A theorey on the cause of porous heads (C20XE and C20LET)

**Nemesis** · 27-02-2006 08:50

This was put to me by somebody in the Vauxhall tuning world...

He reckons the porous heads aren't caused by any sort of metal going porous at all. He thinks the poorer casting on the non-coscast heads is weaker. This means when the headbolts are torqued up, it can cause the head to fracture between the oil and water gallery. This wouldn't happen so much on coscast heads, being of a better quality.

Any thoughts on this?

**Gary** · 27-02-2006 09:28

so, how was that cave on Mars ?

**chip** · 27-02-2006 09:39

Wow chav what an interesting new theory lmao lmao lmao lmao

**chip** · 27-02-2006 09:39

Does he also think that wheels are most effective when they are round?

**htimsllib** · 27-02-2006 09:46

so how does the porous mod fix "this" theory too then?

**Gary** · 27-02-2006 09:47

there, only a light mauling.

(p.s that theory is correct, and was discovered several centuries ago by the Incas)

**artfulmatt** · 27-02-2006 09:47

Chav - old news mate

that were discovered about 10 yrs back lmao

**TurboCavGSI** · 27-02-2006 09:48

Originally Posted by htimsllib

so how does the porous mod fix "this" theory too then?

It by-passes one of the chambers or re sleeves it.

**chip** · 27-02-2006 09:49

Originally Posted by htimsllib

so how does the porous mod fix "this" theory too then?

where it cracks (its NOT porous, thats the wrong word) a tube is inserted to block it up again.

roman soldiers also used to use the same pipe for picking bits of chicken out of their teeth, as they too knew about the way in which the heads fail, in fact everyone except chav does lmao

**TurboCavGSI** · 27-02-2006 09:50

Originally Posted by Chavtastic

This was put to me by somebody in the Vauxhall tuning world...

He reckons the porous heads aren't caused by any sort of metal going porous at all. He thinks the poorer casting on the non-coscast heads is weaker. This means when the headbolts are torqued up, it can cause the head to fracture between the oil and water gallery. This wouldn't happen so much on coscast heads, being of a better quality.

Any thoughts on this?

The tighening sequence of the head bolts were updated because of this.

**chip** · 27-02-2006 09:58

Originally Posted by TurboCavGSI

The tighening sequence of the head bolts were updated because of this.

Yep, 10 years ago vauxhall technicians found an ancient scroll left by the vikings, they found this out in the year 500bc, and is part of the reason why norwegiens know how to make 700bhp LETs

**TurboCavGSI** · 27-02-2006 10:02

Originally Posted by chip

Yep, 10 years ago vauxhall technicians found an ancient scroll left by the vikings, they found this out in the year 500bc, and is part of the reason why norwegiens know how to make 700bhp LETs

lmao "Being John Malkovich" be intresting to have a look around your head Chip.

**astragsiturbo** · 27-02-2006 10:38

Originally Posted by chip

Yep, 10 years ago vauxhall technicians found an ancient scroll left by the vikings, they found this out in the year 500bc, and is part of the reason why norwegiens know how to make 700bhp LETs

lmao lmao Nice one mate lmao lmao

**Aamir** · 27-02-2006 12:54

**sbd16vastra** · 27-02-2006 14:46

when i see this i thought it must have been an old thread bummped

**Big Col** · 27-02-2006 15:06

Originally Posted by Chavtastic

This was put to me by somebody in the Vauxhall tuning world...

He reckons the porous heads aren't caused by any sort of metal going porous at all. He thinks the poorer casting on the non-coscast heads is weaker. This means when the headbolts are torqued up, it can cause the head to fracture between the oil and water gallery. This wouldn't happen so much on coscast heads, being of a better quality.

Any thoughts on this?

nae flies on you, eh flash? lmao

next you'll be telling us what MIG stands for .....

**chip** · 27-02-2006 15:25

Originally Posted by Chavtastic

This was put to me by somebody in the Vauxhall tuning world...

I love the way you say that as if it was someone after your advice on if it was true cause he values your opinion so much.

Nice attempt at looking important, but try not to use a "new theory" that everyone already knows next time lmao lmao lmao lmao

Owned by yourself lmao lmao lmao

**artfulmatt** · 27-02-2006 15:27

Originally Posted by Big Col

next you'll be telling us what MIG stands for .....

(holds hand in the air and asks what ??) lmao

Mike and something ain't it ??

**Scoobler** · 27-02-2006 15:43

Seeings as we are on the subject, I have a file put toghether from info I have read, and recently updated it with the two fixes as a step by step - only there to give people an idea of what they need to do, but I could do with someone double checking it for me?
Clicky Here

**lee303** · 27-02-2006 15:55

Originally Posted by artfulmatt

(holds hand in the air and asks what ??) lmao

Mike and something ain't it ??

mike, ian, gareth iirc, three founder members

**incentive** · 27-02-2006 17:02

funniset thread for a while :P

**Nemesis** · 27-02-2006 17:14

SO why do people call it porous head? Why do people still talk of metal going porous?

Sorry guys - I can guarantee I'm not the only one who didn't realise

**alistairolsen** · 27-02-2006 17:19

because folk assumed it was porosity untill they made your sudden realisation, its just they made it a bit earlier. (watch time team on sunday evening for info!)

**Tathan** · 27-02-2006 17:22

porous metal is caused by gas bubbles in the casting process not being expelled. Machining the surface exposes these pockets and metal can 'leak' under pressure if it's crap quality. That would happen from the factory though, not something that appears a few years later.

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