Compression test what to look for?

[etbsimo]

Hey all before you trash me i've searched this so please read the question, then go ahead if you want ;) OK so i'm looking to buy a b16a2 and the owner is willing to give me a compression test. my problem is what i should look for, i understand that the figures should be consistant from cylinder to cylinder but how close and around what figure? I believe the b16a2 comes with a compression ratio of 10.2:1 factory if this helps. also the engine is unmodified.
thanks for reading, Simo.

[teh_mechanic]

you need atleast 100psi in any engine, any cylinder, for combustion to occur, any less and the engine is totally stuffed and wont fire.

B16 from memory is somewhere around the 150psi - 180psi per cylinder mark. Any lower and id be wary.
Main thing your looking for in a compression test is that each cylinder is aprox 10% within all the others. There will ofcourse be variation in each cylinder but any noticeable difference outside of 10% (especially 15-30% lower for example) is bad sign. Higher psi can sometimes be caused from carbon buildup over time making a better seal, its nothing to major but just keep it in mind if you get one with a higher reading.

Lastly, make sure the owner doesnt put any oil down the spark plug holes, this is an old trick to boost compression for a short while as it boosts the rings seal with the bore until the oil burns off

[etbsimo]

you need atleast 100psi in any engine, any cylinder, for combustion to occur, any less and the engine is totally stuffed and wont fire.

B16 from memory is somewhere around the 150psi - 180psi per cylinder mark. Any lower and id be wary.
Main thing your looking for in a compression test is that each cylinder is aprox 10% within all the others. There will ofcourse be variation in each cylinder but any noticeable difference outside of 10% (especially 15-30% lower for example) is bad sign. Higher psi can sometimes be caused from carbon buildup over time making a better seal, its nothing to major but just keep it in mind if you get one with a higher reading.

Lastly, make sure the owner doesnt put any oil down the spark plug holes, this is an old trick to boost compression for a short while as it boosts the rings seal with the bore until the oil burns off



Thanks mate, exactly what i wanted to know.

Cheers Simo

[paps02]

when he does the test and you see black smoke coming out of the engine tell him to get F*cked cause he has more than likely lined the chambers with oil to get a higher reading... as said above and ur on ur way