renesis removal/rebuild
07-09-2008, 12:24 PM
#76
kevin@rotaryresurrection
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It's a reliability mod, it eliminates the oil thermostat in the front shaft. They rarely fail, but if it were, poor oiling to the internals could result. It's purpose is to accelerate oil temperature increase on a cold engine to promote better cold emissions. IT's a 10 dollar part that should be replaced while the engine is apart.
07-10-2008, 04:33 AM
#77
Thats pretty interesting about the pellet, never knew about that. BTW the 09 rx8 is doing away with the MOP(metering oil pump) below the thermostat housing, it has a new electronic way of handling it, supposedly they solved the cold start issue.
10-14-2008, 06:36 PM
#83
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Excellent Pics and Rotary lesson 101. I am new at this Rotary Family, and loving it every second. I am from Panama, and here there are at most, 10 RX-8. I bought one from a young fella, he had the car sitting in a Whouse for almost 2 yrs, I bouhgt it real cheap, it wouldnt start, but It did finally but had temp. problems, I order housing gaskets and rotors bearings, and thats it.
Have not started the engine yet, will post comment once I do.
Have not started the engine yet, will post comment once I do.
10-30-2008, 03:04 AM
#85
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So is this procedure possible for the average enthusiast who has never worked on a motor before? All that's really needed is the gasket kit, some oem seals and a lot patience is what I would assume.
10-30-2008, 08:51 AM
#86
Keep in mind that those who are really good at what they do will make it appear as if anyone can do it..........
I am by no means an Elitist when it comes to modding the RX-8/Renesis but rebuilding an engine isn't, as Joe Biden might say, "conducive to on-the-job training". The removal/replacement might not be so bad, thanks to ISO9000, but the engine is a different story.
I am by no means an Elitist when it comes to modding the RX-8/Renesis but rebuilding an engine isn't, as Joe Biden might say, "conducive to on-the-job training". The removal/replacement might not be so bad, thanks to ISO9000, but the engine is a different story.
10-30-2008, 08:57 AM
#87
a common 4stroke engine is way harder to rebuild imho, and with the informations provided around the web and the right tools a mechanically inclined folk can succeed taking its time
10-30-2008, 09:00 AM
#88
Giorgio, I hope you read Italian Law better than you read other peoples' posts! Further, website information provides no means to instruct others on the touch and feel required in order to know if the apex seal springs have been installed properly. This is learned only from guidance and experience.
10-30-2008, 09:08 AM
#89
Yes, but i was\am the average enthusiast and before my first rebuild i never worked on an engine. In fact, i'm not able to work on 4cycle engines (only a bit of rotaries, and 2strokes).
Remember when i asked you confirmation about the tolerances? for sure i'm not afraid of exploding the stuff i test\do , but with some instructions i think that a common guy might try and succeed. Obviously not needing the stuff you work on is a must, just in case something goes wrong.
Remember when i asked you confirmation about the tolerances? for sure i'm not afraid of exploding the stuff i test\do , but with some instructions i think that a common guy might try and succeed. Obviously not needing the stuff you work on is a must, just in case something goes wrong.
10-30-2008, 01:19 PM
#90
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I'd say that a first timer with no significant mechanical experience would stand about a 25% chance of being able to do this job from start to finish without either losing patience and paying someone else to take over, or missing a few critical details here or there that result in a non running (or non properly running) car that, again, they lose patience with and pay someone else to re-do the entire job.
Also if you've never gone through the job with someone else more experienced prior, you won't know what to look out for, how to handle the parts, etc. If you've worked with someone who can show you what to expect and certain critical aspects of the work, then it is certainly plausible that you could then do the job yourself with very few issues.
10-30-2008, 01:53 PM
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Possible? Yes. Likely to get everything 100% correct the first time? The odds are not in your favor.
I'd say that a first timer with no significant mechanical experience would stand about a 25% chance of being able to do this job from start to finish without either losing patience and paying someone else to take over, or missing a few critical details here or there that result in a non running (or non properly running) car that, again, they lose patience with and pay someone else to re-do the entire job.
Also if you've never gone through the job with someone else more experienced prior, you won't know what to look out for, how to handle the parts, etc. If you've worked with someone who can show you what to expect and certain critical aspects of the work, then it is certainly plausible that you could then do the job yourself with very few issues.
I'd say that a first timer with no significant mechanical experience would stand about a 25% chance of being able to do this job from start to finish without either losing patience and paying someone else to take over, or missing a few critical details here or there that result in a non running (or non properly running) car that, again, they lose patience with and pay someone else to re-do the entire job.
Also if you've never gone through the job with someone else more experienced prior, you won't know what to look out for, how to handle the parts, etc. If you've worked with someone who can show you what to expect and certain critical aspects of the work, then it is certainly plausible that you could then do the job yourself with very few issues.
I second everything RR said. First engine I did a rebuild on was a 302 out of a mustang. I ended up rebuilding it twice the first time around because of critical steps I missed(not even in the book actually). Simple things like marking pushrods(if you reuse them) by cylinder number and which end is which is very critical. And for the first time noob you wonder why the hell are you doing that anyways, it doesn't make sense.
If I would of paid someone else to do it the first time around it would of ended up saving me alot of money.
11-16-2008, 02:38 PM
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"10 years in development?"
Not bad looking once I wipe it off a bit. Mild wear, light chome flaking on the rearmost edge of the housing. This area is where the short triangle assist piece of the apex seal rides, and due to it's sharp tip, it digs out a groove on that rear edge and causes the chrome coating to flake off over time. All used rotary engine rotor housings with more than 30-40k miles will have some wear/flaking here.
On the rotor housing where the cracks are at the plug holes, you see a thick stripe of carbon buildup on the housing. The reason for this is that the cracks expand under heat, and push out into the combustion chamber. Since the apex seals ride over this, that means they get pushed up off of the housing for a split second in that one spot, over and over. Since the cracks are only in the center of the housing, the rest of the housing in that spot remains flat, and blowby occurs there while the seal is lifted off of the housing.
This is further detrimental in that the apex seal is constantly riding over a "bump" on the housing, and so the center of the seal is going to wear more due to this. So, even when the seal is over on another part of the housing that is flat, the "bump" has worn a bit of material out of the center of the seal, and so blowby can still occur everywhere. This means a loss of compression and power.
There are only a couple of things you can do about this. 1) replace both rotor housings with new ones or used ones with less wear, at a significant cost, anywhere from a few hundred for a used set to over a grand for a new set. 2) grind down the cracks lightly so that they will not expand when the housing is put back into use, and the seal will not skip over them. Compression will not be lost elsewhere on the housing, and compression loss due to blowby at the plug hole itself will be minimized.
I am disturbed by the way mazda cast the irons to prevent any significant porting or reshaping whatsoever. I know others have already posted about this on the forum so I will not comment further, other than to say that these engines are basically going to be what they were in stock form, there is not much at this time that can be done to improve them for a stock or mildly modded street car, without making significant compromises.
One thing I dislike about the renesis, mazda runs a VERY loose side seal clearance, 2-3 times what was acceptable in the previous versions. This causes blowby, carbon buildup on the sides of the rotors, and a bit of compression loss. I am pondering on trying a couple of things to run less sideseal clearance and perhaps improving efficiency. To do this I will use the "extra long" renesis side seals that are available by special order, and hand fit them as per previous versions.
On the rotor housing where the cracks are at the plug holes, you see a thick stripe of carbon buildup on the housing. The reason for this is that the cracks expand under heat, and push out into the combustion chamber. Since the apex seals ride over this, that means they get pushed up off of the housing for a split second in that one spot, over and over. Since the cracks are only in the center of the housing, the rest of the housing in that spot remains flat, and blowby occurs there while the seal is lifted off of the housing.
This is further detrimental in that the apex seal is constantly riding over a "bump" on the housing, and so the center of the seal is going to wear more due to this. So, even when the seal is over on another part of the housing that is flat, the "bump" has worn a bit of material out of the center of the seal, and so blowby can still occur everywhere. This means a loss of compression and power.
There are only a couple of things you can do about this. 1) replace both rotor housings with new ones or used ones with less wear, at a significant cost, anywhere from a few hundred for a used set to over a grand for a new set. 2) grind down the cracks lightly so that they will not expand when the housing is put back into use, and the seal will not skip over them. Compression will not be lost elsewhere on the housing, and compression loss due to blowby at the plug hole itself will be minimized.
I am disturbed by the way mazda cast the irons to prevent any significant porting or reshaping whatsoever. I know others have already posted about this on the forum so I will not comment further, other than to say that these engines are basically going to be what they were in stock form, there is not much at this time that can be done to improve them for a stock or mildly modded street car, without making significant compromises.
One thing I dislike about the renesis, mazda runs a VERY loose side seal clearance, 2-3 times what was acceptable in the previous versions. This causes blowby, carbon buildup on the sides of the rotors, and a bit of compression loss. I am pondering on trying a couple of things to run less sideseal clearance and perhaps improving efficiency. To do this I will use the "extra long" renesis side seals that are available by special order, and hand fit them as per previous versions.
:
11-16-2008, 03:02 PM
#94
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I have already thanked RR in a PM (two, actually) for his generous expenditure of time and effort to bring us this superb post. Please note that ALL bold highlights in his quoted text are by me. Now, here is my question for anyone who cares to answer: It appears that what RR's observations reveal is that Mazda has given us, after "10 years in development" (RX-8), is an engine that is inherently problematic, if not doomed to failure, and cannot easily be improved after the fact (again, all statements are mine, not his). Uh, this doesn't feel too good. Anyone care to weigh in on this? :
:Mazda have been making and developing the rotary for over 40 years, I think they know what they are doing.
The RENESIS was not designed or built to be modded whatsoever. OK.
Everything (side exhaust porting) was done to pass emissions, because it can't be modded does not represent failure.
The future of the Rotary is from an alternative fuel (hydrogen), we all know that.
I really doubt that we will see the 16X anytime soon, if at all.
Series II Rx-8 sales have unfortunately been appalling, I think this is the last rotary we will see for some years.
Until the alternative fuel is mainstream.
Last edited by ASH8; 11-16-2008 at 03:04 PM.
11-16-2008, 03:10 PM
#95
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What Mazda have recognised is the poor lubrication of the centre area of the Apex seals, hence the 3rd (middle) oil injector for series II RX-8's.
I am disappointed that they did not discover this before the RENESIS release as a poor reputation is hard to shrug off.
Mazda was relying on a new generation of rotary fans (youth) to re-lite a revolution.
I am disappointed that they did not discover this before the RENESIS release as a poor reputation is hard to shrug off.
Mazda was relying on a new generation of rotary fans (youth) to re-lite a revolution.
11-16-2008, 03:25 PM
#96
kevin@rotaryresurrection
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For what it is, I think it is great. It makes more power and drives more smoothly than the last non turbo rotary.
I think that if you buy this car, you buy it for what it is, and not what you can build it to be. That is the opposite of older rotaries and rx7s...those cars were not all that awesome in stock form, but were easily modified for power and appearance. So you bought those cars for their potential and not their stock performance.
Usually manufacturers engineer a car to X performance level, and then subtract some of that, and release the car to the public with (X - Y) level of performance. And then to get more power the aftermarket simply makes some tweaks to add Y again, and you have a strong car. What mazda did here is to engineer the car for X, and released it basically still with X, meaning that there is not much more to be added by the aftermarket safely without making compromises.
I do not share the opinion of some of the renesis elitists here on this forum, that think the renesis is a quantum leap ahead of previous rotaries. I think what it does in stock form is impressive, but I think it is slightly under-engineered given that mazda had 10 more years of R&D to put into it since development of the FD in 1992-1993.
I think the irons are made from a lower grade material as they seem to crack and corrode very easily under the right circumstances, compared to older irons. The way they are cast also makes any significant porting impossible. I think the rotor housings still wear just like the older ones did in spite of developments in metals and coatings that could have improved the sealing surfaces. I think the apex seal lubrication is still a sore spot and I think the side seals are left too loose, allowing extra blowby.
I think they also could have made the ignition a bit stronger, as this has always been a strong point of previous rotaries. Ignitions on 2nd gen rx7s could support 500+hp in stock form. The stock ignition of rx8s cannot support stock hp reliably.
I also think they could have gotten better mpg out of it by changing the gearing a little bit and not running it as rich. Even twin turbo FD's could do as much as 24-25 on the highway at 75, yet I have never gotten more than 20 out of an rx-8 (at 60-65mph) or 18.5-19 (75mph).
Again, bottom line the car is fine for what it is, and there are not many cars that are as nice or as smooth in the price range of today's market. To get better performance yo have to buy a higher price newer car, or a lower priced older car and then build it up.
I think that if you buy this car, you buy it for what it is, and not what you can build it to be. That is the opposite of older rotaries and rx7s...those cars were not all that awesome in stock form, but were easily modified for power and appearance. So you bought those cars for their potential and not their stock performance.
Usually manufacturers engineer a car to X performance level, and then subtract some of that, and release the car to the public with (X - Y) level of performance. And then to get more power the aftermarket simply makes some tweaks to add Y again, and you have a strong car. What mazda did here is to engineer the car for X, and released it basically still with X, meaning that there is not much more to be added by the aftermarket safely without making compromises.
I do not share the opinion of some of the renesis elitists here on this forum, that think the renesis is a quantum leap ahead of previous rotaries. I think what it does in stock form is impressive, but I think it is slightly under-engineered given that mazda had 10 more years of R&D to put into it since development of the FD in 1992-1993.
I think the irons are made from a lower grade material as they seem to crack and corrode very easily under the right circumstances, compared to older irons. The way they are cast also makes any significant porting impossible. I think the rotor housings still wear just like the older ones did in spite of developments in metals and coatings that could have improved the sealing surfaces. I think the apex seal lubrication is still a sore spot and I think the side seals are left too loose, allowing extra blowby.
I think they also could have made the ignition a bit stronger, as this has always been a strong point of previous rotaries. Ignitions on 2nd gen rx7s could support 500+hp in stock form. The stock ignition of rx8s cannot support stock hp reliably.
I also think they could have gotten better mpg out of it by changing the gearing a little bit and not running it as rich. Even twin turbo FD's could do as much as 24-25 on the highway at 75, yet I have never gotten more than 20 out of an rx-8 (at 60-65mph) or 18.5-19 (75mph).
Again, bottom line the car is fine for what it is, and there are not many cars that are as nice or as smooth in the price range of today's market. To get better performance yo have to buy a higher price newer car, or a lower priced older car and then build it up.
Last edited by RotaryResurrection; 11-16-2008 at 03:27 PM.
11-17-2008, 11:24 AM
#98
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I believe it would, yes. As the rotary was set up to make more power and meet tighter emissions, mazda has run them hotter and hotter through the years, mainly starting in 93 with the FD.
Coincidentally, this is also when the plug hole cracking became an issue. This problem was NEVER seen on pre-FD rotaries that tended to run cooler on average. Why? They had a larger radiator, mounted almost perpendicular to the ground for good airflow. They had a big clutch fan that pulled lots of air consistently. And they had a massive oil cooler as well, and that oil cooler was fed through the main grille opening in the front bumper, and not through a small opening in the corner of a bumper with a plastic duct behind it.
Then with the FD (the rx-8 is set up identical to an FD for cooling purposes) they put in a half-size radiator with 2 small e-fans, and further they only turn those e-fans on when the temp gets pretty high. I dont know the fan turn-on spec for the rx-8, but the factory fan turn on spec for FD was 220-225. Then you had either one or 2 small oil coolers depending on model (same for the rx-8), and the both of them put together are not as efficient as the one large, thick FC rx-7 cooler.
Coincidentally, this is also when the plug hole cracking became an issue. This problem was NEVER seen on pre-FD rotaries that tended to run cooler on average. Why? They had a larger radiator, mounted almost perpendicular to the ground for good airflow. They had a big clutch fan that pulled lots of air consistently. And they had a massive oil cooler as well, and that oil cooler was fed through the main grille opening in the front bumper, and not through a small opening in the corner of a bumper with a plastic duct behind it.
Then with the FD (the rx-8 is set up identical to an FD for cooling purposes) they put in a half-size radiator with 2 small e-fans, and further they only turn those e-fans on when the temp gets pretty high. I dont know the fan turn-on spec for the rx-8, but the factory fan turn on spec for FD was 220-225. Then you had either one or 2 small oil coolers depending on model (same for the rx-8), and the both of them put together are not as efficient as the one large, thick FC rx-7 cooler.
11-17-2008, 12:08 PM
#100
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Good info. I have to believe that for whatever reason the average 8 runs consistently warmer than 207, to see the amount of cracking at the sparkplug holes that I have seen in the engines I have thus far. Either something about the quality of the rotorhousing has changed (for the worse), or the temps in that area are higher than those in previous rotaries (including the aforementioned hot-running FD which sees 10psi boost in stock form), because of the severity of this issue at relatively low mileage.