2nd Generation Specific (1986-1992) 1986-1992 Discussion including performance modifications and technical support sections.
View Poll Results: What rotor have you blown and what year is your car?
I blew the front rotor in my 86-88 RX-7
11
7.53%
I blew the rear rotor in my 86-88 RX-7
84
57.53%
I blew the front rotor in my 89-91 RX-7
17
11.64%
I blew the rear rotor in my 89-91 RX-7
34
23.29%
Voters: 146. You may not vote on this poll

If you've blown your engine...

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Old Mar 8, 2003 | 10:56 AM
  #1  
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If you've blown your engine...

I'm trying to check out my suspicions regarding whether 86-88's have a propensity towards popping the rear rotor vs. a 89-91 7's favouring of the front.

VOTE!
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Old Mar 8, 2003 | 11:12 AM
  #2  
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good poll...I've heard the same thing too quite a bit..s4's popping rear rotors...s5's front rotors...any suspicions as to why?
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Old Mar 8, 2003 | 11:49 AM
  #3  
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We believe that the rear rotor is under more stress on most engines, because coolant and oil flow have already been saturated with some of the front rotor's heat before reaching the rear, and heat equals friction which equals wear. In other words the rear rotor may retain slightly more heat over it's life, and therefore it's seals wear out slightly quicker.

My personal theory on why 89+ rotaries blow the fronts more often is due to mazda's dumbass electronic OMP, and some kind of uneven flow or failure issue with it. I dont know why they couldnt leave a bulletproof system alone.
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Old Mar 8, 2003 | 12:54 PM
  #4  
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about the the omp...what are your feelings on pre-mix...how it burns cleaner leaving less carbon deposits..getting distibuted more evenly, etc.
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Old Mar 8, 2003 | 01:30 PM
  #5  
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Haha, ive blown one rear and one front in different motors. You forgot to put that one in.
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Old Mar 8, 2003 | 01:52 PM
  #6  
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Originally posted by marcus219
about the the omp...what are your feelings on pre-mix...how it burns cleaner leaving less carbon deposits..getting distibuted more evenly, etc.

http://fc3s-pro.com/TECH/FAQ/premix.htm


An obvious by-product of the cleaner burning pre-mix is very clean spark plugs. Tearing down engines running solely on pre-mix awards you with very clean internal parts; the spark plugs and rotor faces are barely covered with a fine layer of soot. Stock oil injection systems injecting engine motor oil into the combustion chambers tend to cake the spark plugs and rotor faces with lots of crusty carbon deposits. These crusty carbon deposits tend to jam seals in some cases. In extreme cases, piece of carbon chip off and score housings and possibly cause apex seal failure!

Now let's look at the difference in delivery... Stock oil injection uses oil injectors that inject engine motor oil through a tiny hole in the rotor housing (primaries) and in the lower intake manifold (secondaries). The oil is then spread out by the apex seals wiping by - keep in mind, this is not a "spray" of oil; the oil injectors are not under very heavy (injection) pressure. Pre-mix is typically mixed in with the fuel, so it's injected under heavy pressure with the fuel in a stock fuel injection system; this gives better dispersion in the combustion chamber.

Even after going through the combustion cycle, the pre-mix is still designed to lubricate the internal engine parts. This is a big advantage over engine motor oil! The combustion by-products of pre-mix actually leave a "lubricant" on the internal engine surfaces.
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Old Mar 8, 2003 | 05:25 PM
  #7  
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been to that site about a million times man...im already running premix with my omp blocked off...i wanted KEVINS opinion on it...just b/c hes an engine builder..maybe hes seen a rebuild ran on pre-mix vs. a oil injected rebuild..thanks though.
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Old Mar 8, 2003 | 06:41 PM
  #8  
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On the 86-88's ive seen they blew the rear rotor due to carbon buildup scoring the housing surface. (OMP related)
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Old Mar 8, 2003 | 09:24 PM
  #9  
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I blew my front rotor in my N/A 89 but it detonated that way. Not from natural wear so my vote doesent really count. The rear rotor runz leaner in both cars I think wich is why over time the rear goes out first. I would think both cars are the same unless someone has hard proof.
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Old Mar 8, 2003 | 09:54 PM
  #10  
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this is an intreasting poll, my engine died due to waterjacket seal falure, its an 87 n/a. anyone want to bet where im going to find the broken seal
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Old Mar 8, 2003 | 11:20 PM
  #11  
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will pre-mix clean the engine, or just prevent further buildup? After reading about pre-mix, I'm thinking of going that route.
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Old Mar 8, 2003 | 11:56 PM
  #12  
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Check this out:

https://www.rx7club.com/forum/showth...hreadid=146142
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Old Mar 9, 2003 | 03:23 AM
  #13  
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Good thread...we need some pics of a torn down motor that has ran premix all its life.

Premix will not clean your engine...it will prevent it from building up more nasty carbon that motor oil will leave when it burns. I suggest some atf/mmo mix in the motor...let it sit for as long as you can..get it evenly distributed or, the water steam clean works damn good too..
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Old Mar 9, 2003 | 03:30 AM
  #14  
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Originally posted by Amur_
Check this out:

https://www.rx7club.com/forum/showth...hreadid=146142
My rotors looked like first one using the MOP. 216k.

Originally posted by rotary>piston
will pre-mix clean the engine, or just prevent further buildup? After reading about pre-mix, I'm thinking of going that route.
Doubt it. But what you can do:

Get a pitcher of water (like 4L or a gallon). Start the car and let it warm up. Get someone to hold the revs at about 3k. Pull off the boost sensor vac line and stick it into the thing of water. Dont let the car stall. Allow it to drink up all that water then put the vac line back onto the sensor and go drive around. You just steam cleaned your internals
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Old Mar 9, 2003 | 03:34 AM
  #15  
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Originally posted by dr0x
My rotors looked like first one using the MOP. 216k.

Doubt it. But what you can do:

Get a pitcher of water (like 4L or a gallon). Start the car and let it warm up. Get someone to hold the revs at about 3k. Pull off the boost sensor vac line and stick it into the thing of water. Dont let the car stall. Allow it to drink up all that water then put the vac line back onto the sensor and go drive around. You just steam cleaned your internals
Have you personally tried this?
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Old Mar 9, 2003 | 08:41 AM
  #16  
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Im no expert, but IF this was a piston engine, you would of just caused vapor lock right?
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Old Mar 9, 2003 | 11:19 AM
  #17  
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I'm the lone front rotor roaster for S4s.
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Old Mar 9, 2003 | 01:03 PM
  #18  
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your can't hydrolock a rotary...i've tried it...works great...
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Old Mar 9, 2003 | 01:05 PM
  #19  
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o-ring failure for me.
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Old Mar 9, 2003 | 02:55 PM
  #20  
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I am going to be running a set up that will use the MOP to inject 2 cycle oil, I will let you all know how it goes.
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Old Mar 9, 2003 | 07:13 PM
  #21  
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I overheated mine due to a water jacket failure as well...

it was interesting seeing the temp gauge go way past the H and then the engine loosing power and then just shutting off.....

Got it started again like 30mins later, sounded like a lawn mower, no power,.

pushed the car all the way home... was about a 15min drive from home/.
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Old Mar 9, 2003 | 08:56 PM
  #22  
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damn those rear rotors
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Old Mar 10, 2003 | 12:51 PM
  #23  
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i bought my 88t2 with a siezed up engine (no oil), the apex seals were fine. my 91 has 210k on it and the water seals failed.

mike
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Old Mar 10, 2003 | 10:31 PM
  #24  
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Rear rotor just blew on me while I was driving home. Not alot of fun.
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Old Mar 10, 2003 | 10:44 PM
  #25  
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Mine blew from my fuel injectors being dirty, whether it was flow or spray pattern.

I think that 2 cycle MOP is junk. Why? 2 cycle oil is designed to be sprayed in with gasoline as a mixture, not the way the MOP does it. *shrug*
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