Why no big triples?

Ranger50 wrote: In reply to carguy123: Then you could end up with this:

Well that's certainly one way to do it!

in a 4 stroke engine each of the three cylinders needs to spin the crank 1.3 revolutions for the next ignition event to take over, in a 4 cylinder it's 1 revolution meaning lesspower is needed just to sequence the next event, in an 8 cylinder each ignition event is responsibe for moving the crankshaft only .5 revolutions before the next event allowing inertia to really reduce the parasitic power loss of cycling to the next event, at least thats the way it works in my head

Make it 2 stroke turbo diesel.

Conquest351 wrote: Make it 2 stroke turbo diesel.

You can't. Emissions have killed off the two-smokers.

There are loads of 3 cylinder 2 stroke Detroit Diesels out there.

Yeah, but they aren't in cars

Seriously? Three-cylinder engines aren't inherently unbalanced? Why did C&D just rip the Euro-version 999cc Ford Escort turbo 3-banger for "shaking like a frightened Pomeranian?"

I had always been told that 3-cylinder designs were unbalanced. Enlighten me!

Too bad the big triples I work on won't fit in a car. 600 hp at 400 rpm

http://www.youtube.com/watch?v=mtZUdZvlYTI

chaparral wrote: Larger cylinders have less surface area for a given volume. This should save fuel. Fewer cylinders mean fewer components. This should save money. Their balance isn't inferior to Fours. So why don't we see big three-cylinder engines? GM could've easily had a 2.1 liter 3, making about 150 horsepower, when they built the Atlas line.

In theory, theory and practise are the same. In practise they are not.

Would having multiple spark plugs cause problems with the flame fronts flowing across the top of the pistons?

In reply to singleslammer:

Very curious about three pistons in a Starlest, share with the info!

In reply to Ranger50:

I don't know why NR750 info is in this thread, but I love it all the same! The Honda NR rules!

Flame front speed shouldn't be too bad a limitation for a 110mm bore engine, if it never has to go over 6000 RPM.

Ranger50 wrote:

Conquest351 wrote: Make it 2 stroke turbo diesel.

You can't. Emissions have killed off the two-smokers.

2 stroke diesel:

http://en.wikipedia.org/wiki/Two-stroke_diesel_engine

Very, very little oil combusted, as the crankcase is sealed. Requires a blower to run though. Does use a camshaft to time the exhaust valve, and DI for the fuel.

Honestly, this system could be applied to gasoline engines jut as well, especially with the advancement of DI.

1988RedT2 wrote: Seriously? Three-cylinder engines aren't inherently unbalanced? Why did C&D just rip the Euro-version 999cc Ford Escort turbo 3-banger for "shaking like a frightened Pomeranian?" I had always been told that 3-cylinder designs were unbalanced. Enlighten me!

As I already said, 3-cylinder motors are not inherently balanced. They have free moments of both the 1st and 2nd order. They require counterweights in order to be somewhat balanced. And counterweights add to the parasitic loss of the engine components, thus defeating the purpose of going with a smaller number of pistons to reduce friction...

One other thing nobody's mentioned yet: On a four cylinder four stroke, as soon as one piston on the power stroke reaches bottom dead center, another power stroke is beginning. This isn't as smooth as a six or a V8 with overlapping power strokes, but it's much smoother power delivery than a 3 cylinder having 60 degrees where there isn't a power stroke at all.

I have two words for you: Mass & Inertia.

Whether they have anything to do with this conversation, I have no idea.

Re: the longer flamefront issue with regards to piston surface area (and I did not read most of the 2nd page, so sorry if this has already been suggested) - couldnt a second or even third spark plug be added to the cylinder (I know, theres not a lot of room for all this, but its just theory) equally spaced, so that multiple flame fronts could propagate simultaneously, burning the fuel faster?

ScottRA21 wrote:

Ranger50 wrote:

Conquest351 wrote: Make it 2 stroke turbo diesel.

You can't. Emissions have killed off the two-smokers.

2 stroke diesel: http://en.wikipedia.org/wiki/Two-stroke_diesel_engine Very, very little oil combusted, as the crankcase is sealed. Requires a blower to run though. Does use a camshaft to time the exhaust valve, and DI for the fuel. Honestly, this system could be applied to gasoline engines jut as well, especially with the advancement of DI.

I'd like to play with this. Wonder if twincharging it would help performance even more. Supercharger seems like it's a necessity for the operation of the engine, turbo would just help performance. Intercool it and then feed it into the blower with an air to water intercooler in the intake manifold to keep air charge temps in check. Direct Injection gasoline or diesel would work. I see by this illustration and by your statements the piston skirt is relatively long, so it'll keep the crankcase sealed and prevent gasoline from contaminating the oil needed for lubrication except that coming in contact with the side of the piston on the upstroke. Very cool stuff though!

I have nothing to add, other than my head has exploded from all the numbery things flying around...

In reply to pres589:

Sorry for the derail...

This

And this

Getting together with a side of this

To make a whole bunch of this

add the extra spark plugs & added ignition components, extra valves to spread out the intake & exhaust over the bigger pistons and the extra con rods from the NR750 and you now have more parts and maybe even more frictional losses then a 4 cyl in a motor that is going to be longer then a v6.

Make it a V twin for the better exhaust sound (think Ducati, not Harley).

In reply to singleslammer:

need more of this -

2,294cc and 147lb-ft of torque

In reply to Rusnak_322:

Cant see that at work but I bet it is a rocket triple. That would have been an awesome choice but try buying one of those for challenge money. I got an entire ST for not much and still have most of the bike to sell off.

singleslammer wrote: my 3 piston starlet should haul ass

Somehow this doesn't sound appropriate.

tuna55 wrote: Most hyper car type engines have lots and lots of cylinders. I've always wondered why. I think I know the reason, and it's more than just bragging rights.

I've always heard that, for a given displacement, multiplying cylinders is a straightforward way to increase total valve area for that given displacement thereby increasing air-pumping capability; The compromise being increased complexity and frictional losses. Excuse me if someone has already said this.