Compressioin test results?
11-23-09, 12:04 PM
#26
****** money pits
just go to a rotary shop and have them do it. even if they are far away its better than almost $300 and 2 days. id give this place a call. seems to be the closest place.
http://maps.google.com/maps?hl=en&so...-8&sa=N&tab=wl
http://maps.google.com/maps?hl=en&so...-8&sa=N&tab=wl
11-23-09, 05:50 PM
#30
HA HA!!! All that Bitching, and the I'm Right and Your Wrong BS and his car runs fine.
Too funny... I'd say Compression tests are only NEEDED when your buying a car that doesn't run, and you've verfied that its getting spark and fuel and air.
(if you have a mazda rotary tester (twistedrotors also) or access to one, sure go ahead and test cause it's simple)
I'd just turn the engine over by hand as fast as possible to see if it has some compression if you don't have a tester...
If it runs and starts fine why test compression?
Sometimes people on this forum act like the wankel engine is soo much different from a piston engine, but fail to acknowledge that they both operate on the same general concept. Combustion of compressed fuel and oxygen. If its got fuel, oxygen, and compression, add a spark and it should explode.
Too funny... I'd say Compression tests are only NEEDED when your buying a car that doesn't run, and you've verfied that its getting spark and fuel and air.
(if you have a mazda rotary tester (twistedrotors also) or access to one, sure go ahead and test cause it's simple)
I'd just turn the engine over by hand as fast as possible to see if it has some compression if you don't have a tester...
If it runs and starts fine why test compression?
Sometimes people on this forum act like the wankel engine is soo much different from a piston engine, but fail to acknowledge that they both operate on the same general concept. Combustion of compressed fuel and oxygen. If its got fuel, oxygen, and compression, add a spark and it should explode.
11-23-09, 07:56 PM
#32
So if your motor was low on compression (hard starting, fouling plugs, smoking, flooding) you were going to rebuild it before you spend money on upgrades? Or?
All engines wear out, they need to be maintained and rebuilt from time to time.
I wouldn't rebuild it until the thing doesn't run, or barely runs... then upgrade. But If I questioned the motor in the first place something about it must have been bugging you?...?
Good luck! I'm not dissn... I wouldn't question compression on a engine that "runs perfect".
11-23-09, 10:52 PM
#34
only thing that was bugging me is the car only has 96k miles on it..but on the main crank bolt in the front of the engine it has a sticker across it that says void if removed...which tells me the engine has been out or somethin...dunno just did it because i was curious...
thanx
thanx
12-08-09, 09:15 PM
#37
Compression King
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Just found this and decided I would see if any care...
http://www.rotaryresurrection.com/2n...ion_check.html
http://www.rotaryresurrection.com/2n...ion_check.html
12-09-09, 06:36 AM
#38
Right near Malloy
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^
Again, Kevin Landers also verifies that it's not ideal:
What if you have one bad side seal spring and are getting maybe 60-70 PSI on one face and over 100 on the other two.
The overall would still come up good, because the other two faces would bring the tester up to over 100 PSI.
The individual face test would come up okay because that bad side seal is still getting you over 35 PSI.
Again, Kevin Landers also verifies that it's not ideal:
Originally Posted by Kevin Landers of Rotary Resurrection
8) observe the needle bounces. You should see 3 in succession without skips, even bounces, in roughly the 30-35psi range.
9) let out on the valve now, and let the tester reach an overall compression value for all 3 faces(highest of 3 will be displayed).
9) let out on the valve now, and let the tester reach an overall compression value for all 3 faces(highest of 3 will be displayed).
The overall would still come up good, because the other two faces would bring the tester up to over 100 PSI.
The individual face test would come up okay because that bad side seal is still getting you over 35 PSI.
12-09-09, 03:06 PM
#39
Compression King
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Yes I agree. But if you do step 8 correctly (from your quote), you will notice uneven pulses telling you one of the faces has lower compression than the others. No? Am I missing something here? WTF?
When you don't have a choice : Listen
Better : Piston Compression Tester
Best : Mazda Rotary Compression Tester
When you don't have a choice : Listen
Better : Piston Compression Tester
Best : Mazda Rotary Compression Tester
12-10-09, 08:07 AM
#41
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^ So I gotta buy a compression tester, video camera, and editing software?
**** that... It's $250 for a rotary specific compression tester. That ain't that much.
**** that... It's $250 for a rotary specific compression tester. That ain't that much.
12-10-09, 10:13 AM
#42
Aloha Icemark, Play Well.
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I'm with Pele...
Twisted Rotors Tester
Yuenling
Ham and Pineapple
If you don't know anyone with a TR tester and don't want to just buy your own for $265 (includes shipping and you can do as many tests as you want for $2 less than your Mazda dealer wants for a single test) simply send me a $300 deposit and I'll mail you my TR tester. When I get it back from you, I will refund $250-$275 to you, depending on if you got it dirty or not.
Twisted Rotors Tester
Yuenling
Ham and Pineapple
If you don't know anyone with a TR tester and don't want to just buy your own for $265 (includes shipping and you can do as many tests as you want for $2 less than your Mazda dealer wants for a single test) simply send me a $300 deposit and I'll mail you my TR tester. When I get it back from you, I will refund $250-$275 to you, depending on if you got it dirty or not.
12-10-09, 03:27 PM
#44
Aloha Icemark, Play Well.
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Anyway, I'm not sure how "like Mazda's" the tester is, since I've never used a Mazda tester. Mazdatrix sells Mazda testers for $2037.50 They also sell a Lightning Rotors tester for $850, which should let you test both rotors at the same time, but you need a computer to use it.
Twisted Rotors' tester is $250 + shipping, is a stand-alone unit, takes less than 1/2 an hour to use, including warming the engine, comes with a green or blue display, and it will tell you the compression for all 3 faces and the cranking rpm.
If I knew someone with a Mazda tester, I'd put Twisted's up against it in a heartbeat and bet that the numbers would match up or at the very least come close enough for 99% of the rx7club membership.
Considering that a $20 piston tester is good enough for 80-90% of the posters around here, I think it's a safe bet.
Like Pele wrote:
A peak and hold gauge might be helpful, however, rotary specific testers are so cheap that anyone can buy one. I own one. It was approx $250 plus shipping.
Contact TwistedRotors on here for one...
http://www.twistedrotors.com/
Or swing by my house with an acceptable form of payment a spark plug socket, and a ratchet...
Pictures here --> https://www.rx7club.com/1st-gen-general-discussion-207/such-cool-tool-twisted-rotors-compression-tester-864111/
and here --> https://www.rx7club.com/classifieds-violations-265/new-handheld-digital-rotary-engine-compression-tester-816120/
Video here --> http://www.youtube.com/watch?v=1VxHa79wdtw
and here --> http://www.youtube.com/watch?v=dZG28b05H9k
Hope that helps.
Aloha,
~j
edit: Twisted is in Houston; drive down there and check it out in person.
Last edited by jimmy_trader; 12-10-09 at 03:32 PM. Reason: Houston, baby!
12-10-09, 09:06 PM
#46
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TwistedRotors' tester is indeed awesome...
I'm somewhat familiar with the hardware and he has a build thread somewhere on this board.
It consists of an Atmel microcontroller and an industrial style pressure sensor for hydraulic/pneumatic systems. Other than that, it's all self contained. Other people have come up with solutions that involve a computer with data acquisition software. This unit is completely self contained and is VERY simple.
All it does is read the voltage put out by the sensor. It calculates RPM on its own.
Other than that, it works just the same as the Mazda tester, except since the Mazda tester is Japanese, it put out data in kg/cm^2 rather than PSI... It's simple math to convert though.
I'm somewhat familiar with the hardware and he has a build thread somewhere on this board.
It consists of an Atmel microcontroller and an industrial style pressure sensor for hydraulic/pneumatic systems. Other than that, it's all self contained. Other people have come up with solutions that involve a computer with data acquisition software. This unit is completely self contained and is VERY simple.
All it does is read the voltage put out by the sensor. It calculates RPM on its own.
Other than that, it works just the same as the Mazda tester, except since the Mazda tester is Japanese, it put out data in kg/cm^2 rather than PSI... It's simple math to convert though.
12-13-09, 02:50 PM
#49
First of all you can get reliable results without a single modification to a $20 tester. You just need a basic understanding of pressure and some common sense. The only trick is using that knowledge and interpreting what you see.
Either way you have to buy a compression tester. I'm assuming you have a digital camera... most people do nowadays. Video players that come free with operating systems allow you to watch frame by frame. If not, there are open source and freeware video editors for any OS under the sun.
So I could figure out my engine health in an hour without spending a dime. Or I could order a $300 tester and wait a week for it.
I agree with doing things right, but there are multiple ways to pursue that.
12-16-09, 10:57 AM
#50
Compression Tester Guy
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Hey guys, thanks for the kind words and I'm glad you're enjoying your testers. Pele you've got the right idea there! mmm....cheesburgers..... 
There is some good information in this thread and some bad as well. Here's how I see it:
If you get 3 even bounces on your piston tester and you're happy with that, then so be it.
But if you want to know the actual real-life compression of each and every pulse of your rotary then the only option is digital. A pressure transducer coupled with software or hardware is the answer. 'Nuff said.
One thing I'd like to point out when using piston testers, most of them use a rubber hose to connect the gauge to the spark plug hole. There is a certain amount of dead volume of air inside that hose that should be compensated for in your calculations. Rubber hoses can also expand when under pressure, severity depends on the quality of hose. Is all of this important? That's for you to decide.
-John
There is some good information in this thread and some bad as well. Here's how I see it:
If you get 3 even bounces on your piston tester and you're happy with that, then so be it.
But if you want to know the actual real-life compression of each and every pulse of your rotary then the only option is digital. A pressure transducer coupled with software or hardware is the answer. 'Nuff said.
One thing I'd like to point out when using piston testers, most of them use a rubber hose to connect the gauge to the spark plug hole. There is a certain amount of dead volume of air inside that hose that should be compensated for in your calculations. Rubber hoses can also expand when under pressure, severity depends on the quality of hose. Is all of this important? That's for you to decide.
-John
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