Blown Engine
Thread Starter
Registered User
Joined: Oct 2002
Posts: 2,441
Likes: 0
From: Miami Lakes
Originally Posted by Asura,Jan 9 2006, 03:24 PM
1) Check the pan for california gold rush sized flakes of bronze bearing material.
2) Have an engine machinist inspect the crank journals and the crank itself for
trueness. The sleeve installer could/will probably do it along with the block journals.
3) Remove the valves and check for trueness. A bent valve may not show up until after the re-build. You will have to tear the head off again if a guide wgets destroyed from an out of round stem that caused high leak down numbers.
Just saying to check everything thoroughly while the car is down.
2) Have an engine machinist inspect the crank journals and the crank itself for
trueness. The sleeve installer could/will probably do it along with the block journals.
3) Remove the valves and check for trueness. A bent valve may not show up until after the re-build. You will have to tear the head off again if a guide wgets destroyed from an out of round stem that caused high leak down numbers.
Just saying to check everything thoroughly while the car is down.
2) This is already scheduled to be done while the new Darton sleeves go in.
3) This is also being done along with a 3 angle valve job.
Thread Starter
Registered User
Joined: Oct 2002
Posts: 2,441
Likes: 0
From: Miami Lakes
Originally Posted by doorman,Jan 9 2006, 06:16 PM
Oh Shit. I just saw this. I bet it had something to do with plug failure. When I had my denso fail it had the same black ring around the porcelin part. Man and you just got it set right. 
It's Joe's car btw, not mine.
Registered User
Joined: Feb 2004
Posts: 671
Likes: 0
From: Atlanta
Originally Posted by Fyrestrike,Jan 9 2006, 06:21 PM
Well it's obviously a plug failure, we're just trying to prevent the same thing from happening again.
It's Joe's car btw, not mine.
It's Joe's car btw, not mine.
Thread Starter
Registered User
Joined: Oct 2002
Posts: 2,441
Likes: 0
From: Miami Lakes
Originally Posted by RadioZero,Jan 9 2006, 11:26 PM
obvious lean condition on #2. how can you guys use stock plugs on a boosted engine? sorry but newbie to the S2k forums, i come for the VW 1.8T world.
Thread Starter
Registered User
Joined: Oct 2002
Posts: 2,441
Likes: 0
From: Miami Lakes
Some new information:
The notion has been brought up that the likely cause of any spark plug failures is tuning. As I briefly mentioned above, the timing cut was set to 9500rpm and the fuel cut was set at 9700.
When we were at the dyno tuning the car (knowing that the head could rev to ~11k) we tried to find where the max power was. A dyno pull to 9000rpm produced 380.0whp at 9psi, and a pull to 9500rpm produced 380.0whp at 10psi.
At this point we figured that the cams could not keep up with the added boost pressure and we had reached the point of diminishing returns. However, because it didn't lose any power we told the tuner to set the redline at 9500rpm.
This is where the debate starts. There are several ways to set a redline: timing, fuel, or both. The stock ECU cuts timing AND fuel (someone confirm) which is why the rev limiter hits like a ton of bricks. The AEM is more flexible however, and by cutting timing without fuel it is possible to slow the acceleration of the motor by cutting timing.
The tuner then placed the timing cut at 9500 and the fuel cut at 9700. Another tuner is now telling us that this may have been the problem. How long does it take an F20C under 10psi of boost pressure to cover 200rpm? Is it faster than one cycle of the AEM's processor? Is it possible then that timing was cut (creating a misfire essentially) and the plugs began to overheat until their cooling supply (fuel) was cut a fraction of a second later? Was the timing backed down so much that the spark lagged an entire stroke of the engine and created knock?
Food for thought, man I'm starving...
The notion has been brought up that the likely cause of any spark plug failures is tuning. As I briefly mentioned above, the timing cut was set to 9500rpm and the fuel cut was set at 9700.
When we were at the dyno tuning the car (knowing that the head could rev to ~11k) we tried to find where the max power was. A dyno pull to 9000rpm produced 380.0whp at 9psi, and a pull to 9500rpm produced 380.0whp at 10psi.
At this point we figured that the cams could not keep up with the added boost pressure and we had reached the point of diminishing returns. However, because it didn't lose any power we told the tuner to set the redline at 9500rpm.
This is where the debate starts. There are several ways to set a redline: timing, fuel, or both. The stock ECU cuts timing AND fuel (someone confirm) which is why the rev limiter hits like a ton of bricks. The AEM is more flexible however, and by cutting timing without fuel it is possible to slow the acceleration of the motor by cutting timing.
The tuner then placed the timing cut at 9500 and the fuel cut at 9700. Another tuner is now telling us that this may have been the problem. How long does it take an F20C under 10psi of boost pressure to cover 200rpm? Is it faster than one cycle of the AEM's processor? Is it possible then that timing was cut (creating a misfire essentially) and the plugs began to overheat until their cooling supply (fuel) was cut a fraction of a second later? Was the timing backed down so much that the spark lagged an entire stroke of the engine and created knock?
Food for thought, man I'm starving...
Registered User
Joined: Oct 2000
Posts: 4,467
Likes: 3
From: Davie, FL
This really sucks 
. Group hug for Joe.
I'm not too familiar with engine failure modes, but I agree with RWD RCKT - it sure looks like the piston is melted. I don't know if it was the failure mode or not, but there sure is a lot of the piston missing. I'd think that if it happened after the failure, that there wouldn't be so much vaporized material.
. Group hug for Joe.I'm not too familiar with engine failure modes, but I agree with RWD RCKT - it sure looks like the piston is melted. I don't know if it was the failure mode or not, but there sure is a lot of the piston missing. I'd think that if it happened after the failure, that there wouldn't be so much vaporized material.