So if I get one, what can I do to help make my engine last?
For this, you have to understand that each different failure method has to be addressed individually. Some solutions help more than one aspect, but if you ignore one, it's probably going to be the one to bite you.
First Note as you read these: There are some "solutions" presented which conflict with causes listed. Example High Load High RPM helps carbon, but hurts side seal and cooling. It's the excess that gets you into trouble. Don't stay high RPM all of the time for carbon, because you are dramatically increasing the chance of heat related failures, but don't avoid high RPM either because it is increasing the chance of carbon related failure. Dip your feet in both pools...
Second Note: These are fairly basic concepts. They can get far far far more involved. Pursuing any of these should be preceded by research.



Failure causes from the list in post 2:
- Excessive carbon buildup accelerates seal wear, causing compression loss
- Excessive carbon buildup unseats the apex seals, causing compression loss
It is nearly impossible to prevent all carbon buildup in our engines. But some things can help make an impact:
A) High RPM at full throttle (commonly known as "redline a day") produces lots of heat and energy along with high air/exhaust velocities, which can help is breaking down the carbon and blowing it out of the engine. An engine that only sees low RPM and low load (as many automatics do) has been shown to have significantly more carbon buildup than one that is rev'ed hard often. This will NOT prevent all carbon.
B) Premix. Premix is largely a benefit for apex seal wear, however it has been shown on engine teardowns that the carbon in an engine that was premixed is 'softer' than carbon in an engine that wasn't, and seems to lend a slight benefit in this area to decarbing
C) Seafoam / Decarb / Steam Cleaning. See my testing thread here for the effectiveness of it: https://www.rx8club.com/tech-garage-...r-pics-241867/
Soaking with seafoam simply doesn't remove any appreciable carbon. The only way to really strip carbon periodically is with ingestion while the engine is running. And in this circumstance, seafoam is just as effective as distilled water. Seafoam is also ~100 times more expensive per unit of measure, so there isn't much of a reason to actually use seafoam. It is also more benefitial to ingest the water at higher RPMs, and to feed both rotors at the same time. This will indeed strip away carbon. However, it is a VERY slow process. Do not expect a single gallon will do it. 1.5 gallons of water, 0.5 gallons of washer fluid (it's a water/meth mix), and the carbon near the seals was less than half gone. Removing carbon is always a good thing, however don't expect stellar results, and don't think that it's removing all of the carbon, or even that it's removing carbon where it needs to. If you do this, you will need an oil change immediately after at a minimum. If you have a cat installed, the cat can start glowing, so you will need to take breaks to let it cool down. May kill the cat and/or reduce it's life span. See the testing thread for details.
D) Water/Meth injection. W/M injection is usually targeted almost entirely for forced induction as a safety margin by increasing the effective octane rating of the fuel. However it does have side benefits of producing remarkably clean engine internals. If you want to learn more, read up on this opening post on RX7Club: (Making The Case For The <Rotary> Powered FD: The Fix - RX7Club.com). He largely talks about methods of failure for the RX-7, and it has a slightly different application and goal that the writer was going after, but still valuable nuggets in there for our engine's long term health and how effective it is at removing carbon. However, note that W/M is not legal everywhere, many racing organizations prohibit it, it usually requires some sort of tuning, and kits are usually set up to deliver under boost, which an N/A engine won't have. I don't know of anyone running W/M on an naturally aspirated Renesis for the purposes of cleaning only. W/M injection solves a few of the steam and seafoam treatment weaknesses, namely the inability to deliver either with the engine under full load while the car sits in your driveway. Injection also gets the intake valving that none of the other treatments do.

- Excessive heat buildup warps the housings to one degree or another, preventing the apex seals from sealing, causing compression loss
This can be caused from a few different sources. Probably most common is a coolant system overheating, followed by a cat clogging. Most housing warp failures end up leaking coolant and/or oil directly into the housing because the seals and rings can no longer seal properly. The greater the warp, the faster the oil and coolant leak. (Separate from the oil injection. Oil injection rates shouldn't ever produce oil smoke from the tailpipe, which oil control ring failure usually does). This can be a sudden failure from any single cooling system component. A suddenly stuck thermostat, a clogged radiator, too low coolant without realizing it, too much high RPM, high ambient temps in stop and go traffic, etc...
A) Remove the cat, install a midpipe. This isn't kosher with the EPA, environmentalists, federal government, most state governments, emissions inspection stations, your spouse's nose, or your rear bumper paint. However, aside from the power increase it will give you, removing the cat removes the possibility that it will clog on your car, which can cause significant localized heat within your cat, header, and back up into your engine. I believe that my engine failed due to housing warp from a failed cat.
B) Upgrade your cooling system. Do not rely on your temperature needle. By the time it starts to move, the engine is already hot enough to be able to start warping. Damage is almost guaranteed. You have to understand what each component of your coolant system does, don't just go upgrading *****-nilly. The radiator is what transfers the heat out of the coolant. An upgraded radiator means a faster heat dump from the coolant it sees (actual upgrade, many aftermarket radiators are NOT upgrades). However, the thermostat is what controls what coolant gets to the radiator, and if the coolant temp drops to a certain point, it won't even send the coolant to the radiator to dump heat from. So if you have a 200 degree thermostat, and your coolant temps sit at 200 degrees, upgrading your radiator will do nothing to drop this! It will only increase the rate of temperature drop when you are ABOVE your thermostat temp. Upgrading your thermostat to a lower temperature is what can allow your radiator to bring temps down. If you are getting an engine rebuild, there are improvements you can have done to your coolant passages to aid their heat transfer from the block to the coolant. There is also the water pump, which pushes the coolant through the system. It's speed is based on RPM speed, and the OEM water pump can have quite a bit of trouble moving coolant at high RPM. Upgrading the water pump can help reduce heat-spotting in the engine
C) Lower the trigger temp for the radiator fans. The OEM trigger temp is almost 'too high' already. There are a few kits you can buy, as well as it is built into Mazdamaniac's AccessPORT base tune. So your fan runs more, but your system stays cooler.
D) Flush radiator fluid periodically. Already part of regular maintenance, but more critical for our engines than piston engines.


- Excessive exhaust temperatures overheat the side seal springs
This is a failure that most of us don't have to really worry about. It's the number one failure method in race engines, and I suspect most turbo'ed engine failures that don't involve a sudden lean spike detonation. Lots of exhaust heat builds up exhaust port heat, leading to the side seal spring deforming until it gets to the point that it pushes the side seal out of place, the seal catches the exhaust port and shatters. This is usually only a problem in cars putting down ~220whp or more, AND spends most of it's life at high RPM and high load (like a race engine). It is a scale, it's likely more about how much "increments of energy" the spring takes, and a lower power level can get away with more high load than a higher power, etc...
A) The only 'known' solution for this is using the side seal springs from the FD engine. I have nothing to prove this, and you can find race teams that swear there is nothing to do about it and other race teams that swear they no longer have the problem. If you are getting a rebuild and want to reduce this risk, there is likely no harm in going with the FD side seal springs, and it very well may help.
B) Increasing the efficiency of the exhaust system will also reduce exhaust port temps. A more efficient exhaust dumps heat more rapidly, reducing buildup.

- Fuel pump failure or high lateral G left turns with low fuel causes fuel starvation under load, creating a lean spike that causes detonation and shatters seals
This is an all-too-frequent failure seen. If you expect frequent full throttle hard left curves, it is recommended to not let the tank get under 1/4 remaining. (like if you have such a curve in your regular driving and could hit it at all sorts of fuel levels). The actual point of failure is somewhat lower than that, and a sudden starvation doesn't MEAN your engine will fail, but it's certainly possible. The OEM fuel pumps can start failing around 60,000 miles (for 2004-2008, the 2009-2012 should be better), though can certainly last far longer. Most fuel pump failures are due to overheating of the pump, and will suddenly stop pumping, which suddenly shuts off the engine inexplicably. Letting the car sit for a while and then restarting should get it started just fine as if nothing happened. If this happens to you, stay low load, low RPM and get it where you can park it for a fuel pump replacement. Going full throttle with a fuel pump failing is dangerous to your engine. I personally know someone who lost their engine to their fuel pump failure, but didn't know it. The dealer didn't know it either, put in a new engine, and while on the shakedown after installation, the fuel pump gave out again and destroyed that engine too.

- Cat failure (even more common than engine failure) causes localized heat and pressure buildup that overstresses the seals and breaks down oil viscosity, leading to various issues
I've covered the issues with cat failure, so this is largely a redundant point. If you can remove it, do it.

- Clogged oil injection lines prevent oil from being injected, leading to excessive apex seal wear and side seal overheating, leading to compression loss and/or catastrophic failure (depending on which fails first)
This is one of the 'silent killers'. The only real symptom of clogged oil injection lines is when oil consumption drops below the 1qt / 1,500miles rate. You can run seafoam through them using engine vacuum as a good cleaning method. There is no set recommendation on how often to do it, but the longer you go between oil changes, the more likely you are to need it more frequently. No shop or dealer will have any idea on how to do this, or even what you are talking about, so just do it yourself for free.

- Subpar reman engine quality, starting with low compression that accelerates any other issue (reman quality has improved over the years, but bad apples are still reported)
There isn't anything you can do about getting a reman engine that has poor seal clearances or overly worn parts. So, cross your fingers.



For a specific thread on further steps to take, read HiFlight's excellent thread: https://www.rx8club.com/tech-garage-...ries-i-190372/