decided it was time to check the compression and the spark plugs....plugs looking good and heres the compression check ( as a rem. this is a b18c1 with 90+miles on orginal engine...no rebuild and headgasket has never been replaced)

1:230
2:230
3:225
4:225

the comp numbers look good but kinda higher then the last time I check....I think last time I checked it was 205 across the board and this was maybe over a year ago......

is this the norm for higher milage cars
comments.....

 

Those look fine.. i thought the rule was if they are within something like 5-10 percent it was healthy. i had a built c1 with 9.5 comp and mine were around 180.

 

Yeah im pretty sure as long as there in the same area then its ok...I need to do a compression test on my 94 with 140k!

 

those comp #'s look really good, nothing to worry about

 

i read in a sportcompactcar magazine article once that carbon buildup on the valves/pistons can actually raise compression in a high mileage car. i'm not sure if i'll buy that, but what the hell, ya know? your car is in good shape, GSR motors will literally go 250k with no rebuilds, headgaskets, or any of that nonsense. all you gotta do is change the oil and keep up on maintenance. make SURE you get your timing belt done on time.

 

You have a really good compression tester. The tester can significantly affect the readings. My cheap tester has about 2cc of volume before the one-way valve. So I typically read about 200 psig.

 

When your compression numbers were 205 across the board were you using the same tester as this time?

Your numbers are consistant which is the main thing anyway.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by phateless &raquo;</TD></TR><TR><TD CLASS="quote">i read in a sportcompactcar magazine article once that carbon buildup on the valves/pistons can actually raise compression in a high mileage car. i'm not sure if i'll buy that, but what the hell, ya know?</TD></TR></TABLE>

True story. That's what I was going to suggest the carbon buildup decreases the size of your combustion chamber which puts more pressure on the same amount of air/fuel mixture. Thus you get higher compression readings.

 

I chiseled what seemed like about a mm of carbon off my pistons when I swapped the head. Maybe I can do something to get a lot of carbon buildup so I can be running a hi-comp LS head

 

i've heard stories of thin head-gaskets to increase compression... that sounds like bullshit to me, but you never know...

 

Tested the b17a1 in my car the other day, the #'s were 215,215, 210,205, The motor just turned 260k, and has never been rebuilt. Some of the gaskets leak a little, but it doesn't burn oil either.

 

Every tester will give you diff results plus where your located, pressure etc. everybodys is alowys gonna be a little diff

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by phateless &raquo;</TD></TR><TR><TD CLASS="quote">i've heard stories of thin head-gaskets to increase compression... that sounds like bullshit to me, but you never know...</TD></TR></TABLE>

This is equivalent to shaving the head. You can see the effect here.

http://www.c-speedracing.com/h...c.php

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 1point7DA &raquo;</TD></TR><TR><TD CLASS="quote">Tested the b17a1 in my car the other day, the #'s were 215,215, 210,205, The motor just turned 260k, and has never been rebuilt. Some of the gaskets leak a little, but it doesn't burn oil either.</TD></TR></TABLE>

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by jared99 &raquo;</TD></TR><TR><TD CLASS="quote">I chiseled what seemed like about a mm of carbon off my pistons when I swapped the head. Maybe I can do something to get a lot of carbon buildup so I can be running a hi-comp LS head </TD></TR></TABLE>

Run a couple tanks of diesel fuel through her...

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by phateless &raquo;</TD></TR><TR><TD CLASS="quote">i've heard stories of thin head-gaskets to increase compression... that sounds like bullshit to me, but you never know...</TD></TR></TABLE>

LOL, the "stories" you heard are correct.


<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by phateless &raquo;</TD></TR><TR><TD CLASS="quote">i read in a sportcompactcar magazine article once that carbon buildup on the valves/pistons can actually raise compression in a high mileage car. i'm not sure if i'll buy that, but what the hell, ya know? your car is in good shape, GSR motors will literally go 250k with no rebuilds, headgaskets, or any of that nonsense. all you gotta do is change the oil and keep up on maintenance. make SURE you get your timing belt done on time.</TD></TR></TABLE>

This is VERY true. 1 MM of carbon build up could change the compression a decent amount.

 

craziness... so romping on your car really is good for it. heh