2G compression test fail

[Samusisback]

ok so i did a compression test since my friend who told me ''hey there is'nt much compression getting out of the exaust'' so i said ok and there is blue smoke as i already said here on the forum comming out of the exaust. so i did the test to a mechanic. He is supose to have exp since he work in garage for the pas 30 years and have is own garage.
so i took out the spark plug and unplug injector. he plug is thing and have the car starting to get the result for piston. after that he put a few drop of oil in each cylinder and do it again telling me it's for the ring. here are the result

piston Ring
cylindre 4 110 135
cylindre 3 110 145
cylindre 2 105 135
cylindre 1 102 129

he tell me the engine is fine but not perfect that i can continue driving it. my friend told me it was too low...way too low. he didnt know the real number but tell me that its too low to be ok for a turbo car or almost any car so i looked up here and found that it's supose to be 178 and at 133 and below something need to be change. and yes he was with is assisstant doing the test.
So i supose i have to buy new piston and ring but first what are the ratio of those i didint find answer yet...i know its 85mm with 88mm bore but it seem to have 8.5.1 and 10.0.1 or something like that and dont know witch one chose and i will hope tnat the engine is not oversized by being betten to death at cold.
second thing i would like to know can the piston be change without having to take the engine off the car because im not equip or have the place to do that.
finally what kind of piston is good knowing that i dont have high budget and dont need piston that can witstand 600hp...

 

[91tsiawdtalon4g63]

Was the test done on a hot or cold engine? It seems anyways that the engine is needing some new rings or pistons depending on their condition. 2g runs a 8:5:1 I believe or 8:3:1 I cant remember at this very moment. I wouldn't buy rings nor pistons til you'd drop the pan and get them out to inspect them along with the block incase it needs bored out instead of a hone job. To check everything out correctly you'll need to pull the engine out of the car :/ sucks that you don't have the tools but it's what's needed. Get a hoist from somewhere and lift it out and with a mechanically inclined person you'll be able to diagnosis 100% of the problems in a few hours and be ordering parts the same day. OEM or npr are the cheapest pistons I believe but if you're yanking out everything to check it, I'd recommend getting some better rods or a full balanced rotating assembly, like manley, and have a good worthwhile block with extra reliable parts

 

[Samusisback]

the engine wasnt hot but it wasnt cold...it's a very short run to that garage and i dindt hit any boost to go there and run at low rpm for the 5-6 minute drive to him. what is the ballanced totating assembly...you mean crankshaft bearing rod piston or just crank and bearing

 

[luv2rallye]

- Compression ratio on the 2g turbo is 8.5:1.
- 85.0 mm is the bore and 88.0 mm is the stroke.
- Compression should be measured with engine warm (coolant 80-95*C), all spark plugs removed (with tester in one hole), spark and fuel disabled (CPS disconnected), and throttle held wide open while cranking.
- Standard compression pressure is 178 psi with 133 psi minimum. Difference between any cylinders cannot be more than 14 psi max. Your readings are very low (102-110). The fact that added oil significantly increased compression points to rings and/or cylinder inner surface (usually it's rings however unless it was severely overheated). The fact that the difference between cylinders is less than 14 psi is why you can still drive it but it must be very low on power.
- You can remove the pistons without lifting the engine out by removing the head and oil pan (to disconnect the rods). {You'd have to do this even if you lifted the engine out.} Personally that's the way I'd do it so you don't have to remove the hood, axles, and everything that's connected (fuel, cables, motor mounts, air ducting, battery, clutch slave cylinder, radiator hoses, etc).

 

[Samusisback]

the probleme is i wasnt that low on power but it may be because i was boosting at 18 psi. i will check on that and be sure the engine is still in good shape before buying new piston