Compression Test on engine with ~19k miles
#1
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Compression Test on engine with ~19k miles
My RX8 was in the dealership and had to have the fuel pump replaced. I have done compression tests before on my 300zx would report reading such as 130PSI #1, 135PSI #2 Cylinder.......but when they Tech did the write-up of the repair, he wrote the following section
"Run compression test on both rotors. Had 7.2 7.2 7.3 on #1 rotor cold and had #2 was 7.7 7.7 7.8 cold. Ran compression test hot too had marginal readings."
My question is what are these 7.2, 7.2, 7.3 numbers rated in... obviously not PSI?
What would a bad compression number look like using the above methodology?
"Run compression test on both rotors. Had 7.2 7.2 7.3 on #1 rotor cold and had #2 was 7.7 7.7 7.8 cold. Ran compression test hot too had marginal readings."
My question is what are these 7.2, 7.2, 7.3 numbers rated in... obviously not PSI?
What would a bad compression number look like using the above methodology?
#2
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Originally Posted by Jaguar_MBA
My RX8 was in the dealership and had to have the fuel pump replaced. I have done compression tests before on my 300zx would report reading such as 130PSI #1, 135PSI #2 Cylinder.......but when they Tech did the write-up of the repair, he wrote the following section
"Run compression test on both rotors. Had 7.2 7.2 7.3 on #1 rotor cold and had #2 was 7.7 7.7 7.8 cold. Ran compression test hot too had marginal readings."
My question is what are these 7.2, 7.2, 7.3 numbers rated in... obviously not PSI?
What would a bad compression number look like using the above methodology?
"Run compression test on both rotors. Had 7.2 7.2 7.3 on #1 rotor cold and had #2 was 7.7 7.7 7.8 cold. Ran compression test hot too had marginal readings."
My question is what are these 7.2, 7.2, 7.3 numbers rated in... obviously not PSI?
What would a bad compression number look like using the above methodology?
And what do they mean by: "Ran compression test hot too had marginal readings"? Are they suggesting that you had poor enginecompression? Time to consider consulting another dealer in my opinion.
Last edited by Go48; 08-09-2005 at 08:36 AM.
#3
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I took my used 2004 RX8 to a mechanic. One of the things they did was a compression test and here are the results:
Rotor #1 @ 212 RPM: 7.7/7.3/7.5
Rotor #2 @ 216 RPM: 7.6/7.5/7.2
They used a Mazdaspeed tool that is calibrated/certified every year.
Mazda minimum specification is 7.0 Kg/cm^2
Extrapolated to 250 RPM, the engine compression is over 8.0 Kg/cm^2
They told me that these numbers are very good.
Rotor #1 @ 212 RPM: 7.7/7.3/7.5
Rotor #2 @ 216 RPM: 7.6/7.5/7.2
They used a Mazdaspeed tool that is calibrated/certified every year.
Mazda minimum specification is 7.0 Kg/cm^2
Extrapolated to 250 RPM, the engine compression is over 8.0 Kg/cm^2
They told me that these numbers are very good.
#5
Ex- member.
What would a bad compression number look like using the above methodology?
8.5 standard, 6.9 minimum
1.5 difference in chambers and 1.0 difference b/w rotors.
*********************
Compression pressure (kPa {kgf/cm2 ,psi} [rpm])
Standard 830 {8.5, 120} [250 rpm]
Minimum 680 {6.9, 98.6} [250 rpm]
Standard difference in chambers Within 150 {1.5, 21.8}
Standard difference in rotors Within 100 {1.0, 14.5}
Last edited by adrian-1; 08-09-2005 at 10:27 AM.
#7
Jaguar,
The only figures they neglected to give you were the cranking rpms. These are vital because the readings are dependant on cranking speed like ZZ8 illustrated. This is what worries me when dealers are eager to replace a motor and they may not have the most experience and diagnostic skills as regards rotary engines.
Paul.
The only figures they neglected to give you were the cranking rpms. These are vital because the readings are dependant on cranking speed like ZZ8 illustrated. This is what worries me when dealers are eager to replace a motor and they may not have the most experience and diagnostic skills as regards rotary engines.
Paul.
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Originally Posted by Jaguar_MBA
My RX8 was in the dealership and had to have the fuel pump replaced. I have done compression tests before on my 300zx would report reading such as 130PSI #1, 135PSI #2 Cylinder.......but when they Tech did the write-up of the repair, he wrote the following section
"Run compression test on both rotors. Had 7.2 7.2 7.3 on #1 rotor cold and had #2 was 7.7 7.7 7.8 cold. Ran compression test hot too had marginal readings."
My question is what are these 7.2, 7.2, 7.3 numbers rated in... obviously not PSI?
What would a bad compression number look like using the above methodology?
"Run compression test on both rotors. Had 7.2 7.2 7.3 on #1 rotor cold and had #2 was 7.7 7.7 7.8 cold. Ran compression test hot too had marginal readings."
My question is what are these 7.2, 7.2, 7.3 numbers rated in... obviously not PSI?
What would a bad compression number look like using the above methodology?
Your compression is right where it should be. Any lower and u are losing power and any higher and u would be damaging your internals, but over time of course. When he did the test did he remove the spark plugs and plug the hole with a pressure tester gauge, usually they do it with one and crank the engine and the dial will tell u how much pressure built up in the compustion chamber at TDC.
#12
I was just trying to figure what Priscilla meant by " Any higher and you would be damaging your internals", but I was trying to ask that ina slightly discreet way.
Paul.
Paul.
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Originally Posted by Mazmart
I was just trying to figure what Priscilla meant by " Any higher and you would be damaging your internals", but I was trying to ask that ina slightly discreet way.
Paul.
Paul.
U see compression can be bad if it is to high, I would rather have a car suffuring from low compression then compression that is to high because the inturnals of the engine are really at a strain. That is all I ment.
Last edited by priscilla ls1; 08-09-2005 at 05:43 PM.
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hahaha very funny :D
But u know what I meant. Sure it is a rare case when compression is to high and if compression is low, well we all know what the problem is leak somewhere.
But u know what I meant. Sure it is a rare case when compression is to high and if compression is low, well we all know what the problem is leak somewhere.
Last edited by priscilla ls1; 08-09-2005 at 05:35 PM.
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Originally Posted by Mazmart
I try to keep my internal strain down through nutritional means, I guess it's probably similar.
Paul.
Paul.
Funny guy? Anyways like I was saying, too much compression would cause a wide range of problems and a loss of hp and parts. U have to agree with that.
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Here are my compression results. I think they are very bad, but the dealership says that mazda tech line won't let them do anything until they can verify my power loss problem. Can anyone tell me how bad these numbers are if at all?
1ST ROTOR ........................2ND ROTOR......MAX MIN
CHAMBER 1 644 KPA.........599 KPA...........ROTOR 1 79.6
CHAMBER 2 723 KPA.........612 KPA...........ROTOR 2 22.5
CHAMBER 3 717 KPA.........590 KPA...........MAX ROTOR 1&2
...................RPM 217.........RPM 212..............111 KPA
1ST ROTOR ........................2ND ROTOR......MAX MIN
CHAMBER 1 644 KPA.........599 KPA...........ROTOR 1 79.6
CHAMBER 2 723 KPA.........612 KPA...........ROTOR 2 22.5
CHAMBER 3 717 KPA.........590 KPA...........MAX ROTOR 1&2
...................RPM 217.........RPM 212..............111 KPA
#23
Just got a copy of my compression check and was wondering if anyone knows how to read it. It lists the following:
Rotor 1
657KPa. Chamber 1
704KPa. Chamber 2
652KPa. Chamber 3
264RPM. Engine RPM
Rotor 2
519KPa. Chamber 1
590KPa. Chamber 2
631KPa. Chamber 3
266RPM. Engine RPM
51.9KPa max. rotor 1 - min. rotor 1
112KPa max. rotor 2 - min. rotor 2
72.7KPa max rotor 1 - max rotor 2
Car is slow as molasses.
Rotor 1
657KPa. Chamber 1
704KPa. Chamber 2
652KPa. Chamber 3
264RPM. Engine RPM
Rotor 2
519KPa. Chamber 1
590KPa. Chamber 2
631KPa. Chamber 3
266RPM. Engine RPM
51.9KPa max. rotor 1 - min. rotor 1
112KPa max. rotor 2 - min. rotor 2
72.7KPa max rotor 1 - max rotor 2
Car is slow as molasses.
Last edited by 8is>enuff; 01-05-2006 at 01:03 PM.
#25
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Originally Posted by 8is>enuff
Just got a copy of my compression check and was wondering if anyone knows how to read it. It lists the following:
Rotor 1
657KPa. Chamber 1
704KPa. Chamber 2
652KPa. Chamber 3
264RPM. Engine RPM
Rotor 2
519KPa. Chamber 1
590KPa. Chamber 2
631KPa. Chamber 3
266RPM. Engine RPM
51.9KPa max. rotor 1 - min. rotor 1
112KPa max. rotor 2 - min. rotor 2
72.7KPa max rotor 1 - max rotor 2
Car is slow as molasses.
Rotor 1
657KPa. Chamber 1
704KPa. Chamber 2
652KPa. Chamber 3
264RPM. Engine RPM
Rotor 2
519KPa. Chamber 1
590KPa. Chamber 2
631KPa. Chamber 3
266RPM. Engine RPM
51.9KPa max. rotor 1 - min. rotor 1
112KPa max. rotor 2 - min. rotor 2
72.7KPa max rotor 1 - max rotor 2
Car is slow as molasses.