Originally Posted by Omatako
1st question: What is a gas diesel?
2nd question: What is the difference between an automotive engine and a marine engine (other than the obvious marinisation)?
3rd question: Why not provide the list here?
Sloppy writing on my part. I meant to write gasoline turbo and diesel turbo.
Gasoline engines are quite different than diesel engines. A gas engine runs at a much lower compression than a diesel engine. A turbocharged diesel engine has a LOT more pressure than a normally aspirated diesel engine. Generally, the higher the compression, the more important it is to accurate control timing, both spark (for gasoline) and valve (both diesel and gas).
Four stroke internal combustion engines, whether gasoline, diesel, alcohol, turbocharged or normally aspirated, all operate pretty much the same. The difference is in the typical use.
For an automotive engine, the typical use is various RPM and load, very rarely running at high load conditions for extended periods of time. A turbocharged automotive engine uses the turbocharger for short periods of high power output. For most of the engine use, such as highway driving, or around town driving, the turbocharger is not producing any power, or putting any load on the engine. When the engine is subject to high load conditions, such as hard acceleration, power to pull a heavy load, or climb a hill, the turbocharger will spin up, provide the extra power, then spin down for more typical highway type cruising.
The typical use of a marine engine is much different. For a boat that is heading from point A to point B, the engine is started in the morning, the transmission placed in forward, the throttle moved to cruising speed, and the engine will then operate at mostly a constant RPM and load. A boat has no hills to climb, stop lights to wait at, or other cars to pass. The turbocharger in a marine engine will be under load the entire time. The turbocharger puts a significant load on the engine, which requires additional maintenance.
Other significant differences between automotive engines and typical marine diesel engines is in engine management. All modern automotive engines are computer controlled. There are sensors for throttle position, engine temperature, exhaust, RPM, ignition, etc. The computer runs the engine in closed loop, constantly adjusting the amount of fuel injected to ensure the engine is running properly, not too rich or to lean. Turbocharged engines, when the turbo is producing power, are intentionally set to run rich. The extra fuel helps to cool the combustion chamber. As soon as the extra load is removed, the engine reverts to running lean for economy.
Marine engines (at least the ones that I am familiar with, which are small auxiliary engines for sail boats) are quite primitive. The fuel injection is mechanical, and there are no sensors to monitor engine performance. Since the marine engine operates in a relatively narrow range, it is easy for the manufacturer to dial in the fuel injection curve so you get adequate performance over the RPM range. A turbocharger requires a different fuel injection map. If you just remove the turbo, without changing anything else, the fuel map is going to be off.
That's about all I have time for now.
Let me know if there are any additional questions.