[Spencnaz]

What is the max safe boost pressure for a 6.9? I have a Hypermax nonwastegate on mine.

A friend of mine cracked a 6.9 in two when he was running 15psi.

I know that a 6.9 really wasnt meant for boost, but I would like to know what kind of boost limit I should be watching out for when I slap a boost gauge on this mill.

 

[agnem]

12 seems to be the suggested maximum. I don't know about cracking them in half. I'd think your headgaskets would let go before that happens.

 

[94_turbo]

block cracked in half???? had to be defect from factory--hairdryer just showed up the defect--think pistons would melt--and other things break before crack block----

 

[Spencnaz]

yes it was a defect from the factory in fact. there was a hairline crack along a mold ridgeline that popped. in one of Ford's rare customer service moments, they replaced the block for free on the condition that it be sent back to Dearborn for analysis by the engineers.

yeah 12psi sounds about right what with the current compression ratio of 21:1 or therebouts.

I'm going to install a boost gauge in addition to the ISSPRO pyro that's on there now. I just like to see the boost pressure come up when I'm towing stuff /ubbthreads/images/graemlins/laugh.gif