ok i ran a compression test on my freshly built motor with 700 miles on it, here are the results with these parts...94GSR block bored 81.5 mm with CP 9:1 pistons on Eagle H beam rods with all new bearings and assembled, all done at machine shop...i ended up with about 163 +or- maybe 3 psi in each cylinder, that low? or is that about right with the OS pistons running only 9:1 compression? thanx guys in advance

 

don't know if this helps you or not, but I just compression tested my stock LS motor with 125k on it and I had 170-175 on each cylinder. Hope that helps you with your gauging.

 

Sounds good to me, the most important thing is consistency across all cylinders.

 

thanx for the replies guys...yea i had about 175 in there before the tear down..i just wanna see if anyone has info if the #s sound accurate. i figured they were about right and yea i also figured the consistency was the important part, with only maybe 3-4psi difference in each cylinder, i figure im ok...now if i can just figure out why my oil seems watery and olive colored...
anyway any other thoughts on the #s?

 

anyone else?

 

Sounds kinda low in my opinion. In my 99 GS at 50k miles I had 200+ across all 4 cylinders. Stock CR is about 9.2 so that 9.1 shouldn't drop it down that far. Have you tried a leakdown test?

 

actually havent gotten a chance for a leakdown yet...yea at first it sounded low to me too, just trying to see what everyone thought...thanx for the reply

 

there are little tricks to boost those numbers, but for the consistency being so good I think you're in good hands.

 

you got the same bore as me 81.5, i got je 9.1 pistons and eagle rods as well.
also in a 94 gsr block
i got 180 across the board.

how are you doing the compression test?

 

pull all plugs, remove ecu fuse, hold open throttle and crank 4 times over, and watch that bish go up...only not up enough ...jk, yea im happy with the consistency but the numbers seem low...thanx for the response with the similiar setup

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ChillOutWayne &raquo;</TD></TR><TR><TD CLASS="quote">pull all plugs, remove ecu fuse, hold open throttle and crank 4 times over, and watch that bish go up...only not up enough ...jk, yea im happy with the consistency but the numbers seem low...thanx for the response with the similiar setup
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are you doing this while the engine is cold?
if so, that might be why. try taking it for a drive alittle, then doing it.
b.c my numbers(180 across) was after driving the teg a little.

 

sounds like great numbers
i got 160 all across with my stock b16 i know thats low but o well

 

ive noticed my PSI results dropped a little bit since the summer, but im beginning to think its because the tester was ICE cold and the air is at freezing point.. When air is hot it expands so maybe thats why over the summer i was getting 195psi all across and now i just got ~185 psi across...

 

well i hope thats right, i did the test when the motor was warm but the outside temp was maybe 15 degrees...thanx for the replies guys...any other thoughts?&gt;

 

did the compressoin go up any when you did it warm?

 

its actually kinda weird, i did it once before this last time when the miles were lower on the rebuild, and i dont really remember if the motor was warmer or not but i do know that i didnt have the throttle open all the way but i got the same numbers, who knows

 

hahaha, not making fun of you but thought it was kinda funny...you said you let it crank over four times??? You are supossed to give it five cranks and the first should be more than 50% of the fifth(final)crank. Try that again and I almost gaurantee you better results.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by boostinb20vtec &raquo;</TD></TR><TR><TD CLASS="quote">hahaha, not making fun of you but thought it was kinda funny...you said you let it crank over four times??? You are supossed to give it five cranks and the first should be more than 50% of the fifth(final)crank. Try that again and I almost gaurantee you better results.</TD></TR></TABLE>

yeah, try cranking it more. but if im not mistaken, i cranked mine 4 times, it reaches 180 psi, and the 5th crank doesnt make it go up anymore.
but try 5 anyways, see if that helps.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by boostinb20vtec &raquo;</TD></TR><TR><TD CLASS="quote">hahaha, not making fun of you but thought it was kinda funny...you said you let it crank over four times??? You are supossed to give it five cranks and the first should be more than 50% of the fifth(final)crank. Try that again and I almost gaurantee you better results.</TD></TR></TABLE>

two things: im kinda confused on yur explanation of the whole 50% crank deal and all that, wanna elaborate please? also its funny u say that, cause in another post i posted these numbers when i did it at an earlier date, and i achieved the same results with 4 pulls BUT one kid mentioned doin like 7 cranks so i did, and the numbers were like 190 or so in each cylinder, but i didnt go by that cause it was so many cranks...so in other words the numbers did keep goin up, just took more turns