B16A2, I/H/E, Skunk2 Intake Mani., PO6 ECU Skunk2 chipped (running way to Rich)
Running to rich wouldnt have anything to do with the numbers would it?

#1-150
#2-122 *
#3-152
#4-150

Its supposed to be in the 200 range isnt it?

Its pulls pretty damn hard which suprises me with these numbers.Something that needs a rebuild?

 

Those numbers are kinda low for a b16, and it looks like the #2 cylinder is starting to fail on you. You need to do a leakdown or vacum test to narrow down where the problem is(block or head)

 

Have you done that test at WOT, and then try dropping a cap of oil in the cylinders after?

That would prove if your piston rings are bad.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by poison &raquo;</TD></TR><TR><TD CLASS="quote">Have you done that test at WOT, and then try dropping a cap of oil in the cylinders after?

That would prove if your piston rings are bad. </TD></TR></TABLE>

those numbers look like the test was not done at wot. also, how would dropping a cap of oil show you if the rings are ok?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by littlegreenb18 &raquo;</TD></TR><TR><TD CLASS="quote">

those numbers look like the test was not done at wot. also, how would dropping a cap of oil show you if the rings are ok?
</TD></TR></TABLE>

If you get low compresion numbers, you can pour a small amonut of oil down the spark plug hole and try again. If this raises the compression, then it's your rings that are worn. The oil helps create a seal between the rings and the cylinder walls.

 

just curious how do you get a compression ratio out of those numbers?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by turbodreamz0385 &raquo;</TD></TR><TR><TD CLASS="quote">just curious how do you get a compression ratio out of those numbers?</TD></TR></TABLE>

You can't get a compression ratio from a compression test.

 

i would assume they would some how have to be related, the higher the compression #'s the higher the compression ratio, ive never went to school for mechanics anything i know i just got on my own... but that is something ive never realy understood and am just trying to get straight on

 

did u make sure you oiled the rubber seal rings on the compression test before you did it?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by j4yd3um4lyf3 &raquo;</TD></TR><TR><TD CLASS="quote">i would assume they would some how have to be related, the higher the compression #'s the higher the compression ratio, ive never went to school for mechanics anything i know i just got on my own... but that is something ive never realy understood and am just trying to get straight on</TD></TR></TABLE>

I understand why you would think they're related, but the compression ratio has to do with combustion chamber volume and bore and stroke...then they take all those numbers and throw them through a formula to get a compression ratio.

 

Two more questions for you. Was the engine at operating temperature when you did the test? And how quickly did the numbers rise when you did the test. Usually if the rings are worn, the numbers will jump kinda slowly like 20-30 psi per stroke. Normally you should reach full compression after only 2-3 strokes.

 

try another compression guage!!

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by coquitlamEG &raquo;</TD></TR><TR><TD CLASS="quote">If you get low compresion numbers, you can pour a small amonut of oil down the spark plug hole and try again. If this raises the compression, then it's your rings that are worn. The oil helps create a seal between the rings and the cylinder walls.</TD></TR></TABLE>

good to know, theres something to add to my bag of tricks also, you can get your compression ratio from a compression test. but its a complicated formula, and i don't know it. and i'm sure not many people do because its really doing things the hard way

 

yea..that seems kinda low, when i did mine it was 205 all the way across

 

You have gotten the best advice you can get so far.

I will combine it all for you.

Was it warm?
Was it at WOT?
Was you compression tester lubed to seal well?


If you answer yes to all of these, put a table spoon of oil down each hole to perform a wet test OR, try another gauge. They are not all created equal that is for sure. I know mine has gone 192-195 on all four and then with my buddies gauge, it goes 217 to 222 on all four. Check your number 2 with oil (and dry making sure it is screwed all the way down) and let up know whats up.

 

It was warm.

When I turned it over I didnt floor the gas pedal.So it wasnt at WOT.

Not sure if the tester was lubed or not my buddy did it.

Ill check it again and get back to yall.

Thanks for the advice.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by coquitlamEG &raquo;</TD></TR><TR><TD CLASS="quote">

You can't get a compression ratio from a compression test. </TD></TR></TABLE>

You can get close though.

8:1-8.5:1 compression: 150-170 psi per cylinder
8.5:1~9.5:1 compression: 170-210 psi per cylinder
9.5:1~11:1 compression: 210-275 psi per cylinder
11:1+ compression: 250+ per cylinder (highly depends on cams being used)

 

That's a good way to get a rough idea of what your compression ratio is, but unless your doing it on a rebuilt engine or one that still has 100% of it's compression, your numbers are gonna be way off. Imagine you test an engine with a compression ratio of 10:1 but you only get 170psi on the compression test because something like your rings are starting to wear. You'd think you only have an 8.5:1 engine. It's a good rule of thumb, though.

 

how much performance loss would you experience w/ such low numbers ?

also, are there symptoms of low compression ?

 

what does the oil do?

 

I didnt have have the thottle at WOT when I cranked it over.Thats the resone for the low #s correct?

But that still means #2 is lower than the other three right?

 

Not having the throttle wide open would give you those lower numbers. I'd do the test again if you can to make sure you get the same results before worrying about the #2 cylinder being lower.

 

it somewhat seals the area around the piston and cylinder wall. correct me if im wrong but if you add oil and the number increases its more then likely worn rings.

 

Ok the test was done again and it got 215 across.

Is that what a stock B16A2 is supposed to be at?

 

i was pushing 160- 180 across and didnt have it WOT. y exactly does it make a difference if you dont have it WOT? my friend argued that it doesnt make no difference, i think he is an idiot. this coming from someone who has built his b18c5 turbo/nitrious motor.