Rotary Aviation seals, a 10,000 km report.....
03-25-04, 09:25 PM
#52
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Originally posted by peejay
Once an engine's running, even with total **** garbage seals and housings, it will stay running.
The problem is in starting, since the revs are so low.
Heck, if you turn the engine slowly enough, even a "perfect" engine will have zero compression.
There's a big difference between 150ish cranking RPM and a 900rpm idle.
Once an engine's running, even with total **** garbage seals and housings, it will stay running.
The problem is in starting, since the revs are so low.
Heck, if you turn the engine slowly enough, even a "perfect" engine will have zero compression.
There's a big difference between 150ish cranking RPM and a 900rpm idle.
and, you say you measured "0" compression. and we all know you weren't cranking it at 1rpm per minute. so, what rpm was it cranking at? if it's near 500rpm's then why even bring up this "even a perfect engine blah blah blah..."
03-25-04, 09:33 PM
#53
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Originally posted by scathcart
Something isn't right here. How do you take out Mazda seals at 1.92mm width (assuming 0.002" clearance from stock seals) giving a groove width of 0.078" and then put in seals that have a width of 1.83mm and get 0.002" of clearance? Its impossible. The rotor groove would have to be 0.074" wide; smaller than stock!!
If you put in those 1.83mm seals, you would get at 0.006" of clearance on stock rotors, and likely 0.007" of clearance on used rotors. So... maybe you didn;t correctly clearance your apex seals when you assembled it?
Something isn't right here. How do you take out Mazda seals at 1.92mm width (assuming 0.002" clearance from stock seals) giving a groove width of 0.078" and then put in seals that have a width of 1.83mm and get 0.002" of clearance? Its impossible. The rotor groove would have to be 0.074" wide; smaller than stock!!
If you put in those 1.83mm seals, you would get at 0.006" of clearance on stock rotors, and likely 0.007" of clearance on used rotors. So... maybe you didn;t correctly clearance your apex seals when you assembled it?
The seals I have , both sets, are felt pen marked, they also do not measure the same from seal to seal... Its interesting though that the stock seal is suppose to come out to .002 ideally, yet I have a used 2mm mazda seal in a certain rotor that has .001 clearance...
What its looking like at this point, is the seals that are still new that I have not used are to thin, but something has happened to the seals that are still in the motor, considering what I do for a living , I know how to use feeler guages...
Mazda parts are not a constant, refer to the factory manual, the have a both a range for standard, and a limit for service, there are to many variables for all engine parts to be exact everytime..I was told by more than one engine shop in Japan, to always match production runs of parts together, for that very reason..
Bottom line, is it looks like the new RA seals I have in box still are underspec...
The Seals in the car are another story, they were in spec, but something has happened to them, or the rotors... I am meticulous when I put a motor together, and I would not put a motor together with .007 clearance on the apex seals...This motor ran great till they crossed the 10k mark, and wear on a moving part tends to accelarate exponentially, so .002 quickly turns to .004 etc etc, a good motor, can turn to a bad motor rather quickly when somethings wearing....
Whoever questioned me about how it could run with 0 compression, again, when its cold, it has perfect compression, and starts right up, when its hot, the compression just goes away... Also when a motor is running, combustion gases will get under the seal and load it against the housing, aiding the seal in sealing to the housing...
So what do the seals that you guys measured at .076 look like? stamped or felt pen?
When did you buy them?..
Here is an video clip of when I fired it up a couple weeks back after putting the intakes back on..Sounds nice cold....
http://uregina.ca/~reynishj/Movies/maxengine.avi
Last edited by Maxthe7man; 03-25-04 at 09:44 PM.
03-25-04, 09:43 PM
#54
Originally posted by fstrnyou
ok, then this brings me to my next question, how well was it "running" with this bad compression? because mine runs like **** with the compression that it has. mine seemed to run fine with hot compression numbers of 65/85 but after another 40 minutes of driving, it idled (750rpm) like **** because i'm assuming compression dropped low enough to not allow combustion on a few cycles.
and, you say you measured "0" compression. and we all know you weren't cranking it at 1rpm per minute. so, what rpm was it cranking at? if it's near 500rpm's then why even bring up this "even a perfect engine blah blah blah..."
ok, then this brings me to my next question, how well was it "running" with this bad compression? because mine runs like **** with the compression that it has. mine seemed to run fine with hot compression numbers of 65/85 but after another 40 minutes of driving, it idled (750rpm) like **** because i'm assuming compression dropped low enough to not allow combustion on a few cycles.
and, you say you measured "0" compression. and we all know you weren't cranking it at 1rpm per minute. so, what rpm was it cranking at? if it's near 500rpm's then why even bring up this "even a perfect engine blah blah blah..."
03-25-04, 09:56 PM
#55
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Like I mentioned in another thread, I still would like to know if the RA seals are harder or softer than stock. Only comparison they make is with aftermarket ones. Since they are heat treated, a hardness number would be nice to have on their website.
03-26-04, 12:29 AM
#61
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Originally posted by drago86
I wonder how 88intergrals's are holding up
I wonder how 88intergrals's are holding up
I'm concerned about these reports, but I also know that RA never designed these seals for 400hp or 13K rpm, which were the conditions of the two engines that have failed because of them. I'm sure the same could be said for stock Mazda 2mm 3pc seals. My engine looked very good on the inside, too, so it will be interesting to see how long it lasts making only 160 rwhp at most on these seals.
*edit*
My seal set had engraved match numbers on the seals and corner pieces, one through six. I almost couldn't get the .002in. feeler gauge in the gap between them and the rotor groove and had to use sandpaper to get a few of them up to .002 from around .0015.
Last edited by 88IntegraLS; 03-26-04 at 12:46 AM.
03-26-04, 08:35 AM
#64
Originally posted by DamonB
Steel IS an alloy
Steel IS an alloy
03-26-04, 10:21 AM
#65
Lives on the Forum
Originally posted by jreynish
No **** steel is an alloy but the stock seals aren't a Steel based allow! they would not have enough give to them. I canot remember off hand what the base alloy is for the stock mazda apex seals, but I do Know that they are not steel based.
No **** steel is an alloy but the stock seals aren't a Steel based allow! they would not have enough give to them. I canot remember off hand what the base alloy is for the stock mazda apex seals, but I do Know that they are not steel based.
All steels are alloys of iron; iron content is usually more than 90%.
Hence many people call the stock Mazda seals "steel seals" to differentiate them from aftermarket ceramic seals.
03-26-04, 02:12 PM
#67
I wish I was driving!
Originally posted by Maxthe7man
So what do the seals that you guys measured at .076 look like? stamped or felt pen?
When did you buy them?..
So what do the seals that you guys measured at .076 look like? stamped or felt pen?
When did you buy them?..
The pen-matched numbers were from their first batch, which I was told by RWS have been improved since.
Thanks for clarifying your assembly. I look forward to your dissassembly notes.
And as a side note, out of the countless new Mazda stock seals I have ordered and used, I have never had one not measure to spec, whether it be the 3-pc or 2-pc version.
03-26-04, 02:16 PM
#68
I wish I was driving!
Originally posted by fstrnyou
ok, then this brings me to my next question, how well was it "running" with this bad compression? because mine runs like **** with the compression that it has. mine seemed to run fine with hot compression numbers of 65/85 but after another 40 minutes of driving, it idled (750rpm) like **** because i'm assuming compression dropped low enough to not allow combustion on a few cycles.
and, you say you measured "0" compression. and we all know you weren't cranking it at 1rpm per minute. so, what rpm was it cranking at? if it's near 500rpm's then why even bring up this "even a perfect engine blah blah blah..."
ok, then this brings me to my next question, how well was it "running" with this bad compression? because mine runs like **** with the compression that it has. mine seemed to run fine with hot compression numbers of 65/85 but after another 40 minutes of driving, it idled (750rpm) like **** because i'm assuming compression dropped low enough to not allow combustion on a few cycles.
and, you say you measured "0" compression. and we all know you weren't cranking it at 1rpm per minute. so, what rpm was it cranking at? if it's near 500rpm's then why even bring up this "even a perfect engine blah blah blah..."
03-26-04, 03:51 PM
#69
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They are both most likley some low alloy content steel, as the more crap you add the the steel the harder it becomes to heat treat, and it usually looses some strength(there are exceptions). High alloy content steels like stainless would not be good for this application, to brittle, and hard to heat teat. While the alloy content does determine absolute hardness, most of the low alloy content steels are pretty close.
03-26-04, 05:12 PM
#70
Thanks for the additional info Max. Something is definitely wrong with those seals at 1.83mm. If you'll send those back we would like to study them to determine what went wrong and will happily replace them with good parts. Let us know about when you bought this set too if possible.
Tracy Crook, RWS
Tracy Crook, RWS
Originally posted by Maxthe7man
I know its hard to imagine the seal being razor sharp, but its not the face that touches the rotor housing surface thats sharp, its the transition at the corner from the side to the face thats sharp, the actual face is still rounded, but even 100,000 km mazda seals don't get an edge on them like that....
I have measured my other set of RA seals and compared them to used mazda ones, and they are thinner than used mazda ones. 1.92mm vs 1.83mm..
When I get the motor apart, I can fully measure the wear on the seals vs the rotor groove, but from just playing with the feeler guages and and calipers, I can pretty much tell the rotors are now worn...
It took some work to find that the problem was the motor, as when the car was cold, I could reach in through the window , just turn the key and it fired right up, but it got to the point, where when it was hot, it would just crank and crank, and then I could tell by the way it sounded when it was cranking when hot, it had no compression. Let it cool, though, and the motor once again would have the even stong compression pulses, then I verified it with a compression tester... And I went in the exhaust port for a visual, after seeing a motor go 100-100-100 to 0-0-0 after 20 minutes of idling...
Someone said its because I was supposed to use new housings with them, not so, thats not the point of wear thats the problem, someone said the porting, not so either, I make the exhaust port taller slightly, but I also retain the camfer in the port design, and again not the point of wear that is the problem..
I am gonna pull the motor on saturday afternoon and I will have it apart that night probably, so I can see how the corner seals have worn as well...max
I know its hard to imagine the seal being razor sharp, but its not the face that touches the rotor housing surface thats sharp, its the transition at the corner from the side to the face thats sharp, the actual face is still rounded, but even 100,000 km mazda seals don't get an edge on them like that....
I have measured my other set of RA seals and compared them to used mazda ones, and they are thinner than used mazda ones. 1.92mm vs 1.83mm..
When I get the motor apart, I can fully measure the wear on the seals vs the rotor groove, but from just playing with the feeler guages and and calipers, I can pretty much tell the rotors are now worn...
It took some work to find that the problem was the motor, as when the car was cold, I could reach in through the window , just turn the key and it fired right up, but it got to the point, where when it was hot, it would just crank and crank, and then I could tell by the way it sounded when it was cranking when hot, it had no compression. Let it cool, though, and the motor once again would have the even stong compression pulses, then I verified it with a compression tester... And I went in the exhaust port for a visual, after seeing a motor go 100-100-100 to 0-0-0 after 20 minutes of idling...
Someone said its because I was supposed to use new housings with them, not so, thats not the point of wear thats the problem, someone said the porting, not so either, I make the exhaust port taller slightly, but I also retain the camfer in the port design, and again not the point of wear that is the problem..
I am gonna pull the motor on saturday afternoon and I will have it apart that night probably, so I can see how the corner seals have worn as well...max
03-26-04, 05:44 PM
#71
actually, a perfect engine would have compression if you turn it at 1 rpm per minute. you must not know the specifics of a rotary engine, if you doubt this. if you put a compression guage in the trailing or leading spark plug hole it will show compression because by the time the apex seal passes over the hole the engine is not finished the compression stroke. by the way the compression ratio stays the same at all engine speeds. it is the combustion chamber pressure the changes exponentially with increaed rpm.
03-26-04, 06:29 PM
#72
Old [Sch|F]ool
Originally posted by rotariesrule
actually, a perfect engine would have compression if you turn it at 1 rpm per minute. you must not know the specifics of a rotary engine, if you doubt this.
actually, a perfect engine would have compression if you turn it at 1 rpm per minute. you must not know the specifics of a rotary engine, if you doubt this.
It is very hard to air seal a square edged chamber. This was one of the main problems that the Wankel consortium faced. Mazda's implementation works admirably well BUT! it is still not all that great and at low engine speeds (cranking) the engines will have poor compression, even if the seals and sealing surfaces are all in perfect shape.
It's a Wankel issue, in other words.
Ask anyone who's tried to start their engines in the winter with a so-so battery and/or cables/starter... the engine cranks slowly and it doesn't build up enough compression and it floods out. Or how about the best way to unflood an engine... push start it. Why? Because the engines build more compression at higher RPMs than you can get with just a starter. Why? Because even when perfect the stock sealing sucks and it bypasses a certain amount of air in a given amount of time, so you spin it faster so that there is less time for it to bypass so it builds more compression so the damn thing will run.
03-26-04, 06:59 PM
#73
Eats, Sleeps, Dreams Rotary
Max, I am sorry to hear about your engine problems. However, I must say that I am impressed with the concern and customer support by rotary aviation in this thread.
03-26-04, 07:24 PM
#74
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Yah they have always been good to me, and done what I have asked of them... I have no complaints about RA really, I just want to get to the bottom of this seal problem, I like their stuff, so I want to find out if its bad seal, or something I did.. Motor is coming out tomorrow, will have it apart sometime sunday..Max
