GregBBRD

No. The engine doesn't even have smoke/fire residue on the outside....much less on the inside. There is no sign of fire in the front of the car.

The fire was caused by a 10" by 10" hole in the oil pan...all of the oil left and apparently ignited off of the glowing headers.

The fire spread rearward, igniting the gasoline from the leaking fuel cell. The back of the car has melted....everything.

Yeah, I know....who puts a car on the track with a leaking fuel cell...and who techhed that car?
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ptuomov

Carl Fausett

My thoughts as well.

mark kibort

Thats an interesting point about the soot , or "black paint" under the pistons being caused by the fire.. but it sounds like the oil that caught fire was exiting the oil pan, not in the engine. i can sa, as the ONLY one that saw the flames , that the flames were exiting the car to the sides, about 6ft high on either side.. it looked like a top fuel dragster taking off at night. i dont think there would be enough fuel out of one cylinder to cause that amount of fire. and i dont think the fire would go back into the engine and ignite inside the engine. it didnt burn a lot of rubber under the car that i thought would have been toast, and because the fire was moving rear ward, and stagnated at the rear bumper , it was toast, but not melted. just the wrap was mostly damaged . i never knew there was a leak in the fuel cell. thats scary! still a lot of mystery here...........but the bottom line is we dont know what octane the motor required and what was in the car (supposedly , 91 octane mixed with 110 or 100) and we dont know the effect of the remaining gallon of old , 2 year old gas in the mixture......we also dont know the effect of the new tune. even if it was mildly different , it was different. could that have caused the pre-ignition or detonation? or is it just more simple to say the octane was 5 points off and that caused the motor to detonate, pre-ignition and caused forces to develop that cracked all the pistons, cracked rods down the middle, and stopped one piston in its tracks. what a mess!!!!

anyway, not trying to argue the points you have made. you obviously have seen more of this than most anyone here has seen. just bringing up points that would come to mind by any gear head.

what a shame

GregBBRD

The words "new tune" are confusing....even to me....much less to someone following along.

Please keep the data points clear.

The "new tune" Kibort is referring to is the same exact tune that Joseph used when he used this car 6-8 years ago, without experiencing any issues. Of course, he ran the proper fuel.


I wonder if the knowledge of the fuel cell leaking provided Mark Anderson with any additional adrenaline rush as he tried to leave the car.....he must have been aware where the fire was concentrated.

At some point in time, running through life using pure luck instead of thinking and applying logic has to end....badly.

Between the low tire that blew on the banking, using the wrong fuel and exploding the engine, and then being momentarily stuck in a car (which is on fire) with a leaking fuel cell might be a message of some sort.....

FredR

You may disagree with such and that is is fine by me but someone else obviously views such matters differently to your goodself, When someone like GB turns round and says he has "never seen anything like this" one has to wonder what could possibly have caused this trauma to happen and clearly it has to be something quite unusual. If GB has not seen such in a 928 engine then who has?

As I visualise the problem the failure can only be one of two things- either piston No7 slammed into the head [somehow] or the pressure in the combustion chamber resulted in the piston/rod failures- which is it?

GB did not report any signs of the piston slamming into the head [or so I understand] so it would seem the latter is the only logical explanation and thus one is left looking for a mechanism as to how this could happen. No 7 failed but the other pistons showed similar degradation so it was a crap shoot as to which one let go first.

Spark induced detonation causing that level of damage must be impossible given the knock control system so what possibility is left?

We know that at some stage coke formed on the underside of the pistons presumably by overheating and transferring heat into the engine oil present - Greg advises that this was not caused by the resulting post failure fire so such could only have been caused by the piston crowns reaching a temperature well in excess of the lube oil coking temperature[315C]-so can we agree say 350C?

A bit of research suggests that petrol engines [spark ignition] see a piston crown temperature in the region of 290C whereas diesel engines [auto ignition] see piston crown temps of around 360C. We have a stream of air and atomised fuel entering the combustion chamber and being compressed, Compression heats up the charge as do hot cylinder walls. Thus the question becomes one of whether there is enough heat input to cause auto ignition. The fuel system is circulating and this heats up with time, the stock system has a fuel cooler based on the a/c system with a logic that if the a/c is needed so is the fuel cooler. Did the race car have a fuel cooler, did the fuel heat up and eventually reach a temperature that contributed to an auto ignition/detonation event when superimposed on a fuel of suspect quality?

Whatever the detail of the mechanisms in play normal combustion did not cause this event so what did? The author reckons that when this type of problem happens the engine life can be measured "in milliseconds"- - that would explain why a very experienced driver did not see or feel any signs of distress before the motor went kaboom.

GregBBRD

I think Tuomo is referring to the quote that you posted and not to the general idea of how this engine failed.

My understanding of detonation is also completely different than what the author stated. According to what I can tell, detonation occurs ATDC. Pre-ignition occurs BTDC.

mark kibort

After the fact, but still a question. auto ignition has to happen before TDC. why would it happen after when pressure and temps would be going down. detonation happens as the compression is so high that it ignites the fuel air charge. ive heard of passed TDC detonation where you get a normal ignition but it propagates too fast and ignites the air fuel charge after TDC, which obvoiusly is easer on the pistons and rotating assembly. pre-ignition would happen before as well and can lead to detonation. just curious as i have heard it explained many different ways.

as far as the tune. i was under the impression that the new engine got a new tune vs the original tune, and mark said to copy it to his car as well. no? if not , tune didnt change, so strike as a possible issue?

FredR

I appreciate Tuomo's point and yes he is referring the quote or so I understand.

The thought process I am trying to develop here is the notion that detonation can happen before the intended crank angle for ignition is triggered albeit I understand it is a rarely experienced concept. The net result being an exceptionally high increase in combustion chamber pressure being compounded by the compression stroke. The problem with any detonation [read explosion] is that it happens in a very short time frame compared to a controlled burn [that takes longer] so the pressure spike is higher/earlier compared to a regular burn that is more progressive and when timed correctly, max pressure takes place at the optimal position when the crank is at 14 degrees ATDC.

Spark induced detonation [what we commonly refer to knock] occurs after the ignition discharges and is controlled by octane rating and ignition timing, a higher octane fuel having a slower burn velocity thus permits more advance . Lower the octane rating and one must retard the ignition accordingly. The main reason for needing a higher octane is to support higher compression ratios Thus spark induced detonation occurs after the programmed advance and usually before the piston reaches TDC [as far as I am aware] which is why it does the big ends no good at all.

Pre-ignition occurs before the spark is discharged and because of when it happens the heat cannot escape and the temperature increases on the piston crown much more than normal and can burn through the piston [as I have seen happen] particularly so on boosted motors. The Super knock concept [as I can understand] is a detonation type event that is induced by the pre-ignition event having taken place. As I said in my original post on the subject matter I know of such but know virtually nothing about it other than it creates a huge pressure spike. The thermodynamics of why it can happen is well beyond my current knowledge. Tuomo suggested this is a single occurrence event but maybe that is because it only takes one event of such to destroy the motor! What I am suggesting is that the damage profile you demonstrated is totally consistent with an overwhelming pressure spike taking place and my suggestion as to how the failure happened [as I can tell] matches the damage seen.

When things go wrong in the engineering world we can usually work out what happened but the smart bit is to know why [the root cause] - thus why this event intrigues me whatever the root cause may be. One thing I have found during engineering investigations is that rarely does one person know everything about the incident but by kicking the ball about a bit it often opens the eyes of those who do have knowledge but may not see the relevance of what they know- thus why we put a team of people together who can complement each others knowledge. The worst thing that can happen is when folks dismiss pieces of relevant info without giving due consideration to the fact at hand. Thinking that something has [or has not] happened and knowing/proving it has [or has not] happened are two completely different things.

mark kibort

instead of guessing Here is the video , made YEARS ago to describe all the possibilities

mark kibort

GregBBRD

I've heard detonation and pre-ignition explained a bunch of different ways. too. Like anything, especially anything on the Internet (or CNN, ABC, etc.), you need to be really careful about the source. Once you dig down and get to the experts, the truth is pretty simple.

I can't remember who got what tune....way too many years ago. Like I said "new tune" is not a very accurate description. Both of these tunes are 8+ years old....there was no recent tuning done.

I have both brains, so I could compare the two programs, along with the history in my files. While I wouldn't be surprised they would both have similar ignition tables, I doubt the fuel tables would be the same....although neither of these engines were mapped at the track, so it is possible. This is one of several HUGE mistakes that were made.

There's many lessons here, to go with the many lessons I've learned over the years. Don't build race engines for a client that has the ability to change the tune...and does so. When the client says, "It's my money, I'll do what I please to the engine", it's time to quit and go home. Don't build race engines for a guy that can't afford/is too cheap to run race fuel. Don't build a race engine and put it in a car without a data collection device. Don't build a race engine unless the owner has enough money to map it at the track.

The list goes on and on.

GregBBRD

Again, I don't have sound, so I have no idea what they are saying, but it looks pretty good.

Carl Fausett

Greg, does your engine management system allow you to retrieve the engine map/tune from the ECU? As you know, we use the Electromotive systems, and one point of contention that I have with them is that they do not. They have explained to me that the design was laid out for a spec racing series and they were told to design it specifically so that once the tune had been uploaded into the ECU it could not be read or reteived. Always sounded like BS to me, but I like their stuff and it works well for us - so I have put up with this one issue.

Just wondering whether you can actually "read" the tune that they were running from the ECU's.

mark kibort

It basically shows what i am talking about and what has been said. both knocking and pre-ignition can cause extreme heat in the cylinders. pre-ignition usually causes a knock as well, and this knock is before TDC when pressures are high..normally, as you say, cylinder pressures are designed to be highest just after TDC.. But, during the knock,this is not the rule. with a pre-ignition , it usually happens before TDC and this causes damage due to the high , random pressure waves due to the explosion. with a knock, it can happen when pressures become high enough to increase fuel/air temps to ignite, this happens when the flame front is moving and pressure increases. when the right temp for ignition occurs, detonation can happen. this can be before or after TDC. when before, it tends to create greater forces on the moving components

you dont need sound with the video.. but its more clear with it. what is different than what you have seen or heard about detonation or knock,is this is ACTUAL video of the occurance taking place in a cylinder with high speed photography/video. its actually showing it happening and the timing as well.