v12 or v10

[echedey]

I also have another doubt about the angle of the camshafts, taking as an example a 4-cylinder engine in which the crankshaft is at 180º, because the camshafts, each cam of each cylinder is at 90º when it should be at 180º, and a 6-cylinder engine each cam of each cylinder is at 120º, how do I calculate the geometric angle of each cam of each cylinder.

[saviour stivala]

‘’Geometric angle of each cam of each cylinder’’. Geometric angle of each ‘cam-lobe’ of each’ cylinder, cam-lob angle in degrees in relation to crankshaft degrees. Which is going to be number one piston of engine is decided. The positioning of cam-lobes on their shafts in degrees starts with number one piston at TDC. The TDC of number one piston of an in-line vertical engine regardless of number of pistons is 0-degrees. The cam-lobes (exhaust & intake for cylinder number one) separation angle centre line is what is positioned (timed) to the crank angle. In accordance to engine rotation and camshaft rotation, the exhaust lobe comes up first and intake lobe follows. With the decided cam-lobe separation centre line being timed with its respective piston at TDC, the position in degrees of the exhaust and intake lobes (lobe centre line) before and after their separation centre line is known, the lobes are positioned. The rest of the lobes in respect to their respective piston will have to be positioned in accordance with the firing order decided upon. How much degrees the lobe separation angle centre line will be following the piston will depend on the number of cylinders in an engine. Keep in mind that the camshaft rotates at half crankshaft speed. So that means a four cylinder engine which fires a cylinder every 180 degrees, the cam lobes separation angle centre line will have to follow their respective piston at 90 degrees.

[J.A.W.]

counterweights don't act as inertial dampers because they don't move relative to the crankshaft

Ah, no.. not correct T-C, the inertia/rotational weighting vis a vis recip' functions is a damping factor.
https://www.jvejournals.com/article/19933

please indicate where or how your linked article tells us that

T-C, can you at least read the abstract in the linked journal article?

If so, it is self-evident, how the rotating mass affects the main-journal loadings inertia-wise,
& thus the functional force damping inputs of counterweights/recip' movement interactions..

Interestingly - for late WW II service, Allison/GM added full-counterweights to its V-1710 V12,
for reasons of durability at higher boost/rpm/TBO - while Napier/EE was deleting them from
the dual-crankshafts of its H-24 Sabre, due to dynamic balancing/synergistic effects of 2-cranks...

[J.A.W.]

again ....
the angles are ..... 0 240 480 480 240 0 deg
or alternatively .... 0 120 240 240 120 0 deg
depending on the sense of the cylinder numbering relative the sense of the crankshaft rotation

.. Indeed the article s-s has cribbed is correct, since relative to each other, crankshaft front-to-rear,
each crankpin is indeed rotated by 120 degrees, same as every even-fire inline 6/V12/H24....

wrong
about half a billion times - one for each engine made the way I say

the crank throws aren't 120 deg relative to each other front-to-rear
they are in 'mirror image' about the mid-length ie cylinders 3 and 4 have zero angle 'relative to each other'

this symmetry is what cancels all the inertial forces and moments within the block - so notionally zero vibration
no crankshaft fitting the S S or J.A.W description will have this complete cancellation

not applicable to 2 strokes of course

Actually T-C, to use a vulgar, but apropos English aphorism, I 'd reckon you've got this.. ah,
'arse about face', since it is 2-strokes with their 50% more urgent firing intervals which require
such a crankshaft arrangement to accommodate power-impulse/BMEP forces, whereas the 'lazy'
4-stroke routine (though not as as lazy by 50%, as you posited a page or so back) allows the 'easy'
120 degree crankpin spiral routine to continue, for at least a 6 cyl inline length, sans drama...

[Tommy Cookers]

.. Indeed the article s-s has cribbed is correct, since relative to each other, crankshaft front-to-rear,
each crankpin is indeed rotated by 120 degrees, same as every even-fire inline 6/V12/H24....

wrong
about half a billion times - one for each engine made the way I say
the crank throws aren't 120 deg relative to each other front-to-rear
they are in 'mirror image' about the mid-length ie cylinders 3 and 4 have zero angle 'relative to each other'
this symmetry is what cancels all the inertial forces and moments within the block - so notionally zero vibration
no crankshaft fitting the S S or J.A.W description will have this complete cancellation
not applicable to 2 strokes of course

Actually T-C, to use a vulgar, but apropos English aphorism, I 'd reckon you've got this.. ah,
'arse about face', since it is 2-strokes with their 50% more urgent firing intervals which require
such a crankshaft arrangement to accommodate power-impulse/BMEP forces, whereas the 'lazy'
4-stroke routine (though not as as lazy by 50%, as you posited a page or so back) allows the 'easy'
120 degree crankpin spiral routine to continue, for at least a 6 cyl inline length, sans drama...

post a photo or drawing of your 120 degree spiral crankshaft
there is no such crankshaft

[J.A.W.]

See for yourself T-C, the 'pork-chop' counterweight-flywheels show the tri-star 120 degree orientation..

[Tommy Cookers]

See for yourself T-C, the 'pork-chop' counterweight-flywheels show the tri-star 120 degree orientation..

rubbish !
that's an inline 3 cylinder engine - nothing to do with the V12 or inline 6

look at a V12 or an inline 6

though - while you're looking at 3 cylinder 2 strokes ....
you might try looking at the rotation direction relative to the configuration
you might even find the configuration is 240 deg in the intended direction of rotation

[J.A.W.]

Misapprehension again, T-C, as a view of a regular-firing 120 degree crankpin V12 shows,
its an end-to-end repeat from the centre-main, regardless of plain-bearing usage...

[Bandit1216]

didn't Laverda have both 120 deg and 180 deg 3 cilinders?

I don't understand the biggering. Isn't even firing the reason V8 is 90 degrees, The V10, 72 and V12, 60? It not the other way around.

A 90 degrees V6 for example is mostly born because of cutting 2 cylinders of a V8 design. Or one wants more room in the Vee or under your banks. A V6 is always Sh#t, no matter what you do, because you're always stuck with trying to balance two 3 cylinders on one crank, even when 120 degrees

A V16 should be 45 degrees but that leaves you with a rather shallow Vee. Not to mention V20. All those odd things like V5, uncommon crankpins, odd v angles, balance shafts etc are more or less to compensate for problems one would not have by keeping a simple even fire engine.

[Tommy Cookers]

its an end-to-end repeat from the centre-main, regardless of plain-bearing usage...

this is an other kind of definition - a reverse of your previous definition
ie the same as what I said all along
ie what the half a billion did
there is no other kind

and ......
Laverda made a 90 deg V6 (for endurance racing)
there's nothing wrong with that if the crankshaft designer says ok
the V8 can be 90 deg (or 180 deg) without asking the crankshaft designer
the V12 can be 60 deg 120 deg (or 180 deg) without asking
the V16 can be 45 deg 90 deg 135 deg (or 180 deg) without asking

[saviour stivala]

A six cylinder ‘in-line’ engine crankshaft and that of a ‘flat-12’ opposed cylinder engine are the same except for the 6-crank throws journals of the 6-inline each accommodating one con-rod big-end, while that of the flat-12 accommodates 2 con-rods big-ends. The six crank throw journals of both are placed at 120-degree out of phase with one another, which can be arranged only in three planes. Therefore the crank-pin phasing is arranged in pairs.

[saviour stivala]

Unnecessary arguments that creeps-up on a subject being discussed are easily avoidable if one keeps to the subject under discussion. Why push-in different configurations than that the one under discussion such as different number of cylinders/Vee angles as well as two stroke?.

[J.A.W.]

Unnecessary arguments that creeps-up on a subject being discussed are easily avoidable if one keeps to the subject under discussion. Why push-in different configurations than that the one under discussion such as different number of cylinders/Vee angles as well as two stroke?.

Why not?

But while queries are being made...

Why is it s-s - that you C & P blocs of text seemingly sourced elsewhere - sans acknowledgement/links?

[saviour stivala]

Four-of-four.
The crankshafts of the three most famous opposed cylinder flat-12 racing engines.
1975 Alfa Romeo 115-13 3-litre horizontally opposed cylinders flat-12.
The gear train to the camshafts was located at rear of engine, adjacent to the clutch. A spur gear at the nose of the crank drove the engine’s oil and water pumps the Alfa crank was a typical flat-12 in that it carried side-by-side con-rods on a 6-throw crankshaft. Although the endurance racing version had 7-main bearings, the F1 edition followed the example of the FERRARI 312B in having only 4-main bearings. All were plain trimetal bearings. This allowed the use of larger counterbalance masses in the GP engine where the eliminated main bearing had previously been. To augment the crank’s counterbalance mass in a compact crankcase. The peripheries of the counterbalance were fitted with bolted-on crescents-shaped tungsten alloy masses.
The specifications around the crankshafts of these three most famous opposed cylinders flat-12 was as follows.
Porsche 912 4.5-litre flat-12 (1969). Stroke 66mm. Con-rod length 130mm. Rod/crank radius ratio 3.9:1. Main bearing journal diameter 57mm. Rod journal diameter 52mm.
FERRARI 312B 3-litre flat-12 (1970). Stroke 51.5mm. Con-rod length 110mm. Rod/crank radius ratio 4.3:1. Main bearing journal diameter 50mm. Rod journal diameter 36mm.
Alfa Romeo 115-12 3-litre flat-12. Stroke 53.6mm. Con-rod length 112mm. Rod/crank radius ratio 4.2:1. Rear Main bearing was a ball-bearing.
Added to the above three, for those interested.
Cisitalia 1.5-litre flat-12. Stroke 50.5mm. Con-rod length 101.6mm. Rod/crank radius ratio 4.0:1. Main bearing journal diameter 55mm. Rod journal diameter 54mm.

[saviour stivala]

Unnecessary arguments that creeps-up on a subject being discussed are easily avoidable if one keeps to the subject under discussion. Why push-in different configurations than that the one under discussion such as different number of cylinders/Vee angles as well as two stroke?.

Why not?

But while queries are being made...

Why is it s-s - that you C & P blocs of text seemingly sourced elsewhere - sans acknowledgement/links?

''Why not?'' Because it greats unnecessary confusion in a discussion. Who on here including you does not C&P blocs of text sourced elsewhere?.