She made 705 hp @6100rpm and 670tq @ 4600rpm and was pulling power all the way to 7000rpm

OH and its PUMP GAS from 7-11 !!!!!!!!!!!!!!!!!!

that is a KILLER motor!

Very nice!!

What all has been done to the motor? I thought the 502s were right around 625 out of the crate.

502s make 500hp ot of the crate . thats why merc call them HP500s

this thing will idle at 400-500 rpm also , very important for a boat .

Very nice. Gotta love big blocks!

I dont know a thing about boats. Why is the extremely low idle desirable?

Im pretty sure its for control when docking the boat & for no wake zones...........

I was just going to say I think it's because Boats don't have brakes.

also the lower the idle speed the easier it is on the outdrive, higher speeds and it slams in gear when going from forward to reverse. mainnly though for docking manuvering etc.

any pictures of the boat it is going in?

For those not familiar with high H.P. boat motors, the have the same problems we do. They eat outdrive with to much idle speed and H.P. just like we eat transaxles. Fly the boat out of the water and not let off is just like not letting off the gas on a big jump. Parts, scatter.

Lower idle speed is needed to save the drive when shifting from N to forward or reverse , And for docking.

For another perspective, we dynoed the gm performance 572 and it makes 650 hp on pump gas. this engine is a 540 making 55 hp more with a pretty safe tune. it also has a huge power band and pulls all the way to 7000 rpm. we detuned it a little and run the limiter a little lower to make it live a long time. ready to go in the boat it is making 705hp.

Estimate on cost for this thing???

If ya gotta ask...........

Change those header collectors and you'll get 50 more hp.

those are perfect numbers for a boat nice rpm range. what size and type of boat?I am thinking a larger boat with an i/o

Nice! Love the 540s. Ive got 2 in the boat and 1 for the rail. Nothing but 87 octane to be found on Powell so they have to be mild. Both getting r&r and dyno love in next couple months.

Gallons per mile but with a big smile!!

Josh has the same thing but he has 2 motors 2 blowers !!!