sorry about the engine. One thing though. Can't you set up the SECS to buzz when you breach a certain boost level? i expect though that in a car on track with a helmet on the chances of hearing it are slim at best.

JB, I hear what you are saying, but I doubt EGT's were high once Puff was on the move. Again, the track was slippery, and only the back straight could be done at full boost for longer than 5 seconds.

Puff, where did you first hear your car was doing funny stuff.

As much as I would like to speculate myself (for me, I'm almost sure it's det related in the end, but I'm not qualified to actually "make" that statement), the only place EGT's would run high is whilst waiting in the queue for the next session. Even with my FMIC (blah blah) I saw intake temps of 50°C just before setting off. Still, nice cold & damp weather, track asking for some tiptoeing at most places, Puff doing smooth laps, I doubt it was intake temps related.

But... as said, let's have a think about a "thread format" where we can actually gather intelligence rather than guesstimates - as well meant as they are, no doubt about that. Maybe it needs to go on 22B, but you could find as many arguments as to keep it here. Maybe it would need to be moderated firmly, not to shut people up, but to focus on information as much as possible.

Fact is: you don't hear much about WRC or even GrpN cars losing their big end... so my suggestion is that the knowledge is "out there".

Now I fully understand that this is a potentially very tricky subject, a minefield so to speak. So it will be a balancing act between trying to get some good advice for Impreza owners against possible ... erm... legal stuff.

Mods, if you read this, I would like to hear your suggestions about the viability of such a thread on here. The same question goes out to the 22B mods, but I think we all agree this isn't about BBS quality, but about something we know can/should/will be fixed, and hopefully thus help to avoid misfortunes like Puff had yesterday.

Damp track & ambient temperature low. In fact probably ideal weather for intercoolers!

"hot" track I mean the driving - ie lots of load, not that the ambient was hot. I don't think it is as simple as saying it was cold (ambients) so the EGTs were not hot or it was not detting.... were you measuring either? If it is cold then the cylinder pressures can be higher and encourage detonation. There are multiple factors at work, and you can't assume that cold weather will protect an overboosting engine - it could make it overboost more.

A FMIC doesn't always allow a lot of extra timing- the greater charge density can require less spark advance. So you have at least two conflicting factors of low charge temperature discouraging detonation, and high charge density requiring less advance.

A cold track is a great way to encourage overboost.

The ambient was 10C when we had the car at knockhill starting to det.

The PPP does run very advanced ignition indeed, if it is running the correct boost level I can't see a problem, but with effectively unknown levels of overboost which are likely to be well over 0.2 bar it could be a different story based on data I've collected.

This is no slate to PPP, but if it reaches this sort of boost level it is not setup right, or there is a fault - ie the usual causes of overboost.

These thoughts are only opinion! At the end of the day big ends go for no apparent reason on some cars.

I will be removing and stripping Puff's engine on Thursday. With Puff's permission, I will post pictures of the damaged parts.

Rich

Was awake most of the night cos of Shauns ability to belch/fart/snore non stop for 6 hours

I did warn you mate........ ;) :D

Ptmw

was going to slide in a quip regarding oil changes!!!!

hence the flame suit comment... however evil bevel has arrived at the same conclusion i have...

For my sins, i work in the automotive industry as a quality engineer at a tier 1 supplier (tier 1 means we supply the automotive companys direct ) and as part of my job we deal with issues relating to part/ system failure on a daily basis.

At present i am tied up with some college work (work related) but was going to look in the new year at some detailed investigation into this concern.

I know there are certain people out there who have done work into the mechanical side of things, (greasemonkey) springs to mind and can quite rightly identify certain aspects that may have a bearing (no pun intended) on the concern.

what i would need to do is set up a detailed questionare and with some help from the mods and some of the mechanical people which can be made available.. from this i can then have a look from a quality and systems point of view to see if any obvious areas spring to mind.. which may give some more detailed areas for investigation.

however i need to get the college work out of the way ive only got one module to complete, and then my time is my own so to speak

Mart

Just a thought... do WRC/grpn's pull up at a shell/esso/bp garage and use regular joe public fuel? We pull the trigger at the pump but we dont 'really' know what stuff is going in there, what quality it is, what age it is etc.

Richie.

Richie

I'm certain you are on to something there.

My big end failure almost exactly matched PTMW's description above of the mileage, history, oil, and I guess, sensible warming up and cooling down.

I am let's say 90% convinced that the quality of the fuel, in my case Optimax, was at least a contributing factor to the failure.
In the absence of a knocklink warning (why should you have to really in fairly standard cars?)I have to go with my gut feeling which is linked to the very variable nature I had over 25k and 8 months with Optimax. I varied the fuel with SUL and not once did I think "this tank doesn't seem as good" with SUL.

Not starting the usual SUL/Optimax debate yet again, but I do think that fuel quality is a factor with the Impreza (and others).

Pete, have you got any pics of Puff's whirry bits yet? ;)

Well, the engine has been stripped down & the following has been observed...



The Big End bearing has exploded and forced #3 piston to hit the cylinder head, causing #3 piston to crack, damage the head and bend the conrod, at the same time this has damaged the crank too...

:eek:

If you're going to do it, do it in style :rolleyes:

Pics I'm sure will be forthcoming shortly & this of course knackers the crank/bearings replacement I was going to have & now need a new short engine :(

Least it will be as good as new when it hits the road :D

:)

:eek: nasty, that's what I call a big-end failure :D

Did the big end bolts break? (I suppose they did seeing piston hit the head ;)). Now, here's the biggie...what caused it?

A friend of mine would have broken your arm off to get that engine - He's a Metallurgist, and was doing a study on causes of engine failures. Although if he came back home with another broken engine...I'd very much think he'd be homeless ;)



[Edited by ALi-B - 11/18/2003 6:06:43 PM]

Least now you could get the 2.5 short block MMM