Jobro

iTrader: (2)

My car has 242 000 KMS on the clock, still running like a baby, starts first go if I do it right, never more than 3 attempts, if its been run at all during the day it fires first go DEFINETLY.

Apparently the original engine too, still stock ported, stock exhaust, stock carby(which is well and truely due for rebuild!)

I love reving it ~7500rpm but there are weeks when It doesn't see more than 2500-3500.

I just find the buzzer music to my ears, and then it gets a lead food until I get home.

I have a few oil leaks, body rust, and the carby is leaking fuel at the pump or whatever its called.

OMP is leaking slightly, some oil leak near the dizzy, theres a small leak from the oil cooler lines, and another leak from the sump gaskit.

I'm up for a new gearbox now, gonna get a Series 4 Turbo box, lightened fly, and a stronger clutch, after this, when I have money to burn I think I mightn't feel bad driving the car like I stole it :P

Elysian

motor in my FB lasted 143k miles.... then the guy who owned it got a divorce, gave it to his wife, his wife let her 18 year old boyfriend drive it, guy got the car back later on and it was burning more oil than he could pour in it...

OnlyOnThurs

97,300 original miles on my 82' GS.....she has a small oil leak on the oil cooler but besides that she runs perfect.......she is so much fun to drive....

Directfreak

iTrader: (2)

Exactly.

The FD runs at tempertures of 210+ degrees all the time.
The car overheats for anything, and the engine compartment never
gets enough airflow to cool the turbos off. The engine is constantly
cooking itself.

On top of that - Most FD owners, Up the boost on stock engines, without
considering the cooling, or the additional fuel that higher boost requires.

Any way you look at it, Any forced induction (boost, Nitrous) also prematurely ages an engine.

I am sure if you took a brand new 12A, and a brand new 13B REW,
and put both of them in FB's, with a simple carb, stock radiator, stock mechanical fan, and NO Turbos, - the 13B REW would last just as long, (if not longer, due to the improvements made internally) than the 12A.

Again, the problem isn't the engine, it's the enviroment that it is subjected to.

PaulFitzwarryne

Cosmicbang. I agree with you that the 13B REW is an improvement on the 12A. Your list of improvements is very informative.

However straight comparision is not the point. Is the 13B more reliable in producing 255hp than the 12A is reliable in producing 100hp? The evidence is clearly no. The other aspect is that the ancillaries are far more complex, thus there is relatively more chance of an early failure, while diagnosis is more difficult. I suggest, that with a fault the FB will keep running although admittedly not at its best. In comparison the FB will simply stop.

An unusual example of different criteria is tank design in World War 2. The Germans produced some superb designs such as the Tiger tank. The Russians realized the life expectancy of a tank in continual battle was only three weeks. Thus, the T-34 was made simple and expendable with a commercial truck engine.

My view is that the 12A was overengineered for its task and is very reliable. If you detune a REW to Gen 1 power requirements and use a carb it will be more reliable, and you will need repacement bodies before replacement engines.

DJAngelicon

All of this information is great and just want I been looking for. Got my attention alot and specialy all of the things you guys needed to say.

My car is a 81 Rx7 FB 12A with a second engine put in 1993. 3rd owner fully stock with a simple mod which is the flapper off from the cab head or whatever you want to call it. it have two small oil leaks that are very small but will get fix soon hopefully. It have 152K miles on the engine and runing strong. From time to time I push it hard but not burning wheels just straight up racing someone else. Anyways not sure how good my information will help but I am thinking when is time to change or rebuilt the engine if I want to rebuilt mine or just get a different engine. Not sure and would love to start saving for that time to come.

Manntis

Paul, why do you feel carbs are more reliable than EFI?

PaulFitzwarryne

Manntis- My comment on using a carb on a 13B REW was to have a level playing field when comparing it with the 12A. In reality I am not sure which way the field tilts!

Having efi gives better performance, while I have a 12AT engine updated with a Microtech ecu which to date has been very reliable. Efi design has certainly improved over the last 20 years.

However, I think you can make a case that a carb still keeps on working if it develops a minor fault while efi will just cut out when there is a component failure. I have concerns with efi in that it is difficult to repair in the field when there is a fault. The only time I had a specific efi problem which was on a 4wd, it cost me US$600 to have it towed to the nearest service station some 200 miles away. If a carb had failed in most cases I could have repaired it on the spot.

diabolical1

iTrader: (3)

i think this just about says it all.

you also have to consider the fact that most mods made to 12As are pretty basic (exhaust systems) compared to the Turbo engines (which people just crank up the boost for numbers without regards to tuning) and those mods actually tend to be healthier for the engine.

MarkPerez

That is right, always hear about new/rebuilt engines/turbo's in the FD's. anything under the hood just gets cooked, rubber hoses, vacum hoses, turbos, engines. The FC TII isn't as bad as fas as heat under the hood but still gets pretty hot. Mazda, for some reason(s) designed the cars with very little engine bay air-flow by blocking open area's with plastic. even the FB's suffer from no air-flow, i'm not sure if a rotary engine (any 12a,13bt, 13b-rew) run hotter by design then a piston assembly but any venting of under hood heat on the rx7's will add to the life of the engine and hoses and wires.

drunkclever

isn't there something to be said about the type of fuel you put in turbo eninges? as far as octane and pinging. I was told to only use the highest octane you can on turbo engines.

I got a 12A with about 250000+ on it. blew a apex seal a few months ago.

MarkPerez

pretty much, price VP racing fuels any kind of fuel any colour 120 + octane.
The pump fuels are pretty much crap the problem with good high octane fuel is the price and the engine can get addicted real easy to the good stuff

WackyRotary

I couldn't agree more with the parts getting cooked under the hood of a FD.

I know someone who took their FD engine out suspecting it was blown by how crappy it was running, just to find out that many parts that were taken off to get the engine out actually cracked while taking them off!! INFACT, the wiring harness was so overheated from heat, that the harness broke in two in a couple locations. Just brittle as hell. Vacuum lines broke in two just barely flexing them. When the engine was finally pulled apart, it actually was visually fine internally! All important items were in spec yet at 106,000miles. The key is to get the engine bay much cooler then they are. And, stregically place heat sensitive items away from heat sources or have more air flow like said above.

ray green

iTrader: (14)

"Paul, why do you feel carbs are more reliable than EFI?"

Paul, you are right, the carb is simply the most reliable and fun way to get around. That's what makes the 12A a really nice experience. EFI was the thing that took cars into the electronic age, something was lost. Just drive a nicely tuned GSL and tell me it's no better than an SE, no comparison.

Ray

Aviator 902S

These engines do run hotter by design than boingers do, but not by a hell of a lot. Still, this means there is less room for error in cooling system design. HP increases result in even more heat to be dissipated, and the result is that the 13B-REW (even with the design upgrades to combat this extra heat) will not put up the longevity numbers that a stock 12A can in the environments in which each engine lives. The clogged engine bay of the FD only aggravates the situation.

So yeah, as long as the FD's cooling system is modified to carry all excess heat away even on the warmest days, and as long as it's never fed anything less than premium fuel the engine could last as long as a stock 12A in a first gen--- at least in theory. But has anybody actually done this?

purple82

The extra load on an engine from compressing it's intake charge will shorten it's life. There's no theory that could say otherwise. Even if the coolant temperatures were the same, the increased load on internal components due to pressure end temperature related to increased charge compression will shorten the life of the engine.

Mr_Rx7_Au

174,605 miles on original 12A motor and seals/rotors.

Only have had to replace:

water pump
clutch lines
oil cooler

everything else has just been maintenance... ie sparks, filters, tyres etc.

MarkPerez

I'm just guessing and would like to think mazda learned and maybe listened to feedback from service mgr's and the likes devoloping the rotary engines over the years and anything "newer" is a much better engine then the "old" 12a's

85rotarypower

Well, my original 12A with 275k km blew cause of mistreatment. I believe it blew because of detonation. I didn't detect it, but after going over all the reasons it could have went, this is the only reason. The car had great compression for the age. 105 psi both rotors. Not bad. But there was a small amount of nearly undetectable pinging. Also, the throttle stuck open a few times bringing the engine to 9000+ rpm.

If what was said about the FD's overheating problems are true, then its really not a problem with the engine, its a problem with the car it was sitting in. Mazda took too much time in designing the engine itself, and didn't think about the environment it was placed in. If they would have redesigned the car to allow more air flow into the engine bay, the car might have looked a little better too.