I recently put a "new" d16y8 in and apon initial start up it poured white smoke out of the exhaust and gets worse as rpms raise. I did a compression test and results showed around 190 psi except for cylinder 4 had about 60 psi. My initial thought was a head gasket but no oil mixed with coolant and i pressure tested the coolant system and test turned out good. Any suggestions guys? Thank you

 

I don't know if this would apply here but i once rebuilt a diesel engine and it had the same issue with white smoke and that turned out to be a timing problem, but that still wouldn't explain the loss of compression in cylinder 4. just due to the low compression I personally would check that your piston rings aren't fried.

 

white smoke usually means ither cracked head/warped head/blown headgasket, i dont know how to tell witch it is, but ive never seen white smoke come from anything else

 

Do an HC test on the coolant system to detect any exhaust gases present.

Does this car overheat as well?

 

if your pushing 60 psi out of 1 or more cylinders then somethin is really wrong.

try doing a wet compression test on the 2 that had 60. if the readings go up you probably need new rings.

if it doesnt help the numbers than theres a leak on the head. valves,valve seals,cracked head...

 

Your headgasket is obviously blown around cylinder 4, based on your numbers and the fact that your shooting white smoke, unless you got an neverending supply of seafoam going into your intake. If the smoke was black it would be something else wrong with cylinder 4.

 

Unplug each injector one by one and see if the smoke clears it will sound like poop and shake. Check each spark plug and see if theirs any difference between them because the color of it might tell you something. Maybe with this info we might be able to find your problem.