Answer my silly question?
Discussion
Ok so with the whole pollution b
ks and manufacturers forced to reduce emissions, this is leading to the demise of big capacity lumps like v12s and v10s leading to smaller turbo engines.
Now, my silly question is why don't they make engines smaller but with the same amount of pistons. For example, instead of producing a 3.0 v6 with turbos, why not a 3.0 v12 with turbos, apart from the extra manufacture of manifolds, nothing else is changed, just smaller.
So in theory cheaper to manufacture, smaller in size, similar weight?
Go on, shoot me down!
Ps imagine the next astra with a 2.0 turbo v8 B-)
Royce
ks and manufacturers forced to reduce emissions, this is leading to the demise of big capacity lumps like v12s and v10s leading to smaller turbo engines.Now, my silly question is why don't they make engines smaller but with the same amount of pistons. For example, instead of producing a 3.0 v6 with turbos, why not a 3.0 v12 with turbos, apart from the extra manufacture of manifolds, nothing else is changed, just smaller.
So in theory cheaper to manufacture, smaller in size, similar weight?
Go on, shoot me down!
Ps imagine the next astra with a 2.0 turbo v8 B-)
Royce
Surely that extra cost wouldn't be as much as expected.
In my simple mind, A 3.0 litre v6 needs 6 pistons at .5l each.
A 3.0 litre v12 would need 12 pistols but only .25L each. So whilst there is more parts, there smaller so the same amount of materials.
Offset that further against the fact a v12 may sell better than a v6 model may warrant the extra price
In my simple mind, A 3.0 litre v6 needs 6 pistons at .5l each.
A 3.0 litre v12 would need 12 pistols but only .25L each. So whilst there is more parts, there smaller so the same amount of materials.
Offset that further against the fact a v12 may sell better than a v6 model may warrant the extra price
The mass of materials isn't what makes and engine expensive. A 0.5kg pistons doesn't cost half that of a 1kg piston!
(this is because the raw materials are, relatively speaking, pretty cheap, ie you can buy literally tonnes of alluminum in it's raw form for not much money, but everything else adds cost (casting, machining, shipping and installing etc)
But the real reason we don't generally have small capacity multi-cylinder engines is to do with fuel economy.
Thanks to the laws of physics, the surface area to volume ratio for a cylinder gets worse the smaller you make it (because the volume of cylinder is V=πr^2h yet the surface area of a cylinder is A=2πrh+2πr^2 ). This matters because HEAT is lost to the walls of the combustion chamber, so really small cylinder loose lots of heat rather than turn that heat into pressure that pushes down the piston and drives the crank around doing useful work.
Then we get to friction. The largest single frictional effect in an ICE is the sliding friction of the piston and its rings going up and down the cylinder bore. And having lots of small pistons creates a lot more friction than a few big ones.
It's pretty much accepted that due to those two factors, for a road car, the optimum size of a single combustion chamber is a swept volume close to 0.5l. Hence 4cyl 2 litre enignes, 6 cyl 3 litre ones and 12cyl 6 litres ones!
Only in motorsport, where fuel economy is (well, used to be, to be honest) unimportant, and max power is important do multicylinder engines make some sense (because ultimate power is directly proportional to valve area, and lots of cylinders means lots of valve area per swept cc)
(this is because the raw materials are, relatively speaking, pretty cheap, ie you can buy literally tonnes of alluminum in it's raw form for not much money, but everything else adds cost (casting, machining, shipping and installing etc)
But the real reason we don't generally have small capacity multi-cylinder engines is to do with fuel economy.
Thanks to the laws of physics, the surface area to volume ratio for a cylinder gets worse the smaller you make it (because the volume of cylinder is V=πr^2h yet the surface area of a cylinder is A=2πrh+2πr^2 ). This matters because HEAT is lost to the walls of the combustion chamber, so really small cylinder loose lots of heat rather than turn that heat into pressure that pushes down the piston and drives the crank around doing useful work.
Then we get to friction. The largest single frictional effect in an ICE is the sliding friction of the piston and its rings going up and down the cylinder bore. And having lots of small pistons creates a lot more friction than a few big ones.
It's pretty much accepted that due to those two factors, for a road car, the optimum size of a single combustion chamber is a swept volume close to 0.5l. Hence 4cyl 2 litre enignes, 6 cyl 3 litre ones and 12cyl 6 litres ones!
Only in motorsport, where fuel economy is (well, used to be, to be honest) unimportant, and max power is important do multicylinder engines make some sense (because ultimate power is directly proportional to valve area, and lots of cylinders means lots of valve area per swept cc)
Royce44 said:
Surely that extra cost wouldn't be as much as expected.
In my simple mind, A 3.0 litre v6 needs 6 pistons at .5l each.
A 3.0 litre v12 would need 12 pistols but only .25L each. So whilst there is more parts, there smaller so the same amount of materials.
Offset that further against the fact a v12 may sell better than a v6 model may warrant the extra price
If only it was that simple.In my simple mind, A 3.0 litre v6 needs 6 pistons at .5l each.
A 3.0 litre v12 would need 12 pistols but only .25L each. So whilst there is more parts, there smaller so the same amount of materials.
Offset that further against the fact a v12 may sell better than a v6 model may warrant the extra price
It's not just the parts prices that don't add up, it's the manufacture of the the things. 6 0.25l Pistons/rods etc will likely take as long to make as 6 0.5l items. There will need to be 12 liners made instead of 6, a whole new crankcase would need to be developed, new crank made etc etc etc.
Then there is the physical packaging of the things. Sticking a V8 in an Astra would be a packaging nightmare. Besides, if it said ecotec on the engine cover, it would be crap.
Also, more cylinders generally mean more fuel required which nobody wants anymore. Besides, a turbo engine is generally more efficient than an N/A lump which is what all manufacturers want now with emissions regs etc.
As nice as it would be, it just wouldn't work in this day and age.
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