PB4Y Privateer was NOT a B-24D. They had different configurations and the PB4Y had no turbochargers on the engines, being designed to cruise over sea at low alts looking for subs. The engine nacells had a round shape because of this omission.
Further, considering that the max speed for a B-24 with minimal fuel and at full throttle and no ord onboard is 300mph, I find it hard to believe that "max cruise" keeps you above 280 with ease. Please take a look at HTCs speed charts.
As for 100% fuel, it:
1) slows the plane down. The plane is heavier, so level flight will be a little slower, but specifically it slows the plane down by:
2) reduces climb rate. AH currently gives heavy bombers 2-4x their normal climb rate because nobody ever takes more than 50%, and rarely goes more than 25%. Reducing climb rate means the bombers take longer to get to alt, are slower while climbing (best climb speed vs top speed) and if they want to level out to get to target on time are at a lower altitude, helping counter-balance their high top speeds (lower alts = lower speeds, gives attacking fighters better chance to engage).
What we need is a separate fuel multiplier for the 4-engine bombers. Jack the fuel burn up to 8x or so, force them to take 100%, and CRUISE properly to the target and back, and then you'll get historical performance numbers. That or they run outta fuel and ditch before reaching the target!
Oh, and of the US bombers destroyed? By far the majority of ALL bomber losses in the war were from FLAK, so the numbers Stoney gives are misleading. The percentage lost were high, but keep in mind when you have 1000+ US bombers, and maybe 200 US fighters escorting (or much less) at any time, compared to less than 100 LW fighters sent up to attack them, not counting the LW fighters sent up to dogfight with escorts, and taking into account that many LW planes made a single pass and were gone before the US bombers could shoot them down, most LW planes didn't get any kills on their attack runs. So saying 50% of US bombers were killed is misleading because a small small fraction of that was from LW attackers.