Hi there,
I would know if low-temperature is so critical for the Renesis engine, and also if a start and early stop of engine would blow it, like a older rotary's owner told me.

Thanks,

*Rotary_italia*

 

(i tried to simplify my english as best i could)

...do you mean to ask if the RENESIS is easily broken by heat?

no, the new rotary engine is much less sensitive to engine heat than the last rotary, the 13B-REW, as there are many less parts (hoses, huge iron manifolds, no turbos at all) which are fairly heat sensitive, with the hoses the easiest to have break.

there are many old RX-7 owners who have non-turbo engines, and put many many hundred-thousand kilometres on them without rebuilding the engines.

 

there was something posted from one the car owners in japan(i think from the manual) about not turning it off right after it was started. it was something like "if you start the car and pull it out of the garage (for washing or other maintenance) bring the engine speed up to "xxx" rpms for a minute then let it run for 5 minutes before shutting it off"

i'll see if i can find the actual post but that is fairly close (at least in my memory) if someone were to find it before me i would not take offense. *GLARE*

 

Zoom,

I recall that as well, can't remember if it was in a thread itself. Or the thread made mention that the phrase existed in the hard cover book or some other written publication..

 

ah here it is it's from the internal sales/walk around guide posted the other day. here is the pertinent paragraph

"Rotary Engine
The rotary engine in the RX-8 requires premium unleaded fuel with an octane rating of 91 or above. It is normal for rotary engines to consume a small amount of engine oil to lubricate internal engine components. Drivers should use the oil dipstick to inspect the oil level when refueling.
During short periods of cold engine driving (such as backing the RX-8 out of a garage to wash it in a driveway) drivers should use the following procedure to help keep the spark plugs from fouling or the rotary engine from running rough:
-Turn the ignition switch to the START position and hold (up to 10 seconds at a time) until the engine starts.
-After starting the engine, let it idle for about 10 seconds, then move the vehicle.
-After moving the vehicle, let the engine idle for about 5 minutes.
-Rev the engine to 3000 rpm, and then let it return to idle.
-Turn the ignition switch to the OFF position.

For additional details and warnings, refer to the 2004 Mazda RX-8 Owner's Manual."

so that is about running a cold engine which addresses Rotary Italia's question
but is not about how the engine handles heat. i believe 'keech got it right though.

 

huzzah. good 'un.

 

The design of the rotary makes it inherently easy to flood. Because of this, repeated cold starts and shutdowns can cause the motor to be hard to start, or even worse, carbon lock. It's a piece of common sense in the rotary community that if you start your RX, let it warm up before you shut it off.

Another thing to consider is that the rotary is a sandwich of Iron and Aluminum. These metals expand at different temperatures, so when the motor is cold, any high load conditions could warp the housings over time. Therefore, you should never rev a rotary past ~3,000 before it has warmed up, nor should you take it out on the highway before it has reached operating temperature.

 

I live 30 seconds from the 4-lane highway I take to my workplace 40 miles away.

Are you saying I am going to cause problems with the RENESIS ?

 

it doesn't take long to get warmed up, just go for a fun spin around the block before heading to work
...also, unless you're a real banzai merger (i usually make a point of gradually building speed coming onto and through the onramp, not just in the merge lane like most SUV retards 'round here) the stress on the engine at a nice steady cruise is very very little.

 

This may be well known in the "rotary community" but I don't think Mazda can rely on that for a brand new mainstream product like this. With the volumes Mazda are planning most buyers will not be rotary enthusiasts, just people who want a stylish, fun to drive coupe, which they will expect to be totally reliable and bulletproof because it's Japanese.

If they are deluged by warranty claims from people not following the procedure then their (and the rotary's) reputation will be mud, and Mazda can't afford that to happen. I suspect they are just being ultra-cautious in giving out this advice (I hope for their sakes they are - they must understand that most new car buyers never read the manual).

 

Tell me about it. Of course I had only two car in my life(going thru second car). When I was a little kid I would always read the manuals for my parents cars. Always the same type of info. So when I got my new car(second car) I didn't bother reading the manual till way later(when I was bored). And thats when I learned my car had less hp than I speculated. Imagine my dismay. What it only has 106hp and I thought it had 110 hp. lol

 

Almost every vehicle owner's manual I have ever seen (rotary AND piston) cautions to use low engine speeds while the engine is still cold. This is NOT unique to the rotary.

As far as a new car buyer never reading the manual - that is just plain ignorant. My wife has never read the manual for her Santa Fe, but I did and briefed her on the pertinent info. Usually I have to read the manual just to figure out how to set the clock on the stereo!

 

Of course it isn't. I was refering to the very specific advice about not running the engine for short periods and then switching it off before it has time to warm up. I have not seen that before in an owners manual.
I'm not trying to imply that people don't read any of the manual or don't refer to it from time to time when they need some information. Just that a lot of people don't sit down and read it through from cover to cover and many people would miss the warning.

 

I have a 1985 RX-7 GSL_SE with the 13B engine. I was never told about the warm up requirement. I found out the hard way 2 times..It floods and is a real hassle to unflood it. Now I ALWAYS go around a few blocks whenever I have to move it and it is cold...

"no do that again!!!

 

Oops...sorry bout that - must have been late and past my bedtime. Obviously you quoted exactly to what you were referring.

Of course, you are right that many people don't read it from cover to cover, but it is very silly to pay $30K for something and not read the instructions. :p

 

I owned a 1984 1st gen with the 12A engine and it never flooded. This is the first time I hear about the rotarys beign prone to flooding.

 

It effected the fuel injected 13B the ones with carbs did not have this flooding

 

Renesis and all wankel, other rotary's are reliable. The only with reliable problems are ones with stock twin turbo's. The ones that are N/A are like bullets. I hope they make a single turbo for renesis that is reliable.

 

Well, here I am. My very first post to this forum. As my name suggests, I'm thinking about the 8 and questions like this loom large in my decision. Is Mazda just being overly cautious with guidance like this, or is it a no-bull requirement to run the engine 5 minutes after backing out of the garage? For non-rotary enthusiasts, we like the concept of the RX-8 but we want something reasonably practical, not tempermental.

 

hey wannabe, welcome.

letting your car warm up before you shut it off isn't big news for me, i do that even with my Toyota 1.6L... it might even be recommended.
i think that with this sort of "disclaimer", it may in fact just be Mazda being extra-extra carful with the flooding issue (was only a problem in fuel injected 13B's with leaky injectors) so that there aren't any warranty claims or stupid-owner complaints... they can then just say "i told you so".. it's not as if whenever you shut off your car, warmed up or not, there's going to be a chance that it'll flood, this is just being extra careful when it's a cold start/shut-down.

 

With the rotary's spark plug outside of the combustion chamber in a chamber/cavity that is viewable from inside the combustion chamber, the design is vulnerable to the contemporary fuel delivery system leading to a wet condition of the spark plug -- fouling of the spark plug and eventually flooding. (A more detailed explanation upon request)

The rotary lends itself to dry fuel (vapor), the true condition of fuel for the ICE (Internal Combustion Engine); not the contemporary one used.

With the use of some aftermarket products, flooding can be reduced and eliminated altogether.

The fault will fall on the one who doesn't adhere to warnings and through ignorance and/or stupidity disregards reading the recommendations. Yes this doesn't help Mazda in sales, but it's a numbers game, and ingnorance outnumbers intelligence vastly.

Peace
marcus

 

kidmarc, could you explain more about these aftermarket products? I'm pretty ignorant about this whole area of flooding rotaries and want to learn more. Thanks.

 

I have an aftermarket device in my RX-7 that delays the fuel pump by a couple of seconds when I start the car. By doing so, it burns all of the leftover fuel inside the motor ... if it's flooded. If you start it without gas pedal input, it takes about 3-4 seconds to start it. But over the years I've figured out the technique to start it with a few turns of the motor. (ON position, depress gas twice, start with gas around 1/2 throttle)

Unfortunately, the shop that carries this item is no longer in business. I don't think it's really necessary, though. Just don't run the motor for anything less than a minute. For example if you want to wash your car in your driveway, just put it in neutral and push the car out. Anyways it's better for any motor not to suffer through short running times.

 

To start, I will give you some background...

From inside the combustion chamber, the spark plug is behind a hole. This is equivalent to looking at a peephole or keyhole in a door. Under the compression stroke, the fuel is pressed into the hole where it is ignited by the spark plug. Now imagine spraying a mist into a hole and waiting for it to dry... then spray again and so on... Because the hole is on the side and not the top, it is easier for the area to become 'wet' (drainage problem). The reason for the ignition/combustion area becoming 'wet' is the improper use of fuel. Gasoline does not burn; gas does (vapor).

The ICE uses vapor and air to run. Due to convenience of storage and subsequently other reasons, gasoline is used. Gasoline is injected into the combustion chamber and evaporation is used to start the initial burn. Afterwards, the remaining gasoline evaporates from the heat of the initial/primary explosion. However, the time it takes to convert a liquid to a vapor and then burn is 25 - 50+ milliseconds while the combustion to exhause cycle is under 10 milliseconds. This results in a burning of exhaust valves. Yes the rotary has no valves but it does use the same fuel delivery system.

The common solution is to quench the burn by adding additional fuel. This smothers the flame. The system also adds excessive fuel on start-up in order to get enough vapors to burn. So you have fuel on start-up, excessive fuel to prime for start-up, and excessive fuel to quench. If one doesn't get you the other one can/will.

A counter to the problem, Mazda introduced ultra-fine injectors which also betters the fuel economy. Great idea... it's just the wrong direction. Vapor fuel would be better.

Another method is to warm the engine. To increase the efficiency of this, there are products that better the cooling by displacing the heat evenly. One solution you change the entire cooling system. The other uses the existing one. To increase the latter, you use CAW in the water of the 50/50 water-to-coolant mixture. Use the clear; not the dark.

The other method is in the ignition system. Nology uses capacitor wires. This has been argued against by Magnecor. Yet there is an alternative. The alternative does produce some for Rx-7's.

Lastly, you could build an enhancement in the vapor and hydrogen arena. However, this may void warranties.

Peace
marcus

 

The SmartPlugs are spark plugs without a spark -- a self-generating flame front that resolves many problems including lean burn.

Although not ready for prime time, I am posting it as information; a reason for a large spark.

Peace
marcus