alcazar

iTrader: (2)

NO, NOT mine

It's just that when your engine DOES let go, you get interested in why. Mine knackered it's big end bearings due to heatsoak and det. Now I can see why, from an engineering point of view, it did it.

But why/how would an angine put a rod THROUGH the block?

Turbotits

iTrader: (2)

rod bolt snapped or rod cap or rod itself snapped, if at high revs they hit the block so hard that the block cracks

Splitpin

Energy, and bad luck. Rod snaps (especially at the little end), you have several ounces of metal flailing around inside the crankcase - material that is probably travelling at several hundred miles per hour. And don't forget that even if one cylinder suffers a failure, you've got three more plus the inertia of the car's forward motion coming back through the transmission to keep the crank rotating.

It's a matter of pure luck what happens if a rod fails - and where the energy gets dissipated. If you're unlucky and a broken little end wedges against part of the block, it'll punch a hole straight through.

dunx

iTrader: (3)

Try battering anything with a broken con-rod one hundred times a second....

dunx

chris-RB5

My rod snapped in my old engine, went straight through the block casing and straight through the crossover pipe.Went with one hell of a bang then **** loads of oil out of the exhaust, When i stopped and popped the bonnet the engine bay was just covered in oil and water not a very good luck on a engine bay that had just been detailed a week earlier. But still manage to reverse it into the garage off the AA truck though.

Cunaide

if you down shift to quick that can put the rod and piston through the block, i know of some one who had a 500bhp evo and thats what they done

bigsinky

being revved out in 4th up the drag strip and changing back to 3rd instead of up to 5th will do it. a nice hole about 3 inches wide at the top of my block. oil everywhere. not good. no trailer either so i had to leave my car in the IOM and get it some weeks later.

Alan Jeffery

Crank journal seizure is the usual one. The rod bearing lubrication fails due to excessive bearing clearance. The hammering from the rod flattens the bearing, which then rotates in the housing. Friction overheats the surfaces, then the subsequent seizing solid snaps the rod and pokes it up through the top surface, taking the water cross feed housing with it. Quite spectacular when it happens!
We have seen rods snap without bearing failure, but very rare, and I'd say inevitably due to driver input error.

alcazar

iTrader: (2)

Thanks for the input. What's the science behind the mis-shifting doing it?

dunx

iTrader: (3)

13,000 rpm will do it !

Ek !

dunx

bigsinky

it certainly does

Alan Jeffery

Inertia must play a part in an over rev failure situation. I dare say you could make out a case for various different compression and expansion stresses involved.
The worst case I saw was a Ferrari Dino 246 engine totally destroyed by a rock ape who wildly over revved it. I recall the first thing I found when he asked me to check why it wouldn't run was an air filter case full of little tiny bits of piston!
I had the small end from one con rod in my toolbox for ages as a souvenir.

chris-RB5

Or being a idiot and putting a vf35 on without having it mapped. Live and learn

gallois

i remember my kid bro borrowing my dads pride and joy scorpio cosworth for the weekend, and the phonecall, 'the cars broke down, theres oil and bits of metal all over the floor' it smashed the sump and engine block, and although he denies it, i recon my bro was driving it in '2' instead of 'D' (it was an auto) when he said he pulled out to pass a car on the dual and was only doing 90 (at about 9000rpm no doubt), never seen my dad cry before that.