What is the difference between a 496Mag and a 496MagHO?

Uncle Dave said:

If I were going to bothering going into the block with a cam and tune, Id replace the exhaust and maybe heads as well because thats what lets the rest work.

To bother with all that effort and go 2/3rd of the way feels like Im almost finishing the job almost getting some performance gain, but spending a bunch of time and dough for a tiny bump.

Starting in the low - mid 70's you need steering before you can really go any faster safely - ask a 20+ footer loaded with people gas and booze at 75MPH to make a reasonable tight turn at speed and the stock stuff starts showing its weaknesses.

you have to spend more more money to get over the 80 hurdle safely.


UD

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That is the exact reason to just swap the cam and leave well enough alone. Your drive, and engine internals will already support the extra power. The cost of modding the engine with a simple cam swap will be well less than half of the cost of the price difference of a 496 vs an HO when the boat was new. How else are you going to gain 50 reliable HP in a boat for a couple grand and not need a snowball of mods to support it?

HO :eek

TOP DEFINITION
ho
Slutty girls, usually but not exclusively high or middle school. For some reason they think $%@#&* will make them cool or popular. Most are too dumb to realize being called a ho isn't exactly a compliment and most will be remembered as hoes for the rest of their lives.

Or....ho
A word Santa Clause says three times when he sees your wife, mother and sister together in the same room.

jetboatperformance said:

HO :eek

TOP DEFINITION
ho
Slutty girls, usually but not exclusively high or middle school. For some reason they think $%@#&* will make them cool or popular. Most are too dumb to realize being called a ho isn't exactly a compliment and most will be remembered as hoes for the rest of their lives.

Or....ho
A word Santa Clause says three times when he sees your wife, mother and sister together in the same room.

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So what your saying is - you give 'em the bump stick, and it makes them a HO !

Bigbore500r said:

So what your saying is - you give 'em the bump stick, and it makes them a HO !

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Fo S HO:thumbup:

Bigbore500r said:

So what your saying is - you give 'em the bump stick, and it makes them a HO !

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jetboatperformance said:

Fo S HO:thumbup:

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What about the HOs in different area codes?

LargeOrangeFont said:

What about the HOs in different area codes?

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4-9-6, 502's....5-4-0, 632's

"No matta where I gooooooo, I see the same HO's!!"

LargeOrangeFont said:

That is the exact reason to just swap the cam and leave well enough alone. Your drive, and engine internals will already support the extra power. The cost of modding the engine with a simple cam swap will be well less than half of the cost of the price difference of a 496 vs an HO when the boat was new. How else are you going to gain 50 reliable HP in a boat for a couple grand and not need a snowball of mods to support it?

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Is it really 50 you get?

Anybody dyno this?

typically a top end job gets you 100, and cast internals will support this.

Either way wrecks the warranty.

UD

Uncle Dave said:

Is it really 50 you get?

Anybody dyno this?

typically a top end job gets you 100, and cast internals will support this.

Either way wrecks the warranty.

UD

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Isn't every 496 in existence out of warranty?

Merc says you get 50 HP, and we seem believe them for everything else. 375 to 425 in the HO.

I do not know how straightforward an 8.1/496 cam swap is. It looks like only the intake manifold needs to come off, and the oil pan can stay on. I read a guy that had never done a cam swap before did it in his Yukon with an 8.1 and it took 10 hours. With the back seat out of a boat, this seems pretty straightforward.

I found this posted elsewhere, don't know if it's true and its from 2007...

"Thought I would chime in here also and answer a few questions in this thread and offer some biased advice!
First, the only difference between 496MAG and 496MAG HO's are the camshaft and the program in the ECU. Some of the 496MAG's have a smaller bleed hole in the throttle plate in the throttle body so when and if they are converted or equipped with one of our kits or an HO cam and ECM conversion the throttle body plate needs to be drilled out ot 1/4" to 5/16" depending on which cam is used. This extra bypass air keeps the idle air motor at a lower count (operations per second) and thus keeps from having the idle air motor in constant motion.
This is not needed on a stock 496MAG or 496 Mag -HO unless each is modified.
Some early 2001-2002 496 HO's had the forged crankshaft until GM Powertrain - GM quit using them in lieu of GM's own new pressure rolled fillet nodular iron special 496 crank (bean counter decsion). Its nothing like an earlyier GM cast iron crankshaft, much better part and nitirided too.
The forged units are a bit stronger and lighter than the cast crankshafts but both are very capable of handling 600-700HP without failures.
We purchased all the remaining un-used forged crankshafts and we have them in stock still and we use them in our 496 - HO525's and HO600 motors when requested. We also have 4340 forged crankshafts for the 496's and a stroker size crankshafts for the 496-8.1L engines.

As for the 496 connecting rods, they are forged rods, early ones with pressed pins the later ones with full floating pins.
These rods are metric length in stroke (6.683") and will not interchange with 454-502 sizes because they also have a metric daimeter pin (actually measures about 1.043") which is larger than the standard BBC .990" size pin.
The reason we do not use these rods with our custom Mahle 496 pistons is because they are not in our opinion strong enough for over 600HP and the metric 10mm dia. rod bolts are not as strong as good ARP 7/16" rod bolts we use in our Raylar H-beam billet rods that come in our piston & rod sets for the 496-8.1L
You could rework the stock rods for some forged pistons or have custom piston sizes made, but the cost of rework and custom pistons is higher than we sell our Raylar/Mahle piston / H-beam billet rod sets for and they are capable of handling 800-1000 hp quite easily!
We also have quite a few 496HO cams in stock that are take-outs for those who are convinced they need to convert their Mag to an HO, but they will still have to have Whipple or us reprogram there ECM to a HO spec.
My suggestion is to put on a good exhaust like Dana or CMI and get 40HP plus and then when they can see or afford to upgrade their 496mag with our Raylar BCK103 kit and ECM reprogram they will have 560HP - 496 without wasting to much money and time when they will most likely want to upgrade from an HO cam in the future.
One could use this package for the life of the short block, then upgrade the shortblock with one of our exchange shortblocks or build their own with our parts and depending on bore and stroke size chosen they could still have a 496 based engine that delivers between 625 and 675HP, normally aspirated on 89 pump gas.
We can also supply forged supercharger blocks or block upgrade kits with supercharger pistons , special cams and inconnel exhaust valves, then with the addition of the great Whipple supercharger system you can boost up to 750-800 HP levels
Wholla- no built-in obsolesence or wasted use and money!

Just something to ponderwhen considering what to do with your 496.

Best Regards.

Ray @ Raylar"

The HO cam is considerably larger than the MAG cam, and you can really hear it at idle.

496 MAG Cam specs-

204 /209 @ .050
.480 /.483
118 LSA

496 HO Cam specs-

224 /233 @ .050
.510 /.510
114 LSA

The larger HO cam is sporting 20 more degrees of intake duration, and 22 more degrees of exhaust duration, as well as .030" of extra lift @ the valve. LSA decreases 4 degrees to keep the DCR up, and keep the power band where its needed - closer to 5000rpm.

The 50hp gain from a "cam only" is due to just how ANEMIC the stock 496 MAG cam is.

To put it in perspective - A stock LS3 Cam is 206 / 212 .551 /520 117 LSA.......and thats on a 376" Motor ! A cam smaller than that in ALL respects is feeding 496" of engine on the MAG

Bigbore500r said:

The HO cam is considerably larger than the MAG cam, and you can really hear it at idle.

496 MAG Cam specs-

204 /209 @ .050
.480 /.483
118 LSA

496 HO Cam specs-

224 /233 @ .050
.510 /.510
114 LSA

The larger HO cam is sporting 20 more degrees of intake duration, and 22 more degrees of exhaust duration, as well as .030" of extra lift @ the valve. LSA decreases 4 degrees to keep the DCR up, and keep the power band where its needed - closer to 5000rpm.

The 50hp gain from a "cam only" is due to just how ANEMIC the stock 496 MAG cam is.

To put it in perspective - A stock LS3 Cam is 206 / 212 .551 /520 117 LSA.......and thats on a 376" Motor ! A cam smaller than that in ALL respects is feeding 496" of engine on the MAG

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Good god the base cam is pathetic. I need to buy stock in Mercury. $6k for a cam swap

LargeOrangeFont said:

Good god the base cam is pathetic. I need to buy stock in Mercury. $6k for a cam swap

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In their defense - Mercury cams are made from unobtanium, machined with diamonds and lubricated with pixie dust

Bigbore500r said:

In their defense - Mercury cams are made from unobtanium, machined with diamonds and lubricated with pixie dust

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And they are only stored vertically to keep perfect concentricity.

Different cam

Bigbore500r said:

In their defense - Mercury cams are made from unobtanium, machined with diamonds and lubricated with pixie dust

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No unicorn farts?

LargeOrangeFont said:

Isn't every 496 in existence out of warranty?

Merc says you get 50 HP, and we seem believe them for everything else. 375 to 425 in the HO.

I do not know how straightforward an 8.1/496 cam swap is. It looks like only the intake manifold needs to come off, and the oil pan can stay on. I read a guy that had never done a cam swap before did it in his Yukon with an 8.1 and it took 10 hours. With the back seat out of a boat, this seems pretty straightforward.

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496's yeah - new mags and mag ho's no.

Interesting ray says an exhaust is with 40HP.

UD

LargeOrangeFont said:

Good god the base cam is pathetic. I need to buy stock in Mercury. $6k for a cam swap

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Yeah thats pretty piss weak.

I ran a 236/242 @.50 .510/510 / 110LSA in my 406 and it idled at 850

Bigbore500r said:

In their defense - Mercury cams are made from unobtanium, machined with diamonds and lubricated with pixie dust

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You will get shot around these parts for saying anything even slightly negative about the Mercury God's lol

I've decided to leave it alone. It doesn't have through hull exhaust and I literally could not tell if the motor was even running. I really dug that for once.:thumbsup

GRADS said:

I've decided to leave it alone. It doesn't have through hull exhaust and I literally could not tell if the motor was even running. I really dug that for once.:thumbsup

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Use the money your saving to upgrade your helmet [emoji106]

Sorta funny to see a Raylar quote in a thread discussing reliability [emoji12]

That 496 cam is terrible, I can't believe a swap and reflash don't give more than 50 hp.

Would be cool to see a dyno sheet for the 496 and HO for comparison.

pronstar said:

Sorta funny to see a Raylar quote in a thread discussing reliability [emoji12]

That 496 cam is terrible, I can't believe a swap and reflash don't give more than 50 hp.

Would be cool to see a dyno sheet for the 496 and HO for comparison.

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At that point I?d flash it with the whipple stage 1 flash with the cam swap. Those things are so underpowered it is no wonder they last 1000+ hours!

pronstar said:

Sorta funny to see a Raylar quote in a thread discussing reliability [emoji12]

That 496 cam is terrible, I can't believe a swap and reflash don't give more than 50 hp.

Would be cool to see a dyno sheet for the 496 and HO for comparison.

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Maybe one measured at the flywheel and the other at the prop? That's what I was searching for when I found that info.

rvrrun said:

Maybe one measured at the flywheel and the other at the prop? That's what I was searching for when I found that info.

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I've got to think Merc has a consistent procedure for rating their engines, wouldn't you think?

707dog said:

The mag motor has cast lower end parts and the magho has forged steel...please correct me if I'm wrong just going off what I thinki know didnt Google it yet

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My 496HO had forged steel crank & piston rods making it more accepting for upgrading the horsepower. This was a 2001 motor & there's a good chance they quit building them like this due to costs.

GRADS said:

I've decided to leave it alone. It doesn't have through hull exhaust and I literally could not tell if the motor was even running. I really dug that for once.:thumbsup

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So we didn?t know the boat in question would be like cam swapping a motorhome.......lol

pronstar said:

I've got to think Merc has a consistent procedure for rating their engines, wouldn't you think?

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They are rated the same. Why would they be different? Gaining 50 HP from a cam swap on a large V8 is easy, especially considering the base cam.

pronstar said:

I've got to think Merc has a consistent procedure for rating their engines, wouldn't you think?

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I would think, but mfgs do screwy things sometimes for advertising.