Is a V-8 engine better than a V-4 engine? (all else being equal...HP, torque, etc)

General Questions
#61

simplicity. they just want to fit the engine into the space between the tractor wheels, and since 3 cyclinder diesel is smooth enough, they use it… Diesel cylinders can be any size, since all the diesel is ignited at the same time, by the compression.

Petrol gas spark ignition… the fire starts at the spark plug, and then takes time to travel down.
So for gas/petrol, with the spark plug ignition, ~500 cc cylinder size is the sweet spot, and its terrible to go larger limits the RPM too much… the flame front has to travel from the spark plug down through the cylinder… the larger cylinder the longer it takes…

Motorbikes are so efficient, they can choose to be a bit less efficient by using smaller cylinders…to get higher RPM …shorter burn time for the flame front to set the whole cylinder’s worth alight.

#62

Interesting point. There are compression ignition cylinders big enough for people to fit into (e.g. 38" bore, 98" stroke) in the biggest marine diesels. And also finger tip size, for model airplanes (IIRC these aren’t exactly diesels for some reason, but they’re still compression ignition).

#63

Indeed. Here is a 109,000 HP diesel engine:

Here is the crankshaft:

#64

Ya know, … there’s big and then there’s Industrial Strength Seriously BIG.

#65

Is that a turbocharger in the upper right? It’s bigger than my car!

#66

I think it might be. Here is a picture I found of the turbocharger (and yeah, it is bigger than your car):

#67

I saw a comment that said this engine doesn’t move the ship, it spins the earth in the other direction.

Also, I think that is half the engine. They take another one of those and bolt them together into one engine.

#68

The wiki on Wartsila

suggests they come in 3- to 14-cylinder configurations, and that’s the real high powered one. The first pic you showed seems to be a 6- or 7-cylinder module.

#69

Damn.

#70

I am no expert but is that a supercharger or a turbocharger? I do not see a hot/cold side like you would in a turbocharger. Since these engines have low RPM perhaps exhaust force is not sufficient for a turbocharger so they use a supercharger (only speculating).

Note: I am far, far, far from knowledgeable when it comes to engines. I know their basic operation but that is where it ends.

#71

I think the guy on the left is standing on compressor and the guy on the right is on the turbine. Though the more I stare at it, the less sure I am and it could they other way around.

#72

Yeah…imagine the belt needed to run a supercharger that size. Probably doesn’t exist and if it did…have fun fitting it.

#73

The could use a gear drive instead of belt. But yeah, I’m pretty sure that’s a turbo.

#74

IMO that’s correct. As I decode it, the lighter colored cylinder at left is the air intake filter screen. The compressor output is at lower left. The exhaust intake is at far right; we can see the flange with umpteen bolts around the perimeter that connects to the exhaust manifold. The rectangular port facing us on the right is the exhaust that leads up to the ship’s stack. We can see it facing more or less upwards on the engine sitting on the trailer.

I’m going to guess the turbo doesn’t produce huge boost, but it does enough to pay for itself.