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Why does 4vpc(Valves per cylinder) have more benefit than say 2vpc, and 6vpc?
For the sake of arguments lets leave VVT engines of this.
Say you are running a solid cam profile with no VVT, what are the benefits of using 4vpc over 2vpc, and why are some engines 5vpc if 4vpc is the most efficient(by that I mean in terms of area, and not MPG etc).
Why does 4vpc(Valves per cylinder) have more benefit than say 2vpc, and 6vpc?
For the sake of arguments lets leave VVT engines of this.
Say you are running a solid cam profile with no VVT, what are the benefits of using 4vpc over 2vpc, and why are some engines 5vpc if 4vpc is the most efficient(by that I mean in terms of area, and not MPG etc).
I think it has something to do with being able to have valves covering the largest possible surface area and therefore the highest efficiency for any given size? Sure someone with more of a clue will explain this in a proper way.
Like the gent above.
Of course there's a trade-off with additional complexity which is why you don't really see 5+ valves per cylinder apart from in some exceptional cases.
Like the gent above.
Of course there's a trade-off with additional complexity which is why you don't really see 5+ valves per cylinder apart from in some exceptional cases.
ManOpener said:
I think it has something to do with being able to have valves covering the largest possible surface area and therefore the highest efficiency for any given size? Sure someone with more of a clue will explain this in a proper way.
Like the gent above.
Of course there's a trade-off with additional complexity which is why you don't really see 5+ valves per cylinder apart from in some exceptional cases.
VAG have used long stroke 5v engines 3 inlet 2 exhaust.Like the gent above.
Of course there's a trade-off with additional complexity which is why you don't really see 5+ valves per cylinder apart from in some exceptional cases.
As above, you want to fill the biggest area of the combustion chamber with valve as possible to get the gasses in and out, but keep valve weight low to avoid bounce etc. Compare the valve areas of this 8v with the 16v below, there's more covered, and you don't need big piston notches:
DocArbathnot said:
ManOpener said:
I think it has something to do with being able to have valves covering the largest possible surface area and therefore the highest efficiency for any given size? Sure someone with more of a clue will explain this in a proper way.
Like the gent above.
Of course there's a trade-off with additional complexity which is why you don't really see 5+ valves per cylinder apart from in some exceptional cases.
VAG have used long stroke 5v engines 3 inlet 2 exhaust.Like the gent above.
Of course there's a trade-off with additional complexity which is why you don't really see 5+ valves per cylinder apart from in some exceptional cases.
No one has mentioned the advantage of having the spark plug located centrally over the piston. This allows the flame front to spread evenly in all directions and give smoother more efficient burning. In older designs with the plug on one side, the fuel furthest from the plug could actually detonate before it was ignited. This was caused by the rapidly increasing pressure from the burning fuel near the spark plug. In other cases it might not burn completely and raise emissions.
Locknut said:
No one has mentioned the advantage of having the spark plug located centrally over the piston. This allows the flame front to spread evenly in all directions and give smoother more efficient burning. In older designs with the plug on one side, the fuel furthest from the plug could actually detonate before it was ignited. This was caused by the rapidly increasing pressure from the burning fuel near the spark plug. In other cases it might not burn completely and raise emissions.
This is true hence old Triumphs had two spark plugs per cylinder, long before Alfa did.Gassing Station | Engines & Drivetrain | Top of Page | What's New | My Stuff