well i juss did a compression check on my 206k miles 91 b18a1 and the numbers are 120, 110, 125, 140...i was just wondering is that good or bad? it still pulls hard but i'm just curious on why the numbers are off by so much.

 

not perfect. But who cares drive it until it wont move.

 

They seem to be within spec from each other with the exception of the last one which I am assuming is the #4 cylinder.

 

yes that is #4 cylinder

 

I did a check on my B16 a few weeks ago got 210 across all 4 cylenders... does this sound right? motor was warmed up for about 15 minutes befor the test.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by sc00by &raquo;</TD></TR><TR><TD CLASS="quote">I did a check on my B16 a few weeks ago got 210 across all 4 cylenders... does this sound right? motor was warmed up for about 15 minutes befor the test.</TD></TR></TABLE>

210 is great! What year B16?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 91ls-v &raquo;</TD></TR><TR><TD CLASS="quote">well i juss did a compression check on my 206k miles 91 b18a1 and the numbers are 120, 110, 125, 140...i was just wondering is that good or bad? it still pulls hard but i'm just curious on why the numbers are off by so much.</TD></TR></TABLE>
it's low, but doesn't vary too much, except for that last cylinder. engine is also high milage, so compression is expected to be a bit lower. however, did you have the throttle wide open during cranking, and was the engine at operating temp.? this will make a difference.

 

ya those are low as hell, like the guy saud make sure the engine is warmed up fully, and floor the gas when you do the test, also don't stop cranking till the needle stops going up, all those things will get you higher(truer) numbers.

 

think its a 96 not too sure....

 

nope car was not fully warm and i did not press any throttel

 

my b16 before it blew had 160 all across

 

Looks like you have a problem there.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 91ls-v &raquo;</TD></TR><TR><TD CLASS="quote">nope car was not fully warm and i did not press any throttel</TD></TR></TABLE>Try it again, warm, with the throttle wide open. Don't worry about it until you've done that.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 91ls-v &raquo;</TD></TR><TR><TD CLASS="quote">nope car was not fully warm and i did not press any throttel</TD></TR></TABLE>
then your numbers are inaccurate.

do that and report back to us.

 

isn't pressing full throttle while doing a compression check gonna flood my motor with gas?Just trying be on the safe side.

 

Sorry, maybe we should have gone into the whole explanation...

Disable the fuel (unplug injectors or fuel pump fuse)
Engine fully warmed up.
All plugs removed.
Wide-open throttle.
Crank till the pressure doesn't rise any more (maybe 5 or 6 revolutions)

 

is removing the ECU fuse sufficient,

and i'm just wondering, if you disable the fuel pump what affect does blocking open the throttle have? thx

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 2chron4u &raquo;</TD></TR><TR><TD CLASS="quote">is removing the ECU fuse sufficient,

and i'm just wondering, if you disable the fuel pump what affect does blocking open the throttle have? thx</TD></TR></TABLE>

Yes, and I don't understand the question.

For accurate figures you need to have the car warm, and at WOT.

140psi-110psi is 30psi difference. That's not a good thing.

Try it again.

 

i was just curious what purpose flooring the throttle servers, i know it gives you higher readings, just wondering why

i guess because it allows as much air into the engine as possible?

 

numbers seem really low...and having that much psi difference between 1 and 4 isnt good...time to get that checked out

 

also add a capful of oil into the cylinder and check again, if you get higher readings then your piston rings are going.

 

i just recently built my motor and still haven't cranked it yet..i check the compression and got 220, 200, 200, 200, and that was just turnin the key..is that good, b/c i was told when i get it on the road and tuned i should have at least 12.0.1 compression if not higher..thanks

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Wesb18DB8 &raquo;</TD></TR><TR><TD CLASS="quote">i just recently built my motor and still haven't cranked it yet..i check the compression and got 220, 200, 200, 200, and that was just turnin the key..is that good, b/c i was told when i get it on the road and tuned i should have at least 12.0.1 compression if not higher..thanks</TD></TR></TABLE>

that sounds pretty good, cause I got 205, 200,200, 205 on my built motor with only 530miles on it and I've got 11.4 to 1 compression.... so expect higher numbers after break-in and when carbon starts to build up on the pistons.....

 

yeah.... mine is kinda bad i think its 80 acrost the line. and thats bad cause it only has 115k miles on it

 

thanks for your help, i appreciate it blk_db2