CJ240

Hey guys.. I've been doing some testing on the new boat.

It has a 496HO in her and I currently am seeing 61/62 mph on the GPS.
The previous owner said he saw 65.
I am assuming that he was referring to the speedo and not the GPS.
While the GPS blips between 61/62 the speedo reads 65-66 (understandable).
I do have a smart craft system monitor gauge on-board and I noticed at WOT I am only seeing 4750-4775rmps. It's a bravo 3 with dual 26props.

I Know Merc rates the motor from 4600-5000 max rpm. Should I be seeing another couple hundred RPMs? Do these motors make power all the way to 5000 or am I am the falloff point where I am?

Trying to squeeze every last pony and mph I can.
It's a stock 425hp 496HO
Thanks!

SDFever

Prop work.

47EXCALIBUR

you can spin that motor to 5400rpm no problem....lab those props and you will gain 300rpm....that should put you wheere you want to be....call brett at bblades he did mine

Plum_Crazy

??? The rev limiter is 5150 on a stock 496HO.

Baja_man

ECM can be sent in to raise it.

picklenjim

It's only going to go so fast and turn so many RPM for the boat it's in. It's well with in the range merc rates it at. Probably makes power to 5K but your just not going to see it with those props. You can try different props but in the end your probably only going to see a couple mph difference if any and a thinner wallet.

endeavour32

iTrader: (4)

What kind of boat is it?

SDFever

It's not a good idea to raise the limiter and prop that engine to 5400.

Even if you do, the torque curve won't hold up to allow you to actually "use" the additional 200 + rpm.

So you will spin the props faster after you set the limiter higher and you won't see anything worth the effort.

If you are leaving the engine stock, the best bet is to prop the boat/engine to 5100 and leave it at that. This will be your cheapest, most noticeable gain.

This all of course is leaving the other "half" of the conversation out of it (the boat).

If you insist on bumping it up to 5400 with no other upgrades you will most likely regret that decison unless you sell the boat soon after.
It would be good however, to adjust the setup so that you are running the engine at or very near the rev limiter at wot.

This horse has been beaten before if I remember.

thirdchildhood

iTrader: (6)

Prop it to where you are bumping the rev limiter warning buzzer in ideal conditions.

Knot 4 Me

Bob Lloyd of Full Throttle has dyno specs of stock 496 MAG and MAG HO's. They make their peak HP at about 4,700 and 4,900 RPM respectively. The only thing you will gain by raising the rev limiter to 5,400 RPM is a lighter wallet.