What's the correct boost level in each gear?

[BRY]

He had a boost spike - so was driving part throttle for a while.

Driving part throttle is not going to cause a lump of metal to fall out of an exhaust port. If it was the seat or valve that had melted then it would be related. The ports have been opened out too much - it was only a matter of time. I expect he got the head done at the same place my head was done by the previous owner (both work was done by the same garage) - not a good job done on either of them - both have had problems due to bad workmanship.

He does ten thousand miles on his engine, including Castle Combe, and then within half an hour of having a spike, the engine is fooked, and that's nothing to do with the spike?
Just coincidence?

Because another forum member has said he is experiencing spikes, I thought it would be a good idea to warn them about Johnny's engine.

This is a Forum, it's about spreading knowledge and experience, that's why people come on here, The facts are as I stated, you cannot dispute them.
Johnny's engine lost no coolant or oil before the boost spike/s so how can you state it has nothing to do with it?

[Jamo]

Hey guys chill!

[BRY]

That's rich coming from you!
The handbag is out and ready to be deployed

[Jamo]

That's rich coming from you!
The handbag is out and ready to be deployed

Not in my thread it aint!

[audiman]

The damage was just bad luck on Johnnys car. That sort of thing can happen to any car. If the port had been opened up to far on the port job then it would have been weak, and was only a matter of time before it went. Its a real bas£ard, but its just pure bad luck. I recently had the hose split that controls the WGFV and that gave it no boost control. I had massive spikes of 2.4-2.5 bar boost. That was over a 1000 miles ago and my engine port hasnt broken out.

[BRY]

The ported head would have been a factor, as would the boost spike, but without the boost spike there wouldn't be this conversation, as the engine has been to two rolling road sessions and gone round Castle Combe without any mechanical problems relating to the cylinder head, the boost spike comes along and then it's dead.
Where was the overboost protection ?
It still boosted to 24psi after the spike.
How can that be allowed to happen by the Motronic with all it's safety features???

[Greg_S]

BRY, the reason that boost occured on toms car was because the WGFV lost control through the ECU so boost spikes were aloud to occur.

[BRY]

BRY, the reason that boost occured on toms car was because the WGFV lost control through the ECU so boost spikes were aloud to occur.

I get that, the reason I posted was to alert other forum members of the dangers of boost spikes.

[Greg_S]

doh! see what you were getting at now

[Doug_RS2]

Bry, you are right, use a boost controller and by the way, put a K-Jetronic injection on your car, along with that nice Hitachi ECU that has no knock sensors, off the Ur-quattro. It'll be muuuuuuuuuuuch safer!


Mihnea

[BRY]

Bry, you are right, use a boost controller and by the way, put a K-Jetronic injection on your car, along with that nice Hitachi ECU that has no knock sensors, off the Ur-quattro. It'll be muuuuuuuuuuuch safer!
Mihnea

and cheaper and probably have the same results

But remind me, what was I right about?

I was stating facts and haven't gone on about any boost controllers or other ecus.

Spread the knowledge, and chill

[Doug_RS2]

Bry, I have been holding off for a while replying to this thread but it's gone a bit too far. Talk to experienced mechanics, talk to whomever you want, I don't think anyone will ever agree with you saying that Johnny's head has cracked in an exhaust port because of a boost spike, this is the highest level of nonsense that I have ever experienced. Remind me, are you a mechanic/engineer of some sort?

Spread the knowledge, ok fair enough but not when it's about absolute BS without any technical background, ok?


Mihnea, chilled beyond recognition

[BRY]

Bry, I have been holding off for a while replying to this thread but it's gone a bit too far. Talk to experienced mechanics, talk to whomever you want, I don't think anyone will ever agree with you saying that Johnny's head has cracked in an exhaust port because of a boost spike, this is the highest level of nonsense that I have ever experienced. Remind me, are you a mechanic/engineer of some sort?

Spread the knowledge, ok fair enough but not when it's about absolute BS without any technical background, ok?


Mihnea, chilled beyond recognition

Beyond recognigntion - is that why you are logged on as Doug?

Remember I didn't get personal here, you have decided to.

I have a BEng in Mechanical Engineering for the record with a Post Graduate Diploma for good luck too, and I'm using finite element @nalysis right at this moment in time, as it happens, on ProEngineer.
Is that qualified enough for you?
Who the f@ck do you think you are?

Would you care to explain the chain of events?
Because you, or anyone else, haven't yet.

I'll have another try and go slowly:

There was a boost boost spike, the car did not feel "right" straight after this and began to run really badly, Johnny stopped the car. Recovery man arrives and then Johnny trys to pull the car onto the recovery vehicle. One big bang later, there is dead engine due to oil / water in the no 2 cylinder causing the engine to self destruct.
No water / oil loss prior to the boost spike for 10k miles including two rolling road sessions and Castle Combe.
After the boost spike and before the engine hydro-locked Johnny said it had emptied the expansion tank. Do you know where it went? I can guess.
Why would a cylinder head suddenly crack after such a long time in service?
What parameters could have changed which would bring about this failure?
Could it be an increase in load on the cylinder head?
What would cause this increase in load?
Lets examine the operating conditions and see if we can find a sudden change in them.
35psi boost spike would be an increase in one of the operating parameters by about 35-40%.
I think I've discovered the reason for the "sudden" change in parameters which resulted in the failure.

Doug has already stated that the head had been weakened by porting, so you could argue that this is the straw that broke the camels back, a 40% increase in boost is a big straw.
I am saying that without the boost spike it wouldn't have happened at all. There is a fine line between an optimised part and a failure and perhaps this cylinder head was too near to that line.

I can't smell any BS in that lot, can you?

You stripped it, what did you find?

Please go step by step so that myself and others might be able to follow your logic.

Spread the knowledge

I may not have as much S2 experience as yourself and others on here, but I cannot understand your personal approach to this issue and my postings. These are my ideas/theories on what happened and I would be swayed by a reasoned arguement but not by mud slinging.
Convince me, don't rubbish me.

[Fat Audi 80]

Regardless of what has been said before this, I am interested if it is possible for a standard car to run dangerous levels of Boost WITHOUT the ECU knowing. I do not have a boost gauge and at the moment am happily booting my car about assuming it is going to look after itself if something goes wrong and retard the timing or go into limp home mode etc....

Perhaps I should start a new thread, but I think my question is related to most of this thread.

Cheers,

Steve

[martinjs]

Steve, If you have a leak in the small hose from the wgfv to the turbo coldside then you can get high levels of boost as Tom has said. It happened to Mark H also.