sosatime

A 706 Ci Dart Block What Kind Of Horse Power Can I Obtain Naturally Aspirated?

Ebay Ed

i think the pro stock drag racing motors are in the area of 1200 + HP on a carb and racing gas

Young Performance

A good rule of thumb on pump gas in a marine app. is about 1.25-1.30 hp/ci. That would put you in the 900-925 neighborhood. The problem is that the cost to build that engine is as much or more than a comparable supercharged, proven engine that will have more than twice the longevity. With an engine that big, you will need Big Chiefs (and all the valvetrain longevity issues that go with them), a custom sheetmetal intake, etc, etc, etc. Then, the engine is so tall and wide that it can only go in some singles, staggered twins and some cats. There is just a limited market for something with limited uses and a huge price tag. You could do a 540 with a Whipple and make more power than that, and not only would it live so much longer, but it would probably be cheaper.
I would love to build one. I think a 700+ ci engine is cool as hell, I just can't justify it. If someone wants one, I would be glad to do it. I have been involved with them before, so I know what it takes. Since I've done both, I know which is the more sensible route to go. That still doesn't mean that a 700+ ci engine would not be really cool. My .02 for what it's worth.
Eddie

Raylar

A 632 cubic inch reasonable cost big block is about as big as you should go unless you want to spend lots of extra money for limited availability and very specialized parts.
To get those type of cubes you have to go to a 11" or so deck height with difficult overly long strokes or a 5" bore spacing block with its associated special high cost parts.

A good N/A 632 inch pump gas engine can easily make 750 -825 HP and depending on particulars and thats a lot of torque and power for a single N/A engine.

What and how are you planning to power what boat combination with this type of engine??

That may be the even more important question.

Best Regards,
Ray @ Raylar