We ran the 400/512 with light weight crank all summer. We had some issues early on, but seemed to get by them. Quickest it went on pump gas was a 6.19 in the 1/8th at 110....The 440/512 went as quick as 6.14 at nearly 112....We were catching the 440 based one as we kept jetting the 400 up but ran out of season. The 60ft with it has been 1.35, its the top end we have been looking for more. It doesn't pull as hard on the top end as the other engine. Same cam and heads, so we have been wondering why...