i went to go look at a hatch with a stock s13 blacktop and the owner and i performed a compression test. The results are as follows:
Cylinder # 1 = 130psi
Cylinder # 2 = 140psi
Cylinder # 3 = 140psi
Cylinder # 4 = 135psi
I’m not too sure whether these readings are too low or not according to s13 sr20det specs…im having trouble finding it on the internet…so if anyone knows what the compression should be…or range from…please let me know
thats fairly low yes… im guessing it should be around the 150-160psi mark
thanks…its most likely the head gasket if their all low…or all piston rings are fried…but i have a question…should you be cranking until the needle stays stationary?..
yeah keep cranking till the needle doesnt move
Was the engine warmed up? Did you hold the throttle open while cranking? And you aren’t supposed to keep cranking, you should only have to turn it over 3-4 times to get agood reading.
thats not to bad…if it was cold and sitting for a long time those #"s are ok…
open the throttle body while cranking, and also pour a small drop of oil in each cylinder just to seal the piston rings…i bet they are dry cuz its been sitting for ages…
Dont put more then a drop of oil, the comp#"s should never go above 155-160…
^ nod nod
yea i don’t think we kept the throttle open…and it was warm because it was idling for a while and i drove it for a little bit…if throttle was closed and engine was warm…are those numbers ok?
what should you do if your engine was sitting for sometime in the cold ie garage?
drive it so it warms up then take the test…back to my original question, are those numbers ok if throttle was closed and engine was warm?
Redo it with the throttle held open.
And do it without oil, putting oil in defeats the purpose of checking compression since your engine doesn’t run with oil in the combustion chamber in the first place.
see the thing is…it isn’t my car…i went to check it out…and i dont want to ask the owner to redo for me…thats why i was asking if the throttle is closed and i get the values i got…does that sound about right?
The numbers are getting on the low side but are still in spec according to the fsm. The important thing here is that the numbers are pretty even across the board so I wouldn’t worry too much.
sounds good…i was just concerned about the readings because if i do get the car and up the boost on stock internals i don’t want to risk damaging my motor at all
lol so true, “seal the rings”
yea, you will notice that when motors sit for a while, its bad to turn them over without pouring a drop of oil into the top of the cylinder to make sure its wet…otherwise, u can score the walls…
The best way is to wet them a tiny bit, turn over the motor 5-10 times, and then do the comp test so u know for sure there is no more oil in the cylinder, and the walls are glazed with oil.
great…thanks varuun and thank you to everybody that helped on this thread