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I do not have drag racing experience. My RX-7 was used for daily driving and occasional autocrossing. My RX-7 went through two engines, all in a span of less than 125,000 miles. Both of the instances came from detonation. It ran a single turbo configuration at an extremely conservative 10psi, with the correct fuel mixtures, and upgraded cooling systems.
I think in a non-turbo aspect 2mm seals are perfect and know people that got 150,000+ miles out of even 12A's. But when it comes to reliability matched with turbo's my experiences have been frustrating.
I would be very interested in hearing what companies seals you are using in your drag car. Also, I suppose there is no word as to the possible upgrade to 3mm's.
If the engine was suffering from detonation then it was obviously not tuned properly. And in any case, be they 2mm or 3mm seals detonation will break both of them.
The 2mm seals we use are factory Mazda, nothing special there. We have also used these seals in circuit racing applications with no dramas at all.
In the drag car we are running a MoTeC and know that it is tuned nice and safe so no detonation occurs at all.
In an RX-4 street car we built, using a std compression (9.4:1) RX-4 engine, running 18psi on 96 octane unleaded we were making 430+hp and the car ran 10.91@124.8mph over the 1/4 on M&H street tyres, full exhaust, driven to and from the track. We never had any dramas with apex seals or anything else, but once again we know the car was tuned properly.
Many people over hear have found that the 2mm apex seals are definitely easier on the rotor housings, and seal better than the 3mm seals, and with correct tuning reliability is not an issue.
Aside from detonation, what you have told me is contrary to what I have generally been told here in the US. It has almost always been insisted to me that 3mm's are the only way to go.
I'm not sure of the popularity of rotaries in Australia, but I have heard they are more a cult classic there than here. Here I have found a strong follwing, but they are more a myth to the general public with good potential but no reliability. Unfortunately the problem I have found, which you have properly placed, is finding reliable mechanics.
I know of several good mechanics in the country, but have not discovered any in Florida outside of Petit and SAS, which are both a five hour drive away. As for the Mazda dealer mechanics, I would be better to let a problem continue than take it to them for help.
I'm fiercely loyal to rotaries and Mazda, but having grown-up with Corvettes I find myself wavering between a Z06 and RX-8. Though if I bought a vette, I would kick myself everytime I saw a rotary powered car on the road.
I think a lot of so called "experts" insist on going 3mm because they cannot tune the engines properly and so want every measure to ensure that it will last a bit longer.
I think for our small population, we probably have some of the quickest rotaries in the world. Our top 10 Pro Street Rotaries are running in the 7-8 second zone.
After playing on the dyno with a few big hp engines, it is essential to have a good ECU. We only use MoTeC as it is so adjustable and has all of the nice features which allow us to get the most from the engines and make them live.
The biggest enemy for the engine is detonation cause by either too much advance, running the engine lean, high air intake temps or even the engine temperature getting too hot.
Whils it might cost a few hp, running the engine a little richer than normal at big boost and backing off the timing does wonders for engine life.
What about the reliability of this new RENESIS engine? No turbo, so it should have way less issues. I'm contemplating purchasing a new RX-8 or a RSX type r (provided they even ship it to the U.S.). The only resevation I have with RX-8 is its reliability when compared to an Acura/Honda model. In theory, with only 3 moving parts the rotary should be one of the most reliable engines made, but I don't honestly know. I am very new to rotaries and am interested in hearing anybody who has experience/knowledge on the reliability of NA rotaries and how the new RENESIS will compare. I know the basics: moved exhaust ports for greater efficiency/power.
I would also like to know the possible potential for for modding the rotary if it was kept NA.
I have known people that have clocked over 150,000+ miles on first generation 12A engines. The Renesis can only be better.
I have a friend that drove a modified Integra R, and even with thousands of dollars in modifications, his car was not as fast as my RX-7 before I started modifying it. If you have never driven a rotary, I like any other owner, can tell you that nothing drives as smooth, and with as much power as a Rotary. The only car I have driven that even comes close is the newest M3.
If you were considering a high torque car like the vette, it would be down to what kind of power delivery you like in a car. In power band terms the RX-8 should feel like the RSX but much more explosive. And as Dazz stated, if you can find someone that is competent, the potential of a rotary can't be matched by anything Honda/Acura builds.
For 3rd gen rebuilds, its a whole different ballgame, depending on turbo psi and octane intended to run. Ceramic 3mm seals are great insurance, although as posted, hard on rotor housings.
Originally posted by rxtreme What about the reliability of this new RENESIS engine? No turbo, so it should have way less issues. I'm contemplating purchasing a new RX-8 or a RSX type r (provided they even ship it to the U.S.). The only resevation I have with RX-8 is its reliability when compared to an Acura/Honda model. In theory, with only 3 moving parts the rotary should be one of the most reliable engines made, but I don't honestly know. I am very new to rotaries and am interested in hearing anybody who has experience/knowledge on the reliability of NA rotaries and how the new RENESIS will compare. I know the basics: moved exhaust ports for greater efficiency/power.
I would also like to know the possible potential for for modding the rotary if it was kept NA.
well I recently read an articulie (can't spell-brain fart) in my local news paper that was entited "For Love Of the RX-7" it was a good piece on it about how this guy came down looking for a car found an RX-7 for sale in the paper (an 83 not sure what model) that had 245,000 miles on it with no rebuilds or inturnal replacment!!!! ( no apex seals, no seals added over time)
now when he sold it it was mearly because he was getting a new caddy and diddn't have space for it. but it said when he sold it he nearly broke down and cried (poor old guy said he was like 76) he patted the hood and said good bye old friend and the guy that bought it submitted the story to the paper.
good story too.
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Why do I need a signature!!? just so that I can babble on about crap not many people care about.
readers of this you are now under the dreded "Eternal Bunny curse" you will become furry and bushy tailed in areas I'm not going to mention. ( Mu-ha-ha-ha)
The reason for keeping the 2mm in the new engine is because it'll be running at a higher rpm range then the previous rotary engines. At higher rpms rotary apex seals have a greater tendency to "chatter" therefore the 3mm seals will be heavier and have more tendency to "chatter" at high rpms then the 2mm seal.
There is another reason why apex seal life should be greater in the new engine. In the older engines the apex seal passed over the exhaust port and at high rpm there is a minute amount of flexing as the apex seal is unsupported in the middle.
With the new side exhaust ports the apex seal is fully supported and this should contribute to increased sealing and reliability.
I was 20 in 1992 when I bought my first RX7. It was a 1981 Sunbeam Silver beauty with 200,000 miles on it. The guy I bought it from was the first owner of this car, an older gentleman recently retired who had kept all the maintanance records. He really didn't want to part with it, but his wife somehow had convinced him otherwise and so there we were. He gave me some backround on the car besides the records. Outside of changing the fluids,spark plugs and cables the car was stock. This was his baby, he drove it everywhere. He told me it was the best car he had ever driven and the best car he would ever own. Seeing the pain in his eyes as I gave him the money, I almost didn't want to take the car, but I figured if it was going to be sold I'd want it to go to someone who would take care of it and I planned on doing just that. With his wife looking over his shoulder he reluctantly took the money and parted with his longtime friend.
The car had been sitting a month by the time I first saw it but honestly you really couldn't tell. Over the next few years I drove this car quite a bit and was constantly amazed by it's durabilityhandling and it's engineering. By the time I swapped the engine out it had 275,216 miles on it. The engine was not dead however. On one of my trips to the junkyard I had come across a 1982 RX7 with only 40,000 miles on it and decided it would be a fun project to swap out the engine in my yard. So on the morning of the expected engine delivery I proceeded to do some prep work on the car such as removing the exaust and radiator etc. By that night I was able to hear the new engine run in it's new home. Looking back at it now I wish I had left the original engine in to see how far it would go, despite the noticeble power increase with the new engine. Well to make a real long(sorry readers) story shorter, after a few weeks I started a new project, taking the old engine apart. When I was done I decided that I would display one rotor in my living room, the other I would give back to the man who sold me the car. So about four years after I bought it I headed back to his place of buisiness were I first layed eyes on my car. After a little catching up with the car's previous owner I presented him with his gift. He was very gratefull to say the least. A few years later I was starting a family and gave the RX to my younger brother who drove it a few more years before retiring it to the junkyard, the New England winters had secured it's destiny and final resting place. That original rotor still sits on my desk at work these ten years later to remind me of the best car I had ever driven and the best I ever owned, unless the RX8 proves otherwise.
About the 2 mm vs. 3 mm apex seal controversy, two quick points:
1. Technical papers have shown that thinner apex seals seal better because, roughly speaking, they don't "bounce" or "stick" as much as thicker seals. I could cite several papers, but that would be overkill.
2. Racing Beat, which has been involved with Mazda rotaries since Mazda came to the US and has long offered competition parts and service, does not recommend changing 2 mm seals to 3 mm. They should know. See their technical manual. Certain rebuilders advocate changing the seals, but many (not all) have a poor reputation in the field for building rotaries that last just until the warranty period expires.
Hopefully the Renesis will be packing 1mm seals. That'll help high rpm performance even more and cut down the seal friction, which is the greatest source of frictional power loss in a rotary engine.
I think in a non-turbo aspect 2mm seals are perfect and know people that got 150,000+ miles out of even 12A's. But when it comes to reliability matched with turbo's my experiences have been frustrating.
What do you mean 150,000 miles out of even 12A's? Its been my experience that 12A's(in the 1st gen RX-7) are one of the toughest rotarys ever made. I know of 4 cars, all owned by 1 guy(both of his son each drive one, his wife drives one, and he drives one) and he has 250k+ on each of them, all original, never rebuilt. And almost 400,000 miles on another(just about needs a rebuild now). People really don't realise what exactly one of these can do if you can take care of them.
My point was to show that in the 25 or so years since the 12A RX-7, Mazda R&D could only have improved on the design. I think the FD RX-7 has put a bad taste in the public's mouth over rotarys.
In addition, most people are simply not willing to take care of rotarys, don't know how or can't always find skilled mechanics.
But I think it's great to hear accounts like yours, or from others on this thread, that dispells the reliability myths that have recently surrounded RX-7's.
Perhaps someone on here can post a list of tips for looking after your rotary... beyond keeping it well serviced etc...
People have suggested mixing oil with the fuel and some other things... but I'm not sure what the truth is, so I would probably just follow the servicing schedule and keep it fed and watered etc!
Anyone got any links, tips, suggestions or comments?
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"Who is Seg Fault and what is he doing with Kernel Space?"
BlueAdept,
Two very simple rules for keeping your rotory engine alive:
1.) Never ignore an oil leak, fix it immediately.
2.) Never, ever, ever let it overheat.
While obviously there is much more involved in proper maintanence, these were the two most important lessons I learned way back on my '85. :-( I miss her so.....
-Mike
Apex Seals
Linear Mode
