gus

iTrader: (1)

What causes this?

Heard this a bit lately

I'm unsure what causes it

rsmark86

iTrader: (3)

High cyclinder pressures at a guess?

Only happens on big power cars, or with idiots who I've seen run a garden hose into a over heated car so rapidly cooling a extremely hot metal engine

SBT83

I've seen this happen! Such idiots

gus

iTrader: (1)

High cylinder pressures.

What sort of high power?
Boost?
Revs?

SBT83

Weakness in the block over time. High revs build internal pressure and heat. Loads of different reasons.

Ben26

Heat heat heat.+ Mine cracked when a rod came through the front

gus

iTrader: (1)

O dear Ben. Was it a crack or a big gaping hole?

SBT83

that will be the high revs then

gus

iTrader: (1)

How many revs is high revs?

Ben26

ill let the pictures answer your question










yes it was, with standard bottom end as well, but ive learnt my lesson as it cost me a few quid in new stronger parts

gus

iTrader: (1)

Extra core plug?????

SBT83

Good question! At a guess on a NA car probs 5K. Do that in a forced inducted engine and pressures are a lot higher in the cylinders. Pistons maybe able to take it with them being forged but the only other weak link is the head gasket or block.
I knew some one who was in 3rd gear at 50mph and went straight down to 1st just to show what would happen. Pistons through the block private land also

SBT83

Ben how the fuck did you bend that con rod like that I imagine it did cost a few quid too

russ rs

That's bad

Ben26

like I said quite a few revs lol.

basically I was showing off with a few people in the car. they all had to phone for alift home after this happened

had to go forged after that for piece of mind all fully balanced


have a look at my resto on the car

see what u think
https://passionford.com/forum/restor...-new-pics.html

lacey

What did your shells look like in the rod that popped out the side ?

Ben26

from what I can remember they where fine,as they had only done about 800 miles !!!!!!!!!!!!!

frsjon

the last one i saw cracked was right across the front.all i can think of that made it do it was years of running with no antifreeze,just water...

GVK.

Ah, the special ventilated crankcase version.

GVK.

Not a CVH (it's a VAG 1.8t) but check this carnage!





http://www.clubgti.com/showthread.ph...nk-pulleys-Bad

Ben26

^ now that is very impressive , didn't the crank snap ? looks like it

GVK.

Aye, was put down to not having a crank pulley damper on it, had a Neuspeed 'power pulley' on it. Built by ex BTCC engine builders Swindon race engines too!

Ben26

So did it have a guarantee on it then.

Big power was it ?

rsmark86

iTrader: (3)

i dont think its revs or boost, but a combination of the both, abit like a zetec oil pump

one or the other is fine but with both it would cause alot of heat i guess

i bet most of the time the blocks crack when cooling, ive seen alot of rs's that after a good kick in have been fine untill you switch the car off the overheat and chuck water everywhere

rsmark86

iTrader: (3)

i know revs aint the problem as ive had an n/a engine revving to 8200rpm and was fine, although it did snap a brand new solid lifter once.

GVK.

Was a race engine in a Leon for Castle Combe saloon champs, not sure on warranty or power sorry.

Ben26

o right I thought it was for a private customer


No oil in sight, is that the pleasure of dry sump ?

SBT83

I'd have thought the oil got left in a puddle for someone to clean up

CrOwSoN15

Fatigue of the metal? Considering even the youngest CVH lumps are 15+ years old now, with the constant rapid heating/cooling, that has got to be a contributing factor?

SBT83

Exactly this! Years of strain is gonna break its back eventually.

CrOwSoN15

Although saying that, people using Silvertops for a ZT, they aren't exactly young either, so why don't they fail?!

SBT83

They are extremely strong tho. Handling 500hp+ with little signs of stress in some cases.
The cvh was never gonna hit that mark. Around 300s the best your gonna get if built properly, and that's stressful.

It could have been a lingering weakness in the material that eventually gave way to heat, pressure, harmonics although unlikely but never rule it out

gus

iTrader: (1)

hmmmm

more reason to look into getting an ally block made

CrOwSoN15

Why, has yours gone mate?

Could go down the 1900 route, they're stronger.

gus

iTrader: (1)

nope mine is fine

but i think i rev harder with more boost then most

studabear

This is why I now have a blacktop zetec turbo, last year I had 3 cvh's in the bay, the second I driven 3 times and ripped it out again as it was cracked across the front, leaked when hot.

I decided I couldn't chance spending the money building a fully forged cvh in case it cracked.

gus

iTrader: (1)

if i do go ally block i will be doing something either big bore short stroke or visa versa

Ben26

Is that 100% proven ??????. Or is it coz there are less of them around so u hear about less of them going bang !

Karlos G

iTrader: (4)

As already said it's metal fatigue, years of heat cycling making the metal brittle.

SBT83

Not so much stronger as per say. But because they're a taller block they probably carry the load a little better.

Hence the reason ford used it as a base for the zetec

Karlos will tell you the same