f_inscreenname

What are your rpm's at WOT?
I know everyone is a little different but just looking for a number.
For those interested,
I have a stroker/roller Mark IV 496 that I was running at close to 5200 with a 23P due to running out of prop pitch to run (props are limited for Volvo Pentas). Changed gears from 1.61 to 1.35 in the drive over the winter and all options are now back on the table being I'm now at less than 4200 @ wot with the same prop.. I pretty much think my motor would be all in around 4600 and really don't like running it for extended times at 5200 even though I like firewalling it a lot. Thinking maybe 4800 was a better number but if you all are running them hard who am I to be different.

Griff

Carbed 454mag with cam/exhaust upgrade= 5400rpms
525SC with roller cam and increased boost= 5300rpms
502mpi with CMI's = 5100rpms

I see no reason why you shouldn't spin any decent marine engine with forged internals to at least 5000 rpms at WOT.
It actually does more harm running them over propped at lower rpms. It puts more load on the engine across the entire rpm range.

f_inscreenname

Well that's good to know Griff. I get ya on lugging the motor and the drive for that matter. That's how I broke the vertical shaft in the drive I got the 1.35 gears out of. Just to much torque and to big of a prop for the little Volvo 250. After 13 or so motors in this boat and after replacing all the cast iron in the motor (block, heads) and building an outdrive (with very rear 1.35 gears) this winter and not having this boat most of last year I thought this time I would do things a little different even if it means loosing an mph or two.

articfriends

Yes, as griff said, torque loading a motor is very bad, spark knock/detonation , prop it for where your cam peaks at. I turn 502's 5500-5700 with stock internals and slightly better cam, my 540 turned 6300 under boost fwiw

f_inscreenname

Wow I should be looking for a 19 to get me back to 5000 then. I have some tuning to do and will get a couple more hundred rpm's out of the motor so 5200 is a real number I should be shooting for. Do you all run wot much and for long periods? I may do it for a minute (60 seconds) but not much more then that before I feel like I should pull back to the low 4's at least.

Black Baja

I run 6300 rpm from Harve de Grace to the Bay Bridge and back.

class6

From the George Washington bridge to Cape May. about a hour and 40 minutes

SB

An engine's peak torque is at peak cylinder pressure. AT WOT you want to accelerate past this, not be stuck at it.