ZDan

There are many well-cared-for 1970-'83 Datsun L6-engined cars still on the road today, some no doubt with more than twice the mileage of your 12a.

My anecdotal rotary experience: Bought pristine perfectly maintained (with all records) stock 1990 RX-7 convertible with 65k on the clock. Enjoyed the **** out of driving it on the street (had a 240Z as my track car), including semi-frequent runs to its 8k redline, which it loved to do. Eventually took it to an autoX at 103k on the clock. 2nd run, blew apex seals. And not a single rotor-head was remotely surprised...

None of my piston-engined cars (240z, E28 535i, S13 240SX, '95 Z28 M6, S14 240SX, '01 S2000, LS2 FD) has ever had any issues with engine internals simply failing for no good reason under 90/10 street/track usage, even at 240,000 miles on the clock.


Anyway, I *do* hope they make a new rotary, and I hope that reliability and longevity are greatly improved vs. previous production examples (FC, FD, and RX-8 versions, anyway). Would be nice to have a little better fuel efficiency too...

RotaryEvolution

iTrader: (30)

most 12a car owners manage 200k+, in one case i believe the engine made it to nearly 450k miles on the original engine and i don't believe that was the only one either.

https://www.rx7club.com/1st-generati...ge-12a-951574/

racing the engines destroyed them rather quickly with the 3mm old chrome housings, but if you took care of the car then the coolant seals didn't fail and the engines ran the chassis into the dirt.

the 12a was in fact the most reliable rotary engine ever built. you could find one in a wrecking yard and if it wasn't seized or had stuck seals you were usually rewarded with a decently running engine. most of the cars wound up there simply due to faulty fuel systems.

but with more horsepower comes less reliability. the renesis generates more pressure and heat so on a cold engine it has a much higher possibility of damaging the soft rubber seals separating everything. mazda did do the renesis right by moving the coolant seals back into the rotor housings but they did wrong by not limiting power more until the engine was fully warmed up or by not creating a limp mode when a temperature threshold was surpassed allowing the engine to run on 1 rotor to attempt to cool it off and alerting the driver to a major problem.

all of this was on the table, but they opted not to use it. it is still there in the ability to reflash the ECU as well, but still not utilized.

one of my previous customers has the highest mileage renesis which should be at close to 260k or above now, it is definitely a dog up to 3k due to the obvious lacking compression but strangely it has no starting issues many others run into with the same compression numbers.

ptrhahn

iTrader: (9)

Piston engined cars, especially high performance ones, break plenty, but you can't very well blame pistons for it.

They'll also almost certainly cost more to rebuild when they do—that's why I was saying, "motor rebuild" doesn't mean as much in rotary terms. If you blow $5000 on a new one every 50k miles, or $10k for a new piston motor every 100k miles, what's the difference?

RotaryEvolution

iTrader: (30)

if you're spending $10k for a rebuilt boinger you're probably wasting money.

in fact most cars i would simply go to the salvage yard and pick up another engine, knowing they come with some sort of replacement guarantee. even rotary engine builders often times can't warranty an engine for more than a year due to the simple inherent flaws in the original design.

there's always exceptions though, like a honda engine you could pick up for $300 and virtually know it's working. or spend $1500 on a used rotary engine and cross your fingers, or spend $3500 to have yours rebuilt and installed which is probably close to what a SBC would cost.

j9fd3s

iTrader: (3)

probably. an E46 M3 engine is 16K+core, RealOEM.com BMW E46 M3 Short Engine

the non M3 engine is $7500, reman

the 13B-MSP is $3500+core.

RotaryEvolution

iTrader: (30)

everyone knows germans are nuts! oh wait...

wstrohm

Yeah, it's tough, I know. 109K miles on our original (bought new) '94 FD and it still runs like new. But I have to put in about a pint of oil every 400 miles or so... tsk, tsk. Waiting for that catastrophic failure... it's so scary.

ZDan

WOW! 109k miles, for REALZ?! Holy crap, that's AMAZING! It is SO RARE for internal combustion engines to survive that long!

Congratulations!

fbse7en

You need to do some further research on what Mazda has done w/rotary reliability. They KNOW it is and have proven time and time again in their rotary powered race vehicles. You can NOT win endurance races w/o reliability. There's a reason they made a "Bathurst" edition FD.

arghx

iTrader: (3)

Mazda has done a great job with making reliable purpose built, high performance applications. The wide variety of conditions encountered by a mass market product hasn't been as successful, especially not since the FD and later.

t-von

iTrader: (8)

Yep the 3mm sealed 1st gens rotary's were the most reliable rotary's lasting well over 100k and even into the 200k zones. The secret was those big *** 3mm 2 piece apex seals. Sure they may have created more housing wear but the seals themselves took much longer to were down. Long term durability went out window the minute Mazda went to those damn 3 piece 2mm apex seals in the 2nd and 3rd gens. Sure the they seals better and had higher revving potential but, that damn thin top piece was too prone to carbon lock and breakage because they get thin like tooth picks. This is why if Mazda went 2mm 2piece ceramic in the next rotary, 200k + would be the norm (provided we don't have cooling seal problems).

ghost1000

iTrader: (1)

12a was king. My friends first gen gave out at 210,000 miles. I helped him swap the motor and then bought the car off him. I know of several first gens still running today in the 200k+ club.

I wish Mazda would go back that simple type of car.
They always had style and handling. Now it's time for power and reliability. I'm not sure what drives Mazda these days but can imagine engineers marketers and budgeters arguing about what the rx7 should be just like we do. The end result is a unreliable flawed over compromised sports car. I hope they get it right this time.

t-von

iTrader: (8)

See my above post about the 2nd gens.


I've actually owned 2 1st gens 12A's and 1 2nd gen. My 81 model blew because I warped the engine from over heating due to coolant loss. My 2nd 1 st gen died because of carbon lock from granny driving it all the time and the OMP rod lost attachment to the lever on the pump. So she wasn't getting enough lube from the OMP. Both of those 1st gen were well over 100k. It's funny because I bought my 91 convertible 2nd gen under the same conditions as yours. 65k but mine already had a rebuilt engine in it. That reman only lasted to 130k as the rear apex broke on startup from carbon build up. I reused the same housings and rebuilt it with RA 2 piece seals and put another 40k on it so far. Hell this past weekend I fired it up for the 1st time in 4 1/2 years and she started without a hitch. If I had rebuilt with stock 3 piece seals, she probably would have had a bad case of carbon lock. In the early 80's not too many piston engine vehicles lasted over 200k by comparison to the 1st gen rotary. As soon as Mazda put those 3 piece seals in the engine, long term reliability went to ****.



If they build that next rotary with ceramics, you will have that long term reliability.

RotaryEvolution

iTrader: (30)

they might have had their reasons due to their own research that we don't know about though. the ceramic seals might have been even more susceptible to carbon sticking than any other metallic seal alternatives.

i will admit i haven't seen any ceramic seal engines actually driven on the street with any regularity, or even that have seen well into the 100k figures to see what potential 'other' issues they might present. their light mass does have drawbacks we should consider and the fact that most people who have those engines built aren't driving them with the OMP system on busy city streets.

i'm sure they weighed it out but why they opted to not use them will probably always be a mystery to us.

RX7 RAGE

iTrader: (22)

Mazda RX-7 to return in 2016 | Autocar

HiWire

Pretty speculative, still. That Autocar sketch looks a bit like the Jaguar F-Type,

Thanks for the good news, though.

fmzambon

How exactly do they plan to improve the low end torque of the engine (as they stated some time ago) with a smaller displacement?

One thing is good though: if it were indeed a 1.2 NA engine with 250hp, it would FINALLY break the 200hp/liter barrier in NA form, as well as, most likely, break the 10000rpm barrier too.

Andrea.

Bwarrrrrp

By reducing weight...

If it's smart it may not need too.
I have to say though, without some confirmation I'm putting this firmly in the 'unlikely' box.

Bwarrrrrp

Dammit, can't edit now.
Firstly reducing weight goes a long way for everything. Driveability, fuel use, acceleration, braking etc. To use a piston analogy, they have made the engine very undersquare or stroked. This typically increases low speed torque but adversely affect high speed torque. It also greatly increases fuel burn/fuel energy efficiency. While it is obviously a rotating rotor, the same basic principles do apply because you can brake the rotor down into directional components. I wonder how they will have overcome the high rpm barrier of a wider reduced thickness rotor.

ZDan

I don't think that's an accurate comparison.
I've put over half a million miles on my piston-engined cars, most of which I've tracked regularly, and never had an unprovoked engine failure. I did run the Z low on oil at the track once, and wasn't running a proper baffled pan. That ended badly, spent ~$3200 on the rebuild (including some custom stuff like machining reliefs in the pistons and also a Nismo 8 quart pan with swinging plates). Then several years later one of the carburetor bolts backed off and i got an air leak and holed a couple of pistons, spent $1500 to fix that (other 4 cylinders were fine). Both of those were clearly owner/crew chief/operator (me/me/me) error, and didn't cost anything like $10k to set right.
For the record, the 240Z was by far my most tracked car (~150 track days), and while it a street car, it's pretty "high-performance". 3.1 liter, 11.5:1 CR, 3x2 45mm carbs, 255rwhp at 6500rpm, rev limit 7200. I should never have traded it for the FD, I should have scraped together more $$$ and kept it :cry:

Absent any neglect, the piston engines I've owned are known to last pretty much for fooking EVER. Meanwhile the rotary I owned (not tracked, only autoXed once) died for no external cause at 103k and not even the most diehard rotory-fans (of which I am one!) or apologists finds that unusual or remarkable. Because it wasn't. They just don't last.

12A might be a different story, but doesn't exactly have the beans to pull the skin off a grape, either...

But *anyway*, here's hoping for a new improved rotary-engined RX7! And a piston-engine MX-7 variant. But also a rotary RX-5. I'd like to see all of those

fmzambon

You mean that making the engine internals lighter will increase torque? I doubt it works that way, at least not directly. It's like changing the flywheel weight, it affects how quickly the engine changes speed, but the torque at constant speed remains the same.

However, if the smaller rotor weight was used to reduce clearances around the rotors (less leakage, thus better compression), then that could make a difference as far as torque and fuel economy is concerned.

I wonder if Mazda would consider using aluminium rotors, like they already did years ago for the HE-10X and HE-13X experimental engines: link

Just to be precise, are you referring to the whole article or just to that portion about the 1.2 liter displacement and 250hp?

Andrea.

Bwarrrrrp

No, I meant reducing the weight of the car will increase the usable torque of the engine. So instead of needing 100Nm to start moving it will now only need 80 (random figures) - leaves more usable torque to accelerate.

Reducing reciprocating weight doesn't increase torque directly, but it does reduce inertia, which increases the torque output (less force for engine to overcome = more force to wheels) and also allows for higher engine speeds - more power.
I would be certain they considered it, whether it was implemented is another thing. Also makes me wonder if they tried the AL housings that are used in aero industry.

Yup.

RCCAZ 1

iTrader: (10)

I had heard that Mazda was looking at changing the shape of the trochoid to improve torque. Possibly a narrower, but slightly taller rotor? I sure hope they improve on the design shown in Autocar. It's marginal in my mind. I'm liking the more aggressive look of the next Gen Miata at this point, but again, I'm sure this is just a very early conceptual sketch. Fingers crossed that they actually build it, and again, please oh PLEASE Mazda. You can make it standard 2 rotor NA, but please give us a large enough engine bay to shoe-horn in that 3 rotor option

fmzambon

Sure, improvements in the combustion chamber geometry can help with torque, but if the starting displacement gets lower, the engineers will have to work hard just to retain the same torque that was available before, let alone improve it.

If this 600cc per-rotor displacement is true, I really hope it's because they are planning a three rotor as well, which would be too large with the 16Xs 800cc per rotor.

Andrea.

Bwarrrrrp

No disrespect intended, you don't seem to have a good grasp of fundamental engine knowledge. There are several ways to skin a cat. Engineers know this, Mazda know this. Consider just how far outputs of piston engines have come in the last 15 years. Flywheel power of 250 hp compared to 240 for the reny is very much within reach.