Hi, i have just had my engine built parts include Cp's 9.01, manley rods, supertech valves(stock size) & dual springs etc. I was expecting to get 180 comp all round for a 9.01 on a b18c, but after i tested it i got the following results 200 200 180 200
Am i correct in saying comp should be 180 and what could ause this?

 

did you adjust all the valves after?

 

yea i did, im pretty confused at what it could be
what compression ratio would give 200 all round?

 

i get like 220 on a 9:1 compression motor

 

i think i had 170-160 on my sohc w/ 9:1, but that motor was trash to start with. I dont think its a big deal. i would be more worried about that 20psi lower cylinder.

 

Cam timing has a huge impact on a compression test.As does your guage and even your starter.Here's some good tech reading. http://kb-silvolite.com/article.php
Glenn

 

how many miles are on the motor?

 

yeah i get 180 on my 9-1 je pistons crower rods 600 miles on setup

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by gritsak &raquo;</TD></TR><TR><TD CLASS="quote">how many miles are on the motor?</TD></TR></TABLE>

I think the motor has about 200 miles on it. before i got the valves put in last week, i had the engine run in 100 miles on the new pistons and then it read 200 180 180 200. After installing the valves ive got different results altogether.

should i sit around and try and figure the problem, or should i just Sack it and bolt on the turbo run some sick boost and hope it, sorts itself out

 

thats pretty low miles on the motor. I let mine break in for about 800 miles. Wait a while longer put a few hindred miles on it. Maybe it will sort itself out. Then boost the turds outta it.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by kabaroo &raquo;</TD></TR><TR><TD CLASS="quote">thats pretty low miles on the motor. I let mine break in for about 800 miles. Wait a while longer put a few hindred miles on it. Maybe it will sort itself out. Then boost the turds outta it. </TD></TR></TABLE>

800 miles is quite a bit. I had 180 across the cylinders after twenty five minutes. Although our startups were most likely different. At 1,000 miles I had 190 across. It was probably sooner but I didnt feel like testing until 1,000 miles

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by f1 vtec &raquo;</TD></TR><TR><TD CLASS="quote">I think the motor has about 200 miles on it. before i got the valves put in last week, i had the engine run in 100 miles on the new pistons and then it read 200 180 180 200. After installing the valves ive got different results altogether.

should i sit around and try and figure the problem, or should i just Sack it and bolt on the turbo run some sick boost and hope it, sorts itself out </TD></TR></TABLE>

What kind of valves did you put in? Valves can increase compression..

In any event 200 compression is okay!

 

o.k ill just hold till ive done like 1000 miles and then ill bolt the turbo on and get it tuned.

So whats the sitaution with the 180 cylinder?
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ekb18c &raquo;</TD></TR><TR><TD CLASS="quote">

What kind of valves did you put in? Valves can increase compression..

In any event 200 compression is okay!</TD></TR></TABLE>

Ive used stock size supertech valves

 

depending on the bore size a 9:1 comp eng will give you about 200 psi on your comp gauge.

my 84mm gsr with gsr head gives me about 225 across the board with 9.5:1 cr pistons.