I did a quick search but didn't find anything definitive.

 

Found a 78 brat with 3 subaru motors in the back: an ea71, ea81, and an ea82. I've been looking for an 1800 ea81 to stick in my 79 wagon. From a glance its hard to figure out if the ea81 is 1600 or 1800. From appearance, the only differences are the oil filler has more of a twist, the water outlet (thermostat) is horizontal rather than slanted upward, and I think the pulley was 3 grooved. There's no air cleaner but the original Hitachi carb is there. Any tips appreciated.

 

This guy is looking to sell the Brat which looks a bit beat up but not much rust and the engines for $500 if anyone and happens to be in Flagstaff.

Try this link:

 

http://www.ultimatesubaru.org/forum/showthread.php?t=23166

 

It is too a thread titled "VIN code help", where the guy really was looking for engine designators.

 

Short story: the engine-type is cast in big letters on top of block near RH head (driver's view).

all ea81s are 1800s. ea71s are 1600. look for the stamp as mentioned above. older ea71 engines (pre '80) have the stamp towards the rear of the engine on the drivers side.

all ea81s are 1800s. ea71s are 1600. look for the stamp as mentioned above. older ea71 engines (pre '80) have the stamp towards the rear of the engine on the drivers side.

 

Thanks for the replies. Color me confused because according to this chart there are 1600 cc EA81s in a several of the gen 2 early 80s cars. http://www.ultimatesubaru.org/80s/specs/mechanical/engine-specs.html

 

I can't remember the starter location. That's the real give away? On the side for ea81s and on top if its an ea81. Anyway, its stamped an ea81 but it sure doesn't look much different. And the VIN number won't help since its typically on the dashboard of what is now a crushed and recycled car.

yeah, that chart has some problems. it was originally copied from somewhere else about 6 years ago.....

And another question I might add-how the heck did they squeeze another 200 cc if the pistons are the same size? Can I get that much out of a rebore on my 1600? Anyway, it sounds like if its an ea81 its definitely 1800 and not 1600.

EA71 engines are all 1600cc

EA81 engines are all 1800cc

 

Both have 92mm bore (pistons),

but the EA71 only has a 60mm stroke compared to the EA81's 67mm stroke.

 

Due to the difference in stroke, EA71 engines are slightly narrower from valve cover to valve cover than EA81 engines.

this is Best answer to solve your question and is very correct.

 

EA71 engines are all 1600cc

EA81 engines are all 1800cc

 

Both have 92mm bore (pistons),

but the EA71 only has a 60mm stroke compared to the EA81's 67mm stroke.

 

Due to the difference in stroke, EA71 engines are slightly narrower from valve cover to valve cover than EA81 engines.

Okay I get it. And apparently because of the shorter stroke on the ea71 the wrist pin location is different. Thus, you can use an ea71 piston in the ea81 and increase compression ratio a bit because of the longer stroke. Would that also increase horsepower or just low end torque? I have a set of ea71 pistons that have been in a box for 18 years since my 78 2dr was totaled in 1986.

 

Thanks for the info!