thanks guys...my mechanic said the ej207 + ej20k idea wont work since the ej207 and ej20k are two different engines and told me to forget about it... this contradicts from what everyone have said on here and my research on other forums

honestly if he says it wont work i might as well scrap the idea cause if i still go ahead with it and it doesnt work in the end... its going to be money down the drain

anyways... i found out some history about my car (subaru crowd here is small and there are only a few "subaru specialist" here)... i went with this guy cause he pointed out most of the parts that needs replacing once the engine threw a rod bearing

the engine has been rebuilt a year ago by another mechanic but my mechanic pointed out the previous mechanic only replaced the crank and some parts to get it running and thats it... the block has not been bored before so i might have a chance to reuse this block if i bore 0.5mm from the cylinder walls if the grooves can be cleared

to be honest...the garages in hong kong are more of plug and play/pray type... they assemble it and move on to the next car...not many are willing to do engine/gearbox rebuilds and even if they do..they usually half ass it..
finding someone to tune it is impossible... usually when someone wants something tuned, they get people to fly in and do it

if i have the space and the tools to do everything myself... i wont let them touch my car
it is worrying putting my life in some mechanics' hands after seeing how they fix cars

"Everyone on here"?

Please re-read my posts and realise your mechanic is on the right track.

I understand your predicament, there are a number of those 'Hong Kong' type garages in Australia who also have shops full of gauges, turbo timers and strut bars but no idea how to change a synchro ring.

Here is a viable option you may be able to make work within the confines of your workshop situation.......Buy a new in crate EJ207 short engine (I'm not sure of the retail price in HK but they are very reasonably priced in Australia)
Then buy a new set of EJ20K Forged pistons (genuine or aftermarket) and get your guy to slide them in without splitting the case. It's a relatively straightforward process. He will need to measure the clearance but usually they are within tolerance without an machining.

There are some differences in the EJ207 block, rods and crankshaft but none will prevent this from working. Your heads will fit, your gearbox will refit, all your ancillaries will refit. Note; you cannot go the other way, cannot fit 207 pistons to EJ20K rods.

thanks

ok so...ej207 shortblock + ej20k pistons + ej207 normal head gaskets + ej20k heads is a working combination without engine management to compensate for the compression ratio problem?

a ej207 shortblock is less than 800-1000usd shipping included

I would use EJ20K headgaskets. Effectively you would have a brand new EJ20K with a stronger block and better rods and crankshaft. All dimensions and compression ratio would be the same as an original open deck EJ20K.

thanks for the clarification
ej20k stock thickness gaskets? or do i need the cometic hybrid gaskets?

also...do the heads determine which harness and ecu i use? or is there a relationship on which intake manifold i use as well?

Yes, standard EJ20K headgasket thickness whether it be genuine Subaru or aftermarket.

As for the heads/manifold/wiring harness question, short answer is yes.

Long answer is basically there are two different bolt patterns, All EJ Quad cam engines prior to 99 and post 99. It's not simply the bolt pattern but the distance between the ports. In short, you can change inlet manifolds between all pre 99 versions with each other and all post 99 with each other but you cannot cross over early and late.

The manifold and throttle body largely determines the wiring harness that attaches to it and matches the car. What can be done with some creativity (and often compromises) is to use for example a later engine in an earlier car but 'dress' the engine with the electrical sensors and harness from the earlier version that the car's wiring harness suits.
This often requires adapting the throttle body so that the throttle position sensor that suits the wiring can be retained. Then there's all the problems of no mounting points for the throttle cable, no mounts for the ignition coil, stuff hits other stuff etc.
I've done it before, but not without good reason.

thanks for your detailed explanation..
in other words... mixing and matching engines requires fabrication of parts and a big hammer

anyways...i have decided to just get an engine, swap it in and worry about it later...
too much risk and too costy to have someone that doesnt seem sure what hes doing if it breaks down again
maybe its time for me to figure out how to rebuild it myself

thanks everyone... i will most likely come back with questions in the future when i need help rebuilding