Tatsu

So I've owned my RX8 about a month now and it's been a blast to drive. Well, except the first couple weeks when I was still learning manual transmission and I found myself stopped on hills with the lovely Florida tailgaters behind me.

Anyway, before I develop any bad habits, I was wondering where most of you shift to keep your cars running healthy. I've been told that shifting too low produces more carbon buildup and should be avoided, but what is too low for rotary?

Researching carbon buildup it I've read that the main ways to prevent it are:

• Premium Gas
• Cleaner before every oil change
• Redline often
• Premix

How important is premixing? And as far as redlining goes, I've heard to do it in neutral and do it in 3rd, is either more beneficial? Is 7k enough or should it be higher?

I lucked out on this car not having any problems at purchase, and I really don't want to create any for it now. I tried finding these answers but the most I could find was the generic "redline it often" or "premix" without much detail about either. I've never premixed before so I'm a bit hesitant to start if it's not really important.

Legot

iTrader: (1)

Isn't premium gas a cause of higher carbon buildup? It's only required on the Renesis to help prevent detonation due to higher compression ratios, on older rotaries it was specifically not recommended to use higher octane rated fuels.

By cleaner do you mean seafoam? Because there's allot of discussion on it, and I think the most accurate consensus is that it doesn't do much unless you substitute it for water and use several gallons. It doesn't have anything to do with oil changes, since none of the oil in the combustion chamber ever goes back into the system. As for premixing, there's a thread that's a couple hundred pages long about it. In summary 4-12oz per tank is good, and TWC-3 is useless.

Redlining will do virtually nothing in neutral. The idea behind it relies on heat and pressure to temporarily loosen the carbon so it can be scraped away more easily by the keystone. In neutral, there's not much load to build up pressure/heat, but in 3rd it might be difficult to reach the redline. I tend to do it in first (for fun) on surface streets whenever I feel like it, and from 1st through 3rd (focusing on 2nd) when merging onto a highway.

If you shift fast enough and your tires are terrible enough, you can even get your wheels to spin going from 1st to 2nd and 2nd to 3rd at redline

logalinipoo

If your going to redline for engine benefits then do it in gear to get the load high and a surge of oil injection. I do it 5-10 times a day fir the fun if it. Never premix and my first engine lasted 138k. It died due to neglect of cooling equipment.

Tatsu

Thanks for the replies. I'm not too knowledgeable about cars yet, only owned an old civic before this.

I had not heard about premium gas being a cause of higher carbon buildup, but having a Renesis I guess it's a risk we have to take? I've been putting in 93 since I bought it.

I did read about seafoam cleaner a bit, but what I saw a lot was just regular fuel injector cleaner I think. I'm not sure if there's a difference but they were talked about as if there were.

Thanks for the tips on when to redline. I saw videos on youtube of people doing it in neutral, but on rx7 forums they said to do it in gear. I'll try to keep in mind to hit it in the lower gears every now and then.

Kind of relieved to hear your engine lasted that long without premix. I'm afraid to start in fear of messing it up somehow, but my engine only has 40k at the moment so it should hopefully stay with me for a bit. Luckily Pettit is not far away if anything ever does happen to it.

RIWWP

iTrader: (2)

NO, there is just as much carbon in gasoline regardless of the octane rating, and it burns just as inefficiently regardless of the octane rating.


Yes, seafoam is primarily marketed as a fuel injector cleaner. Using seafoam in the gas tank (as it was originally designed) is far more effective in carbon removal than letting the engine soak in it, and possibly more effective than even ingesting it. Seafoam requires heat and/or pressure to strip carbon effectively.

The people on youtube are just as clueless as you might expect. "Look at me! I'm doing it wrong because I have no idea what is important and what matters!"

More lubrication won't mess up the engine. It won't replace worn metal, but it won't mess anything up and could help it. And it's something that you can test a tank of gas at a time. Or even less. Like add 3oz to a gas tank 1/3rd full and see if you don't like what you feel. If you don't, fill up the rest of the way with premium and it will be gone by the time you have to fill up again.

BigCajun

iTrader: (1)

Welcome, I've been premixing for over 1 1/2 years with mine, about 18k miles so far, nothing apparent so far.
I think it may have contributed to some abnormal deposits on my plugs, but I wouldn't know for sure since it was only the second set & the ones from the previous owner were carboned over with only 18k on an 04 in 8 years.
I've put about that much on mine in 2 years of enthusiastic driving, redlining often.
Performance wise it runs great.
I use Lucas semi-synthetic 2 stroke oil from O'Reilly's, about $10 a qt.
It's also a good idea to change oil frequently, every 3k at least since all that redlining and heat breaks the oil down faster than most engines.

RIWWP

iTrader: (2)

BC, the limited mileage you put on it probably contributes. You shouldn't let premix sit in the gas tank, or it will start separating, and I think it settles to the bottom. Averaging 1,000 miles a month might be too little to premix on full tanks of gas.

That being said, changing plugs every 10-15k is something a lot of people subscribe to, because our engines are so filthy.

BigCajun

iTrader: (1)

Yeah, I fill up about every 4 days when I get to a 1/4 tank.
It's not so much the # of miles, but the manner of driving I do equates to about 14 mpg.
20 mile (*edit; one way, 40 miles round trip), commute of mostly open interstate highway 5 days a week & some joy riding on the weekend's, it doesn't sit for long in my tank.
It also sat for about 3 months the 1st winter I had it, so my actual average mileage is down a little in that time.
I admit I was surprised at the condition of the plugs, it's good to know it's normal.

niteshade247

I premix every tank with the exception of a oil change tank and that's because I load up on tecron fuel system cleaner but go back to premix when the tank is done. 145k miles and going strong. I don't red line it as hitting red line can cause the rotors to slap the sides of the engine if porly balanced instead I take it to about 7-8k RPM rotors can slap the sides from what I've read at around 8500RPM. keep your cooling system in good working order, change oil regularly, keep your ignition system healthy, use some fuel system cleaner on regular intervals and of corse run RPMs high when you can and you should get the max life out of your engine.

BigCajun

iTrader: (1)

I've not heard that.
While it's hard to argue with your results, it seems to be contrary to popular belief here.
Do you have a link pertaining to this issue?
Thanks.

Legot

iTrader: (1)

I think that was true for previous rotaries, but the modern eccentric shaft of the Renesis is stiff enough that it won't happen until above 13k.

gwilliams6

I have premixed on all seven of my rotary cars over 42 years, and never had an rotary engine failure in easily over a million rotary miles on street and track. The added lubrication of premix I am convinced contributed to the longevity of my rotary engines. There is large debate here on this matter, but for me the proof has been shown over four decades.

niteshade247

Engine Balancing - We strongly recommend balancing the rotating assembly if you intend your race engine to run above 8,500 RPM or if the engine is a non-standard assembly. The rotating assembly includes both rotors, main pulley, front and rear counterweights, and the eccentric shaft. We also recommend balancing the pressure plate and the flywheel on the rotating assembly.
In our experience it is not necessary to re-balance a stock or mildly modified engine operating below 8,500 RPM if the rotating parts were originally intended by Mazda to be used together.


Race clearancing of engine rotors is recommended when operating at or above 8,500 RPM. The clearancing machining process removes material from both sides of the rotor to minimize the likelihood of contact with the side housings in high horsepower, high RPM engines (see Internal Engine Tips). The weight of the rotor is only slightly changed. Please note: Rotor bearings must be installed before clearancing.


All pulled from racing beat but a quick google on rx8 club rotor hitting housing will give you days of reading. Yes it is more unlikely in the rx8 but in a engine with good miles on it things wear giveing more play and uping the chances. This is more true for racing purposes as you hold it longer at these RPMs but it's still a possibility and personally I'd rather not take the chance and rarely run it higher than 8k RPM.

Legot

iTrader: (1)

Nether of the things we're going into need to be understood by a new owner. You don't need to worry about smacking rotors unless you're keeping your engine at very high rpms for minutes at a time (under load), if you hear them there's a problem, if you can't then red line away. Don't be paranoid, it's a waste of time.

Premixing is an option. A fact is that it's not as beneficial to the Renesis as it was in previous rotories due to significant design changes, but if you feel like it it is something you can do. It might help things, it might not. In my experience old people are the least reliable source of information anyway, lol.

Khurram

As mentioned above just stay on top of regular maintenance such as; oil change, air filter clean up/replacing, ignitions parts, cooling system is very crucial, also change your tranny and differential fluids. Redline every once in a while, I like to hit 8k a few times each time I drive.

I have never premixed and my motor is at 260k kms however, I don't see premixing causing any harm if anything it would only provide more lubrication.

I'd say don't be paranoid, just drive her the way she is meant to be driven, have fun and keep up with maintenance.

Read the new potential owner sticky by RIWWP its an awesome guide.

Cheers

Loki

iTrader: (1)

For chamber pressure and temperature (which is the thing that burns off carbon), the difference between 8500 and 9000 is negligible. So if you feel safer going to 8500 than 9000, I'm sure it's fine. What you want is a sustained high load condition, so a 1st gear pull to redline should not be as effective as a 3rd gear pull -- but I obviously don't have a lab to test this stuff in. So if you feel safer revving to 8500, it's fine.

The Star Mazda cars rev to 8500 for what its worth.

RIWWP

iTrader: (2)

Don't worry about rotor tips hitting the housings.

1) Your tach isn't accurate. 9,000rpm indicated is more like 8,500

2) The "redline" starts before 9,000rpm indicated

3) The beep starts at about 8,000rpm actual.

Just shift at the beep under full throttle, it's not hard to do, and it's not a scary problem unless you start messing with the ECU parameters about the rev limit.

archwisp

iTrader: (1)

Nobody mentioned this and you see a bunch of people doing it on youtube but *do not* redline your engine while sitting still or in neutral - under no load.

It may be playing it safe but it's not difficult to do it in gear.

BigCajun

iTrader: (1)

Not as much fun either.

Tatsu

Thanks to everyone that replied. I hate asking questions that have probably been asked before but after hours of reading stuff and not being able to come to conclusions myself on a few things I just had to.

I would probably fall into that category myself. I'll have to dig into the premix topic more before I do anything.

I have Maztech here in Tampa that I plan to take my car to. Already been once to replace ignition parts and such and it seemed like a good place.

How long should it be sustained?

I've never heard the beep so I guess I've never been close to high enough. I know I was in the 8s a few times. Pretty sure the car's ECU is normal since Mazda didn't complain when I took it in for inspection/recalls.

Legot

iTrader: (1)

You're overthinking the redlining. Just go until you hear the beep once or twice a day. If you miss a day of doing it it doesn't matter that much. It isn't a science, just do it when convenient/fun. What is being said is that neutral and first gear don't do as much as 2nd to 6th. Carbon doesn't build up quickly, it's just much easier to keep the rather small amounts that build up through the day away compared to removing a month or years worth.

I very rarely redline in 3rd actually, because it would take going above 80mph (a personal speed limit on most days).

BigCajun

iTrader: (1)

That's another of "The Little Things" about my 8;
80 feels like 55, 55 feels like 40.