HP rating: 496HO vs. 525EFI

[Carl C]

Are both rated at the crankshaft? That would put the HO @425hp & the EFI @ 525hp. I was told that the 525EFI is actually closer to 570 crankshaft hp. Is that true or is there only a 100 hp diff between the 2 motors?

[BigGrizzly]

Carl, I don't think the 525 is 570. Merc never under estimates.

[Carl C]

Thanks Griz, that's what I thought. Merc did lowball their outboard ratings in the past though to make them look better over the competition.

[DC18]

Both are Crankshaft ratings.

[Carl C]

Thanks guys, that's all I needed to know right now.

[BigGrizzly]

Actually Merc now has an issue with EPA. on the outboards. You see there is an enissions requirement and it is plugged into a computer, if it doesn't work out they have to prove it, and that is very difficult to do in this day and age. If thay make a line change to any emissions part it has to be recertified, been in this one before, and they love us.

[handfulz28]

What happened to "Blue rated at the crank, black at the prop"?

It's "common" knowledge the 525s crank dyno higher than 525 and unlikely the 496HO would crank dyno above 470hp (assuming 10% drivetrain loss). But there's plenty of reading to be had...

http://www.speedwake.com/upload/showthread/t-55363.html

[BigGrizzly]

You should read closely one of those guys think a 496 is a stroked 454. The 525 runs well but it is no where near 570. I also see dyno numbers scattered all over the place. I can only go by what I see. At this point Carl has his info.

[Pismo]

According to Ray who has dynoed many of these...

Regardless of the merc marketing system, a 496HO puts out about 425hp crank and a 525 puts out about 540-550hp crank.

[Carl C]

What happened to "Blue rated at the crank, black at the prop"?

It's "common" knowledge the 525s crank dyno higher than 525 and unlikely the 496HO would crank dyno above 470hp (assuming 10% drivetrain loss). But there's plenty of reading to be had...

http://www.speedwake.com/upload/showthread/t-55363.html

Yup, I remember that thread. I'm in it! I am CC there. Stay tuned, getting ready to set the water on fire.........................

[Air 22]

http://www.mercuryracing.com/sterndrives/hp525efi/specs.php

[Carl C]

[quote=Air 22;503751]http://www.mercuryracing.com/sterndrives/hp525efi/specs.php[/quot

Dwight, will it bolt up to the Bravo X? Are you switching drives?

[Air 22]

[quote=Air 22;503751]http://www.mercuryracing.com/sterndrives/hp525efi/specs.php[/quot

Dwight, will it bolt up to the Bravo X? Are you switching drives?


Yes it will bolt up fine to your drive...your engine mounts may or may not need some tweaking...I have an BX as well w my HP500EFI..not switching anytime soon...it only has 80hrs on it..:pimp:

[Carl C]

[quote=Carl C;503752]


Yes it will bolt up fine to your drive...your engine mounts may or may not need some tweaking...I have an BX as well w my HP500EFI..not switching anytime soon...it only has 80hrs on it..:pimp:

Thanks. Stay tuned..............

[Donziweasel]

Carl, I have a line on the brother to my engine. 9,900.00, CMI's, 600 hp, less than 20 hours.....built like a chit brickhouse, will handle 800+.

[The Hedgehog]

According to Ray who has dynoed many of these...
Regardless of the merc marketing system, a 496HO puts out about 425hp crank and a 525 puts out about 540-550hp crank.

Yep,

Eddie has dynoed a few himself. That is what he says too.

[Carl C]

Carl, I have a line on the brother to my engine. 9,900.00, CMI's, 600 hp, less than 20 hours.....built like a chit brickhouse, will handle 800+.

I am working on something else now. Can't say much at this time.

[Air 22]

Yep,
Eddie has dynoed a few himself. That is what he says too.


Hedge..That makes sense.... the 525HP Mercury Racing prints is PROP HP? Thus a 10% +- HP loss from the Crank to Prop does this sound correct?
ex..550HP Crank - 10%+- = 495-500HP@ Prop?

[The Hedgehog]

Hedge..That makes sense.... the 525HP Mercury Racing prints is PROP HP? Thus a 10% +- HP loss from the Crank to Prop does this sound correct?
ex..550HP Crank - 10%+- = 495-500HP@ Prop?

I heard it was something like that.

[CHACHI]

You should read closely one of those guys think a 496 is a stroked 454.
Not to confuse the issue but you can build a 496 from a 454. Bore it .060 over and stroke it .250. Slight clearance issues but very doable.

Carl, I guess you are on your way to new power, but I haven't read anything about you bolting on external steering.

Are you just "collecting" parts for the future?

Ken

[BUIZILLA]

Not to confuse the issue but you can build a 496 from a 454. Bore it .060 over and stroke it .250. Slight clearance issues but very doable. my brother and I probably built a dozen or more like this, had to clearance the block in a few areas, but all in all a GREAT combination...

[Carl C]

Not to confuse the issue but you can build a 496 from a 454. Bore it .060 over and stroke it .250. Slight clearance issues but very doable.

Carl, I guess you are on your way to new power, but I haven't read anything about you bolting on external steering.

Are you just "collecting" parts for the future?

Ken

Stay tuned ;). Going on a road trip Monday. Looks like an overnighter since my second driver fell through.................

Yes, I know about the two diffrerent 496s. Opie on Speedwake should have known better;)

[CHACHI]

Hummmm..............the 525 on OSO is sold and Carl is taking a roadtrip on Monday.
Is it possible that..................

Ken

[Carl C]

hehe...I suck at keeping secrets...It's not a done deal until it is in my truck and on it's way to Michigan. I am looking forward to the trip to the South. Southerners rock; Might even try some of those hominy grits........Pecan pie for sure......yum.....

[BUIZILLA]

suck it up.....

Nashville isn't that far.... :convertib:

[Carl C]

suck it up.....

Nashville isn't that far.... :convertib:

I will see how it goes. The problem is that I work hard on Sunday (today) and won't be starting out real well rested. I'm on the lap-top @ work now. Maybe I can make it a one day deal but if I'm falling asleep at the wheel I will stop.

[hot shot]

Carl: You still have time to get it and the steering in the boat and make it to aoth.....

[Carl C]

Mick, I am going to run this last season under warranty with stock power. This is not going to be a week-end project. I will be reinforcing the hull and Murphy's law will certainly kick in. It will be a winter project.

[Brian41]

Carl, Drop off 1 of the pups on your way by and you can see Mic's boat. Brian

[Carl C]

Carl, Drop off 1 of the pups on your way by and you can see Mic's boat. Brian

That will be about 4 AM. I will knock hard ;)

[harbormaster]

The blue motor torque comes in at higher rpms than the 496ho.

We had a customer who put 500efi's in his formula 400SS and endedup pulling the out and replacing them with 496HO engines because the blue motors did not perform as well at lower rpms...

[donzi2287]

You are being brutal!! I like blue!:yes:

[Carl C]

I like higher rpms:yes:. Got to try to get to sleep by 8:00 so I can be on the road before 4 AM. It is snowing like crazy here right now, we've already got an inch, and after a real mild March. I'll be wearing shorts though. Expecting around 70* in Nashville.

[donzi2287]

Sorry @ that Carl C. It is 82 in the Keys!!!!! Come on down! Have a safe drive!!!!

[Cuda]

Sorry @ that Carl C. It is 82 in the Keys!!!!! Come on down! Have a safe drive!!!!
It was even warmer in Eustis yesterday, wasn't it? :)

[Carl C]

2 inches now:eek:. 'Night Johnboy.