What heads on engine?

I see a Donzi in the back ground....I can only wish it would fit in my Donzi. Put it on the Donzi FB page

Nice, what upgrades were made during the rebuild that produced that 150 hp gain?

@BnBz28... It is probably worth noting that the numbers may be a little apples to oranges, compared to your 540... At what RPM did you make 650? - This engine is being twisted to 6200 to make that number, (more RPM at a given displacement somewhat emulates larger displacement at lower RPM) Think in terms of the engine acting as a simple air pump... You gain more CFM with RPM... more air + more fuel = more power... If you look at the numbers between 5k-5.5k the engine is making the modest gains you'd expect over a HP500 given the cam swap, additional bump in displacement, and compression (keep in mind it is now a 509)... So the numbers seems pretty realistic, all things considered. Frankly speaking, I think the cam choice may not be optimal, as the power keeps climbing into an area where the engine would generally see little use, and begins to reach relatively high piston speeds for the hardware involved. That said, however, it should fair well in terms of reliability as it is not built to the bleeding edge to make bloody murder at 5.5k RPM.