What makes a marine engine a MARINE engine

[mkast]

Re: What makes a marine engine a MARINE engine

Profile
If a cam profile has more ?area under the curve,? it has the potential to make more power. Roller profiles can be more ?aggressive? and accelerate the tappet more than a flat tappet profile.

Flat tappet profiles can only be shaped up to the point where the tappet ?digs into? the profile. Roller tappet profiles are not limited by this condition-so much that even ?inverted radius? profiles are possible.

This benefits engine performance in two ways: more tappet lift can be achieved without the added duration that would normally be required to ?ramp up? a flat tappet to the added lift-making the lift curve more ?pointy?; the lift curve can be made ?broader? without increasing lift. Of course, both of these benefits can be combined to create a profile that can easily outperform flat tappet cams.

From Dennis Moore's book:
Valve Opening Speed
Ideally, opening the valve immediately when it is needed would give us maximum performance. Since this is not possible with current technology, opening the valve as fast as is practical is the way to increase performance. When Chevrolet designs a camshaft for a marine engine, much thought is given to warranty problems and long-term durability (read "reversion"). When these two factors are taken into consideration, slow to medium valve opening speeds(velocities)are almost mandatory.

Street/strip cams use lobe event speeds too fast for marine use.

As before, get his book, it can't hurt.

 

[Tail_Gunner]

Re: What makes a marine engine a MARINE engine

Here is the enviroment marine exhasut lives in..both exhaust and a cooling system in one.. The exhaust and water get dumped into the mix at the same intersection..Notice that the water is shot into the exhasut it is already somewhat atomized or agitated into smaller drops..

Here is a simple explanation or revesion after months of research the exhaust valve stay's open slightly while the intake stroke begins and the piston pulls (vacuum) from both valves reversing the exhaust flow and pulls both exhaust and water into the engine Now as you increase Lift and Duration you magnify the effect...See where that black boot ends that is where the mix happens you get a negative pulse's sucking up dropplets many time's a minute... for hours and well its sucks literally..

This should be a factory cam spec..
202/213 @ .050, valve lift .404/.410 and LSA of 112 Stock 4.3L Marine/Auto Cam
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