Alfadan 654 HP inline four

[Autobahnschleicher]

Originally Posted by samwichse

Everything I can find basically says it's a big displacement 4, but designed with a flat plane crank and somehow significantly shorter con rods than you would normally see.
Sam

1. Your average 4-cylinder has a flat-plane crank.
2. Shorter connecting rods would make the issue worse as they are running at even more of an angle, wich makes the imballance worse.

[freebeard]

cRiPpLe_rOoStEr -- They claim Freevalve as a partner, and 50% parts reduction.

[Autobahnschleicher]

Thinking about it:
The only way I can think of that could work would be an absolutely massive bore, relatively short stroke and massively long connecting rod.
The imballance would be lower as the rod angle would get less extreme.
The piston speed would also be under controll that way.
The block would be absolutely MASSIVE that way and the combustion chamber shape would be rather suboptimal.

[freebeard]

As soon as they ship product....

[samwichse]

Originally Posted by cRiPpLe_rOoStEr

Considering some large marine engines resorted to camless valvetrains before all the hype around Freevalve, and that a Swiss company was also developing an automotive camless valvetrain some years ago, it wouldn't surprise me if this engine actually resorts to a system different from the Freevalve.

In the thread I linked, the founder repeatedly says it has a standard valve train. Also, digging some more, the bore and stroke are approximately 5.9" and 4.8"
Direct quote:

The information is correct but all of our performance numbers are based on a standard valvetrain design configuration without the camless option.

Originally Posted by Autobahnschleicher

1. Your average 4-cylinder has a flat-plane crank.
2. Shorter connecting rods would make the issue worse as they are running at even more of an angle, wich makes the imballance worse.

1. I am aware, just telling what I know about it.
2. Yeah, they claim some kind of magic about 2nd order harmonics? Someone dug up this patent filing by the inventor Alberto Araujo


So it looks like it's just a Scotch Yoke engine. Dead in the water.

[freebeard]

Aha!

The Scotch Yoke.

[Autobahnschleicher]

There is no way in hell that works in an engine like that.
The loads are just way too high.
One of the limiting factors in normal car engines that limits maximum rpm is are the connecting rods.
They can be ripped appart at high rpm.
And if you scale things up, it's getting even worse...

[wdb]

Originally Posted by Autobahnschleicher

There is no way in hell that works in an engine like that.
The loads are just way too high.
One of the limiting factors in normal car engines that limits maximum rpm is are the connecting rods.
They can be ripped appart at high rpm.
And if you scale things up, it's getting even worse...

I think that's the point of the scotch yoke. The connecting rods and pistons will not be moving up and down as fast as they would in a conventional piston engine.

With modern materials and manufacturing technologies, hmmm.

[Autobahnschleicher]

Originally Posted by wdb

I think that's the point of the scotch yoke. The connecting rods and pistons will not be moving up and down as fast as they would in a conventional piston engine.

With modern materials and manufacturing technologies, hmmm.

The average piston speed will be the same for a given RPM and what "modern materials" are you talking about?
Connecting rods are often forged for a reason, these are highly stressed components

[samwichse]

Dead. In the water.