What difference does the frankenmotor give with the EJ25D bottom end vs. the EJ251 bottom end? (with 91-95 2.2 heads, porting, cams, & headers)

I.E. - which one gives a higher compression anyone have approximate CR numbers?, & 91 octane would be required with said block?

General Disorder has said the comp ratio of the ej251 with ej22 heads is well over 12 :1

i run a 2.5 block with 2.2 crank and rods gives me about 8.5-1 comp ratio

^nice, about the most perfect ideal CR for a boosted motor,

I have a turbo car at 8.5:1 CR

i run a 2.5 block with 2.2 crank and rods gives me about 8.5-1 comp ratio

 

which ej25 pistons are you running Ivan, I've considered building a destroked ej25 but couldn't find anything one the compression ratio

General Disorder has said the comp ratio of the ej251 with ej22 heads is well over 12 :1

 

NOT what I said.

 

EJ251 is 11.5:1

 

EJ25D is 10.6:1, or for '96 pistons ONLY it is over 12:1

 

GD

run any 2.5 piston you whant i like the sti pistons for the destroker as they are resably tough and easy to find for cheap butt it works good with 2.5d pistons or 2.51 pistons but they are weaker. I can biuld a destroker engine with used parts for under 150$ so longevity is erelavent but of the 4 i built all are still runing strong. The prototype destroker has 6 years of buggy and offroad use on it

I just purchased a '96 Legacy L with the 2.2L engine (bad trans).

I figured at a minimum I would use the 2.2 SOHC heads and the '96 wiring/computer.

 

Now I just have to decide the crankshaft/rods/block/pistons/cams that would be best to go with those heads for some type of frankenmotor build around 8.5:1 CR for turbo boost.

Put the whole 2.2l engine in as is and drive it, then build up a 2.5l block as you see fit later.

 

Focus on the harness and getting the engine in and running before anything else.

I'm a custom builder, I know that is a good answer for most people thanks, this car purchase and my project goals are driven by different reasons and will be built as I see fit first.

If you are planning a turbo build I would not start with the 96 legacy harness then. Start with a newer harness and computer that are user tunable without the use of a piggy back.

 

A harness out of an 02 WRX would make your life much easier down the line as you upgrade or change things around. Look up open source tuning for Subaru's. The extra money you spend getting the harness and ECU will be more than saved by not having to buy piggy back or stand alone aftermarket ECU's to work with the 96 legacy harness.

 

As far as the 2.5l short block, use a phase 2 block and crank because the rod journals are the right size for the later 2.5l turbo rods and aftermarket ones. The EJ25d has smaller rod journals and the thrust bearing on 3 instead of 5 like the Phase 2's.

 

Figure out the EJ22e's head chamber cc and pick a piston with a deep enough dish to compensate. You may have to go aftermarket, but a cheap option would be stock STi takeouts from a brand new block that someones putting forged pistons in.

 

This is assuming you're using a pre-EA82 body, because that's the only reason to run the ej22e heads. Otherwise go DOHC and do a proper turbo engine build up.

I am learning more and more about all these frankenmotors, what i was thinking was a destroker was not quite the parts I thought it was, but ya..

Seems the old '96 2.2 heads would only be good for a cheaper N/A 2.5 frankenmotor build..

Do the Frankenmotors have headgasket issues?