Horizon vs Mercruiser....Difference?

[davefin]

Never gave this much thought before, but can someone enlighten me.

Is the only difference between these two motors the fact that the Horizon is fresh water/closed system cooled and the Mercruiser is not. I am about to purchase a complete stbd engine for my dancer that is currently raw water cooled. My plan is: If the cooling system as I described is the case I would like to buy a Horizon 5.7 EFI for the stbd and a fresh water conversion kit for the port Mercruiser 5.7 EFI engine that was replaced only a couple of years ago. Thus making them now both closed cooling systems.

 

[HUMPH]

True story that the Horizon is a closed cooling system model of the MPI but it also comes with a better warranty. Closed cooling system in a salt water boat is a very good idea! Well worth the money IMO.

 

[fwebster]

Horizon and SeaCore are just marketing names for the salt water versions of various Mercruiser power packages. Generally, the salt water versions will have better corrosion protection and some parts choices are made for longevity in salt environments.

When shopping, try to pick a Horizon or SeaCore model because, in addition to the obvious advantages, your market for resale is much better as saltwater guys generally prefer them.

 

[320Bob]

When I checked the differences between the Horizon and MX MPI version of my 6.2L engine I found the Horizon had a 0.25" longer stroke and slightly more weight.

 

[Go Aweigh2452]

As stated, the Horizon is a better built engine and better corrosion control. The raw water side is ceramic coated inside, it has the engine guardian system, composite oil pan, dry joint exhaust, brass sea water pump, its set up for digital throttle & shift, smartcraft CAN capability and advanced engine control systems and single point air actuated water draining system.

I love my 6.2 Horizon...

 

[Great lakes pirate]

All 6.2L Mercs have the same stroke and bore. The 6.2L has .25" extra stroke over the ol 350 cid.

 

[rblatter]

In 1999, the 340 Sundancer was offered with a MPI 310 H.P and a MPI Horizon at 380HP. Not sure but the Horizon motor always had a higher HP rating the regular MPI. (taken from the searay archives)

R.Blatter

 

[LTD.330]

It has been my understanding that the Horizon-badged motors are a high performance version of Mercruiser's other motor sharing the same block. Most notably the Horizon motors have different cam-shafts that produce higher horsepower and a flatter horsepower to RPM curve.

 

[jason78]

It has been my understanding that the Horizon-badged motors are a high performance version of Mercruiser's other motor sharing the same block. Most notably the Horizon motors have different cam-shafts that produce higher horsepower and a flatter horsepower to RPM curve.

I would say the HO is the High Performance Model- At least on the later model 8.1 496 engine-

8.1 Horizon=370HP
8.1 S HO=420HP
496 MAG MPI= 375HP

Still don't know the true difference considering all the above engines are closed cooling.

 

[Go Aweigh2452]

All 6.2L Mercs have the same stroke and bore. The 6.2L has .25" extra stroke over the ol 350 cid.

and 30 more hp...

 

[Captain Crispy]

Do NOT install a freshwater conversion kit on a block that has been operated in salt water for a couple of years. The cooling passages have salty corrosion in them, and antifreeze will gel in the smaller passages under those conditions. You will overheat.Many sellers of conversion kits have warnings of this on their websites. I suspect Merc does too.

 

[Henry Boyd]

In the 496/8.1 liter case the Horizon models are the vee drive/ inboard variant and the 496 Magnums are the sterndrive version. There is also a 496 HO at 420 HP as well.

And as stated above all of the big blocks are closed cooling.

Henry

 

[Jimmy Buoy]

In the 496/8.1 liter case the Horizon models are the vee drive variant and the 496 Magnums are the sterndrive version.

Henry

Well... in my case the 8.1 engines are mated to straight inboard trannies - not V-Drives. (but my engines aren't installed backwards):grin:

 

[Henry Boyd]

Well... in my case the 8.1 engines are mated to straight inboard trannies - not V-Drives. (but my engines aren't installed backwards):grin:

My apologies to any and all inboard owners. The original statement has been edited to now include inboards. There was no intent on my part to exclude the inboard concept, and I fully believe that all of us at CSR should be diligent to always be inclusive of our less fortunate brethren.


Henry

I will be attending drive orientation diversity training at the first possible moment.

 

[davefin]

Thank you for all of the valuable information. Looks like I made the right choices. My mechanic has verified the use of the conversion kit for the other motor and has the expertise to flush the motor completely with an additive to "clean" the passages after we run the engine a week or two. Then will add the coolent required for the closed system conversion. This conversion has been completed on other application by the same mechanical team I am using. Both on my engines will now have the DRY joint manifolds/risers. Also, I did indeed purchase the Horizon 5.7 MPI for repowering the bad Port engine. Thanks again.

 

[Nehalennia]

Do NOT install a freshwater conversion kit on a block that has been operated in salt water for a couple of years. The cooling passages have salty corrosion in them, and antifreeze will gel in the smaller passages under those conditions. You will overheat.Many sellers of conversion kits have warnings of this on their websites. I suspect Merc does too.

+1. Just let that engine run it's course and then when it pukes get a matching Horizon package.
Good luck.