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View Full Version : Compression Test: D16Z6

kio
02-18-2007, 01:57 AM
What have you guys tested? whats it supposted to be at straight across? 120?
STIBungy
02-18-2007, 08:09 AM
These are the numbers I got for my D16Y8: 162 167 156 162.
kio
02-18-2007, 09:06 AM
ok thanks. the motor im looking into has a compression of 110,100,100,105. it was tapped and check about 3 months ago and has been sittin ever since. what do you think? i was planning on boosting this engine right away.
riceburner700
02-18-2007, 09:51 AM
thats kind of low dude. my d15b8 has 180,000 on it and has 150 across the board with right around a 9.0.1 compression
STIBungy
02-18-2007, 09:53 AM
Did you do the test cold? It shouldnt be that low unless you have low compression pistons.
riceburner700
02-18-2007, 03:34 PM
try warming the engine up to operating temp and then retry the test and make sure the gauge is snug
Nick_S
02-18-2007, 04:04 PM
my d15b put 165 across the board when I first bought it.
kio
02-18-2007, 07:57 PM
its actually a motor im thinking about buying locally.
ComputerJLT
02-19-2007, 05:20 PM
they're low but if it was tested cold like they said that could be normal. They're not way off from each other so i'd say you're fine.
Also altitude has a big effect on compression test numbers.
MrsGhandi
02-19-2007, 05:46 PM
^^ :werd: ^^
If the motor has been sitting for a while it will test low as well. All the oil starts to drain off the rings. Squirt some oil down into the cylinders and retest. You should see a significant increase in the numbers.
kio
02-19-2007, 10:17 PM
ok thanks for the help guys. what if the compression numbers really turn out to be that low. what are the pro's and cons of boosting a motor with such low compression? how will it then affect the life of the motor on boost? id only be planning on boosting anywhere from 5lbs - 7lbs, on a T3 turbo.
ComputerJLT
02-19-2007, 10:25 PM
ok thanks for the help guys. what if the compression numbers really turn out to be that low. what are the pro's and cons of boosting a motor with such low compression? how will it then affect the life of the motor on boost? id only be planning on boosting anywhere from 5lbs - 7lbs, on a T3 turbo.

Compression won't be that low i can almost garuntee it. If you do the oil squirt trick they should shoot WAY up. If they're that low with oil then you have some worn ass rings but almost NEVER will they wear that evenly. If for some highly unlikely reason they are that low then the motor is simply worn out. turbo'ing woul be a waste as it would surely blow soon after.

One thing to remember when you're looking at compression numbers is that equality is more important than how high they are.

On a side note my built d16z6 warmed up w/ oil wouldn't ever do more than about 130psi with around 7.8:1 compression.
kio
02-19-2007, 10:35 PM
how much boost were you playing with? did you ever dyno or tune? what were your numbers?
boostedEG
02-22-2007, 07:32 PM
If for some highly unlikely reason they are that low then the motor is simply worn out. turbo'ing woul be a waste as it would surely blow soon after.




not necessarily. one of the main causes of broken ring landings on stock pistons is because the rings butt up against each other when they expand with the higher cylinder temps of a boosted motor. if you have a good amount of ring gap they wont do that.
ComputerJLT
02-22-2007, 09:38 PM
not necessarily. one of the main causes of broken ring landings on stock pistons is because the rings butt up against each other when they expand with the higher cylinder temps of a boosted motor. if you have a good amount of ring gap they wont do that.

I've seen plenty of popped ringlands; compression is in the 40-60s when that happens