compression test on your B18C R
01-25-2005, 12:32 PM
#2
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Re: compression test on your B18C R (HERO)
I did a test on my stock usdm motor and got between 230 and 235 for all four.
the key is not to have to much variation between them.
the key is not to have to much variation between them.
01-25-2005, 09:03 PM
#4
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Re: (99 TYPE R)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 99 TYPE R »</TD></TR><TR><TD CLASS="quote">700 miles later from the dealer-220 across teh board</TD></TR></TABLE>
220-225 in my 'good cylinders'
Depends on the gauge, how warm the motor is, etc.
Like BBasso said, make sure all the numbers are close. Some people say 5% or 10%. Typically good motors see relatively small variance.
-Chris
220-225 in my 'good cylinders'
Depends on the gauge, how warm the motor is, etc.
Like BBasso said, make sure all the numbers are close. Some people say 5% or 10%. Typically good motors see relatively small variance.
-Chris
01-25-2005, 11:51 PM
#5
Re: (Chris F)
Doesn't matter what you get as long as they're consistent. If they're all 10psi and consistent.. then your gauge is 99.9% likely to be fucked. If they're like 210, 220, 210, 265, then you have a problem.
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01-26-2005, 07:10 AM
#10
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Re: compression test on your B18C R (danny98r)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by danny98r »</TD></TR><TR><TD CLASS="quote">255 all four's</TD></TR></TABLE>
ditto
ditto
01-26-2005, 09:58 AM
#11
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Re: compression test on your B18C R (chad)
Doing the compression test with the throttle open vs. closed makes a big difference too. I like to do my compression tests at WOT on a warm motor. And you have to do it pretty quick because I've seen a motor cool down and change the readings by 10 psi within 20 minutes or so.
01-26-2005, 05:12 PM
#12
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Re: compression test on your B18C R (fsp31)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by fsp31 »</TD></TR><TR><TD CLASS="quote">Doing the compression test with the throttle open vs. closed makes a big difference too. I like to do my compression tests at WOT on a warm motor. And you have to do it pretty quick because I've seen a motor cool down and change the readings by 10 psi within 20 minutes or so.</TD></TR></TABLE>
have done back to back test...tbody open and closed....no difference
have done back to back test...tbody open and closed....no difference
01-26-2005, 05:19 PM
#13
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Re: compression test on your B18C R (chad)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by chad »</TD></TR><TR><TD CLASS="quote">have done back to back test...tbody open and closed....no difference</TD></TR></TABLE>
I have too, by accident. I also saw ~ no difference. Maybe they get up to their peak compression after more revolutions?
After 10 crank rotations, it seems to even everything out.
Some people prefer to do 4-5 rotations though.
I have too, by accident. I also saw ~ no difference. Maybe they get up to their peak compression after more revolutions?
After 10 crank rotations, it seems to even everything out.
Some people prefer to do 4-5 rotations though.
01-26-2005, 10:23 PM
#14
Re: compression test on your B18C R (Chris F)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Chris F »</TD></TR><TR><TD CLASS="quote">
I have too, by accident. I also saw ~ no difference. Maybe they get up to their peak compression after more revolutions?
After 10 crank rotations, it seems to even everything out. Some people prefer to do 4-5 rotations though.</TD></TR></TABLE>
Open or closed it'll give you the same results as long as each cylinder was tested the same. Usually the plate being open won't make a significant difference.
I have too, by accident. I also saw ~ no difference. Maybe they get up to their peak compression after more revolutions?
After 10 crank rotations, it seems to even everything out.
Some people prefer to do 4-5 rotations though.</TD></TR></TABLE>Open or closed it'll give you the same results as long as each cylinder was tested the same. Usually the plate being open won't make a significant difference.
01-27-2005, 09:27 AM
#16
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Re: compression test on your B18C R (Nameless RB26)
Hmmm. That's strange. I've tested 2 motors that read nearly 20 psi differently with the throttle open vs. closed. I can't imagine this would make any difference, but they were both turbo d series motors...
01-27-2005, 09:33 AM
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Re: compression test on your B18C R (HERO)
235psi across the board when OEM..
265psi after a chamber re-shape and mild mill.
Like everyone says, as long as your readings are close to each other, you should be fine.
265psi after a chamber re-shape and mild mill.
Like everyone says, as long as your readings are close to each other, you should be fine.
02-19-2005, 08:52 PM
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Re: compression test on your B18C R (StorminMatt)
our jdm b18-r (11:1 CR) made 219, 225, 221, 222 (warm)
our jdm gsr (10.6:1) made 227, 230, 230, 232 (warm)
2nd time doing the jdm gsr we did it wide the throttle wide open, and the numbers were 242, 241, 242, 242. can any explain why they are higher with wot?
what do you guys think of the vartion between both motors? both engines were tested at the same time, and the exact same way (5 cranks)
the gsr motor dynoed 170whp/128.8 torque and the R made 188whp/128.4 torque.
can anyone explain why the R motor came up lower on the compression test. I know the peak number doesnt mattter, as long as they are all consistant. but to my understanding the higher compression the motor, the higher psi.
Modified by Downey at 11:36 PM 2/19/2005
our jdm gsr (10.6:1) made 227, 230, 230, 232 (warm)
2nd time doing the jdm gsr we did it wide the throttle wide open, and the numbers were 242, 241, 242, 242. can any explain why they are higher with wot?
what do you guys think of the vartion between both motors? both engines were tested at the same time, and the exact same way (5 cranks)
the gsr motor dynoed 170whp/128.8 torque and the R made 188whp/128.4 torque.
can anyone explain why the R motor came up lower on the compression test. I know the peak number doesnt mattter, as long as they are all consistant. but to my understanding the higher compression the motor, the higher psi.
Modified by Downey at 11:36 PM 2/19/2005
02-22-2005, 02:10 AM
#20
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Re: compression test on your B18C R (Downey)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Downey »</TD></TR><TR><TD CLASS="quote">our jdm b18-r (11:1 CR) made 219, 225, 221, 222 (warm)
our jdm gsr (10.6:1) made 227, 230, 230, 232 (warm)
2nd time doing the jdm gsr we did it wide the throttle wide open, and the numbers were 242, 241, 242, 242. can any explain why they are higher with wot?
what do you guys think of the vartion between both motors? both engines were tested at the same time, and the exact same way (5 cranks)
the gsr motor dynoed 170whp/128.8 torque and the R made 188whp/128.4 torque.
can anyone explain why the R motor came up lower on the compression test. I know the peak number doesnt mattter, as long as they are all consistant. but to my understanding the higher compression the motor, the higher psi.</TD></TR></TABLE>
First of all, when I compression test, I don't go for a given number of cranks. I crank until the needle settles. But this ususally doesn't take ALOT more than 5 cranks.
As for the numbers themselves, there are other factors besides static compression ratio that affect the pressure. One, of course, is the general health of the motor. It is possible that a healthy motor with lower compression can give better numbers than a more worn motor with a higher compression ratio. Throttle position is another. When the throttle is open farther, more air enters the cylinders. And the more air that gets into the cylinders, the higher the pressure will build during compression. Battery/starter health is another consideration. The faster you spin a motor, the less opportunity you give the air in the cylinders to leak past rings and/or valves. This increases pressure readings. Finally, cams make a difference. If a motor has more high-RPM biased cams, pressure readings will be lower for a given compression ratio. More radical cams generally keep the intake valves open longer past BDC for more complete filling of the cylinders at higher RPMs. But at lower RPMs, this causes air to be blown back out open intake valves as the piston starts to rise above BDC. This is a major reason why radical cams like high static compression (to compensate for the pressure loss due to late valve closings). And this is a reason why radical cams decrease low end torque (displacement at low ROMs is effectively reduced by these late valve closings).
our jdm gsr (10.6:1) made 227, 230, 230, 232 (warm)
2nd time doing the jdm gsr we did it wide the throttle wide open, and the numbers were 242, 241, 242, 242. can any explain why they are higher with wot?
what do you guys think of the vartion between both motors? both engines were tested at the same time, and the exact same way (5 cranks)
the gsr motor dynoed 170whp/128.8 torque and the R made 188whp/128.4 torque.
can anyone explain why the R motor came up lower on the compression test. I know the peak number doesnt mattter, as long as they are all consistant. but to my understanding the higher compression the motor, the higher psi.</TD></TR></TABLE>
First of all, when I compression test, I don't go for a given number of cranks. I crank until the needle settles. But this ususally doesn't take ALOT more than 5 cranks.
As for the numbers themselves, there are other factors besides static compression ratio that affect the pressure. One, of course, is the general health of the motor. It is possible that a healthy motor with lower compression can give better numbers than a more worn motor with a higher compression ratio. Throttle position is another. When the throttle is open farther, more air enters the cylinders. And the more air that gets into the cylinders, the higher the pressure will build during compression. Battery/starter health is another consideration. The faster you spin a motor, the less opportunity you give the air in the cylinders to leak past rings and/or valves. This increases pressure readings. Finally, cams make a difference. If a motor has more high-RPM biased cams, pressure readings will be lower for a given compression ratio. More radical cams generally keep the intake valves open longer past BDC for more complete filling of the cylinders at higher RPMs. But at lower RPMs, this causes air to be blown back out open intake valves as the piston starts to rise above BDC. This is a major reason why radical cams like high static compression (to compensate for the pressure loss due to late valve closings). And this is a reason why radical cams decrease low end torque (displacement at low ROMs is effectively reduced by these late valve closings).
03-28-2005, 02:48 AM
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Re: compression test on your B18C R (CaRzY AsIan)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by CaRzY AsIan »</TD></TR><TR><TD CLASS="quote">mine is 215 for all four on a stock 99 jdm itr. ...............is it bad????? </TD></TR></TABLE>
to answer the post you already started regarding the same issue.....NO! Consistency is key
</TD></TR></TABLE>to answer the post you already started regarding the same issue.....NO! Consistency is key
03-28-2005, 03:01 AM
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Re: compression test on your B18C R (Jon D)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Jon D »</TD></TR><TR><TD CLASS="quote">to answer the post you already started regarding the same issue.....NO! Consistency is key </TD></TR></TABLE>
so whats the meaning or higher number and lower number?????
is that mean my hp power is weaker???
</TD></TR></TABLE>so whats the meaning or higher number and lower number?????
is that mean my hp power is weaker???
03-28-2005, 03:35 AM
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Re: compression test on your B18C R (CaRzY AsIan)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by CaRzY AsIan »</TD></TR><TR><TD CLASS="quote">
so whats the meaning or higher number and lower number?????
is that mean my hp power is weaker???</TD></TR></TABLE>
not at all....that may simply mean that during the test you did not crank the motor as many times as someone who has higher #s. For example: The guy who cranks his motor 5 times at WOT vs the guy who cranks his motor 10 times at WOT, will in most cases not have a reading as high as the guy who cranked 10 times. As stated previously....consistency is always key. When you see higher #'s it simply means the overall compression is higher in that motor or they performed the compression cranking the motor several more times then you did!
theme of dilemma....CONSISTENCY IS KEY
so whats the meaning or higher number and lower number?????
is that mean my hp power is weaker???</TD></TR></TABLE>
not at all....that may simply mean that during the test you did not crank the motor as many times as someone who has higher #s. For example: The guy who cranks his motor 5 times at WOT vs the guy who cranks his motor 10 times at WOT, will in most cases not have a reading as high as the guy who cranked 10 times. As stated previously....consistency is always key. When you see higher #'s it simply means the overall compression is higher in that motor or they performed the compression cranking the motor several more times then you did!
theme of dilemma....CONSISTENCY IS KEY
