Well that's where things get really strange, and this block question comes in to play..How much Boost you push through these motors???
Ya have 2 identical engines, both running same RPM and HP most of the time. Both tuned identically. With boost in the 30-40 range, no issues on either Above 40psi, one engine starts leaking into cooling, while other engine is fine.
Running the Evans coolant, the Happy engine has less than 3psi on the system at any time no matter how hard ya push it. However on the dyno we noticed some coolant pressure creep on the Stbd or Problem Child engine soon as we got into the mid 40's psi or above 800hp range. You can actually see it on a gauge we had hanging in those videos.. Soon as we pushed 50+Psi and 900hp, it popped the cap. We wrote that off to those early LML head gaskets.
Now 3yrs, 4 Victor head gaskets, and 2 different heads later, problem childs leak pops up again, soon as I cranked up the power into that 850-950hp range. Just like it did on dyno. Other engine has literally ate a billet turbo wheel, and then drank couple gallons of salt water next day out, and still only make 3psi on the coolant system.. It's a beast.. lol
So if this was a single engine setup, one could speculate a bunch.. However, when ya have 2 with identical hours, and only one has this issue... Believe this project has taught us, if one fails, second is not far behind. Except for this issue.. My money is on the deck surface.