05-03-2014, 06:45 PM
Heat - it's the main reason Peugeot went away from Indirect injection once CR Direct and computer airflow simulation came in - the precups need to stay hot to keep the next combustion cycle clean and smooth, but understandably under high load, keeping enough heat in them for the next combustion cycle vs them overheating vs requiring too long to heat up on cold start is a fine line.
When you tune them, trust me, those cracks become significantly worse!!! As Darren found - they can end up being released from the head in the end...
Remember, these things take the full brunt of *every* combustion cycle for that cylinder - the burning hot diesel floods past them every stroke.
If you're interested, at 2750rpm that's 330,000 times every hour they have diesel, midway through combusting rammed through them.
When you tune them, trust me, those cracks become significantly worse!!! As Darren found - they can end up being released from the head in the end...
Remember, these things take the full brunt of *every* combustion cycle for that cylinder - the burning hot diesel floods past them every stroke.
If you're interested, at 2750rpm that's 330,000 times every hour they have diesel, midway through combusting rammed through them.
