Originally Posted by aquaforce (Post 3838299)

Merc predominately uses the Chevy product design and since, as I understand, Merc bought GM's BBC program out they have test data that they can use and build on that to apply stresses from water and displacement detonation, shock load etc. Running a test stand engine gives one set of data but the data loggers used in the actual racing event will give some of the best test data since it is gathered in an actual racing event of max stress levels and all the variations that go with it.

Originally Posted by Velocity Vector (Post 3838461)

For those of us in the marine industry, a common occurrence is to be questioned by customers about auto vs. marine parts. A common scenario is to have a customer ask for a replacement part for his boat. The part in question is a starter for a 350 cu.in. GM block. You give the customer a price, and he looks at you with a blank look on his face. He, then states (very angrily) "I can get one at the local auto retailer for $29.95".

In the marine industry, this little scenario occurs all the time. Many boaters are unaware of the difference between an automotive and a marine engine and their respective accessories. The most notable differences include the exhaust systems, the cooling systems, the electrical systems, and the fuel systems. Additionally, items such as heads and cams are usually different. For the purpose of this thread, we will only be hitting the highlights on select systems.

In regard to the cooling systems, one of the major differences is found in the water-circulating pump. This is especially noticeable when you have a raw water cooled engine. Unlike their automotive counterpart, a marine pump works in an open cooling system. This type of system is extremely corrosive to the pump. Therefore, the pump must be altered for longevity. A marine pump has a special ceramic seal, stainless steel backing plate, and a bronze impeller to resist corrosion. An automotive style pump, with its stamped steel impeller, would fail due to corrosion in a short time.

The electrical systems in a marine application are also extremely specialized. In an automobile, any gasoline vapors that accumulate will readily dissipate through the bottom of the engine compartment. However, a boat with its sealed engine compartment, does not have that luxury. Therefore, any spark could literally cause a boat to explode. All electrical components in a boat are either completely sealed or specially vented to prevent such a catastrophe. This includes the starter, alternator, distributor, and many other engine electrical components.

Carburetors typically have what is known in the industry as J type fuel bowls. These allow for the extreme vibration, pitching and yawl experienced on boats. This allows fuel to be drawn in extreme conditions and keeps fuel from being ejected from the carburetor barrels.

Heads and cams are set up for a completely different torque curve. A marine engine must develop most of its torque on the low end of throttle range. This allows for the ability to use a single gear transmission system. Think of it this way:
You get in your car
Start it up
Drive to the highway
Put your foot to the floor and hold it there for an hour
Its a little different, well for most of us.

Although we have only briefly touched on some of the differences between an automotive and marine application; hopefully, it will serve to remind us that there is a difference, and that the reasons for these differences need to be shared with our customers and friends in the boating community. Hopefully, when shared, this information can eliminate some of the "blank stares" in regards to parts, and maybe prevent some dangerous situations.

Originally Posted by ICDEDPPL (Post 3838592)

I don`t know about anyone else but I used to beat the crap out of my sports cars way more than I do to any boat.
My boats mostly see about 3500-4K rpms and easy does it up there.... WOT every so often for a short period of time.

MY LS1 I used to romp on most stop lights and take it to the max on the highway.. mostly cause there wasn`t some weak ass Bravo based drive behind my Trans AM

Originally Posted by Rwbrew3 (Post 3838696)

This all has me wondering more and more....

How is it no1 has jumped in to compete against Merc?, build a package for a lot less ! It happens in every other market.

Same could be asked bout bravo outdrives...

I could only imagine the amount of money that could be made, and saved!!

Originally Posted by icdedppl (Post 3838592)

i don`t know about anyone else but i used to beat the crap out of my sports cars way more than i do to any boat.
My boats mostly see about 3500-4k rpms and easy does it up there.... Wot every so often for a short period of time.

My ls1 i used to romp on most stop lights and take it to the max on the highway.. Mostly cause there wasn`t some weak ass bravo based drive behind my trans am

Originally Posted by GAZ (Post 3838714)

It will probably happen, and unfortunately it will be most likely be Japanese.

Originally Posted by Rwbrew3 (Post 3838696)

This all has me wondering more and more....

How is it no1 has jumped in to compete against Merc?, build a package for a lot less ! It happens in every other market.

Same could be asked bout bravo outdrives...

I could only imagine the amount of money that could be made, and saved!!

Originally Posted by Velocity Vector (Post 3838753)

Most of us will use a reputable custom engine builder for our engines. They can build as much HP is Merc at a much reduced rate. Although still pricey not even close to a Merc price especially 700HP and beyond.

Originally Posted by Rwbrew3 (Post 3838759)

I was lucky in my purchase, the boat I wanted, with the bonus power!! There is no doubt if I ever change, it will be done by a custom builder, probably Eddie Young!!