Originally Posted by Raylar

Just to give everyone here some more credible info:

Raylar has dyno tested on ours and other dynos probably more 496Mag and 496HO engines both stock and with our various upgrades, kits and engine packages than almost anybody on the planet.
A stock full y equipped 496Mag makes about 365-380HP at 4800 rpms at the crankshaft.
A stock fully equipped 496MAG HO makes 421-430 HP at 5000 rpms at the crankshaft.
This is on calibrated, SAE standard testing, with correction factors and specific fuel gravity calculation adjustments and these numbers are pretty much spot on - PERIOD!

Best Regards,
Ray @ Raylar

Originally Posted by jeffswav

Wow, thats good info, all the info I have seen rates those types of numbers at the prop. If you figure 10% loss that is way over estimated.

Originally Posted by tcelano

According to the figures I've computed before, the TRS or III with a transmission will approach 10% driveline losses, while a Bravo is 5% or so.

Originally Posted by Raylar

I will post this one last time!
I know there is printed and website info from Mercury Marine and others that is confusing and sometimes just flat wrong.
My sources and tell me that since 2000, all Mercruiser (black)engines up to 2010 are dyno tested at the crankshaft on Mercruisers Stillwater dyno's.
The Mercury Racing (Blue) engines in Fond Du Lac are dyno tested on Mercruy Racing dyno's and are rated for approximate horsepower at the propshaft with their drive HP correction factors added.
This is why the HP525efi for example will test SAE on a new properly running engine fully equpped at about 540-550HP on most good dynos at the crankshaft and is rated at 525 HP at the propshaft.

Best Regards,
Ray @ Raylar

Originally Posted by WildRooster

I just did a repower myself....had a 496 and researched it quite a bit before selling it and going with brand new horses. I've heard good and very bad stories about trying to beef up the 496. It has cast internals and needs to be completely replaced to make any kind of difference with maintaining reliability. I've got the 25 OL(not the 26) and it's 150 lbs less...and my 496 mag(375 HP) pushed it to 63-65mph at 5000 rpm depending on temp. If you are turning a 26p B1 at 4900 rpm, you should be seeing 70 at least. I'm not a fan of the B1 as it creates azz lift instead of bow lift like the baja hulls require. The B1 is made for a heavier boat. My opinion is if you find the HP and start getting 75-80 mph out of this setup...the B1 will create some issues in handling vs going to a 3 blade Mirage. I'm


Artic, i'm curious about your comment on a 5 blade prop? You think the 5 blade will help in bow lift? Wouldn't it be hard to turn that thing to any rpm's with this setup? If you're getting 560 HP....IMO it should be turning a 25 Mirage. BBlades can offer a more professional than mine.