2nd Generation Specific (1986-1992) 1986-1992 Discussion including performance modifications and technical support sections.
Sponsored by:

Is 50 psi compression good enough??

Thread Tools
 
Search this Thread
 
Old 07-13-05, 03:35 PM
  #1  
Junior Member

Thread Starter
 
trufc's Avatar
 
Join Date: Jun 2005
Location: Hawaii
Posts: 40
Likes: 0
Received 0 Likes on 0 Posts
Is 50 psi compression good enough??

I just blew my rebuilt motor! Its only been a few months and not long after I had it fine tuned with an Autronic. I pushed 1.2 bar and it blew at 7000rpm. My question is, after I blew the 1st rotor, the second rotor is showing only 50psi on each bounce. Is this right? Is this a sign of another type of seal blown? I know the 1st rotor is blown because I only get one bounce, but that's at 50psi also. I'm in the process of taking out the motor but wanted to know if this might be an obvious sign that someone might've seen before. There hasn't been any fluid mixing in my coolant or oil so I can't figure it out. I'm worried that when I take apart the motor, I won't be able to figure it out either. Do you guys think this motor is not rebuildable?
Old 07-13-05, 03:43 PM
  #2  
I live in an igloo

 
BlaCkPlaGUE's Avatar
 
Join Date: Jul 2004
Location: calgary alberta
Posts: 2,546
Likes: 0
Received 0 Likes on 0 Posts
Any 13B is rebuildable, it just depends on what parts need to be replaced

The second rotor thing is wierd since all the faces show only 50psi.. I can't explain that. With the first rotor blown you may have to replace the rotor and housings if the seal did any damage.
Anyone who knows how a rotary works, how it builds compression, will be able to tell what went wrong with the engine apart in your situation. Its gotta come out anyways, post pics of the dissasembly if you still can't figure it out.
Old 07-13-05, 08:11 PM
  #3  
Junior Member

Thread Starter
 
trufc's Avatar
 
Join Date: Jun 2005
Location: Hawaii
Posts: 40
Likes: 0
Received 0 Likes on 0 Posts
Thanks. I just thought of something. If I blew the water seal, could that be why I'm getting the 50psi compression? If I did blow the water seal, is that probably due just to the high temp or could it be because of a bad rebuild or bad housings? I did push the car to where it was super hot but what temp would the water seals go at? And I don't know how to tell if my housings are bad in terms of coolant passage seals. Maybe my housings are messed up, could that be it too? I would just hate to rebuild this motor and it happen again.
Old 07-13-05, 08:47 PM
  #4  
****** of the Engine Swap

iTrader: (2)
 
dcrews's Avatar
 
Join Date: Apr 2001
Location: Springfield, MO
Posts: 260
Likes: 0
Received 0 Likes on 0 Posts
How hot did you get it, exactly?
Old 07-13-05, 08:51 PM
  #5  
Old Fart Young at Heart

iTrader: (6)
 
trochoid's Avatar
 
Join Date: Apr 2004
Location: St Joe MO
Posts: 15,145
Likes: 0
Received 7 Likes on 7 Posts
I would try a different compression tester, something doesn't sound right with 50 psi being the highest on both rotors. I suspect the tester is leaking somewhere.
Old 07-13-05, 08:57 PM
  #6  
Junior Member

Thread Starter
 
trufc's Avatar
 
Join Date: Jun 2005
Location: Hawaii
Posts: 40
Likes: 0
Received 0 Likes on 0 Posts
About 116 degrees Celsius or about 240 degrees Fahrenheit. I know, pretty bad because my 3 row front mount intercooler is blocking all the air. The motor still ran strong but I noticed a super small leak after on the top of the block. It look like it was coming from where the lower intake manifold met up with the block.
Old 07-13-05, 10:23 PM
  #7  
I live in an igloo

 
BlaCkPlaGUE's Avatar
 
Join Date: Jul 2004
Location: calgary alberta
Posts: 2,546
Likes: 0
Received 0 Likes on 0 Posts
In my opinion, this is very bad. Coolant runs through passages, wich in turn feed the turbo through a metal hose that is atached to the LIM. Now if coolant is leaking from the LIM after your engine was heated up and not before, that tells me that the irons/housings expanded to much becuase of the intense heat, and you warped the flange on the LIM or something.
anyone else think so?

Originally Posted by trufc
About 116 degrees Celsius or about 240 degrees Fahrenheit. I know, pretty bad because my 3 row front mount intercooler is blocking all the air. The motor still ran strong but I noticed a super small leak after on the top of the block. It look like it was coming from where the lower intake manifold met up with the block.
Old 07-13-05, 11:04 PM
  #8  
Endure Persevere Succeed

iTrader: (30)
 
Jaiyurai's Avatar
 
Join Date: Apr 2005
Location: Berkeley, CA
Posts: 1,693
Received 37 Likes on 30 Posts
did you break-in the motor properly? seeing how you just got your motor rebuilt a few months ago, improper break-in period and 1.2 bar of boost will easily blow the keg up.
Old 07-13-05, 11:18 PM
  #9  
Super Raterhater

iTrader: (6)
 
SonicRaT's Avatar
 
Join Date: Dec 2001
Location: NY, MA, MI, OR, TX, and now LA or AZ!
Posts: 10,624
Likes: 0
Received 2 Likes on 2 Posts
chipped apex or stuck side seals on the second rotor, blown on the front, and stuck seals as well on the other face. Happens a lot.
Old 07-14-05, 12:16 AM
  #10  
Junior Member

Thread Starter
 
trufc's Avatar
 
Join Date: Jun 2005
Location: Hawaii
Posts: 40
Likes: 0
Received 0 Likes on 0 Posts
Wow, everyone hear is awesome. I just got home from work and am pulling the motor tonight. I hope everything inside is ok. I did break in the motor but maybe not enough. What was hard was that I had the autronic put on right after I did the rebuild so the first thousand or so miles was a basic map that wasn't fully tuned. After that, we burnt the rest of the miles on the dyno, then tuned the crap out of it. It basically took us 7 hours to get the tuning right cause we kept uping the boost and the transition between the 550 and 1600cc injectors were tricky. I already have an upgrading cooling system but I don't think its getting enough air because of the intercooler and I have my 3 MSD ignition boxes up front. I'll probably move those and make more ducting and this time break in the motor a lot longer. Maybe 3mm might be better also?? A lot of people say Mazda OEM are better but does that mean using the older rx-7 3mm seals because there are no listings for our cars stock right? Man, this is fustrating because I actually wanted to get a bigger turbo. I was maxing out the Greddy TD06 at high rev (exhaust side too small). Between .8 bar and 1 bar, my max hp didn't go up, only the mid range shot up. Actually, when I was at .8 bar I had 315whp, but at 1 bar it was at 310. Anyways, rambling huh? I guess since you guys reply so quickly I figure I'd better get in everything before I get off the comp. Hmm, maybe water injection?
Old 07-14-05, 01:07 AM
  #11  
Displacement > Boost

 
88IntegraLS's Avatar
 
Join Date: Oct 2002
Location: Mississippi
Posts: 3,503
Likes: 0
Received 0 Likes on 0 Posts
I'd like .8 bar.
Old 07-15-05, 12:26 AM
  #12  
Rotorhead

 
RX_AV8TR's Avatar
 
Join Date: Jul 2005
Location: San Diego, CA
Posts: 94
Likes: 0
Received 0 Likes on 0 Posts
50psi?? You should be getting close to 90psi. The break in for a rebuild should be around 500 miles, some shops say 1000 miles with factory apex seals, with ceramic seals is minimal but I can't say since I've never used them.
A friend of mine that has what was the fastest 13BT FC in the world until a few years ago (Rafaelito from Falito Racing in Puerto Rico) used factory apex seals on his car. Problem is that they are VERY expensive and if you break with ceramic seals usually the housings die too, good thing....they can handle a LOT of boost.
Old 07-15-05, 12:43 AM
  #13  
Senior Member

 
Join Date: Jan 2004
Location: Vancouver, B.C.
Posts: 302
Likes: 0
Received 0 Likes on 0 Posts
i read there is a more advanced way to break in then just a drive in period ....

- first couple hundread miles stagger rpms and rev to about 3k
- next couple hundred stagger rpms and rev to around 5k
- last couple hundred same thing and go to redline once in awhile

cant remember where i read that ... but the site had more exact details
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
trickster
2nd Generation Specific (1986-1992)
25
07-01-23 04:40 PM
elfking
3rd Generation Specific (1993-2002)
3
08-19-15 09:48 PM
86glxNA
New Member RX-7 Technical
7
08-18-15 03:33 PM



Quick Reply: Is 50 psi compression good enough??



All times are GMT -5. The time now is 12:11 AM.