Pantera24

Ok let's say you have a 330hp 454 with a TRS, what would the prop shaft hp be approx.?
Any help appreciated.

BY U BOY

i thought all the black motors were rated at the prop shaft.

Pismo10

They didnt start prop hp until the late 80s/early 90s. 300-310hp at the prop.

KAAMA

iTrader: (1)

Just FYI, the Merc 330hp usually dyno'd out by independant dyno shops at lower HP than what Merc was advertising. I was often told anywhere from as low as 270hp thru 313hp was the best seen with Merc's stock cast iron exhaust.

I don't know what others may have heard/found, but over the years I was also told that you could pretty much subtract about 30hp by the time it went through the tranny to the prop on a TRS. A Bravo drive might be slightly different.

Westcoast

THat is just great

KAAMA

iTrader: (1)

I hope I didn't spoil it for you by what I said. I use to do a lot of research on the Merc 330 back in the early/mid 1980's. I remember Ray Baker tellng me back then that from what he has found is that a new Merc 330 usually averaged anywhere from 280-290hp with 270hp being the lowest----heck it may have even been lower than that, but it was so long ago that I cannot remember everything he said.

I remember another independant shop in the Detroit area said the best they found on a new stock Merc 330 was only 313hp, but found them to usually be in the 280-290hp range as well and I guess the best way to look at it is that's probably why Merc gets a lot of hours out of the 330.

Actually, you can have a little fun by upgrading your 330's to at least 400+hp or so (depending on how far you want to go). Do a word search and you will find some interesting threads on performance mods of the old Merc 330. Have fun~

Pantera24

Guys I appreciate all of your input.
But let me explain why I ask...and mind you I am not an engine builder obviously..but this is the way I see it.
I have a boat that when original had a 454 with a TRS and ran 54-56 at WOT. So what I'm thinking is this, take out the 454 and TRS and replacing it with a Supercharged SBC and a Bravo XR. More specifically the new Magnuson MP112
http://www.magnacharger.com/pdf/flyer-GenOne.pdf
In my mind this little package saves a lot of weight and produces very good HP and more importantly torque which I will need to get this heavywieght moving decently.

My question is for you supercharger and blower guys..this Magnuson is kind of like a Hybrid between a Roots style and a Centrifugals..I'm not sure if it will maintain constant boost through out the power curve. Does anyone have any experience with the Magnuson MP112??

Any help is appreciated.

bobl

I haven't tested the TRS/transmission package but I've done a lot of dyno testing on Bravo style drives. I built a supercharged small block that dyno'd at 555 HP at the flywheel. I installed it in the boat and dyno'd it at the propshaft and it made 490. I just finished dynoing a 496 HO. It made 387 at the prop and 431 at the flywheel. So, it becomes apparent that Bravo's lose approximately 10-11%. I'm sure the TRS loses more than that.

KAAMA

iTrader: (1)

Pretty interesting comparisons! Heck, I didn't realize/think it would be that much of a loss---especially on a Bravo drive! Thanks for the eye opener though. I guess that's even more depressing info a performance boater could be sad about!