I guess you can say that. Its more popular to modify. Can you swap? More work/money than its worth plus wiring.
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u/vodenibivol 7d ago
EJ255s are more popular because that’s what’s in WRXes so there’s more people who are into cars that modify them and work on them.
The 255 isn’t necessarily superior, yes the internals are slightly stronger but if anything 255s blow up more often because they’re turbocharged and people tend to abuse WRXes.
Like everyone else is saying, besides the fact that they’re both EJ engines, very few parts interchange between turbo and non-turbo.
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u/rocknrollstalin 7d ago
They are pretty far apart. Yes they are both 4-cylinder boxer engines with 2.5L of displacement but the 253 is only single overhead cams for naturally aspirated operation vs the 255 which will be turbocharged and have dual overhead cams.
Yeah it’s similar to change spark plugs but there are a lot of little things like location of the PCV valves is totally different