What makes a Mag and Mag?

[JV II]

You guys can't be serious! A 40 - 45 MPH boat is NOT fast, a 60 - 80 MPH boat is fast....

A boat built to go 60-80mph would not be scary. A 17,000# floating mobile home that goes 50mph is scary. Get it?

 

[JV II]

Horizon's are fresh water cooled and can be on a stern drive. I have them on mine. Mercury now calls them "Seacore"

No, you can have fresh water cooled stern drives that are not Sea Core engines/BIIIs. They do not call all fresh water cooled stern drives Sea Cores. Sea Core is an upgrade.

 

[ultratiger89]

A boat built to go 60-80mph would not be scary. A 17,000# floating mobile home that goes 50mph is scary. Get it?

What's scary to one person is not to another. :grin:

Plus, how many people cruise at WOT?

 

[JV II]

Anyone know what makes a Magnum a Magnum?

 

[JimG]

My 0.02 dollars... In the early days the Magnum was always more HP because of the electronic, high output ignition. There are likely other improvements to increase performance.

My boat has twin 350 Mags at 300HP each.

Foot-note: The Horizon is a closed circuit cooling system available at least on V-Drives, not sure about I/O's.

 

[ultratiger89]

Anyone know what makes a Magnum a Magnum?

some research produced this:

Here are the differences:
Regular 350: 350 Magnum:
Cast iron pistons Steel pistons
Cast iron crank Steel crank
Regular intake manifold High rise intake manifold
260 HP 270 HP

like others on here have said, more HP, stronger internals.

 

[K-9]

Magnum=bigger

 

[keokie]

Anything Merc chooses to call a Magnum is a Magnum. Their reasons over the years have changed.

 

[JediJD]

Anyone know what makes a Magnum a Magnum?

Yes. It refers to a 1.5 liter bottle as opposed to the standard .75 liter.

 

[rondds]

When ordering my previous boat, I opted for the 350 Mag Horizon/B3 package. There was no Seacore then (2002). I paid $2600 more for this package b/c:
a) 40 additional HP
b) full FWC
c) MPI
d) duo-prop
d) three year warrantee on engine and drive (one year was standard on the carb'd 350)

That was a long time ago and I'm working from memory only, which isn't the most reliable source!

 

[Tail Chaser 661]

So, nobody really knows. If a 496 Magnum is high output at 375 HP, then there is the 496 Magnum HO with 425 HP. Would that be a 496 Mag Mag? Then shouldn't there be a plane old 496 with 325 HP?


So, when someone askes me what a 496 Mag is when they see the cool black covers on my engines and hears that start-up baritone music, I'm going to say it is a high output version with 50 extra HP per engine.

Your question was answered a few times.
Now days, A New Mag engine really means nothing.
A base GM 8.1 marine engine is 375 HP. Thats about as detuned as they come. It would not have been cost effective for MFG's to change cams, etc to have HP in the 320HP range like the base 454ci. The 8.1 is a replacement engine for the 454ci and 502ci.
HO is the higher HP engine now days.
The 8.1 HO has a different cam and fueling calibration to get the extra HP over the basic Mag engine. The max TQ is the same on both engines. The HO models max HP/TQ is at a higher RPM then a Mag engine.
The 8.1 Mag has about the same Grunt/TQ as a 320HP 6 cyl inline diesel. Over 500 lbs tq at 3200rpm :grin:
The 5.7 engines have tq around 355 lbs. Adding HP does not help the 5.7 tq much. :smt089

 

[Bridog]

No, you can have fresh water cooled stern drives that are not Sea Core engines/BIIIs. They do not call all fresh water cooled stern drives Sea Cores. Sea Core is an upgrade.

i wonder what the differences are between the Horizon's and Seacore?

 

[Tail Chaser 661]

i wonder what the differences are between the Horizon's and Seacore?

Seacore is a Merc upgraded corrosion protection package.
FWC, Stainless bolts, etc. Nothing to do with engine power.

 

[sprink56]

http://www.gm.com/experience/technology/gmpowertrain/engines/specialized/marine/marine_engines.jsp

Check that Super Charged LSA engine...I would really like to be in a position to drop a pair of those into a late model 34DA and see how it would perform. When you compare the TQ curve to an 8.1 and then look at the weight difference it's a real eye opener. You would pick up about 200 Ft. lbs in the water and shave about 1000 lbs of displacement off the boat....bound to be significant in a boat that size.:thumbsup:

 

[JV II]

i wonder what the differences are between the Horizon's and Seacore?

http://www.mercruiserseacore.com/

It is significant. Anodized inside and out.

 

[JV II]

Your question was answered a few times.
Now days, A New Mag engine really means nothing.
A base GM 8.1 marine engine is 375 HP. Thats about as detuned as they come. It would not have been cost effective for MFG's to change cams, etc to have HP in the 320HP range like the base 454ci. The 8.1 is a replacement engine for the 454ci and 502ci.
HO is the higher HP engine now days.
The 8.1 HO has a different cam and fueling calibration to get the extra HP over the basic Mag engine. The max TQ is the same on both engines. The HO models max HP/TQ is at a higher RPM then a Mag engine.
The 8.1 Mag has about the same Grunt/TQ as a 320HP 6 cyl inline diesel. Over 500 lbs tq at 3200rpm :grin:
The 5.7 engines have tq around 355 lbs. Adding HP does not help the 5.7 tq much. :smt089

Thanks. That makes it more clear. I was thinking that the torque of the 496 Mags feel exactly like a diesel.

Am I right in thinking that the "detuned" 496 Mag having 375 HP will last longer than the HO 496 Mag? There is a formula using HP and displacement to determine a ratio. I forgot where I read about this. The lower the ratio the better in terms of longevity. 375/496 = 0.76. 425/496 = 0.85
If the 496 Mag and HO have the same HP, why bother with the HO?

 

[Tail Chaser 661]

Thanks. That makes it more clear. I was thinking that the torque of the 496 Mags feel exactly like a diesel.

Am I right in thinking that the "detuned" 496 Mag having 375 HP will last longer than the HO 496 Mag? There is a formula using HP and displacement to determine a ratio. I forgot where I read about this. The lower the ratio the better in terms of longevity. 375/496 = 0.76. 425/496 = 0.85
If the 496 Mag and HO have the same HP, why bother with the HO?

The max torque is the same but at different rpms 3200rpm for the Mag vs 3600 rpm. Max Tq for the 8.1 HO is 3600 or 3700rpm. The HO actually has a little less Tq at lower rpms then the Mag.
The HO has more HP at a higher rpm and has a higher redline.
They have specs on them engines on GM powertrain.com
I would think the valvetrain may be more stressed on the HO. No telling if the cam has a higher lift or longer duration to get the higher rpm/hp on the HO.
I believe the dependability ratio you read about was from a 20 yr marine surveyor. His article was about the new high rpm diesels not being any more reliable then a good gas BB. The most reliable engines were low HP Big block gas carbed crusader engines and big low rpm diesels. The 8.1 seems to have a very good reputation for reliability.
I almost repowered with a Volvo 260hp D4 diesel. 200 pounds heavier then the 8.1 Cost 10k more, 60 lbs less Tq and seems to have some reliability issues. I would have got 3 mpg with the diesel though :huh: Expecting to get 2 mpg with the 8.1 loping along at 2500 to 3000 rpm. 23 to 30 mph.:grin: Major delays getting parts for the repower :smt013

 

[Tail Chaser 661]

http://www.gm.com/experience/technology/gmpowertrain/engines/specialized/marine/marine_engines.jsp

Check that Super Charged LSA engine...I would really like to be in a position to drop a pair of those into a late model 34DA and see how it would perform. When you compare the TQ curve to an 8.1 and then look at the weight difference it's a real eye opener. You would pick up about 200 Ft. lbs in the water and shave about 1000 lbs of displacement off the boat....bound to be significant in a boat that size.:thumbsup:

That engine does show some nice numbers.
If I was freshwater into going fast a lot. That engine would be a very good choice. It may be a bit overstressed for long term dependability.
With my boat being a converted fishing boat. I kind of wish I had a simple carbed big block with 500 lbs Tq. Not enough power in a 454ci and I could not get a turn key 502ci.
500 lbs of Tq is was needed to move my boat at least 26 mph at 3000rpm or under. Hopefully having easier starting with a EFI engine is going to be worth it.
Would be fun to have the money to drop in and try out different engines at will. Maybe even let someone else do the work

 

[sprink56]

That engine does show some nice numbers.
If I was freshwater into going fast a lot. That engine would be a very good choice. It may be a bit overstressed for long term dependability.
With my boat being a converted fishing boat. I kind of wish I had a simple carbed big block with 500 lbs Tq. Not enough power in a 454ci and I could not get a turn key 502ci.
500 lbs of Tq is was needed to move my boat at least 26 mph at 3000rpm or under. Hopefully having easier starting with a EFI engine is going to be worth it.
Would be fun to have the money to drop in and try out different engines at will. Maybe even let someone else do the work

I wouldn't hessitate for "Salt Life" with the LSA...look again...it comes "closed cooling only":thumbsup: God only know what they will ask for that bad boy...would be fun to open the hatches and watch some jaws drop.:grin:

 

[Tail Chaser 661]

I wouldn't hessitate for "Salt Life" with the LSA...look again...it comes "closed cooling only":thumbsup: God only know what they will ask for that bad boy...would be fun to open the hatches and watch some jaws drop.:grin:

I already have the 8.1 sitting in my garage. All I have to do now is turn the computer off long enough to install it :smt021