Fuzz

It seems from people that have had engines "let go" big styleeeee
that the main bearings fail on three and four.
Is this the most common failure or just co-incidence of hearing 3 with same thing happen.
Assuming this is true,
Is there anything that can be done to prevent it ever happening.
Perhaps we could have a list of peoples catastrophies on here so we can see what needs to be strengthened before certain mods are done ?
Just a thought

Andy

flossy

change oil maybe more often using a fully synthetic oil like 5w/40 i sugest castrol magnetec. run engine a bit before moving off.

T-uk

magnatec might be better if you do many short journeys but I would not go near a track with it in.I only do about 5000/6000miles a year,mostly short,less than 10min journeys and run magnatec but when I go to track,or on a long journey I change to either motul or mobil1 motorsport.

JohnD

iTrader: (5)

There seems to be an assumption that Castrol Magnatec is a full synthetic. It is semi-synthetic. It states on the polycan "synthetic engineering" Don't be fooled! It's a good oil, but it's not fully synthetic. (Could you see Castrol charging only £20 for 4.5 litres of full synthetic? Besides, their RS 0/40 or 10/60 is around £32 for 4 litres!)
JohnD

MorayMackenzie

I would hazard a guess at the most common reason for engine failure being "bad attempts at tuning". Sad, but quite possibly true.

Fuzz

Moray,
That's the very reason I want to see a "what went wrong and why" section.
people will undoubtedly "fiddle" with their engine without realising what's actually going on under the bonnet and then wonder why it let go.
The more information peeps can put together about, for example better oils (as metioned above)and what mods should be done before other mods. the better chance we have of keeping the flat 4 in one piece.
The other day I was told of a bug eye with circa 30,000 miles and it had let go !!!!! no clue as to mods tho

ustolemyname??stevieturbo

iTrader: (1)

Regarding a fix to the big end/crank problem. A fix might seem to be in the form of a crank made by GGR. It is apparently a new billet item, where the big ends are fed from main journals, 1,2,3 and 4. No 5 main journal is no longer used to supply oil to No4 big end, as they claim that that was a weak spot on the crankshaft, so no drilling was preferred. This crank should allow much better oil flow to the big ends, hopefully reducing the chances of failure.
I wouldnt rate magnatec as a high performance oil. I think it would be more suited to high performance N/A cars, where im sure oil temps would be a little lower. My choice would be Mobil 1 Motorsport 15/50, or I have always heard good things about Motul's oils, although never used them myself. Castrol RS 10/60 is also very good, although I havent seen it in any shops for ages.
The subaru engine can be fragile, but it is a high performance engine. Why put crap/cheap il in it. Im sure most of you dont run it on std UL petrol, so choose oil wisely. It isnt that expensive.

Bob Rawle

Theory's change by the year, at one time everyone advocated drilling extra holes in the bearing shells, also the feed to no 3 was said to be furthest from the oil pump, in practice there is no difference in oil feed length and drilling holes in shells just reduced the pressure of oil in the bearing, its still an enigma but the common factors are ... recently serviced/servicing technique, oil quality and ... high revs for extended periods. Its fair to say (I think) that if an engine is rebuilt it rarely fails again ... probably cos most people uprate at the same time, there are exceptions of course but those serve to "prove" the rule.

There is no doubt that if an engine is allowed to detonate it will eat pistons and overpower the oil film strength but there are a large number of failures where this is not the case.

Most people I have info from would admit to the high revs for extended period though.

Bob (still collecting info if its available)

Pavlo

I was looking at the closed/open deck block thing today, and was wondering if the closed deck block helps a bit, simply by keeping everything more rigid, like keeping the bearings square and so on.

I wonder if the later blocks suffer distortion, that leaves the bore no longer square to the big end bearing.

Engine failures to seem to be more prevalent in newer style engines, judging from the number of people that have mentioned failure on here.

What happened to Andy "The exception" Forrest's thread with failure survey.

Paul

ustolemyname??stevieturbo

iTrader: (1)

funny you mention drilling things... I drilled out the last section of the block, that feeds the centre main. It was only 7.5mm compared to 10mm+ for all the rest of the pipes leading to it. I only drilled to 8mm, but maybe it will make a difference. I also drilled out the main journal drilling for supplying the big ends. Its a 5.5mm hole, that feeds both journals 2 and 3. I drilled it out to 6.5mm, as it does split into 2, so in my wisdom, i reckon it should be bigger. The other big ends are fed individually from a similar 5.5mm drilling in the main journal.
Perhaps my crank will break, but WTF, Im always game for trying ( stupid ) ideas.
I wouldnt reccommend anyone else doing it though, as a lot of my bright ideas do backfire.
I did not alter the bearings in any way though, but was tempted.

[Edited by ustolemyname??stevieturbo - 7/31/2002 3:09:23 AM]

Pavlo

when's your car going to be back together?

Paul

David_Wallis

how long to you need to to run for to class it as reliable... 1000 miles is reliable in a car for me

David

ustolemyname??stevieturbo

iTrader: (1)

1000??? You expect a lot, Im happy to get to the petrol station and back.

mutant_matt

Just in case it wasn't clear, there was a huge thread which discussed this on the board last year and Bob collected quite a lot of data on cars that blew up. Hopefully, someone can dig that thread out for people to read again.

If there is anyone out there who has had a blown engine, please let Bob know the details so he can add them to his database.

Cheers,

Matt

nichop

Think this was it...

http://www.scoobynet.co.uk/bbs/threa...hreadID=103976

EvilBevel

Try this one :

http://www.scoobynet.co.uk/bbs/threa...ThreadID=29769