Blown engine theory

[Doug_MPS6]

And Riley had the cross-flow head in the 1920's too! It was much vaunted by Ford as recently as the 1970's onwards, I forget precisely when, not being a Ford man.

[rd415]

Notice I didn't mention FORD they make some outrageous claims. It was the Dodge brothers who actually designed and built the first fords - every FORD design can be traced back to another manufacturer. Don't get me started on Fords - great cars but why do Ford have to lie and mislead so much.
Sorry a bit off topic

[Doc]

CrankCase Evacuation System - Mazdaspeed Forums

whos game?

---------- Post added at 08:33 PM ---------- Previous post was at 08:31 PM ----------

http://i797.photobucket.com/albums/y...dmazda/pcv.jpg

inside our PCV.. just FYI

[Wardski]

You first

[rd415]

Starting to see a pattern with the "Blown Engine Theory" one word DYNO.

[tricache]

Actually ECU/TUNE MODIFICATION are better ones I think

[Doug_MPS6]

Hmmm - all the oil through the exhaust is an interesting cue....

[RedDjinn]

Good reason to rebuild... mrs might understand more ...................but i have to rebuild it now honey

[Doug_MPS6]

Well the first question to ask, and I haven't seen it asked yet, is: "does anyone have an example of a dead stock engine that has blown up in this fashion?". Answering that will go a long way to getting to grips with the problem.

If there are such examples, then it is a fundamental design issue, possibly in combination with certain running conditions and/or a sudden failure of a component or setting, including runaway ECU.

If not, then it appears that the problem is caused by a combination of certain mod's, settings, running history and immediate circumstances prior to the blow up.

A common situation seems to be that whereby a long sustained run is followed by a slow-down then a gradual and even gentle increase in speed, often in a relatively high gear. The mods don't appear extreme in some cases, nor do the pressures. I don't consider either extreme in mine (max boost setting 17.5psi, protective retard approaching peak, FMIC and DP), yet cars with similar setups are dismantling themselves suddenly.

[bd581]

Well the first question to ask, and I haven't seen it asked yet, is: "does anyone have an example of a dead stock engine that has blown up in this fashion?". Answering that will go a long way to getting to grips with the problem.

If there are such examples, then it is a fundamental design issue, possibly in combination with certain running conditions and/or a sudden failure of a component or setting, including runaway ECU.

If not, then it appears that the problem is caused by a combination of certain mod's, settings, running history and immediate circumstances prior to the blow up.

A common situation seems to be that whereby a long sustained run is followed by a slow-down then a gradual and even gentle increase in speed, often in a relatively high gear. The mods don't appear extreme in some cases, nor do the pressures. I don't consider either extreme in mine (max boost setting 17.5psi, protective retard approaching peak, FMIC and DP), yet cars with similar setups are dismantling themselves suddenly.

Talking once to the guys at mps garage and they did say that yes they have had stock motors blow.
But who knows how these cars had been treated in the past.
Of the blown motors, how many had been on a dyno?

The last part of your comment I think puts more weight to the sticking wastegate theory.

Another question to ask that I don't know the answer to, are there any cases of gen2's having failures?

[CharlieBrown]

Another question to ask that I don't know the answer to, are there any cases of gen2's having failures?

Too early to tell at the moment - they've been released 12 months to the day today.

[tricache]

Wait till warranty runs out and then you will hear them blowing up

[rd415]

Wait till warranty runs out and then you will hear them blowing up

What's warranty got to do with blowing engines????? A good few of the engines I've read about were still under warranty and relative low kilometres. ALL HAD BEEN ON A DYNO.

Engines shouldn't blow with modern technology and materials. An opinion - no proof - Colin Capman of Lotus once said that at the end of a formula one race the Lotus should require a full rebuild. Maybe just maybe the 2.3 litre motor is built to maximum stress specification with no safety margin producing in it's form the maximum safe performance level. Any performance modifications may put the engine over it's stress design.

If I may indulge for a moment to explain - a VW horizontally opposed motor is extremely understressed, adding a supercharger with no internal mods will double the horsepower. Replacing the std. crank with a counterbalanced crank will double the allowable RPM. These motors are so understressed that mods have no effect on the reliability of the engine.

Modern technology has motors producing their maximum output for the strength of the engine, making the engine stronger in it's configuration adds weight, lowers revs or lowers power output, so a completely redesigned engine would have to be used to gain output and the cost would dramatically increase. A good deal of modern designed engines are considered non serviceable, by this they have no ability to be machined, no rebores, no crankshaft machining etc - replacement engine required. All the allowable tolerances produce maximum performance.

What does all this mean - 193kw out of a 2.3 litre is pretty dam good - you all realise that's similar output to to the older V8's (Australian Muscle Cars) - WOW what a car is the Mazda MPS.

[tricache]

Its called a humorous remark...wow...didn't know this topic had the attitude taken from the genocide of baby seals

[Doug_MPS6]

I agree that a sticking waste-gate seems like a reasonable conclusion under the conditions I described - except that to my knowledge (and I could be wrong or under-informed) no one seems to have sensed or reported any over-boost under their "gentle acceleration" after a short period of slowing down, as through a built up area, and upon regaining more open road.

But if this is the case, then the fact that many of those reports refer also to accelerating in a relatively high gear (5th), this may be a situation in which extreme over-boost (due to a sticky waste-gate for instance) may easily go unnoticed without a boost guage, and the resultant heavy engine loading due to being in a high gear may over-stress the motor (probably the rods) to the point where it comes apart. It still seems hard to imagine that this imposes more stress than running up a steep hill in a relatively high gear at relatively low rpm.

It also is at odds with the dyno related blowups which presumably occur at high rpm. I'm not so concerned at dyno blow-ups as we all know that anything can happen right on the limit. Nonetheless, knowing how these engines come apart may be a clue to other problems faced by drivers in day to day commute.

Sooo....the next question is; have any engines with forged aftermarket rods blown up under the "on-road" conditions described? (bearing in mind that anyone running forged rods probably works his engine harder than the average punter on stock internals).

[Doc]

There have been a few forged one go boom.. but it is usually blamed on poor build.. so its very hard to tell

Doc

[Scaredycrow]

^ I guess once you start introducing 3rd party components (like rods, pistons etc) its very hard to draw accurate conclusions. Questions around the quality of the partsm themselves, the workmanship in tearing down and rebuilding the engine etc all start to pollute the facts... Whatever they may be.

[Doug_MPS6]

S/CROW (& DOC), sure - and that is why I posed the first question re stock engines going kerfutt.

I was musing on it all today as I launched in 4th at modest throttle opening from about 2500rpm past a few feeble minnows in the way, and thought just how much torque these engines have at low rpm. It would be very easy for a non-mechanically aware driver to try to floor the throttle in 5th or 6th at quite low speeds, get quite satisfactory performance for whatever they wanted to achieve at the time, but be blissfully unaware of the huge loads they are placing on the engine. This raises the question: "to what extent is an engine such as this tested by the developers, not so much using performance styles of driving (mechanically aware and keeping some revs on), but with a view to making them idiot- or granny-proof?".

Some time ago we had someone write here with a query, wondering why they were getting "rattling" (detonation) and smoke when flooring the car at ~1700rpm in 6th on the freeway, so this sort of thing does happen. And accepting that it does, and maybe most of our engines get exposed to a few instances of this, perhaps by misadventure, a foreign driver, inadvertently starting off in the wrong gear, etc, how much does this sort of loading predispose the engine to failure much later?

[kmh001]

I posted on an earlier page that I've had the death rattles a few times and I'm absolutely convinced that my stock engine was a poofteenth away from failure each time. The death rattle episodes have almost always occurred while in cruise control in 6th. The car was being driven in a completely normal way at highway speed and was controlling the throttle itself, the way Mazda programmed it. On each of these occasions it wasn't the cumulative effect of repeated stress that nearly broke it, it was a sudden and acute malfunction that lasted a second or two then was gone again.

Without trying to have the debate all over again, after these near death experiences and after reading a gazillion pages of discussion on various forums, I still believe there is a software error causing these engines problems. If this issue ever does get resolved, I'll bet the term "map transition" will feature somewhere in the cause.

[rd415]

I posted on an earlier page that I've had the death rattles a few times and I'm absolutely convinced that my stock engine was a poofteenth away from failure each time. The death rattle episodes have almost always occurred while in cruise control in 6th. The car was being driven in a completely normal way at highway speed and was controlling the throttle itself, the way Mazda programmed it. On each of these occasions it wasn't the cumulative effect of repeated stress that nearly broke it, it was a sudden and acute malfunction that lasted a second or two then was gone again.

Without trying to have the debate all over again, after these near death experiences and after reading a gazillion pages of discussion on various forums, I still believe there is a software error causing these engines problems. If this issue ever does get resolved, I'll bet the term "map transition" will feature somewhere in the cause.

Totally agree Mal with your comment - I believe that the mapping fault is just more likely to occur on a Dyno