It is really hard to get a good handle on the compression
of a rotary engine as things happen too fast. The usual
way is to take the Shrader valve (tire valve) out of an
ordinary compression tester and watch it as the engine turns
over. You should get at least three pulses in a row all "about" the
same value. "About" is the problem. At 250 RPM the compression
should be 85 psi plus or minus 10 psi chamber to chamber.
It also varies with cranking RPM and altitude of the shop.
At 10,000 feet it is down to 57 psi. At sea level and 300
RPM it is up to 95 psi or so. At 200 RPM it is 73 psi or so.
Mazda has a special device that shows the pressure in three windows.
Special tool 49 FO18 9A0 is it. I have never seen one.
A very very expensive tool. I have never seen or heard of
a rotary engine builder or re-builder that had one. They should have
them as that is a major issue with after market apex seals. Stock seals
have a slight crown. You can see it when you put them belly to
belly. The after market ferrous apex seals I have seen so far have
no crown. This means you lose compression and power.
This is another area where a PICAXE will help greatly.
You can use one of the analog to digital converters to
measure the compression with a Free Scale pressure sensor.
Say ten times a second. Send the data to a PC which is easy to do
with a PICAXE through the serial or USB port and you have an
under $75 rotary engine compression tester. Not counting the cost
of the PC but you already have one of those or you would not
be reading this.
Paul Lamar ...No rotor no motor.
??????????????
Mazda has a special device that shows the pressure in three windows.
Special tool 49 FO18 9A0 is it. I have never seen one.
A very very expensive tool. I have never seen or heard of
a rotary engine builder or re-builder that had one.
????????????????????????????
Paul -- I have THREE of them. Two have broken over the years (transducer
died), and Mazda/Kowaseki (sp?) wants $1000?+ to fix.
We also sell an aftermarket one that I actually like better than the OEM one
(cheaper also) -- it can read in kg/cm2 OR psi, and can record it for
downloading/printing on a computer.
http://www.mazdatrix.com/toolmisc.htm
Lightning Rotors Compression Tester
This compression meter records data and quantifies the sealing condition on
each face of a rotor. The ultimate accessory for the longtime rotary
enthusiast. This tester will operate in PSI, Kg or Pa, and includes a
computer interface for graphing and data storage.
Mazdatrix Price Check
Part Name Description Part Number Price
TOOL COMPRESSION TST LIGHTNING COMP TESTR 49-F018-NZ $850.00
Dave
Mazdatrix Inc.
2730 Gundry Ave.
Signal Hill, Ca. 90755
Phone: 562-426-7960
Fax: 562-426-9646
www.mazdatrix.com
I saw my first compression tester today as Dave made sure he showed it to me :)
BTW He promised to market the PICAXE version if any one can make
them and sell them to him at a discount. That is a real good deal
and is how to get a rapid start in biz. If they are cheap enough
every rotor head will buy one.
Paul Lamar
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