took my car to the dealership and got a compression test done... results were 14 bar on all.

no idea how good/bad is this.

i'm not sure if being at sea level affect the psi or not, and how much does it have of an effect.

comments please..

thanks!

 

sounds fine to me

 

shouldn't the stock block read 10.3:1 approx. ?

 

I think you're confusing Static Compression with Compression Ratio. 10.3:1 is the Compression Ratio

Static Compression testing in simple terms is a way of measuring a motor's health. The idea is to have consistant pressures along all 6 cylinders. Most common cause for low compression in a cylinder would be a worn pistion ring.
1Bar=14.7psi if i remember correctly..that should put you at about 205psi per cyl.

Jared from Z1 confirm above that this is in spec, so congrats man. You have a healthy VQ.

 

Thanks man... i knew i was confused somehow...

so basically my engine is good and can accept a supercharger with no problem.?

 

yes, you should be ok. how many miles do you have on the car? even if you have some decent miles on the car it should be ok for the SC to go on, i just wouldn't beat on it all the times if it has a decent amount of miles.

 

has around 22k miles..

 

Interesting that you needed a compression test

 

^better safe than sorry...

 

need it? well obviously after the test you can second guess it. was it smart to do so before making a decision to go F/I on a stock block, very much so.

 

agreed.

 

umm.. trying to clarify my doubts on those numbers..

so there might be different compression readings from different testers..? and does those numbers have value other than knowing the variance between cylinders and if leak is present?

what if the same tester/gauge was used on two different engines, and both produced constant readings, but a big gap between the two.??

e.g.
---------------------
engine 1

140, 140, 145, 150, 145, 150

engine 2

200, 210, 205, 200, 205, 210
--------------------

 

bump

 

not sure what you're asking here. in ur example you are saying that the tests resulted with two DIFFERENT results in two DIFFERENT motors, whats to question? I'd like to be of more help, but I cannot make sense of what you're asking.

 

thanks...

what i meant is, assuming those numbers were taken from two VQ35DE.

 

The differance could be a few things.The differance between a wet run and a dry run with a shot of oil in each cyl. The mileage could be a big factor.If the motor had boost added to it.

 

Engine 1 is still acceptable. Normal wear and tear occurs and causes a loss of compression. As long as that all cylinders are consistent, then that is an indication of normal wear and tear.

On the other hand, if you have a motor with 200, 200, 200, 200, 200, 150. Then that is an indication of one bad cylinder, even though the cylinder with 150psi is still within spec.


I doubt that all of the high strung, turbo'd stock block daily driver are still in the 200 range. And I highly doubt that a smooth running VQ with 150,000 miles on it would still have 200 on all six cylinders.

 

Anybody on this site knows what are the compression numbers for a new engine?
185, 190, 200 ?????

 

According to the '07 SM, the standard at 300rpm is 185psi. Minimum is 142psi, and max allowable difference between cylinders is 14psi.

Having the test done at sea level will give the higher readings than having it done at higher elevations.

 

BTW, the maximum pressure is higher than 14.7 times the compression ratio because the air is heated during compression.