Contour Enthusiasts Group Archives Forums Modifications 3.0L Duratec Piston durability

My engine in N/A form used to run 800 Celsius at 6700 rpm! This was after it was dyno tuned into the correct 12.5:1 A/F at 6700 rpm. I ran it a bit leaner in the lower rpm range but as it got up in rpm the temp still would climb. These engines just run hotter and they are made of more advanced materials than the average ford pushrod motors.
Turbo Tom's zetec is turbo so he is probably using fuel to keep the mixture cooler.
I try to run 12:1 or 12.5:1 with my turbo unit right now.
The only modifications that most of these people have made to their motors is boost. Some cracked pistons without having a dyno tune, like me.
-The hand porting jobs can be hit or miss I agree.
-BTW, I used the same tuning before and after the intercooler on my car. BEFORE I put on the intercooler I cracked two pistons. I put new pistons in the motor and then carefully drove it to the dyno in AZ to get the intercooler fitted and dyno'd with A/F.
The very first run with the intercooler on it and THE EXACT SAME A/F curve as previously when I cracked the pistons!! I put down 300 wHP and the A/F was 12.5:1

Therefore, the problem was in high combustion pressures/temps and possible that threw the A/F off enough along with the excess heat to make light detonation or it was just plain too much pressure.

Since then I have been running 50% more boost and no problems that I know of.

All your points are good except that:
1. Duratecs in good tune run high combustion temps.
2. The 99 and earlier pistons are definitely a weaker design...we have the pictures of the two types of pistons to prove it.