How long will a 12A engine last?
 

QUOTE by rxrotary2_7 Super Moderator on 3rd gen forum

"just hit 50k on my fd and i am on motor #5 still. i dont feel a number #6 comming on for about another week or so. "

ANOTHER FD QUOTE

" I always keep $4000 saved just in case I have to get a new engine. I've already spent over 12K in mods and engine work and I still need to spend another 3K to get what I want.


Having read the above quotes on the gen 3 thread about the reliability of the FD engine, what life should you expect from a 12A?

I think the gen1 response would be " I always keep $400 saved just in case I need a parts car.

Well, all I can say is that mine is past 190,000 miles and showing no signs of age (knock on wood)...:)

133,000 for me

I'm sorry but if after motor number 2 you can't get it tuned right maybe you aught to let someone do it that knows how to. It seems that alot of the problems come from user error not component failure.

106k on original engine

I have had them fail in the 120 - 180 range.

210,000 and running strong, just adjusted my timing and am replacing exauhst tomorrow. 125psi on each face last test, which was about 4 months ago.

292556 miles. Running great. Take care of them and they will last

145,000 in 12A . . one rear face a tick low on compression (still in spec and same since 1988) tracked since 1984

51,000 on 13BTT ... 25% track use .. last five years 80% track use

and both orgininal and still ticking

all mine died at 140 or less. But I was a careless kid back then and never really took care of them. I've seen these cars run over 200 if maintained properly. I just bought one with 131k on the clock and its got a strong engine.

I'm 230.000 miles on OEM engine, runs strong no smoke. it's not about how much money one dumps into the car/engine. it's all about common sense. it would seem that if one mods. the living crap out of the 12a or expects alot more out of it will be let down. Spin the engine up from time to time, they like that and every once in awhile give it some MMO in the fuel. i run 20-50 oil because of the high milage.

149,000 on the original engine. Then rebuilt and streetported, lasted 10,000. Rebuilt again, now going on 250 miles.

120k on the 83 I bought new, I'm the only one who's driven it and it's the smoothest strongest 12A I've ever seen. At idle you can barely detect that it's running.

70k on the 85 I bought 3 yrs ago with 49k is pretty good but not as smooth as the 83.

85SE is strong with 120k but needs the water seal treatment.

74REPU has 120k with 25k on new engine (I was told), stronger than hell.

I put about 8-10 oz. of either MMO or 2-cycle oil in each tankful.

B

146k and runs beautifully

218k on '84 and still runs! (still in great condition!) :rolleyes:

Well I got 180K on my 12a I am the 3rd owner I had her for 5 years I was really really hard on her didnt change the oil regularly all that jazz. Well I pulled the block apart becauses I needed to replace the water jacket seals and well out of 12 corner seal's I had one :( so yea 2 slots on one rotar are completly toast there spread further apart where the seals have been beat around in the engine and one cornor seal that came out of the rotar and was beat up which now has distroyed my rotar housing's. but I have 4 spare's so I think I will be okay ;)

Forever.

I've been driving 12As so long, I can't remember how long it's been. They just keep going and going...

Ray

There's a couple reasons why FD engines don't last....THEY'RE CALLED TWIN TURBO'S....

A 12a is completely different. I'm over 150,000 miles right now and it's perfect. Just do routine oil changes, and let the damn thing warm up before you go crazy...

The apex seals start to chatter around like 6500 rpm's or so.....I mean, if you're revving it to 8k all day everyday it's obviously not gonna last as long...it's pretty much common sense.

Just take care of it and you'll be fine...12a's are tough little suckers.

I don't think it was intended as a literal comparison. Else, one would need to ask how long a 12A engine would last if run at comparable level of boost, or compare longevity of a 12A to longevity of a FD 13B without turbos.

Cosmicbang- yes I was interested in a comparison. Usually a manufacturer designs in a life period as a matter of costing. The 12A could have been overengineered as at the time rotary engines were suspect. It is also relatively simple so the chances of early failure are small. In contrast the FD engine is very complex which means a higher probability of early failure evan if the average life expectancy of the engine is the same.

Remember the story of Henry Ford, if a part broke he wanted to know why the other parts still worked as they must be overengineered and so more costly.

In the case of Gen1s does the 12A keep on going after the body dies of rust?

Have over 200,000 on my 81 stock original w/ RB exhaust.

13Bs in GSL-SEs are similarely stable. Overboosting or not changing the oil frequently enough are two main causes of premature failure.

Then I disagree--at least according to how I understand your statement. Comparing the 12A and FD 13B-REW engines themselves does not explain why the FB's 12A seems to run forever relative to the FD's 13B. There is very little additional complexity in the FD's 13B (the engine itself) that would lead to earlier failure. To the contrary, the 13B-REW incorporates significant refinements which make it much more capable (and potentially longer lasting) than the 12A or earlier 13B versions. A few years ago Paul Ko wrote a nice paper describing these, but unfortunately it seems to be off-line. I'm sure I will miss a lot, but here are a few examples of how it is superior to a 12A or earlier 13B:

On the FD's 13B-REW, the areas around the dowel pins on the side housings are reinforced and ribbed with thicker castings. This was a major problem with earlier engines which tended to crack in those areas.

The 13B-REW shaft has a larger oil bypass/crank pulley bolt.

The 13B-REW has larger front-end thrust bearings than the 12A and 13BT. The larger thrust bearings allow better loading and thus tighter torque setting of the pulley bolt. This design reduces the chance of the eccentric shaft bending at the front section, which sometimes happens on other high-output rotary engines.

The newer design corner seal springs in the 13B-REW have superior longevity.

The 13B-REW front cover has an additional attachment bolt to prevent the gasket from blowing out.

The 13B-REW rotor housings were refined for reliability, with the water passage machined around the spark plug areas to increase cooling at the spark plug tips.

The 13B-REW has factory-hardened stationary gears.

Inside the stationary gears, the main bearings on the 13B-REW motors are the multi-hole type and are locked into place by an anti-rotation set screw. The holes allow extra oil to flow around the oil groove thus providing a thicker oil film for the eccentric shaft to ride on. This design is similar to the "3 window-type" bearing pioneered in the earlier LeMans and IMSA motors.

The 13B-REW has higher oil pump capacity.

The 13B-REW oil pan design helps to minimize air induction into the oil strainer. The thinner pan with an inner bulge maintains oil level to keep the oil strainer submerged in oil.

These and many other refinements make the 13B-REW a much more potent powerplant which can easily handle high horsepower output well beyond what it was originally designed for. In summary, for equivalent power output levels, (even taking into accout the 12A's smaller capacity) the 13B-REW is capable of much greater longevity.

Now of course this (equivalent power output) is a hypothetical comparison, but my point is that 13B-REW engines do not fail because of any fundamental weakness which the 12A does not have.

There is a fundamental weakness, it's just not in the engine design. The weakness is in the cooling system, exhaust and the engine compartment airflow design.